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FIG. 1. MODEL OF THE HOMAN BRAIN [Aozoux]
ELEMENTS OF
HUMAN PSYCHOLOGY
BY
HOWARD C. WARREN
STUART PROFESSOR OF PSYCHOLOGY, PRINCETON UNIVERSITY
AUTHOR OP HUMAN PSYCHOLOGY
HOUGHTON MIFFLIN COMPANY
BOSTON NEW YORK CHICAGO SAN FRANCISCO
Cfje &tbersit>e tytss Cambridge
COPYRIGHT, 1922
BY HOWARD C. WARREN
ALL RIGHTS RESERVED
CAMBRIDGE . MASSACHUSETTS
PRINTED IN THE U.S.A.
CONTENTS
CHAPTER PAGE
I. SUBVEY OF THE FlELD 1
II. STRUCTURE OF THE NERVOUS SYSTEM .... 19
III. OPERATION OF THE NERVOUS SYSTEM .... 39
IV. THE SENSES: SIGHT 57
V. THE SENSES: HEARING AND OTHER SENSES ... 85
Hearing, 85; Smell, 98; Taste, 103; Cutaneous Senses, 105;
Organic Senses, 109; Pain, 113; Muscle Sense, 114; Static
Sense, 117
VI. CONSCIOUS LIFE 121
VII. PERCEPTION 143
VIII. MEMORY AND IMAGINATION 178
IX. FEELING AND EMOTION 203
Feeling, 203; Emotion, 209; Sentiment, 218
X. INSTINCT 224
Reflex Behavior, 229; Instinctive Behavior, 234
XI. INTELLIGENCE 247
Conditioned Reflexes, 248; Intelligent Behavior, 250
XII. VOLITION 271
Conation, 272; Volition, 274; Ideals, 281
XIII. LANGUAGE AND THOUGHT 284
XIV. MENTAL SUCCESSION 306
XV. HUMAN CHARACTER 331
Attitude, 332; Character, 345
XVI. PERSONALITY AND CONTROL 360
REVIEW QUESTIONS 383
SUGGESTIONS IN USING THE BOOK 391
GLOSSARY AND INDEX .... . 395
ILLUSTRATIONS
FIGURE CHAPTER PAGE
1. Model of the Human Brain Frontispiece
2. Seeing and Acting I 4
3. Different Kinds of Cells II 20
4. The Neuron and its Parts " 21
5. Various Types of Neurons " 22
6. Various Types of Synapses " 23
7. Brain and Cord in Position " 24
8. Central Portion of Nervous System " 25
9. Cross-Section of Cord " 27
10. Base of Brain facing " 28
11. Middle Cross-Section of Brain . " " 29
12. Cortex from Above " 30
13. Cortex from Left Side " " 31
14. Centers in the Cortex " 32
15. Autonomic Nervous System " 35
16. Nervous Arc in Spinal Reflex Ill 41
17. Collection of Nerve Impulses " 47
18. Distribution of a Nerve Impulse " 47
19. Muscle with Nerve Endings " 50
20. Diagram of Muscular Contraction " 50
21. Cross-Section of Eye IV 59
22. Layers of the Retina " 61
23. Map of Blind Spot " 62
24. How to Find the Blind Spot " 63
25. Eyeball and Eye Muscles " 64
26. Focusing Objects on the Retina " 65
27. Course of the Optic Nerve " 66
28. Long and Short Light Waves " 68
29. Refraction of Light " 68
30. Color Mixer " 69
31. Color Spindle and Color Belt " 71
32. Series of Color-Shades and Tints " 72
33. Perimeter " 74
34. Contrast Color " 78
vi ELEMENTS OF HUMAN PSYCHOLOGY
FIGURE CHAPTER PAGE
35. Color Zones of the Retina IV 81
36. Cross-Section of Ear V 85
37. Labyrinth of the Ear " 87
38. Section through Cochlea " 88
39. Organ of Corti " 89
40. Musical Intervals " 93
41. How Overtones are Made " 94
42. Nasal Cavity and Olfactory Region " 98
43. Olfactory Cells " 99
44. Odor Prism " 101
45. Olfactometer " 102
46. Tongue, Showing Papillae facing 103
47. Taste Bulbs and Taste Cells " 103
48. Pressure and Temperature Spots 107
49. Cutaneous Receptors 108
50. Semicircular Canals and Sacs 117
51. Jastrow Cylinders VI 137
52. Filled-in Perception VII 144
53. Illusion of the Crosses " 145
54. Curve of Weber's Law " 148
55. Space Perception in Touch " 150
56. Visual Space Perception " 151
57. Convergence of the Eyes " 156
58. Stereoscope " 158
59. Who is This? " 164
60. Double Interpretation " 169
61. The Illusory Cubes " 169
62. The Reversible Cube " 169
63. The Reversible Staircase " 169
64. Muller-Lyer Illusion " 170
65. Bering Illusion " 170
66. Zollner Illusion " 171
67. Poggendorff Illusion " 172
68. Vineland Form-Board " 175
69. Curve of Forgetting VIII 190
70. Intensity of Feeling IX 208
71. Simple Reflex X 231
72. Distributed Reflex " 232
73. Mazes for Investigating Habit Formation ... XI 252
74. Changes of Path in Habit Formation " 254
75. Curve of Learning " 259
ILLUSTRATIONS vu
FIGURE CHAPTER PAGE
76. Reading Mirror Script XIII 290
77. Language Centers in the Cortex " 293
78. Mental Levels " 303
79. Hipp Chronoscope XIV 309
80. Handwriting with Different Muscles XVI 368
PREFACE
THIS book was written to meet numerous requests for an
introductory text-book of psychology based on the functions
of the nervous system. The standpoint is the same as that of
Human Psychology, which recognizes both the introspective
and behavioristic methods. Material has been freely drawn
from the earlier work, but the arrangement of topics is differ-
ent and the treatment has been simplified. Most of the theo-
retical discussions are omitted and the practical applications
of psychology are emphasized.
Where the book is used as a class text, the instructor is re-
ferred to the SUGGESTIONS on page 391.
Besides the assistance acknowledged in Human Psychology,
thanks are due to A. P. Weiss, H. S. Langfeld, E. M. Weyer,
C. M. Cantrall and his students, and Alvin Bruch for many
valuable criticisms and to numerous others for helpful sugges-
tions. I am especially indebted to my colleagues, Henry C.
McComas and Carl C. Brigham, for reading the manuscript
critically, and to my office assistants for painstaking aid in
preparing the manuscript and proof.
Acknowledgments are due to the following authors and
publishers for permission to make use of illustrations from
the works mentioned: C. J. Herrick, Introduction to Neurology
(W. B. Saunders Co.); Knight Dunlap, Outline of Psychobi-
ology (Johns Hopkins Press); E. A. Schaefer, Text-book of
Physiology (Macmillan Co.); E. L. Thorndike, Elements of
Psychology (A. G. Seiler) ; J. D. Lickley, The Nervous System
(Longmans, Green & Co.) ; Joseph Jastrow, Fact and Fable in
Psychology (Houghton Mifflin Co.); C. H. Judd, Laboratory
Equipment for Psychological Experiments (C. H. Judd) ; E. J.
x PREFACE
Swift, article in Psychological Bulletin (Psychological Review
Co.); R. M. Yerkes, in Harvard Psychological Studies (Har-
vard Psychological Laboratory); Helen B. Hubbert, in
Journal of Animal Behavior (Henry Holt & Co.) ; The Farm
Journal (W. Atkinson Co.).
HOWARD C. WARREN
PBINCETON, NEW JEPSKT
May, 1922
ELEMENTS OF
HUMAN PSYCHOLOGY
CHAPTER I
SURVEY OF THE FIELD
Meaning of the Term ' Psychology/ The word psychology
is often used in conversation and in newspapers or popular
magazines without a very clear idea of its meaning. In most
cases the speaker or writer is referring to human nature; he
thinks the mysterious term psychology sounds more dignified
and imposing, just as stilted writers speak of the ' celestial
luminary ' when they really mean the sun. Psychology does
not mean human nature; but it does mean something very
nearly equivalent to the study of human nature, jluman
psychology is the systematic study of man's daily experi-
ences^ It is not merely a description of our doings, feelings,
^pKfioughts, but an attempt to discover why we act and feel
and think as we do.
Thinking and doing things is not studying psychology, any
more than tossing a ball is studying physics, or mixing a Seid-
litz powder is studying chemistry. In either case the action
may be the starting-point for systematic study; but the study
itself involves a great number of accurate observations, and
these observations must be put together in an orderly way
before we can discover their causes and relations. In other
words, when we make a serious business of studying any class
of events in nature we (1) collect a large body of facts, (2)
classify them, and (3) try to explain how they come to pass.
This is what is meant by scientific investigation. The results
obtained in this way make up the science physics, chemis-
try, or psychology, as the case may be.
2 THE FIELD OF PSYCHOLOGY [CH. i
Psychology is concerned with the scientific investigation of
feelings, thoughts, actions, and other events of life. Many of
these occurrences are by no means confined to man. Dogs
see, hear, and act. The ant is found to possess a keen sense
of smell. Even the amoeba, one of the very lowest known
species of animal, reacts in quite definite ways to certain ob-
jects outside of itself which affect it. The field of psychology
embraces all these occurrences. It includes the study not
only of human beings, but of all species of animals.
Psychology is not concerned with life in general, but only
with certain definite sorts of events in life. It is not the
study of bodily growth, nor of digestion or the other processes
which maintain the body. The events which we study in
psychology are of a different sort from these. They have to
do with the interaction between the living creature and the world
in which he lives.
Every living creature is continually being acted upon by
the surrounding world (his ' environment '), and in conse-
quence he reacts upon his surroundings. First the environ-
ment affects the creature; then the creature produces some
change in the environment. Some of these changes are very
obvious ; when you open a door, or when your dog paws a hole
in the ground, the position of things in the outer world is
altered. In other cases the change in the environment is not
so evident. But even when you merely turn your head you
see things differently; your visual environment is different.
There is always some change in a creature's environment
when he reacts.
Our feelings, thoughts, and volitions arise in connection
with this interplay between our bodily organization and our
environment. These j^effonal experiences, and all the other
_ events that occur while the reaction is proceedingrare wluit
1 Some chemical and physical reactions between the body and its sur-
roundings, such as absorbing food-stuff, the action of oxygen on the lungs,
CH. i] MEANING OF THE TERM 3
This special kind of interplay between the creature and his
surroundings is called mental life. It takes place in a very
definite way. (1) Men and animals have a number of special
receiving organs, called receptors, such as the eye and ear,
which gather in the impressions from outside. (2) There are
motor organs, Called muscles* distributed throughout the
body, which enable the creature to move in various ways.
(3) The receptor organs are connected with the motor organs
by means of a vast network of permanent pathways called
nerves, along which certain impulses travel.
The nerves do not connect the receptors directly with the
muscles; they extend from the receptors up to the brain and
from the brain down to the motor organs. The brain is the
connecting link. 1 It consists of a mass of nerve cells and
fibers which join the various incoming nerves together and
connect them with the various outgoing nerves, somewhat
after the manner of the central switchboard in a telephone
exchange. The incoming and outgoing nerves and the brain,
taken together, make up the nervous system, which is the spe-
cial organ of mental life.
The mental interplay between man and his environment is
always by means of receptor organs, nerves, and motor
organs; and of these the nerves (particularly the brain) are
the most 'mportant part. In studying psychology we have
to investigate not merely feelings, thoughts, actions, and the
like, but the nervous system with its receptor and motor con-
nections; we must study what takes place in these organs
when one feels and thinks and acts.
The operation of the nervous system in human life may be
illustrated as follows: Suppose a baseball fielder sees a ball
coming toward him through the air and raises his hands to
catch it. [Fig. 2.] First, his eyes receive the visual impres-
etc., are part of the processes of bodily growth and maintenance and do not
belong to psychological study.
1 There are also short-cut connections below the brain. See ch. ii.
THE FIELD OF PSYCHOLOGY
[CH. I
sion of the ball. Then the nerves from the eyes convey an
impulse to his brain. From the brain a motor impulse is
conveyed through other nerves to the muscles of his arm and
hand. Finally, as a result of these motor impulses, the
muscles are contracted in
such a way that his hand is
raised to intercept the ball.
The actions of animals
are due to a similar system
of receptor organs, nerves,
and muscles. A dog follows
a trail because the scent
affects his nostrils. A bird
flies away because the sound
of the hunter's footsteps af-
fects its ears. In every case
the impression is conveyed
from some receptor organ
by means of nerves which
finally end in some motor
organ, producing the action.
Definitions. Various def-
initions of psychology are
given in different text-books.
Psychology is often defined
as the science of conscious
phenomena, which means
the study of feeling, think-
ing, and the like. Some of
the newer books define psychology as the science of behavior,
which means the study of how human beings and other crea-
tures act. Both of these definitions are correct so far as they
go. But each tells only a part of the story and very dif-
ferent parts at that. It is perhaps better to call psychology
the science of mental life; but this definition is not altogether
FIG. 2. SEEING AND ACTING
St. stimulus; light waves from the ball.
R = receptors; the eyes. S = sensory nerves,
running from eyes to brain. C = center of
nervous system; the brain. M = motor nerves,
running from brain to arm. E = effectors or
motor organs; muscles of arm and hand.
CH. i] DEFINITIONS 5
satisfactory, because it does not explain what is meant by
mental life. In this book we shall adopt the following defi-
nition, which is reached by putting together the results of
our previous discussion:
Psychology is the science which deals with the facts and events
arising out of the interaction between a creature and its environ-
ment by means of receptors, nervous system, and effectors. 1
This book is concerned especially with the mental life of
man; and in human beings certain phases of mental life are
far more developed than in other creatures. Thinking and
willing are distinctly human affairs; and we can study many
other mental events more closely in ourselves than we can in
lower animals. This is particularly true of feeling, perceiving,
and even emotion. In human psychology it is important to
emphasize these mental facts, experiences, they are called:
Human psychology is the science which deals with the inter-
action between man and his environment by means of the nervous
system and its terminal organs, 2 together with the mental events
which accompany this interplay.
Problems of Psychology. These definitions indicate at
the outset the fields of study that are not included in psychol-
ogy. It is evident that mathematics and astronomy, physics
and chemistry, are not directly concerned with ' interactions
between creatures and their surroundings by means of the
nervous system.'
In the second place, psychology is not especially interested
in the general problems of animal and plant life which biology
studies. It is not difficult to distinguish between biological
life and mental life. Biological life depends upon assimilating
food and throwing off the waste products. The organs which
perform these processes are the mouth, stomach, and intes-
tines, rather than the nervous system. Biology studies such
1 Effectors are muscles and other organs (such as glands) by which the
creature produces an effect.
1 The terminal organs of the nervous system include both the receptors
and effectors.
6 THE FIELD OF PSYCHOLOGY [CH. i
processes as nutrition and growth and reproduction. These
processes are for the most part chemical and other changes
within the body itself. They are quite different from the
events of mental life which psychology studies.
Biology is interested in finding out, (1) How plants and
animals keep alive; (2) How they grow from the egg to
maturity; (3) How they repair injuries; (4) How they pro-
duce offspring like themselves.
Psychology is interested in studying, (1) What sorts of
impressions living creatures get from the world around them;
(2) How they get this information; (3) How they use it so as
to move and act on their surroundings; (4) How social
creatures like man communicate and work with one an-
other.
Interactions between the creature and his surroundings
take place continually. In human life they are much more
important concerns than feeding and growing. Interplay
with the environment is involved in all our pursuits our
studies, business, sports, and home life. Man has devised
countless ways of protecting himself against the dangers and
rigors of his environment. He makes clothing and dresses
himself. He builds houses. He plants crops, raises herds,
and catches fish. He has worked out an elaborate system of
distributing these food products and other useful material.
All this has been accomplished by means of the nervous system.
Psychology is concerned with discovering how all such actions
are performed.
Human psychology, then, deals with the following ques-
tions :
What sorts of information do we get from the outside world and from
our own body?
How is this information put together into perceptions, thoughts, desires,
emotions, and other mental experiences?
How do we remember things and how do we learn to do things in the right
way?
How do human beings develop a social life, by means of which they talk
and work together?
CH. i] PROBLEMS 7
How do men come to get such control of their environment that they
master it and use it for their own ends?
What is man's personality, which receives this information about the
world and puts it together and uses it?
These are the main problems of human psychology; but
each of them includes many lesser ones. For instance, learn-
ing to play golf is a very different thing from learning to
control your temper; and still different is learning how to
manage a business or how to bring up a family. But we shall
find that there are certain general rules or laws which apply
to all kinds of learning.
Collecting the Facts. The first step in any science is to
gather a great mass of facts. In all the sciences that study
nature this is done by observing carefully the ways in which
nature works. There is always a temptation to guess at
things to imagine that things work in a certain way, be-
cause this seems the most likely way for them to act. For
instance, men used to think that a heavy body falls faster
than a light one. For a long time no one tried it out. Fi-
nally, Galileo thought it safer to observe than to guess. He
dropped two balls, a heavy and a light one, from the Leaning
Tower of Pisa; and both reached the ground at the same
time. The notion which every one had taken for granted
proved to be wrong.
In psychology we are especially apt to use the guesswork
plan, because the facts are so much a part of our every-day
life that we think we can see them without looking. Every-
body who has not studied psychology thinks he has just five
senses with perhaps a ' mysterious sixth ' called intuition.
But when psychologists began to observe carefully, they
found that man has several other senses which had been over-
looked. We know now that there are at least eleven senses,
and possibly more. The first rule in psychology (as in every
study of nature) is to observe carefully.
Each science has its own special methods of observing its
8 THE FIELD OF PSYCHOLOGY [CH. i
facts. Psychology uses three different kinds of observation:
(1) observing ourselves, (2) observing the behavior of others,
and (3) observing the nervous system and its terminals.
(1) SELF-OBSERVATION, which is also called introspection,
means the study of our own individual experiences. At the
present moment you see this book and other things around
you. You are thinking perhaps about psychology or perhaps
about your dinner. You may be remembering something
that happened to you yesterday. Maybe you have a tooth-
ache, or are angry, or are drumming on the table with your
fingers. These and other experiences are events in your own
mental life; by paying close attention to them you gather
material for the study of psychology. Self-observation
means examining your own experiences carefully. By strict
attention you often observe experiences that would otherwise
escape notice; the touch of your clothes against the skin,
the tingle in one finger, the throbbing of the heart, a faint
noise in the distance.
Self-observation is the most important method in human
psychology. It can also be used indirectly. Your friends
tell you their experiences; this enables you to get at certain
mental facts which do not come into your own life, so that
you can check up on your own observations. In animal
psychology this method cannot be used either directly or
indirectly, because even the highest animals do not ' observe
their experiences carefully,' nor can they report them to the
psychologist.
(2) OBSERVATION OF BEHAVIOR is the study of the way in
which human beings and animals act. Notice a group of
men listening to a lecture. One man turns his right ear
slightly toward the speaker. Another wrinkles his forehead
and screws up his mouth. A third scratches his head and
twirls his mustache. These are different attention-attitudes.
When you observe them carefully you are using the behavior
method of studying psychology. Notice what the fielders
,CH. i] COLLECTING THE FACTS 9
do in a baseball game when the batter makes a hit. Their
actions are different, but each act is a form of behavior. All
behavior is the result of some impression through the receptor
organs. The lecturer's words or the flying ball start the
activity; they are called stimuli. The attitudes and actions
which follow are called responses.
It is difficult to observe one's own behavior. If you are
fielding a ball you scarcely have time to observe the way you
are doing it; your attention-attitudes during a lecture usually
escape your own observation. On the other hand it is easy,
after a certain amount of training, to study with precision
the behavior of others. Behavior study is even more im-
portant in animal than in human psychology.
(3) OBSERVATION OP THE NERVOUS SYSTEM AND ITS
TERMINALS is used to supplement the two other methods.
It means examining the brain to find out how the various
nerves run into it and out from it and how they are con-
nected together. Where certain parts of the brain are de-
stroyed by disease, we find disturbances of the mental life.
If one region of the brain is affected the man loses the sense
of touch; destruction of another region means loss of speech.
Paralysis of one side of the body is due to injury of certain
regions in the opposite side of the brain.
This method is carried further in animal study by cutting
out definite regions of the brain and noticing the effect on the
animal's behavior. The results of this animal work are ap-
plied to human psychology in so far as the brains correspond.
But the human brain is exceedingly complicated; animal ex-
periments do not help us in studying the higher mental proc-
esses, which occur only in man.
Another way of observing the nervous system is by making
experiments on single nerves and nerve fibers, in order to
discover the nature of the nerve current and the laws of nerve
activity. This is done by stimulating some nerve with an
electric current and noting what sensation or movement
10 THE FIELD OF PSYCHOLOGY [CH. i
occurs. If electrodes be placed on your forehead and the
back of your neck, and a weak alternating current be passed
through the circuit, you will see flashes of violet light. Other
electric stimulation causes twitching of the fingers.
Examination of the receptor organs also gives some facts
which bear on psychology. The eye and the ear are very
intricate organs. A study of their structure helps us to
understand some of the peculiarities of sight and hearing.
Observation of the nervous system has not given as much
useful information as one would expect, because in such ex-
periments we observe only part of the effects that occur in
real life. Little is known as yet about the real nature of the
nerve current in the living body. For these reasons the
method of nerve-observation is useful only for checking up
some of the results obtained by the two other methods.
Observation and Experiment. We have used the word
observation in speaking of these three methods. But in each
case the psychologist is often able to make use of experiment.
The distinction between observation and experiment is this:
in observation we watch the way in which things happen by
themselves, while in experiment we arrange the conditions
beforehand.
If we watch some one learning to typewrite, and notice his
mistakes and how he improves, we are getting at the facts by
observation. But if we give him a page to copy and measure
the time it takes him to do it and count the number of errors,
our observation becomes an experiment. We tell him to
practice an hour a day, and at the end of each day we time
him for a single page; then we have an experimental measure
of his daily improvement. One of the experiments on color
sensations consists in giving a person a great many bits of
wool of different hues and shades and asking him to match
them. The results will show how many colors he can dis-
criminate and whether or not he is color blind.
Experiment is more satisfactory than observation, because
CH. i] OBSERVATION AND EXPERIMENT 11
it enables us to get at important facts much more quickly.
It may take a long time to discover that a certain person is
color blind if we merely observe his actions, while an experi-
ment in sorting out colored wools will usually settle the ques-
tion at once. On the other hand it is not always practicable
to use experimentation. When we try to study our own ex-
periences, we generally find that we cannot arrange the con-
ditions beforehand without spoiling the effect. For instance,
it is almost impossible to make yourself angry deliberately.
In studying anger in yourself, you must wait till something
unexpected happens which arouses your anger, and then ob-
serve it if you are enough of a psychologist to do so.
The study of the human nervous system is almost entirely
a matter of observation, because we know of no way to take
nerves out from the human body or to investigate the brain
of a living man without injuring him seriously. In the study
of our own experiences, observation and experiment are used
about equally.
In applying the behavior method, experiment can almost
always be used, and its results are much more satisfactory
than mere observation. The wool-sorting test for color
blindness is an experiment which uses the behavior method;
the person tested arranges the wools in groups or series in-
stead of describing what he sees.
Most of the work in the human psychological laboratory is
experimental a kind of experiment in which human be-
havior plays a very important part. It would be difficult for
any one to determine by mere observation just how long it
takes him to think or to recognize a word; but this is measured
quite accurately in the laboratory by experiments on human
behavior. An electric circuit is arranged which starts a clock
(called the chronoscope) the instant a shutter falls, and stops
the clock the instant the observer presses a key. Behind the
shutter a word is placed, and then the shutter is released by
the experimenter. The person experimented upon sees the
12 THE FIELD OF PSYCHOLOGY [CH. i
word, and as soon as he recognizes it he presses the key. The
clock is running from the instant the word comes in sight to
the instant the key is pressed; it records time in thousandths
of a second. This enables the experimenter to measure the
time required to recognize the word. 1
After we have arranged the conditions of an experiment,
we must watch the events carefully and must not interfere
with the way they work themselves out. We are not free to
arrange results to suit ourselves. An experiment means
putting a definite question to nature. It is for nature to
answer the question, and we are bound to accept the answer
given, even though it is not what we had expected. There is
often a great temptation to amend the results so as to bring
them out as we think they ought to be. But this is not deal-
ing fairly with nature. If we doubt the correctness of the
results, the only proper course is to repeat the experiment,
taking care to avoid any errors that may have occurred the
first time in arranging the conditions or making the measure-
ments.
We find, then, that psychology uses three methods to col-
lect the facts: (1) Self-study, (2) Behavior study, and (3)
Nerve study; and in connection with each of these methods
it may proceed either (a) by observation of events as they
occur in nature, or (6) by experiment that is, by arranging
the conditions so as to bring out certain facts.
Divisions of Psychology. We have already noticed the
distinction between human and animal psychology. There
are a number of other branches of the science which cover
special fields of study. In the first place, the name Human
Psychology, or General Psychology, is usually applied to the
study of the normal, adult human being. This is distin-
guished from the study of the human child.
1 We know how fast light travels, and about how fast the nerve impulse
travels from the eye to the brain and from the brain to the finger. This
transmission time must be taken into account. The chronoscope is shown
in Pig. 79, p. 309.
ca i] BRANCHES OF THE SUBJECT 18
The object of Child Psychology is to discover how each
different sort of experience originates in childhood and de-
velops to the precise form found in adult beings. For in-
stance, we may study the beginnings of speech in the child
and trace its gradual improvement; or we may study the
child's expression of anger and other emotions, and observe
how they become suppressed and altered in later life. Simple
habits, such as buttoning clothes, tying bow-knots, lacing
shoes, are learned by degrees; the first attempts are awkward
failures; child psychology seeks to trace the growth of these
habits from their very start.
Animal Psychology, also called Comparative Psychology, is
interested in this same problem of mental growth on a larger
scale. In animal psychology we study the evolution of men-
tal life from the lowest species to the highest. It is found
that the amoeba is not capable of learning by practice. The
crayfish can learn a little. If we place a crayfish in a simple
maze ] with food at the other end, after repeated practice he
will learn the proper path to the food; he gradually makes
fewer mistakes and reaches the food in a shorter time. Ani-
mals higher up in the scale of evolution learn more quickly.
It is found that the white rat is very intelligent and can learn
the solution of rather complicated mazes. Animal psychology
also studies the growth of sight, hearing, and other senses,
following the course of biological evolution from lower to
higher species.
Another branch of the subject is Abnormal Psychology.
This investigates, among other things, the changes in mental
life due to diseases of the brain or other disorders. There
are many types of insanity, which come from various causes.
Some show themselves in mental depression or wild excite-
ment; other cases are marked by strange delusions; others by
inability to speak (aphasia).
It is important to distinguish between disordered minds and
1 See Fig. 73, p. 252.
14 THE FIELD OF PSYCHOLOGY [CH.I
undeveloped minds. The class of individuals called idiots,
imbeciles, and weak-minded are not insane; their minds are
merely undeveloped. They are like children in their ways of
thinking and acting, though their bodily growth in other
respects may be normal. The study of mental retardation,
or backwardness, is a division of abnormal psychology quite
distinct from insanity. 1
Physiological Psychology makes a special examination of
the nervous system. It studies the different parts of the
brain, traces the course of nerves to and from the brain, de-
termines the special activity of nerves and receptor organs,
and investigates the relation of nervous activity to mental
life. Its findings are used by psychology to throw light on
mental processes and behavior.
Experimental Psychology is the name given to the experi-
mental study of human mental life in the laboratory. It is
especially concerned with measuring the events instead of
merely describing them. For instance, experimejatal psy-
chology tries to discover just how many colors can be dis-
tinguished; how long it takes to memorize a poem, and how
much we forget in a day or a week; how quickly one idea sug-
gests another idea, and what sorts of associations are most
frequent between two ideas; the rate at which we improve
in learning new habits, as shown by our speed in performing
the act or by the decrease in the number of our mistakes.
Physiological and experimental psychology are really parts
of the general branch called human psychology. We sepa-
rate them for special study because they involve the use of
delicate instruments and require special training on the part
of the student. Many of their results are included in text-
books on human psychology.
1 The study of blindness, deafness, and other peculiarities which depend
on defective receptors, might be included under abnormal psychology.
But these defects do not make the individual 'pathological,' like insanity
and mental retardation; so they are generally studied in connection with
normal psychology.
CH. i] BRANCHES OF THE SUBJECT 15
In the same way we may pick out any topic for special
study and regard it as a division of psychology. The psy-
chology of religion is a special study of religious experiences;
psychophysics is an experimental study of the relation be-
tween stimuli and sensations; the psychology of play investi-
gates the origin, development, and varieties of play in man
or in different species of animals.
Social Psychology studies the events which occur when one
being acts upon another, or when a group of individuals act
together. For instance, imitation means that one person
copies the actions of another; the second influences the first
it may be quite unconsciously. Teaching means that one
individual tries to arouse certain thoughts in another. Speak-
ing and writing are social events; they are generally directed
toward some one else. Our moral acts depend on our recog-
nition that other human beings have feelings like our own.
In a crowd and in a community there is always a tendency for
individuals to think along the same lines and to act more or
less as a unit; an individual acts differently in a crowd than
when he is alone.
All these are examples of the kinds of events which social
psychology studies. Social psychology should not be con-
fused with sociology. Sociology studies social and industrial
relationships of every sort, while social psychology is con-
cerned only with actions and behavior which are accomplished
by means of the nervous system.
Applied Psychology is not a division of psychology like
those just discussed; it means the art of using in practical
ways the results obtained from psychology. After we have
discovered how the human mind works, certain tests may be
arranged by which we can size up any individual mind. For
instance, if we know what sort of mental processes are needed
in a certain occupation, we may devise tests for picking out
the most promising persons from among the candidates who
are seeking the position. Mental tests are used to discover
16 THE FIELD OF PSYCHOLOGY [CH. i
whether a given person has the mental qualifications to make
a good salesman or a good telephone operator. Other kinds
of tests are used to indicate whether a child belongs in the
same school-class as those of his own age, or should be placed
in a higher or lower class. The degree of mental retardation
in morons and imbeciles is determined in a similar way. 1
Another use of applied psychology is in connection with
advertising. One advertisement will attract more notice
than another; some advertisements unintentionally repel the
average man. It is the task of applied psychology to find
out what sorts of advertisements appeal to the average human
being to lay down laws about what to do and what to
avoid in advertising. These laws depend on a knowledge of
human nature; they are applications of principles which have
been discovered by the study of psychology. In general,
applied psychology is the application of psychological princi-
ples to practical problems of life.
The important divisions of psychology, then, are as follows:
Human or general psychology (study of the normal adultf
Child psychology
Animal or comparative psychology
Abnormal psychology (insanity and mental retardation)
Physiologic^ Wchology U^ alized studies
.Lxpenmental psychology )
Social psychology
Applied psychology (practical applications)
Summary and Outline. Psychology is the science that
studies the interaction between human beings and their en-
vironment which occurs by means of the nervous system.
Like every other science, psychology gets its facts by obser-
vation and experiment. There are three methods of observ-
ing psychological facts: observing our own experiences, ob-
serving the behavior of others, and observing the workings
of the nervous system.
1 A moron is less deficient mentally than an imbecile. The word was
coined as the result of mental tests, which showed that in addition to idiocy
and imbecility there is a third, superior grade of mental retardation.
CH. i] SUMMARY AND OUTLINE 17
Besides the study of human psychology there are several
other fields of psychological investigation, such as animal,
child, and social psychology. Applied psychology is the
application of psychological laws and principles to practical
problems in life.
In this book we are to study human psychology. How shall
we go about it? By our definition, human psychology is the
attempt to discover systematically how men are in-
fluenced by their surroundings; what sorts of experiences
occur in human life; how men react upon the world around
them; how human character and personality are formed.
When we study these problems we must begin at the founda-
tion. You will not understand the meaning of personality
unless you first examine the various kinds of experiences that
enter into its make-up. Speech and voluntary action cannot
be explained without some knowledge of the nervous system
and how it works.
The objection to most attempts at psychology by untrained
writers is that they generally begin at the wrong end. Most
of the popular articles on metaphysical psychology, new
thought, mental concentration, and the like, treat mind as a
simple unit instead of a composition or product. They com-
mence with the universe instead of the atom. If we wish to
understand mental life and human nature we must start at
the bottom and work up.
The first step is to study the nervous system (ch. ii) and
how it works (ch. iii), since all our thinking and acting de-
pend on nerve connections. Then we examine the receptors,
and the sensations which we get through their operation
(chs. iv, v). This furnishes the foundation for the science.
Man's conscious life is made up of experiences, and each
particular experience is a union of many separate sensations.
After we have made a survey of the senses, we are in a posi-
tion to examine their relation to conscious life (ch. vi). The
next step is to study the different kinds of experiences that
18 THE FIELD OF PSYCHOLOGY [CH. i
enter into man's daily life (chs. vii-xiii). But mental life in-
cludes actions as well as experiences. So in studying certain
kinds of human experience we have to examine the various
forms of behavior, such as instinct and intelligence (chs. x, xi).
Thus far our study is confined to single, definite experi-
ences and actions. We now go further and examine the suc-
cession of experiences which change from moment to moment
(ch. xiv). Finally, we may trace the process by which man's
personality is built up out of these successive experiences and
how he gradually gains control over his actions and becomes
master of himself and his surroundings (chs. xv, xvi).
This is a systematic order of studying the subject. One
step leads to the next. It avoids the popular error of as-
suming that such complex things as mind, will, and intelli-
gence are simple and fundamental.
PRACTICAL EXERCISES:
1. Report briefly (1) some feeling you have had lately; (2) some memory
you have recently recalled; (3) some thought; (4) some action you have
just performed. Bring out as far as possible the difference between
these four experiences.
2. Take two recent instances in which the environment has affected you
and then you have acted on the environment. Describe the whole
chain of events as far as you can observe them.
S. Say the word "Man" out loud. Now describe this occurrence (your
speaking) in two different ways: (1) As you observe yourself talking;
(2) As another person would observe you doing it. Compare the two
descriptions.
4. Observe a young child's speech or handwriting; compare it with that
of an adult and point out any evidence of mental immaturity which
the comparison brings out.
5. Report some instance where you have been carried away by the in-
fluence of a crowd. Describe how your actions and feelings have been
influenced, and explain the reason so far as possible.
[Exercise 1 is on the different sorts of experience; 2 is on our relation
to the environment; 3 is on the distinction between self-observation and
behavior-observation; 4 is on child psychology; 5 is on social psychol-
ogy. See p. 391 for Suggestions in performing the exercises.]
REFERENCES:
On definitions of psychology: Wm. James, Principles of Psychology, ch. 1;
J. B. Watson, Psychology, ch. 1.
CHAPTER II
STRUCTURE OF THE NERVOUS SYSTEM
Cells. The human body is composed of a vast number of
units called cells. These cells are formed of substances which
are chemically very much alike, and every living cell contains
a nucleus, which is essential to its life. There are many kinds
of cells which differ in shape, degree of rigidity, and other
characteristics. [Fig. 3.] Each of our bones is made up of a
number of bone cells united firmly together. Our blood con-
tains a mass of floating corpuscles, each a separate cell. Our
skin is a network of epithelial cells which are not so firmly
compressed together as the bone cells, and allow stretching
and other changes in shape. The stomach, heart, and other
internal organs are made up of cells, each organ being built
up of some special sort of cell.
The nervous system and the terminal organs connected
with it are formed in the same way. The nerves are com-
posed of cells of a very unusual kind: they are very long and
thin, like threads, so that the name cell seems a misnomer.
The special receptors (such as the eye and ear) are composed
of several different kinds of cells. The muscles are formed
of muscle cells joined together into long bands or strips:
when a nerve impulse affects them each strip contracts and
the whole muscle is shortened.
Our body grows by the enlargement and splitting up of its
cells. When a cell reaches a certain size, it divides by a com-
plicated process into two cells, each of which is like the
' parent ' cell. In course of time a cell may die, just as a
living being dies. It is then disposed of as waste matter, and
a new cell (formed by the division of some living cell of the
same kind) takes its place. When a man reaches maturity
the death of old cells just about balances the production of
20 STRUCTURE OF THE NERVOUS SYSTEM [CH.II
new, so that he ceases to grow. But man is still able, until
late in life, to restore sections of skin and flesh, and to knit
together bones that have been injured.
Every living creature starts as a single cell of a special sort,
called a germ cell, which, when it is fertilized by union with
Germ Cell Bone Celb Nerve Cell Receptor Cell
(Retinal Cone)
Muscle, Cells
Epithelial Cells
\
Blood Cell
FIG. 3. DIFFERENT KINDS OF CELLS
Some of the principal cells which make up the body; greatly enlarged in the drawing. The
human body contains many other varieties of cells.
CH. n]
CELLS
DandriUi
Cell B
Collateral
another germ cell of the opposite sex, begins to grow and
subdivide. The cells first formed in this growth process are
not all alike; they are the starting-point for the bones, skin,
inner organs, nerves, and other components of the body.
As the division of cells continues the body gradually takes
shape, and its various parts begin to be formed.
The cells composing the human nervous system develop
rapidly in the embryo, and practically all of them are formed
before birth. Their number is astonishingly great; there are
over nine billion nerve cells in the outer layer (cortex) of the
brain alone.
The Neuron. The separate cells
which make up the nervous system
are called neurons. In the neuron
the main body of the cell, which
contains the nucleus, is very small
compared with the rest of the struc-
ture. The important feature is a
long thread-like fiber which pro-
jects out from the cell-body, and
usually has several branches.
Fig. 4 shows one sort of neuron,
in which a long fiber, called the
axon, extends from the cell-body in
one direction, terminating in very
fine fibrils, called the telodendrion,
or endbrush. The axon is usually
provided with branches, called col-
laterals. At the other end of the
cell-body there is a larger network
of fibrils, called dendrites, which
branch out like a tree. There are
several other varieties of neuron [Fig. 5], in some of which
the fibers extend in both directions from the cell-body. 1
1 In both Figs. 4 and 5 the thickness of the fibers is exaggerated, otherwise
Fio. 4. THE NEURON AND
ITS PARTS
22 STRUCTURE OF THE NERVOUS SYSTEM [CH.II
The length of the axon varies considerably. Some axons
are very short; they belong to neurons which link together
two neighboring neurons in the spinal cord within the back-
Pic. 5. VARIOUS TYPES OF NEURONS
Six different sorts of neurons. Notice the small size of the cell-body and great length of the
axon. In the drawing the thickness of axon and collaterals is exaggerated, and the finer fibrils
do not show. [From Thorn dike.]
bone. There are other neurons whose axon fibers are more
than two feet in length, extending all the way from the toes
to the spinal cord. The point to remember especially about
the neuron is that it is a line of conduction, or pathway along
which_nerve imjsulses travel. .
they could not be seen in the picture; in Fig. 4 the size of the cell-body is
drawn too large compared with the projections, so as to show the nucleus.
CH. n]
THE SYNAPSE
23
The Synapse. In the general arrangement of the nervous
system each neuron connects up end to end with_another
neuron. 1 A series of neurons joined together in this way forni^
a chain or circuit which extends from the eye or ear or some
other receptor to the brain, and from the brain to some muscle
or gland; every receptor is the starting-point of a nerve cir-
cuit, which terminates in some effector. These circuits_are.
called nervous arcs .
The connection of successive neurons in the nervous arc is
not a complete soldering of the ends together. Itjs^peculiar
sort of cormectioji,
not fully understood.
The minute branch-
ing fibrils at the far
end of one neuron
are meshed in with
the fibrils at the near
end of the next neu-
ron, like the branches
of two bushes close
together in a clump.
At these intermesh-
ing points the nerve
impulse passes across
from one neuron to
the next, just as in a
copper wire of many
strands the electric
current passes over
to another piece
of wire when the
strands of the two are meshed together. The junction point
of two successive neurons is called a synapse. [Fig. 6.]
1 The side connections by means of the collaterals should not be forgotten.
They correspond to the branching of an electric lighting system.
PIG. 6. VARIOUS TYPES OF SYNAPSES
S=synaptic regions, where two neurons mesh together.
[From Thorndike, after Van Gehuchten.)
24 STRUCTURE OF THE NERVOUS SYSTEM [CH.H
The synapse does not transmit nerve impulses as readily as
the nerve fiber; it offers more or less resistance to the passage.
Sometimes the resistance at a synapse is so great that the
impulse is unable to pass over at
all into the next neuron. In such
cases the pathway is blocked, and
either (1) the impulse goes no fur-
ther, or (2) it passes into some col-
lateral and through the synapse at
its end into a neuron belonging to
a different circuit. The synapses
and the resistance which they offer
to the transmission of nerve im-
pulses are very important factors in
determining what pathway a given
nerve impulse will take. Our abil-
ity to learn new actions depends on
the shunting of nerve impulses into
new paths by means of collateral
synapses.
General Plan of the Nervous
System. The neurons are not scat-
tered through the body promiscu-
ously. They form great masses in
the head, constituting the brain;
elsewhere in the body a number
of neurons run close together in
FIG. 7. BRAIN AND CORD IN POSITION
In the head is the brain, consisting of the cerebrum
and beneath it the cerebellum (CBL) and medulla
(MED). The spinal cord is the long white line extend-
ing down from the medulla. The peripheral nerves
branch off from the cord at intervals : their beginnings
are shown projecting down toward the right in the
drawing. C I to C VIII = cervical nerves; TH I to
TH XII = thoracic; L I to L V - lumbar; S I to S V
= sacral; COC I = coccygeal.
CH. II ]
GENERAL PLAN
-I CEStVKAl HEH7B
MIDDUS CERVICAL SYMPATHETIC...
OAWSUON
COCCYOCAL nxsrs
mm TssMMAif
FIG. 8. CENTRAL PORTION OF NERVOUS SYSTEM
Viewed from the front. The brain extends down to '1 cervical nerve'; below this is the
spinal cord with beginnings of the peripheral nerves as they leave the cord (numbered at right).
To left (very black) are shown the sympathetic ganglia of the autonomic system: the corre-
sponding ganglia to right of cord are not shown. [From Herrick, after Allen Thompson and
Bauber.)
26 STRUCTURE OF THE NERVOUS SYSTEM [CH.H
bundles. The nerves which are visible to the naked eye
are bundles of neurons lying side by side. The individual
neurons in any such bundle or nerve are insulated from one
another. The nerve impulse does not jump across from one
neuron to those beside it, but passes along the same fiber to
the synapse at the end, and over into another neuron which
is the extension of the same path.
The main nervous system 1 consists of the brain, spinal cord,
and peripheral nerves. [Figs. 7, 8.] There is also a somewhat
independent system of nerves called the sympathetic or
autonomic system, which controls our digestion, heart, and
other internal organs. [Fig. 8; cf. Fig. 15.]
Peripheral Nerves. The peripheral nerves are the path-
ways which connect the centers in the brain or spinal cord
with the receptors or effectors. They are of two sorts:
sensory and motor. The sensorv_ nerves connect the receptors
with the cord or with the brain; they carry nerve impulses
inward from some receiving organ to some centeg The
motor nerves connect the cord or brain with the muscles and
other effector organs throughout the body. They carry nerve
impulses out from some centertospmeeffector. 2 The sen-
sory and motor nerves which connect with parts of the body
below the head pass into the cord on their way to or from the
brain; they are called spinal nerves. There are also sensory
and motor nerves in the head which enter the brain directly,
without passing through the cord; these are called cranial
nerves. For instance, the olfactory nerve is a sensory cranial
nerve leading from the smell receptors in the nostrils to the
center for smell in the brain. There are also motor nerves
leading from the brain to the face muscles which are used in
smiling; they do not pass through the spinal cord.
Spinal Cord. The spinal cord runs up the back from the
1 Called the cerebrospinal system.
1 There are also mixed peripheral nerves, which contain both sensory and
motor neurons, grouped into separate bundles, but running side by side.
.. n]
SPINAL CORD
lower extremity of the trunk to the head, where it enters the
brain. Roughly speaking it is about as thick as your little
finger. It lies inside the backbone. The separate segments
(vertebrae) which make up
the backbone are hollow,
and the cord lies within this
hollow tube. The nerves
enter or leave the cord in the
space between each pair of
vertebrae. [Fig. 7.] At each
vertebral juncture two sen-
sory nerves enter the cord
one from the right, one from
the left and two motor
nerves go out. [Fig. 8.] The
sensory and motor nerves on
the left side join together
just outside the cord [Fig. 9]
and run as a single nerve to
the region of the body where
they terminate; there the
nerve breaks up and each
neuron proceeds separately
to its final destination. The
corresponding sensory and
motor nerves on the right
side proceed in a similar way.
Both of the sensory nerves
(right and left) enter the
cord from the dorsal direc-
tion that is, at the back;
while the motor nerves pass
out in the ventral direction that is, toward the front of the
body.
If we cut through the cord horizontally, it is seen as a mass
FIG. 9. CROSS-SECTION OF CORD
The central gray matter (G) is shaped like
an H, and is surrounded by white matter (W).
From the ventral or front horn (VH) of gray
matter emerges the motor root (MR) of a
spinal nerve (SP); the sensory root (SR) of
the same nerve enters the dorsal or back horn
(DH), which is more pointed than the ventral.
Near the junction of the two roots is the spinal
ganglion (SG) consisting of sensory cell-bodies.
The nerve shown in the figure is on the left
side of the body; the roots of the correspond-
ing right-side nerve join the cord at the farther
pair of horns. [Modified from Testut.]
28 STRUCTURE OF THE NERVOUS SYSTEM [cn.n
of whitish substance, surrounding a grayish mass which looks
somewhat like the letter H. [Fig. 9.] The gray matter is
composed largely of cell-bodies with the fibers leading into
them. The white matter is composed of axon fibers with no
cell-bodies. The difference in coloring is due to the grayish
tinge of the cell-bodies.
The peripheral sensory and motor nerves from all over the
body below the head pass into the gray matter of the cord
and terminate there. At their terminus in the cord they con-
nect with two distinct paths: (1) There are reflex connecting
neurons in the gray matter which join the ends of the sensory
neurons directly with the ends of the motor neurons in the
cord, so that a nerve impulse may come into the cord and pass
out immediately, without going up to the brain. This direct
connection is what causes the knee-jerk and other spinal
reflexes. (2) There are also secondary sensory neurons con-
nected with the ends of each sensory neuron in the gray
matter of the cord which lead up to the brain, and corre-
sponding secondary motor neurons which descend from the
brain and connect with the peripheral motor neurons in the
cord. These indirect connections are used in voluntary
movements. The white matter of the cord is made up of
these conducting fibers which connect the brain with the
peripheral sensory and motor neurons.
The H shape 1 of the gray matter in the cord is due to these
connections: (1) The direct reflex connections between the
sensory and motor fibers form the two uprights of the H ; and
(2) the sensory fibers (with gray cell-bodies), crossing over
from right to left before they pass up toward the brain, make
the cross-bar.
The thickness of the cord varies. It is thickest near the
head and tapers down at the lower end. This is because a
pair of nerves pass out at each of the vertebral openings,
reducing the size of the cord as we proceed downward. The
1 Turn Fig. 9 left side up and you see the H clearly.
FIG. 10. BASE OP BRAIN
Brain viewed from below, looking upwards. Front of head is at top of the drawing, back
of head is at bottom. In the drawing the pons, medulla, and cerebellum are supposed to be
nearer you than the cerebrum. Basal ganglia lie in center of picture. Lobes of cerebrum
(lobus) are underscored. Small folds of the lobes, called convolutions (gyrus), are named
(right side). Cranial nerves are named (right) and numbered (left). Beginning of
spinal cord (medulla spinalis) is shown below. [From StrUmpell and Jakob.]
_
S't
- -
5 S
$> i
i- M<5 3
S'Pl
z .2.S a
2 - c I
H u. 5 B
U3 = S 2
-f.'i
-^ > C
"- S
CH. n] SPINAL CORD 29
decrease is not uniform; there are two distinct bulges: one
where the great nerves of the arms leave the cord, the second
where the nerves pass out to the legs.
The spinal nerves are named according to the region of the
body which they serve, and within each region they are num-
bered from the top downward. There are in all thirty-one
pairs of spinal nerves. [Fig. 8.]
The sensory nerves which enter the cord from the right side
connect with neurons that cross over and pass up on the left
side, and vice versa; in every case the sensory paths in the
cord are on the opposite side from that on which they enter.
The motor fibers generally cross at the upper end of the cord,
so that the motor paths in the cord are on the same side as the
peripheral motor nerves with which they connect. But in
every case the sensory and motor nerves which serve the right
side of the body connect with the left side of the brain, and
vice versa. In other words, the left side of the brain receives
impulses from the right side of the body and controls move-
ments on that side, while the right side of the brain is con-
nected with the left side of the body.
The Brain. The human brain is a very intricate affair. 1
It consists of the medulla oblongata, cerebellum, ports Varolii,
and cerebrum or great brain; the cerebrum is divided into the
basal ganglia and the cortex or covering. 2 In addition there
are twelve pairs of cranial nerves, which connect with re-
ceptors and effectors in the head. [Fig. 10.]
Of the twelve cranial nerves, some are sensory, some motor,
and some contain both sensory and motor branches. Sen-
sory nerves or branches connect with the eye, ear, and organs
of taste and smell, and with receptors for the sense of touch
in the lining of the mouth and nose, and in the skin of the face.
1 See Frontispiece. If possible a brain model or specimen should be
examined.
1 The term brain-stem is used to designate all the brain except the cerebd*
lum and the cortex with its connecting tracts.
SO STRUCTURE OF THE NERVOUS SYSTEM [CH.II
It is through these nerves that we get sensations of sight,
hearing, and the other special senses, as well as touch sensa-
tions from the skin of the head. Motor nerves lead to the
various muscles in the head, including the eye muscles and
those of the lips, tongue, jaws, and throat which are used in
eating and speaking. The cranial nerves and receptors will
be examined in more detail in connection with sensation
(chs. iv, v).
The medulla is really a continuation of the spinal cord, but
is much thicker. It is the region where the motor fibers cross,
and it is also the assembling point for fibers connecting the
cord with the various parts of the brain beyond.
The cerebellum is a spherical mass of nervous matter which
lies at the back of the medulla and somewhat above it. It
contains centers for coordinating our movements; by means
of its activity we are able to maintain our equilibrium and to
make other simple motor adjustments without special at-
tention.
The pons is a broad band of nerve fibers lying in front of
the medulla and crossing it horizontally. It is situated some-
what above the cerebellum.
Immediately above the parts just mentioned is the cere-
brum or great brain. Its interior consists of a number of
odd-shaped masses of nervous matter called the basal ganglia,
which serve various purposes in the reception and treatment
of nerve impulses. Some of these masses connect with the
cranial nerves; others are intermediate stations between the
cord and cortex. It would require an undue amount of time
to describe their relative position and uses, and this can only
be done satisfactorily in connection with an examination of a
brain model or actual dissection. For our purpose the most
important basal ganglia are the two optic thalami, 1 right and
1 This name was adopted because the thalami were found to lie at the end
of the optic nerves. Later they were found to be the terminals of other
sensory nerves also; the olfactory nerve is apparently not connected with
FIG. 12. CORTEX FROM ABOVE
Showing the hemispheres, separated by the medial 6ssure. Front of head is at top of
the drawing. FL = frontal lobe; ACC = anterior central convolution; RF= Rolandic (or
central) fissure; PCC = posterior central convolution; PL = parietal lobe; OL = occipi-
tal lobe.
H -8 a
. c gg
2 tc v o .
y*~s c ^ ?*" *^r
S <g g-'o^
8 fall
S * I l
B > I e
Hl
'i
car. n] THE BRAIN 31
left, which contain the primary centers for stimuli from all
the receptors. [Fig. 11.]
The Cortex. The cortex is a thin sheet of gray nervous
matter which lies above and around the basal ganglia, almost
completely surrounding them. 1 The cortex and underlying
portion of the cerebrum is divided by a deep medial fissure
into two parts, called the right and left hemispheres, which
are connected beneath by a mass of white fibers called the
corpus callosum.
The surface of the cortex is covered with rounded creases,
which give it the appearance of being wrinkled or folded.
[Fig. 12.] Two deep creases on each side divide the cortex
into readily distinguishable parts. They are called the fissure
of Sylvius and central fissure or fissure of Rolando. [Fig. 13.]
For convenience in reference, the regions marked off by these
and the medial fissure are called lobes and are given separate
names, though their functions are not always distinct. In
each hemisphere there are four lobes; the frontal, temporal,
parietal, and occipital.
The surface of the cortex is gray, covering a mass of white
matter beneath. 2 This means that the cortex is made up
largely of cell-bodies, while the part beneath consists of fibers
leading to or from the cortex. The thin cortex is the final
goal of the sensory fibers and incoming nerve impulses and it
is the starting-point of the most highly organized motor im-
pulses. The cortex is the great central control station of the
nervous system.
There is no single dominating center in the cortex, where
all incoming impulses gather and from which all motor im-
pulses are generated. On the contrary, the cortex contains
many separate receiving centers and many separate motor
thalami. In the illustrations of the brain the Latin names are used; the
English equivalent is obvious in every case,
1 The name cortex means bark or rind.
8 Note that this arrangement is the reverse of the cord, where the gray
matter lies inside the white.
32 STRUCTURE OF THE NERVOUS SYSTEM [CH.II
centers. [Fig. 14.] The higher or control centers for sight
(vision) and hearing lie in widely separated regions of the
cortex. They connect with the lower or primary centers for
these senses, which are situated in the optic thalami beneath.
Near the cortical hearing center is a special center for audi-
*
FIG. 14. CENTERS IN THE CORTEX
Same view as Fig. 13. Diagram showing the touch and motor centers from toes to lips, and
relation of language (speech) centers to centers for sight (vision), hearing, tongue, and lips.
[From Herrick, after Starr.]
tory language that is, for hearing and understanding
spoken words. There are also special cortical centers for
speaking, writing, and reading.
The arrangement of the cortical centers for touch and for
moving various parts of the body is rather striking. [Fig. 14.]
They lie along the fissure of Rolando, and are arranged in
much the same order as the parts of the body which they
serve: first, at the top, the centers for the toes, then for the
foot, leg, thigh, and so on to the centers for cheek, jaws, lips.
Notice that the order is inverted: the centers, for the very
lowest part of the body the toes are highest up in the
cortex. The motor centers in this group lie on the front wall
CH. ii] THE CORTEX 33
of the Rolandic fissure; and just opposite each one, on the rear
or posterior wall, lies the corresponding sensory (touch) center.
In Fig. 14 the center for touch sensations from the toes lies
just to the right of the center for moving the toes, and so on.
The cortical centers for sensory and motor functions which
we have described are called ym^/.?/^, /*/*,?, )wg.iiB the
impulses are projected up from the primary sensory centers
(and down to the primary motor centers) in the basal ganglia
beneath. They are concerned not so much with the recep-
tion of sensory impulses as with combining and elaborating
them. To take one example: the primary center for sight is
in the thalami. A person gets visual impressions and is able
to avoid obstacles in walking if the optic nerves leading from
eyes to the thalami are intact, even though the visual center
in the cortex is destroyed; but he cannot recognize objects
without the cortical center for sight; and he cannot read if the
word-seeing center is destroyed, though he can see the letters
on the page as black marks.
Besides the projection areas, the cortex contains masses of
connecting neurons. The regions in which they are located
are called association areas. The association areas are filled
with bundles of nerve fibers which form connections between
the various projection areas. When you touch and see and
smell a flower, all at the same time, the association fibers
connecting the cortical centers for touch, sight, and smell are
brought into play, so that these three impressions combine
into the perception of a single object the flower. In read-
ing aloud the association fibers joining the word-seeing and
word-uttering centers are used to connect the cortical proc-
ess of understanding words with the cortical process of
speaking. The cortical centers in one hemisphere are con-
nected with the corresponding centers in the other by com-
missure fibers passing through the callosum.
In general there are corresponding centers for each sensory
and each motor function in the two hemispheres. The corti-
34 STRUCTURE OF THE NERVOUS SYSTEM [CH. n
cal centers for the right half of the body are in the left hemi-
sphere, and vice versa. The visual centers form an apparent
exception. The fibers from the left half of both eyes run to
the left thalamus, and those from the right half to the right
thalamus, half of each optic nerve crossing over at a place
called the optic chiasm. But since the visual picture is re-
versed on the retina, the right half of each eye sees objects
situated to your left, and vice versa, so that even here the law
holds.
The four language centers (for speaking, writing, hearing
words, and reading) are found in only one hemisphere not
in both. In right-handed persons the language centers are
all in the left hemisphere of the brain. This is proved by
cases of brain disease. If certain areas of the cortex are
destroyed or injured, there is a language disturbance, pro-
vided the injury is in the left hemisphere; if the corresponding
region in the right hemisphere is destroyed, there is no
language disturbance, showing that there is no language area
on this side.
Autonomic System. The operation of the digestive
organs, heart, lungs, and other internal organs is regulated
by a system of nerves which do not form part of the main
(or cerebrospinal) system. This is called the autonomic
system. [Fig. 15.] It consists of a number of more or less
independent groups of nerves, each of which has a small
central mass of its own, called a ganglion. There are im-
portant nerve groups (called plexuses) belonging to this sys-
tem in various parts of the body : at the base of the heart, in
the upper abdominal cavity, and in the lumbar region. They
control the circulation, digestion, and reproductive organs.
There are also smaller ganglia in the head. Two series of
ganglia are situated near the spinal cord, one on each side of
the body. [Fig. 15; cf. Fig. 8.] Each of these ganglia con-
nects with the next higher and lower ganglia, and with the
neighboring spinal nerve.
CH. II ]
AUTONOMIC SYSTEM
Superior cervical ganglion
of sympathetic
Ph&ryngeal plexus
Middle cervical ganglion
f sympathetic
tnj>>-iQp cervical ganglion
of sympathetic
.Thoracic
plexuses
Abdominal
plexuses
Pelvic
plexusea
FIG. 15. AUTONOMIC NERVOUS SYSTEM
Sympathetic ganglia and plexuses are shown in heavy black; numbering of autonomic gang-
lia corresponds to that of neighboring spinal nerves; C I = first cervical, T I = first thoracic,
L I = first lumbar, etc. Compare Fig. 8. [From Lickley, after Schwalbe.)
36 STRUCTURE OF THE NERVOUS SYSTEM [CH. n
The activity of the autonomic system governs the or-
ganic or biological life processes, so that usually these operate
without conscious control. But the connection between the
autonomic ganglia and the main nervous system makes
possible an interplay between our organic and higher mental
processes. By means of this connection, for instance, we are
able to regulate our breathing, although breathing ordinarily
goes on independent of brain supervision, by means of the
autonomic system. In the same way our worries sometimes
affect our digestion, through motor impulses from the brain
which pass over into the autonomic digestive nerves. On the
other hand, chronic indigestion often affects our temper or
makes us depressed. In this case the autonomic system acts
indirectly upon the cerebrospinal system : the digestive trouble
causes toxic chemical products, which stimulate the organic
senses and give rise to unpleasant sensations.
Summary. The nervous system is composed of many
millions of special cells called neurons. The distinctive
features of the neuron are its long white axon fiber projecting
from the gray cell-body, its collateral branches, its dendrites,
and the minute fibrils in which all these terminate. Neu-
rons connect together, end to end, by the intermeshing of
this fibrillar network; the connection is called a synapse.
The nervous system is divided into the main (or cere-
brospinal) and the autonomic system. The autonomic sys-
tem is concerned chiefly with the bodily life processes
digestion, circulation, etc. It connects with the main system,
however, so that our mental and bodily life processes influ-
ence each other.
The cerebrospinal nervous system consists of the brain,
cord, and peripheral nerves. The sensory peripheral nerves
lead inward from the receptors; the motor nerves lead out-
ward to glands or muscles. The sensory nerves always carry
impulses in from a receptor toward a center never in the
other direction. The motor nerves always carry impulses
CH. n] SUMMARY 87
out from the center toward the effector. Some peripheral
nerves connect the end organs with the cord and lead to the
brain through pathways within the cord; the cranial nerves
in the head connect directly with the brain without passing
through the cord.
The cord contains both conducting nerves and centers.
The gray matter within the cord consists of cells which serve
as centers for the immediate connection of incoming and
outgoing nerves. These spinal centers cause quick, uncon-
scious movements called reflexes. The knee-jerk is a spinal
reflex. The white matter of the cord surrounds the gray
matter; it consists of masses of sensory fibers which continue
the sensory paths on toward the brain, and motor fibers con-
necting the brain with the peripheral motor nerves.
The brain comprises all higher nerve centers, where sensory
nerves connect with other sensory nerves, motor with other
motor nerves, and sensory with motor nerves. The cere-
bellum lies at the base of the brain, and contains a system of
centers for regulating our equilibrium and general posture.
Above this lies the cerebrum, or great brain, consisting of basal
ganglia and cortex. The basal ganglia contain the lower
control centers for receiving impulses from the receptors.
Surrounding the basal ganglia is the cortex, divided into two
hemispheres, which acts as the highest controlling station of
the system. In it are the projection centers for incoming and
outgoing impulses, and association areas for connecting these
together. The cortex contains many million neurons. Our
highest intelligent activities, such as perception, language,
thought, and voluntary movements, depend on the intricate
connections of neurons in the cortex.
PRACTICAL EXERCISES:
6. Report any instances of indigestion or other bodily disturbance due to
anxiety or disappointment.
7. Describe any brightening of your outlook on the world due to improve-
ment of your bodily condition; or depression caused by bodily ailment.
8. Test the involuntary eye-wink of some friend by an unexpected loud
38 STRUCTURE OF THE NERVOUS SYSTEM [CH. n
noise or quick movement past the eye; note the voluntary resistance
to the wink when the experiment is repeated several times. Report the
experiment, including his description of the experience. Test the iris
reflex with a flash-light in a dark-room.
9. Describe (or name) the different sorts of muscular movement which
you can observe in your face and head.
10. Make a sketch of the cortex of the left hemisphere, indicating the
various centers.
[Exercises 6 and 7 are on the relation between the cerebrospinal and
automatic systems; 8 is on the reflex nerve paths; 9 is on the motor-
nerve terminals; 10 is on the topography of the brain.]
REFERENCES:
On cells in general: E. B. Wilson, The Cell.
On the nervous system: J. D. Lickley, The Nervous System; C. J. Herrick,
Introduction to Neurology; K. Dunlap, Outline of Psychobiology.
On the cortex and its centers: Ladd and Woodworth, Elements of Physio-
logical Psychology, Part I, chs. 9, 10.
CHAPTER IH
OPERATION OF THE NERVOUS SYSTEM
How the Nervous System Works. Despite the complex-
ity of the nervous system, its general manner of operation
is simple: (1) Some one of the receptors is stimulated. (2)
The stimulus starts a nerve impulse in the sensory neuron
connected with this receptor, and this impulse travels along a
sensory path to a center in the cord or brain. (3) Impulses
which reach the sensory centers at the same time are col-
lected and combined with the traces left by previous impulses
and proceed to a motor center. (4) A motor impulse goes out
from the motor center along some motor nerve to a muscle or
gland. (5) The muscle contracts and a bodily movement
occurs, or if a gland is affected, secretion results.
This entire circuit is called a nervous arc. Nerve energy
always passes through a nervous arc, and always in the same
order. A concrete example is the way the nervous system
operates when a man tries to catch a baseball. 1 (1) The light
waves from the ball reach the player's eye and stimulate it.
(2) The optic nerve carries the effect to the visual center in
his brain. (3) In the brain the impressions from all parts of
the ball and the background around it are put together. The
resulting picture is combined with other impressions received
at the same time and with the player's memories; then a nerve
impulse goes to the brain centers for arm and hand move-
ment. (4) The motor nerves thereupon carry nerve impulses
down from the brain through the cord and out to the muscles
of the arm and hand. (5) When the impulse reaches these
muscles it causes them to contract. The ball is caught if the
motor impulses are well coordinated. If the brain coordina-
1 See Fig. 2. p. 4.
40 OPERATION OF THE NERVOUS SYSTEM [CH. ra
tion is poor, the muscles do not contract just right and the
player misses or fumbles the ball.
In some cases the process is simpler and in others much
more complicated than this. Winking is the result of a very
simple nervous operation. When an object passes close to
your eye, the eye is stimulated very suddenly. The sensory
nerve impulse in the optic nerve goes only to the lower visual
center. No time is lost in collecting or distributing: the im-
pulse passes directly over to the center for lowering the eye-
lid; the motor impulse goes out to the eyelid muscle at once,
and you wink. These very simplest nervous activities are
called reflexes. Winking is a cranial reflex; its arc lies within
the head.
There are other simple arcs which do not enter the head at
all; they are called spinal reflexes. [Fig. 16.] When some-
thing unexpectedly touches the skin of your hand, a sensory
impulse is carried by the sensory nerve to the cord. There it
passes over from the dorsal to the ventral part of the gray
matter (on the same side of the body), and passes out along
the motor nerve to the muscle in your arm; the muscle con-
tracts, and you jerk your hand away.
Many human actions are very complicated and involve an
intricate nervous arc. Suppose you are going to answer a
letter. A large number of stimuli affect you as you read the
message. When they reach the brain you do not start to
write at once, but you think it over; that is, there is a period in
which nerve impulses are traveling from center to center in
the brain, arousing memory pictures and thoughts. After a
time your thoughts are satisfactorily marshaled, and it is
then that the motor impulses from the writing center begin
to flow out to the muscles of your fingers and wrist.
In every case, whether simple or complicated, the nervous
activity consists of a succession of five steps: (1) Stimulation
of a receptor; (2) conduction of nerve impulses toward a
center; (3) adjustment of impulses at the center or centers;
CH. in] THE NERVOUS ARC 41
(4) conduction of motor impulses to an effector; and (5)
response or activity by the effector. Each of these steps must
be examined before we can understand the process as a whole.
We may combine the two conduction processes and discuss
the questions in the following order:
What is stimulation?
What is nervous conduction, and what are the other characteristics
of the nerve impulse?
What is response?
What happens at the nerve centers?
Stimulation. Stimulation is the effect produced on a
receptor by some object or force in our surroundings (environ-
Musc
Fio. 16. NERVOUS ARC IN SPINAL REFLEX
Showing path of reflex nerve impulse when the skin of hand is
stimulated. A sensory impulse travel' in direction of arrow to the
cord, entering at the back (dorsal root); the impulse crosses imme-
diately to front of gray matter; thence a motor impulse goes out
through the ventral root to muscle in the arm, producing muscular
contraction. [From Herrick, after Van Gehuchten.]
ment) or within our body. When you touch a book or an
apple before picking it up, the surface of the object presses
against your skin and quickly produces a change in certain
receptors called touch corpuscles, which lie scattered about in
the skin; that is, the pressure on the skin stimulates these
42 OPERATION OF THE NERVOUS SYSTEM [CH. m.
corpuscles, and the effect is communicated to the endings of
sensory neurons which lie in close connection with the touch
corpuscles. When light waves from an object stimulate
your eye the effect is communicated to the neurons of your
optic nerve in a similar way. In the case of touch the stimih
lus is a material body; in the case of sight the stimulus is a
force. The stimulus acts in a mechanical way on the receptor
in touch and hearing; in certain other senses, such as sight
and taste, the stimulus produces a chemical change in the
receptor.
The stimulus may act either from inside or outside the
body. Hunger is caused by stimulation of the receptors in
the lining of the stomach and alimentary canal. Here the
stimulus is inside the body. The muscle-sense stimulus is
also inside the body. When you bend your arm the muscle-
sense receptors are stimulated by the change in muscular
tension and this starts the nerve impulse which gives you a
sensation of movement. In the case of sight, hearing, smell,
and touch the stimulus is outside the body, in the surrounding
world, and acts upon receptors situated at or near the surface
of the body.
Nerve impulses do not start themselves; they do not origi-
nate in the neurons. They always depend on some stimulus
which works upon a receptor organ, such as the eye or touch
corpuscles; this effect is transmitted immediately to the
sensory neurons whose endings are in close connection with
these receptors. There is one partial exception to this rule.
The nerves which give us pain sensations have no receptor
organs. Pain is caused by wear and tear of the tissues of the
body; the destruction of tissue is a stimulus which works
directly on the sensory nerves for pain. This means merely
that in the case of pain there is not a double process of stimu-
lation. In all other cases the stimulus affects the receptor
and then the receptor affects the sensory nerve.
The nature of the impulse in the sensory nerve is deter-
CH. ni] STIMULATION 43
mined in the first instance by the nature of the stimulus.
The intensity of the impulse is determined by the intensity or
force of the stimulus. The brighter the light which strikes
the eye, the more intense is the resulting impulse in the optic
nerve; the greater the pressure of an object on the skin, the
more intense is the resulting impulse in the nerve for touch.
The quality of the stimulus also determines the impulse in
certain cases. The different light waves which strike the eye
produce differences in the nerve impulse, which enable us to
distinguish colors.
The sensory impulse depends also on the nature of the
receptor, and how it is affected by the stimulus. A well-de-
veloped eye is capable of distinguishing more differences of
intensity and more colors than an eye of the primitive type
found in very low animals. A human being can tell more
readily than a starfish that it is getting lighter or darker.
This is because the human eye is more perfect; its reactions
to light are more finely graded. Consequently the human eye
passes on to the optic nerve a greater variety of different
effects, and these differences are transmitted to the brain;
so that man is able to detect much finer gradations of light
than the starfish.
In point of fact, the receptor has more to do with determin-
ing the form of the nerve impulse than the stimulus. If two
coins, a cent and a nickel, be placed one above the other be-
neath the tip of the tongue, so that they touch the tongue and
each other, we get a peculiar metallic taste sensation. Neither
coin separately can be tasted. There is no taste stimulus
properly speaking, but chemical action (electrolysis) is set up
by their connection with the tongue. The electrolysis stimu-
lates the taste receptors and this sets up a nerve impulse in
the taste nerve. In other words, the impulses set up in any
sensory nerve are determined not merely by the stimulus,
but by the make-up of the receptor. Whatever the stimulus,
the impulse is specific to the receptor stimulated: the taste
44 OPERATION OF THE NERVOUS SYSTEM [CH. in
receptors always give us tastes, the eye always gives us sensa-
tions of light, if they give any sensation at all.
The Nerve Impulse. The exact nature of the nerve im-
pulse is not yet known. This is because the neurons are very
small and their activity cannot readily be observed. We
know that nerve conduction is not a flow of material, like the
passage of water or gas through a pipe. We also know that
the nerve impulse is always accompanied by an electric cur-
rent; but it is uncertain whether this electric current is the
nerve impulse. There is certainly some chemical action in
the neuron during the passage of the nerve impulse, and
possibly the nerve impulse is really a chemical change in the
nerve substance. In other words, the nerve impulse may be
electrical, or it may be chemical, or it may be a combination
of the two. Until physiologists have settled the question
definitely, psychologists must be content to call the nerve
impulse a chemico-electric event, which covers all three possi-
bilities.
Properties of Neurons : Excitation and Conduction. The
substance which composes the neurons has a number of
characteristics or properties; its two fundamental properties
are excitation and conduction. Excitation means that a neu-
ron is capable of being aroused into activity by some force
acting upon its fine branching ends. A peripheral sensory
neuron is excited by the receptor, as a result of stimula-
tion. Every other neuron in the arc is excited or aroused to
activity by impulses from some other neuron which connects
with it at a synapse.
Conduction means that a neuron, when once it has been
excited at one end, transmits the impulse along its main fiber
and branches to the synapses at its farther end. Conduction
takes place only in one direction. The impulse always pro-
ceeds towards the center in sensory nerves and away from the
center in motor neurons. This is due to the construction of
the synapses. They are so made that the impulse can pass
CH. m] PROPERTIES OF NEURONS 45
through them in one direction only like the entrance to a
mouse-trap. The synapses of the collaterals follow the same
principle. They transmit impulses in one direction only.
The result of this law of conduction is that all impulses
tend to proceed from receptor to center and from center to
effector. There is no ' back-wash ' in the reverse direction.
Retention and Fatigue. The course of the nerve impulse
along the arc is not always the same. The path which a
given impulse takes depends upon physiological conditions
in the neurons and synapses. There are two properties of the
nerve substance which determine and alter the course of the
impulse: retention and fatigue.
Retention means that if an impulse in a certain neuron has
once passed over a given synapse, that synapse thereby be-
comes a less resistant or more permeable pathway; that is,
in future, similar impulses along this neuron are more likely
to pass out through this particular synapse than through
another. It also means that every nerve impulse leaves a
trace of some sort in the nerve substance, which has an effect
on future impulses passing along the same neurons. For
instance, when we look at a printed page the black and white
of the printed background stimulate a great many separate
neurons; after the impulse has passed on, the neurons retain
a trace or permanent impress, which influences any subse-
quent impulses passing through these same neurons. This
permanent ' set ' or ' mold ' is the basis of memory, one of the
most important facts in mental life. The retention traces or
set left in certain central neurons by the letters and words we
have read, make it possible for us in future to recall our
former experience of reading these words to get a mental
image of the same words and sentences long afterwards,
without consulting the book.
The persistence of retention is readily observed in the case
of motor habits, such as swimming or bicycle riding. If you
once acquire one of these habits, it can be revived after a
46 OPERATION OF THE NERVOUS SYSTEM [CH. m
long lapse of time with very little practice. The same is true
of mental habits. If you memorize a poem by repeating it
over and over again, you will find that you can recall it after
a long period during which it has apparently been forgotten.
Fatigue is an effect which is the opposite of retention. It
means a loss of efficiency. Through constant use of the same
neurons and synapses there comes about a wear and tear of
substance, which impedes the nerve impulse. This effect is
similar to the fatigue that occurs in the receptors and muscles.
If you look steadily at a bright object, the eye is fatigued ; if
you carry a heavy suitcase, the muscles of the arm are
fatigued. The efficiency of the eye or the muscle is tempo-
rarily impaired. Just so the synapses in the nervous system
become fatigued if we use the same nervous arcs constantly.
A fatigued synapse offers more resistance to the passage of im-
pulses; if the resistance is very great the impulse is unable to
pass through that synapse at all and is shunted over another
synapse into another path. This accounts in part for the
variety of our actions. If the synaptic connections grew
continually more and more fixed, we would in time have only
a lot of stereotyped habits.
The fatigue effect occurs only when the same neurons are
used steadily, with no let-up. If the stimuli are varied, the
synapses have a chance to rest, the nerve substance is gradu-
ally restored, and the fatigue finally wears off. This is quite
different from the retention effect, which persists in spite of
the lapse of time.
This explains why we become fatigued after studying the
same subject for a long time without intermission. By
changing our mental work to something quite different, we
rest the brain and can accomplish more.
Collection and Distribution. These are two other charac-
teristics or properties of the nerve impulse. Collection is the
gathering together of several impulses into a single neuron.
[Fig. 17.] When we look at any object, a great number of
CH. m] PROPERTIES OF NEURONS 47
nerve impulses are started along the various fibers of the
optic nerve and proceed separately to the visual center of the
brain. Here the separate impulses are gathered together, so
that we see the object as a single thing. All our perceptions
of objects and events are due to the collection of many sepa-
rate impulses.
Distribution is the opposite of collection. Nerve impulses
do not always proceed along a single pathway. Often they
pass out of a neuron by several synapses at once, into as many
different motor paths. [Fig. 18.] Whenever you perform a
i A.. S. S. B..
s, B,
FIG. 17. COLLECTION OP FIG. 18. DISTRIBUTION OP A
NEBVE IMPULSES NERVE IMPULSE
Nerve impulses in two separate neu- The nerve impulse in neuron A di-
rons AI, A), passing through synapses vides and passes out through the syn-
St, St, enter the same neuron B and apses Si and 82 into two separate neu-
proceed onward as a single complex ron paths Bi and Bo.
nerve impulse.
complicated movement, involving several muscles, distribu-
tion of the motor impulse takes place. When you grasp a
stick, all your fingers work at the same time. If you watch
the movement carefully, you will see that the several joints
of each finger bend at once; there may be a wrist movement
also. This complicated movement is brought about by the
distribution of the nerve impulse from a motor center into a
number of motor neurons leading to different muscles.
Distribution may also occur in the sensory nerves. When
you are startled by a sudden noise, the nerve impulse is dis-
tributed; part goes directly into the motor nerves and causes
the reflex movement of jumping or ' starting ' ; the rest of the
impulse passes up to the higher auditory center and enables
you to hear the noise.
Importance of these Properties. The six characteristics
48 OPERATION OF THE NERVOUS SYSTEM [CH. m
just described are properties of neurons and nerve substance.
They indicate just what different operations the nervous
system can perform. The stimuli and receptors furnish
certain material for the use of the nervous system: light
waves strike the eye; sound waves affect the ear; pressure
stimulates the touch corpuscles, and so on. How does the
nervous system use this material? It is able to make use of
the stimuli in the following ways: (1) The neurons are excited
in various ways, according to the quality, intensity, and
duration of the stimulus. (2) The impulse caused by the
stimulus is conducted along the peripheral sensory neuron to
the next neuron, and so on through the entire nervous arc
to the effector. (3) The effect of an impulse is retained for
future use, through the trace or set which it leaves in the
nerve substance. The route of an impulse in the nervous
arc is in part determined by the traces left by former im-
pulses. (4) Synapses become fatigued through constant use,
which makes possible a shunting of the impulse into other
paths, giving variety to our experience and actions. (5)
Impulses from several neurons are collected or gathered to-
gether into a single neuron, producing complex nerve im-
pulses and unified experiences. (6) An impulse may be dis-
tributed into several different motor neurons, which makes
possible the performance of coordinated movements. 1
These properties belong not only to the individual neurons,
but to the groups of neurons called nerves, and in fact to the
nervous system as a whole. If you examine your own every-
day experiences, you will find that they all depend partly
upon the stimulation of your eyes, ears, skin, and other
receptors, partly upon the properties of the nervous system
just described. Memory, perception, in fact every event of
mental life, can be described in terms of these fundamental
properties. 2
1 Another property, less important, is modification. When several im-
pulses combine they may undergo changes of quality.
8 This will be brought out more fully in ch. vL
CH. in] RESPONSE 49
Response. A response is the effect produced by nerve
impulses upon the muscles and glands, together with the
bodily movements and changes brought about by muscular
and glandular activity.
Winking is an example of a simple response; it involves
only the muscle of the eye-lid. Grasping with the hand is
more complex; it is brought about by nerve impulses from the
centers to the muscles of all the joints of the fingers and thumb.
Most of our common acts are very complex responses. Take
the act of reading aloud. The stimuli are the printed words
on the page. A very intricate series of nerve impulses is set
up when you look at the letters, and the final result is a suc-
cession of vocal utterances due to contraction of the muscles
of your throat, lips, cheeks, and thorax. Many human re-
sponses are even more complicated than this. When a man
goes out from his home town to set up in business or engage
in a profession elsewhere, his ' going ' is a response to a
tremendous number of stimuli that have acted on him, often
for a number of years.
Our actions are called responses because they are our
answers to situations in which we are placed, and which are
made known to us by stimuli from the environment affecting
our receptor organs. All movements which are produced
through the activity of our nervous system are due directly
or indirectly to stimuli. No nerve impulse is started inside
the nervous system; every nerve impulse originates in some
stimulus which works upon our receptors and sensory nerves.
Even our voluntary actions are responses to situations in the
outer world; these situations are reported to the brain by
sensory nerves, and arouse perceptions and thought, leading
finally to volition.
The term response as used in psychology applies only to
movements or changes brought about by the action of the
individual's own nervous system. If we stumble over a wire
and fall, the falling movement is not a response; but the wild
50 OPERATION OF THE NERVOUS SYSTEM [CH. m
gestures we make in trying to save ourselves are responsive in
character. When a convict is taken to prison, his going there
is not a response, psychologically speaking, though each of the
steps he takes may be a separate response. Going to prison
may be a social response, and falling down is certainly a
physical response, but neither of these is a psychological re-
sponse. Psychology is concerned only with actions which
are brought to pass through the workings of the nervous
system.
Responses are of two sorts muscular and glandular.
Muscular responses are due to contraction of the muscles.
[Fig. 19.] When a motor nerve impulse reaches the muscle
it causes a chemical change in the muscle fibers, which
FIG. 19. MUSCLE WITH NERVE
ENDINGS
The long horizontal strips are strands of
muscle fibers. The dark vertical lines are
motor nerve fibers which terminate in the
several strands. Nerve impulses cause the
strands to contract they become shorter.
[After Dunlap.)
FIG. 20. DIAGRAM OF MUSCU-
LAR CONTRACTION
A. Strands of an uncontracted muscle.
B. Same muscle when contracted. The
strands are shorter, the muscle is thicker
in the middle.
shortens them lengthwise; the ends are brought nearer to-
gether. The muscle is thickened in the middle at the same
time. [Fig. 20.] One end of the muscle is often fastened
to a bone which plays in a socket, so that when the muscle
contracts the bone turns like a hinge.
CH. ra] RESPONSE 51
Muscles usually go in pairs. The flexor muscle bends the
arm at the elbow, the extensor straightens it. Such a pair are
called antagonistic muscles. The name is somewhat mislead-
ing, for the two antagonists usually work together splendidly.
When one contracts the other relaxes, so that the arm or
finger or other member bends at a regular rate and is held
securely in position all the time by the pair.
A muscle may be contracted at various rates of speed.
These differences depend on the intensity of the nerve im-
pulse. A quick bending of the finger is brought about by an
intense motor impulse; a very slow movement occurs if the
impulse is weak but continues to operate for some time.
Differences in quality of the nerve impulse have not the same
importance in motor nerves as in sensory nerves. The muscu-
lar contraction is the same whatever the kind of impulse.
In addition to the motor nerve endings there are receptors
and sensory nerves in the muscles. These report to us how
the contraction is progressing. When you are bending your
finger you know all the time how the finger is moving and
how much it has moved, even without looking. These
muscle sensations enable you to regulate the response. If
you start to lift a box and it is heavier than you thought, the
sensory nerves in your arm muscles report to you the amount
of resistance and the fact that the movement is slow. There-
upon a more intense motor impulse is sent down to the
muscle and the movement is speeded up.
Glandular responses are not so important in mental life as
muscular responses. The glands are more concerned in
growth and in maintaining the body than in responses to the
environment. When the glands take part in our responses it
is generally in a subsidiary way. In extreme emotion we
weep a response by the tear glands. Anxiety sometimes
affects the sweat glands. The sight of a luscious peach pro-
duces activity of the salivary gland; the mouth waters. It
has been found also that certain emotions operate on the
52 OPERATION OF THE NERVOUS SYSTEM [CH. in
ductless glands inside the body, though these glands are
chiefly concerned with nutrition and growth. Fear brings
about the production of chemical substances (such as adre-
nalin) in the body, which affect our general bodily condition.
The ordinary operations of the glands are not part of the
response; in general, the secretion of saliva, urine, sweat,
tears, etc., are part of our bodily life-processes and are of no
special concern to psychology.
Central Adjustment. In chapter i, the brain was likened
to a telephone exchange, where wires come in from every di-
rection and are connected up with a vast number of other
wires. It may also be likened to a great switching-yard,
where freight trains come in and are broken up, some cars
going to one destination, some to another. Both of these
analogies are imperfect, for nerve impulses travel along any
given nerve only in one direction: in the sensory nerves the
impulses always proceed inward, toward the cord and brain,
while along the motor nerves they only travel out from the
brain and other centers. Also, many impulses are always
coming in from all directions at once, and many complicated
motor impulses are being sent out, all at the same moment.
But the main point in the two analogies is correct: the brain
is a great receiving, switching, and distributing center
with many thousand times more connections than exist in any
telephone central or railroad freight-yard.
The brain centers and the lower centers in the cord are the
regions where the nerve impulses from the receptors are
switched over to the motor nerves and sent out to the effect-
ors. In addition the brain centers collect many sensory im-
pulses and distribute impulses to many motor neurons. Both
of these processes are of the utmost importance.
The collection of nerve impulses in the brain is called
integration. It is more than a mere addition process; the
separate impulses are put together in such a way that their
relations closely resemble the relations along the stimuli.
CH. m] CENTRAL ADJUSTMENT 53
When we look at a landscape the integrated affect of the
visual impulses in the brain is like the landscape outside of
us which stimulates our eyes and optic nerves at the moment.
The resulting picture or perception of the landscape the
way it appears to us is like the real landscape in form.
This is due to the integration of separate impulses from a
large number of nerve fibers in the visual center. We see
things for the most part as they actually are. The same is
true of hearing, touch, and other sense impressions.
In looking at a landscape you will notice that some objects
are featured they stand out and attract our attention.
This means that the nerve impulses are not collected uni-
formly. Some are reinforced and others are weakened, so
that the various parts of the visual field are of different
vividness they receive different emphasis. When you are
reading an interesting story you do not hear the conversation
going on around you. The impulses coming through the ear
reach the brain, but they are almost shut out from the general
assembly of your impressions at the time. Here again some
of the impressions are featured at the expense of others.
Integration is the systematic assembling and marshaling of
all the impulses which reach the brain at a given moment.
In the integrating process some elements are focused and
others are scarcely noticed. This selective character of
integration is an important factor in the regulation of re-
sponses. If you are gunning, the great idea is to hit the
partridge not to shoot up the landscape generally. You
must pick out the bird from all other details of the scene
before you can respond properly. This is accomplished by
the integration of sensory impulses in your brain.
The other important feature of the brain's work is the
proper distribution of motor impulses. This is called co-
ordination. It is one thing to see your bird, and quite another
thing to wing him. When you raise the gun, the various
muscles of your shoulder, elbow, wrist, and finger joints must
54 OPERATION OF THE NERVOUS SYSTEM [CH. m
be contracted just so much and no more. If you continue
the motor impulse to any of these muscles too long or press
the trigger too soon, you miss your shot. In order to per-
form any complex response correctly, the brain must start a
number of impulses along different motor paths at the same
time, and each impulse must be regulated to the proper in-
tensity and must continue just so long. Coordination in-
volves all this. It is more than mere distribution it means
systematic distribution.
One generally thinks of his movements and voluntary
actions as being performed by his muscles. As a matter of
fact the muscles are merely our agents. They are controlled
by our brain centers. Coordination is a brain process, not a
muscular process. It is a question of sending the right motor
impulses out from the brain to the right muscles at the right
time.
The two processes of integration and coordination work
together. All our responses to stimuli, except in the very
simplest cases, involve them both. Most of our actions
depend on a great number of changing stimuli and are ac-
complished by a series of complicated movements. We must
learn to fit the response to the situation. This means inte-
gration of all the stimuli and coordination of all our motor
activities. The systematic combination of integration and
coordination is called adjustment. We are continually ad-
justing our actions to constantly changing situations.
The hunter shooting at the bird is a case of adjustment.
Until he sees the bird there is no impulse to pull the trigger.
For a time he sees all sorts of other objects in the landscape.
Suddenly he spies the bird; the perception is due to an in-
tegration of many stimuli from the retina of the hunter's eye.
At once the nervous activity in the hunter's brain passes over
to motor centers and out through various motor nerves to his
arm and fingers, so that he lifts the gun and pulls the trigger.
The adjustment process here includes the integrated percep-
CH. m] CENTRAL ADJUSTMENT 55
tion and the coordinated motor impulse, both of which take
place in the brain. Adjustment is the most important feature
of mental life.
It is important to keep this in mind in reading the following
chapters; we shall take up a great many special topics: sensa-
tions (the elementary impressions derived from stimuli),
experiences of various sorts, and different kinds of behavior.
These separate facts are simply fragments of our mental life.
Mental life as a whole is a continuous succession of stimula-
tions leading to responses. The significant part of the proc-
ess is the central adjustment of the response to the stimulus.
Mental life is not the fact that we see, or that we act, but the
fact that our actions are adjusted to what we see; the adjust-
ment takes place in the brain.
Summary. The nervous system serves as a network of
pathways over which nerve impulses pass from the receptor
organs through the centers to the muscles and glands. The
nerve activity starts with stimulation of a receptor. This
produces an impulse in the sensory neurons which travels
along the sensory paths to sensory centers in the cord and
brain. In the sensory centers impulses are integrated and pass
over to motor centers, where coordinated motor impulses are
set up in the motor nerves. The motor impulse travels along
motor paths to the appropriate muscles or glands, and dis-
charges its energy into them; the activity of these effectors
constitutes a response.
The nerve impulse varies in intensity and quality, these
two characteristics being determined in the first place by the
nature of the stimuli and receptors. There are also certain
properties of the nerve substance which determine what the
impulse shall be, over and above the stamp which it receives
from the stimulus. These properties are excitation, conduc-
tion, retention, fatigue, collection, and distribution.
The activity of the nervous system proceeds through a
circuit or arc from receptor to effector. Each arc is composed
56 OPERATION OF THE NERVOUS SYSTEM [CH. ra
of three sections : sensory, central, and motor. Corresponding
to these there are three phases of activity: stimulation, ad-
justment, and response. The adjustment process is the most
important of all. It includes integration of sensory impulses,
and coordination of motor impulses. Integration and co-
ordination work together and tend to make our responses
appropriate to the total situation at any given time. Ad-
justment is the most significant fact of mental life.
PRACTICAL EXERCISES:
11. Describe one of your earliest definite recollections of childhood. How
old were you when it occurred? Can you tell why the recollection has
persisted?
12. Try to memorize a definition when sleepy. Compare this with memo-
rizing when you are fresh and wide awake.
IS. Practice keeping a ball tossing in the air with a tennis racquet. Notice
the adjustments of your own movements to the different angles of the
falling ball, and describe the experience.
14. Study several cases in which you can readily perform two independent
actions at once, and other cases where one action interferes with
another. Compare them and determine if possible why they codperate
or interfere.
15. Observe a child trying to use knife and fork or fold a napkin. Describe
any lack of coordination that you notice.
[Exercise 11 is on retention, 12 is on fatigue, 13 on adjustment, 14
and 15 on coordination.]
REFERENCES:
On the nerve impulse: K. Lucas, Conduction of the Nervous Impulse.
On the operation of the nervous arc: C. S. Sherrington, Integrative Action
of the Nervous System.
CHAPTER IV
THE SENSES: SIGHT
The Receptors and Sensation. We have seen that mental
life depends upon nerve impulses which are started by activity
in the receptor organs. All our experiences and actions may
be traced to some stimulation of these organs by objects or
forces outside our body or by conditions within the body.
Before taking up the study of perceptions, memories, thoughts,
and other sorts of experience, we must examine the simple
elements of which every experience is composed, and which
are aroused by the activity of the receptors and sensory
nerves. These mental atoms which combine into experiences
are called sensations.
The receptors are commonly known as sense organs or
senses. Formerly man was supposed to have only five
senses that is, five distinct sense organs, each giving a
different sort of sensation. Popular psychology and poetry
still recognize only the senses of sight, hearing, taste, smell,
and touch. Scientific investigation has shown that there are
several more. At present we can distinguish eleven senses,
with the possibility that some of these may be subdivided
still further. [Table I.]
The senses fall into three groups: (1) the external senses,
which are stimulated by objects outside the body; (2) the
internal or systemic senses, which are stimulated by condi-
tions within the body; and (3) the motor senses, which are
stimulated by our movements and bodily position, and de-
pend on both the outer world and our own body. The
external senses fall into two subgroups: (a) distant senses,
which are affected by stimuli usually originating in objects
situated some distance away from our body, and (6) con-
58 THE SENSES [CH. iv
tiguous senses, which are stimulated only by objects in im-
mediate contact with the body.
TABLE I. CLASSIFICATION OF THE SENSES
Class Sense Receptor Kinds of Sensation
1. External ( Sight Eye Colors and grays
(a) Distant < Hearing Ear Tones and noises
C Smell In nostrils Odors
{Taste In tongue Tastes
Touch In skin Contact and pressure
Warmth In skin Warmth
Cold In skin Cold
9 a i 5 Organic In internal organs Hunger, fatigue, sex, etc.
i Pain Free nerve endings Pain
( Kinesthetic In muscles Effort, strain, etc.
3. Motor -s (muscle sense)
I Static Semicircular Position, rotation, etc.
canals, sacs
Sight is a distant sense. The things that we see are often
far away. In reading, we hold the book several inches from
the eye. The sounds that we hear and the odors that we
smell are from sources some distance off. In every case the
stimulus must reach the receptor before it can start a nerve
impulse and cause a sensation. But in the case of the distant
senses the stimulus is a wave or emanation from some object
which does not itself come into contact with our body at all.
By means of these senses we gain information about things
that lie at a considerable distance from the body. This is
extremely important, for it widens our field of experience
tremendously : our environment is extended as far as we can
see, and hear, and smell. One who is both blind and deaf
has a very limited environment compared with the normal
human being.
1. SIGHT (VISION)
The Eye. The receptor for sight is the eyeball, together
with the muscles attached to it, which enable it to move.
The eye is a nearly spherical body. [Fig. 21.] Its outer
CH. IV]
STRUCTURE OF THE EYE
59
coating is a tough substance called the sclerotic, which covers
all the sphere except the extreme front surface. The sclerotic
Come
Pupil
-Iris
.Accommodation
k muscle
FIG. 21. CROSS-SECTION OF EYE
Horizontal section through right eye, viewed from above. In left eye the
optic nerve pierces the retina at the right of the fovea.
is almost impervious to light. The front surface of the eye-
ball is covered by a transparent coat called the cornea. Light
passes readily through the cornea, just as it does through a
window-pane.
Looking at the eye from the front, we observe back of the
cornea a transparent oval body called the lens. The lens is
convex on both surfaces, like a camera lens, and focuses the
light waves on the rear inner surface of the eyeball. The
lens is held in place by a ring-shaped muscle at its edge, which
serves also to change its shape. When this accommodation
muscle contracts, it squeezes the lens so that it bulges out;
this changes the focus. The space between the lens and
60 SIGHT [CH. iv
cornea is filled with a transparent liquid called the aqueous
humor, which permits the bulging of the lens.
The iris is a flat muscle situated just in front of the lens.
It resembles a disk or circular curtain with a large hole in the
middle. The iris is opaque, and serves to regulate the light
entering the eye, like the diaphragm of a camera. No light
can reach the lens except through the central hole of the iris.
This hole is called the pupil. Bright light causes the iris to
contract, so that the opening becomes smaller, and less light
is admitted. When we go into a dark room the iris relaxes
and the opening becomes very large; more light is admitted
into the eye and we see more clearly. 1
Behind the lens, filling most of the interior of the eye, is a
tough, transparent, jelly-like substance called the vitreous
body, which prevents the lens from slipping backward.
Back of the vitreous, forming the inner surface of the eye-
ball, is the retina. 2 [Fig. 22.] The retina is a thin woven
coat composed of a network of cells and tissues of various
sorts. It consists of ten layers, the most important of which
is the layer of rods and cones (marked 9 in the figure).
The rods and cones are the real receptors for visual stimuli.
They are exceedingly small from 0.002 to 0.006 mm. in di-
ameter. 3 Each rod and each cone is connected with a neu-
ron of the optic nerve. The cones are shorter and thicker
than the rods ; the two can be easily distinguished in the figure.
If we take a tennis ball, cut away about a third of it, and look
inside the remainder, what we see corresponds to the area in
the eye covered by rods and cones. They are crowded to-
gether all over the inner lining except in front.
Looking at the surface of the retina, four regions should be
1 A cat's eye is extremely sensitive to light. Notice that the pupil con-
tracts to a thin, line in bright daylight; in the dark it becomes very large.
This is why a cat can see quite well when there is very little light.
2 Between the (outer) sclerotic coat and (inner) retina is a third coat called
the choroid.
1 A millimeter is about one twenty-fifth of an inch.
CH. rv]
STRUCTURE OF THE EYE
61
noticed: the center, the blind spot, the intermediate field, and
the periphery.
(1) CENTER OF RETINA: The center of the retina lies at the
' opposite pole ' of the eyeball from the center of the pupil.
Interior of eyeball; vitreou*
. ,10
Exterior of eyeball; choroid coat
FIG. 22. LAYERS OF THE RETINA
Section through the retina, showing its ten layers from the vitreous to the choroid coat just
inside the sclerotic: (1) inner limiting membrane, next to vitreous; (2) layer of nerve fibers; (3)
layer of nerve cells; (4) inner molecular layer; (5) inner nuclear layer; (6) outer molecular layer;
(7) outer nuclear layer; (8) outer limiting membrane; (9) layer of rods (long, narrow) and cones
(short, thick); (10) pigment cell layer, attached to choroid. There are many thousands of rod*
and cones, covering the entire back inner surface of the eye; the diagram shows only a few.
[Based on PiersoL]
62 SIGHT [CH. iv
A line joining the center of the pupil with the center of the
retina passes through the center of the lens and through the
center of the eyeball. The region about the center of the
retina has a yellowish tinge and is called the macula luiea
(yellow spot). It contains only cones no rods. Near the
center of the macula there is a depression in the retina called
the fovea centralis. Here the cones are crowded together
more closely than elsewhere. The result of this crowding
is that we can discriminate fine lines and points most sharply
at the fovea. It is the region of clearest vision. When we
wish to examine any object closely we turn the eye so that
the picture of this object falls on the fovea.
(2) BLIND SPOT: The optic nerve does not distribute its
fibers on the outer surface of the eyeball in man and other
vertebrates. The whole nerve passes in bodily, through the
outer coating at the back of the eye, and distributes its fibers
over the inner surface. In the place where the nerve breaks
through the eyeball there are no rods or cones.. This region
is called the blind spot; it is somewhat circular but irregular in
shape, and di3eiFs~m~different individuals. [Fig. 23.] You
cannot see an ob-
ject whose picture
falls on this part
of your eye. The
blind spot lies some
distance to the na-
sal side of the cen
FIQ. 23. MAP OF BLIND SPOT te . r in each e y e > and
Blind spot of the author's right eye. Drawn from two s "g nt ly below the
nearly identical records made a year apart. F = fixation- level of the Center,
point
If you look stead-
ily at a small mark on a white surface with the right eye, the
left being closed, a figure somewhat to the right of the fixa-
tion point will not be seen at all. [Fig. 24.] The blind
spots of the right and left eyes are in different parts of the
CH. iv] STRUCTURE OF THE EYE 63
retina, so that with both eyes open we do not notice any
break in the field.
O * O
FIG. 24. How TO FIND THE BLIND SPOT
Close the left eye. Hold the book about 6 inches off and look at the star fixedly with right
eye. Move the book slowly to and from the eye till the right-hand spot disappears. Repeat
with right eye closed and the left-hand spot will vanish.
(3) INTERMEDIATE FIELD :_The region of the retina
the macula (except the blfafl gMt) flpr^ 1 '"-" k"*-* 1 rods and
cones. 1*he rods are more numerous than the cones and
surround them.
(4) PERIPHERY: The outer rim of the retina, toward the
front of the eyeball, is called the periphery. It contains no
cones, only rods. In this region we see things rather indis-
tinctly and cannot distinguish colors; all objects appear
grayish, as in a photograph. This effect may be observed by
closing one eye and bringing a small bit of colored paper
slowly into the field of the other eye from behind your back,
taking care to keep the eye fixed steadily straight ahead.
Eye Muscles. Sight is assisted greatly by muscular ad-
justments. The iris and accommodation muscles inside the
eyeball have already been described. The iris regulates the
amount of light admitted to the eye, and the accommodation
muscle focuses the picture clearly on the retina. There are
also six muscles attached to the outer surface of the eyeball,
which serve to move it about in the socket and keep it in
position. [Fig. 25.] These are arranged in three pairs,
One pair produce movements from side to side, horizontally;
they are called the internal rectus and external rectus muscles.
(The internal is on the nasal side.) A second pair cause the
eyes to turn up and down; they are called the superior rectus
and inferior rectus muscles. The third pair pass obliquely
across the eyeball, one above and the other beneath it; they
64 SIGHT [CH. iv
are called the superior oblique and inferior oblique muscles.
The oblique muscles assist in up and down movements; they
trochlei
Opening far
*1- OCULOMOTOR, W.ABCJ
f KAfl. MA*0 CILIA* TRIO
FIG. 25. EYEBALL AND EYE MUSCLES
Right eye viewed from right side. The external rectus muscle is in central foreground, the
internal rectus slightly below and behind it. The four other muscles are shown above and be-
neath the eyeball. Upper edge of optic nerve is seen just above external rectus. [From Smith
and Elder.]
also hold the eyeball in place during its movements and pre-
vent it from twisting circularly like the hands of a clock.
How the Eye Acts. From every point of a lighted surface
the rays of light spread out in all directions: but only those
that strike the open pupil can pass into the eye and stimulate
the retina. Take for example the point A, in front of the eye
and above the center. [Fig. 26.] A bunch of rays from A
pass through the cornea and aqueous, then through the pupil
into the lens. On account of the curved shape of the lens,
the rays are bent together before they pass into the vitreous,
so that they come together at a point (or focus) on the retina
at A'. 1 The rays from a point B, below A, focus on the
1 If the lens is too rounded (near-sightedness) or too flat (far-sightedness)
the rays do not focus on the retina, and the point is blurred. Eye-glasses are
CH. IV ]
ACTION OF THE EYE
65
retina at B', above A'. Points to the right of A focus to the
left of A', etc. In other words, t}\<* picture of a^y object is
completely inverted on foe retina, like the image in a camera.
By means of the focusing pro-
cess each point of the object be-
fore us stimulates a single rod or
cone on the retina. The stimu-
lation is some sort of chemical
action. Each nerve fiber termi-
nating in the retina is excited in-
dividually by a rod or cone, and
the resulting impulses are con-
veyed to the visual center in the
brain. [Fig. 27.] The separate
fibers come together and form the optic nerve, which passes
out of the eyeball through the blind spot. The optic nerves
from the right and left eyes come together at the^gftc chiasm,
FIG. 26. FOCUSING OBJECTS
ON THE RETINA
Rays from A (dotted lines) spread in
all directions, but are bent in by the lens
and meet at A' on retina. Rays from B
(broken lines) are focused at B'. Rays
from points between A and B focus in the
same way, giving a clear but inverted
image on the retina.
where the nerve fibers from the nasal half of each eye cross
over, while those from the outer hah* continue along on the
same side. Consequently the center for the right half of
each retina is in the right side of the brain, and that for the
left in the left side.
In order to see an object clearly, the picture on the retina
must be focused accurately. This focusing is not done (as in
a camera) by moving the sensitive plate back and forth, but
by changing the curve of the lens. When we look at objects
near by, the accommodation muscle squeezes the rim of the
lens and makes it more rounded; when we look at things
farther off the muscle relaxes and the lens becomes flatter. 1
The change takes place automatically.
used to correct these two faults concave lenses for near-sight, convex for
far-sight.
1 In astigmatism the accommodation muscles contract irregularly, so that
the lens does not focus for both axes at once. This is corrected by eye-
glasses which are more curved in the horizontal direction than in the vertical,
or vice versa.
66
SIGHT
[CH. IV
FIG. 27. COURSE OF THE OPTIC NERVE
The optic nerves (ON) from the two eyeballs (E) run back into the head and meet at the op-
tic chiasm (OC). Fibers from the nasal half of each retina cross (broken lines CF); those from
the outer half (unbroken lines UF) curve out again and proceed on same side of head through
the optic tract (OT) to visual centers in the brain. The lower visual center is in parts of the
thalamus called the pulvinar (P) and external geniculate body (EG). Center for touch sen-
sations from eyeball is in the upper quadrigcminal body (UQ). From the tbalamus, projec-
tion fibers proceed to the higher visual center in the occipital lobe of the cortex (C).
N3, N4, N5, = nuclei of III, IV, V cranial nerves, for eye movement; GC = commissure of
Gudden, connecting the lower visual centers on the two sides of the brain. [Modified after
Lickley.)
CH. iv] ACTION OF THE EYE 67
The iris muscle also works automatically. Bright light
causes the iris to contract, so that the pupil becomes smaller.
The dazzling effect of a sudden glare of light is due to the
fact that the iris has not had time to contract sufficiently.
The muscles for eye movement work both automatically
and voluntarily. An inherited system of nerve connections
controls their operation; when the rays from a bright or
noticeable object fall on any part of the retina except the
center, the appropriate eye muscles are contracted so as to
turn the center of the pupil directly toward this object.
This is called involuntary fixation* We also turn the eyes
voluntarily, by contracting one of the four rectus muscles,
or by contracting one of the horizontal pair and one of the
vertical pair at the same time. 1 Eye movement, whether
voluntary or involuntary, helps us to see more clearly, since
the center of the retina is the region of sharpest discrimina-
tion. We see an object best when we fixate it on the fovea;
if the object is in motion, we follow its course with the eye,
keeping it on the fovea.
Stimuli for Sight. Jlie liffht rays which stimulate the eye
%re not piftteyjyd pftTtipJpg. but waves in the ether. ITiey are
exceedingly minute and travel very rapidly, the largest
visible light waves are only 760 millionths of a millimeter
Guju) 2 in length; the smallest waves that affect the eye are
about 390 /iju. All light waves, whatever their length, travel
through the atmosphere at the same speed about 300,000
kilometers or 200,000 miles per second. This means that a
greater number of short waves reach any given point every
second. In other words, short waves have a relatively large
number of vibrations, long waves a relatively small number
of vibrations per second. [Fig. 28.]
When sunlight, which contains waves of all lengths, is
1 There is always some adjustment of all the other muscles when the eye
moves.
2 Pronounced mew-mew.
5
SIGHT
[CH. IV
passed through a prism its direction is changed. This bend-
ing is called refraction- The short waves, because they are
short, are deflected from their course more than the long, so
that the different waves spread out like a fan. [Fig. 29.] If
FIG. 28. LONG AND SHORT
LIGHT WAVES
The upper wave is twice as long as the
lower. Since they travel at the same
speed from A to B, only half at many of
the long waves will reach B in a Riven
period of time. The longer the wave
length, the fewer waves per second.
FIG. 29. REFRACTION OP
LIGHT
A ray of sunlight, containing waves
of all lengths, coming from S passes
through the prism and is refracted.
The shortest waves (violet end of color
series, V) are bent most, longest waves
(red end,R) least. They spread out on
a reflecting surface and form a spec-
trum of colors.
refracted light is thrown on a white surface each wave length
gives a different color; the entire series of colors obtained by
refraction is called thej^edrum. 1 Each distinguishable color
is caused by a certain definite wave-length of light, or by a
certain uniform number of light waves striking the eye every
second; we can express it either way.
In addition to their differences in wave-length, light waves
vary in intensity* Bright light is caused by more violent
vibrations the waves swing farther from side to side as
they move along. Intense (or bright) light acts more power-
fully upon the rods and cones of the retina and produces a
sensation of greater intensity when the resulting nerve im-
pulse reaches the visual center.
Qualities of Visual Sensations. In studying each of the
senses one of the first questions is, What are the different
sorts of impressions that it gives us? So in examining the
sense of sight we have to determine the various qualities of
visual sensations. First of all, we find two distinct groups of
and grays.
1 The spectrum is seen in the rainbow.
CH. IV]
VISUAL SENSATIONS
Pure color sensations, or hues, are produced by stimuli
which consist of uniform I*- va- If the waves that
strike the retina are about 400 nn in length we see violet; if
they are 650 or more we see red. The series of colors lies
between the limits 390 and 760 MM-
spnsatio" g
hy stimuli of
waves in which no single wave predQjBJnatea.. The pure gray
sensations form a series of their own, the extremes of which
are called white and KocL
ln addition to these two pure groups there is a third class
impure sensations, which combine in various ways the
color effect with the gray effect. They are produced by a
mixture of color stimuli with gray stimuli. Most of our
visual sensations are of this sort.
The relations of visual sensations to one another may be
studied by means of colored disks which are fitted together
and placed on a color mixer. [Fig. 30.] When we spin the
FIG. 30. COLOR MIXER
The colored disks (A) are slit from circumference to center so they can be
fitted together, with a segment of each disk showing. The disks are fitted
around a projection to the axis of B and screwed fast. The mixer is rotated by
turning a handle C. By the series of belts connecting the three wheels with B
the speed of rotation is greatly increased.
interlocked disks around very rapidly, the colors (or grays)
blend together and give an intermediate sensation. If we
70 SIGHT [CH. iv
start with a pure red disk and little by little add a segment
of yellow, we can determine just how much yellow must be
added to red in order to produce a noticeable change in sen-
sation. And so for the changes from yellow to green, etc.
In the same way we can observe the just noticeable changes
in a gray series by mixing a white disk with a segment of
black or vice versa. The impure sensations are obtained by
combining each of the pure color disks with a black or a
white or a gray disk on the mixer.
When we have made all possible combinations of colors and
grays on the color mixer we shall have found all the different
qualities of visual sensations. The relations of these sensa-
tions to one another may be shown by a diagram which takes
the form of a spindle. 1 [Fig. 31 A. The central cross-sec-
tion, with the belt of pure colors, is enlarged in Fig. 31 B.]
Bear in mind that the spindle-shaped figure represents only
the relations of the colors and grays as seen by the eye not
the relations of the physical light waves which stimulate the
retina. The various visual sensations are represented on the
spindle as follows:
(1) HUE OR COLOR TONE: The relations of the pure colors
are represented in the form of an irregular belt, shown in
Fig. 31 B. The sectors in this diagram mark off the more
prominent hues red, orange, yellow, olive, green, peacock
(or blue-green), blue, and violet. Each of these names really
applies to a number of distinguishable hues; for instance, even
in the pure colors seen in the spectrum we can distinguish
several sorts of red, which look more and more like orange;
then several sorts of orange which look more and more like
yellow, and so on to the extreme violet.
There are also a number of hues which are not produced by
single light waves, but are due to mixing red and violet light
in various proportions. These hues make up the purple sector
of the belt. They are just as real hues and just as simple
1 It is also called a color cone or color pyramid.
CH. IV]
VISUAL SENSATIONS
71
'.I
1 H
sensations as any others, though they are
not due to simple waves. This explains
why we represent the hues by a continu-
ous belt instead of by a line. If we start
with red and keep changing the hue we
pass through all the spectral colors to vio-
let, and then through purple to the red we
started with. All told there are about ^60
distinguishable pure colors, including the
purple hues.
(2) SHADE OR BRIGHTNESS: The pure
gray sensations are represented by the cen-
tral axis in Fig. 31 A. One end of the
Clock
FIG. 31. COLOR SPINDLE AND COLOR BELT
A. Color spindle: showing schematically the various dis-
tinguishable visual sensations, arranged according to shade
(vertical direction), tint (radii from central axis), and hue
(angles about axis). The gray series is represented by the
central vertical axis. The purest hues (most saturated
color tones) lie on the circumference of the color belt. The
relative proportion of shades, tints, and hues is indicated
by the relative number of units assigned to each. (Notice
the great preponderance of shade-units over others.)
B. Color belt, enlarged; showing relative number of dis-
tinguishable hues of each spectral color and of purple; rela-
tive saturation of the various pure hues is indicated by dis-
tances of the belt from central gray axis. Colors repre-
sented by the sectors: Red, Orange, Yellow, Olive, Green,
Peacock (= blue-green), Blue, Violet, Purple.
72 SIGHT [CH. rv
axis represents the whitest white, the other end represents
the blackest black. There are about 700 distinguishable gray
shades 1 between these two extremes.
A color may be made brighter or darker by mixing it with
white or black. If we take a red disk, for instance, and inter-
lock it with a white disk, the mixture is bright red. If we put
a red disk and a black disk together, the mixture is a dark red.
These are different color-shades. The color-shades are repre-
sented on the spindle by vertical lines parallel to the gray
axis.
Figure 32 A shows how a series of red color-shades may be
obtained on a single disk. Such a series may be found for each
distinguishable color hue. A color-shade may be compared
with a gray-shade by interlocking a disk of each and rotating
them slowly on the color mixer. If one is brighter than the
B
FIG. 32. SERIES OF COLOR-SHADES AND TINTS
A. Color-shade series. The mottled surface represents red. If disk A be rotated on a
color-mixer, we get a series grading from bright red at the circumference to dark red at the cen-
ter; same amount of color (saturation) everywhere.
B. Tint or saturation series. Mottled surface represents red. If disk B be rotated, we get
a series of tints grading from pure, saturated red at the circumference to pale, unsaturated red
ending in colorless gray at the center; same amount of brightness (shade) everywhere.
other they will flicker; if they are of the same shade there is
no flicker at all.
(3) TINT OR SATURATION: There is still a third way of
varying the quality of visual sensations, namely, by mixing
1 Artists use the term value instead of shade or brightness.
CH. iv] VISUAL SENSATIONS 73
together a pure color and a gray in various proportions. If
the color and the gray are of the same brightness, these
mixtures will all be of the same shade; yet they will be quite
different. If the mottled portion of the disk in Fig. 32 B is
reproduced in red, when the disk is rotated on a color mixer
we observe a pure red at the circumference; passing toward
the center we observe a graded series in which the color be-
comes less and less pronounced; the center is a pure, colorless
gray. This change, which is neither a change of hue nor a
change of shade. js_called saturation^ar rhmrna^ oyjjni^ A
pure color is said to be ' completely saturated ' ; its saturation
decreases as more and more gray is added to the mixture.
Gray is 'completely unsaturated.' The partly saturated
colors observed by rotating Fig. 32 B form a series of tints. 1
The differences of tint are represented in our spindle dia-
gram by radii from the axis toward the circumference. The
farther from the axis, the greater the saturation. It will be
noticed that some of the radii are shorter than others. This
means that some pure colors in the spectrum are found to be
less saturated than others. Yellow, for instance, is decidedly
less saturated than violet; there are more steps of difference
in passing from violet to gray of the same shade, than in
passing from yellow to gray. When any two hues are mixed
the resulting color is less saturated than either of them taken
separately. Consequently the purple hues, which are ob-
tained only from mixtures, are represented on the belt by a
straight line. All purples are relatively unsaturated; they
have fewer tints than the spectral colors.
Every visual sensation has a certain assignable position on
the spindle figure. Every color has a certain hue, shade, and
tint. Gray has only shade; we might say that its saturation
is zero. Our diagram also brings out the fact that very bright
1 A vivid tint means that the color is very pure or saturated. A pale tint
means that the object is mainly gray, with very little color; it may be either
dark or bright that is a question of shade.
SIGHT
[CH. IV
and very dark colors are quite unsaturated; near the white
and black poles there are relatively few steps between pure
color and gray. It is estimated that, all told, about 30,000
visual qualities can be distin-
guished by the normal human
eye.
Primary Colors. Artists and
physicists, as well as psycholo-
gists, are interested in the ques-
tion of what colors are primary.
Newton's list of seven colors is
familiar to every one; but it has
no special significance. Newton
was misled by the analogy of the
musical scale and thought there
must be seven tones in the color
scale also. It has long been
known that by taking three hues
red, green, and blue and
combining them together on a
color mixer in various ways any
hue can be obtained. This has
led to the idea, which still pre-
vails popularly, that these three
hues are primary or fundamental
colors. In a way this is true.
But on the other hand psycholo-
gists find that yellow is quite as
distinctive a color as the three
just mentioned. It is also a fact that orange, violet, and
indeed every separate hue in the spectrum, is a simple color
the result of a simple stimulus. Are there three primary
colors, or four, or a hundred?
A curious fact suggests the answer to this question. If the
eye be fixed on a point straight ahead, and a small btt of
FIG. 33. PERIMETER
Observer's chin is placed on a rounded
chin-rest at A, which is so adjusted that
one eye is directly over semicircular top
of rod B, the other eye being closed. A
smnll hole through the axis at C serves
as fixation point. Color stimulus is
moved on a carriage along the semicir-
cular arm, D, of perimeter toward or
away from center. On the back of the
arm is a scale of degrees. The arm D
rotates, so that all parts of the visual
field can be explored. On outer side of
plate E (which rotates with D) is fas-
tened a chart, ruled radially and circu-
larly to represent degrees of 'latitude'
and ' longitude ' from center of vision.
Experimenter records the readings on
the chart, which is bidden from observer
by E. [From Judd, after Meyrowitz.]
CH. TV]
PRIMARY COLORS
75
colored paper be moved slowly from the fixation-point out
toward the periphery, it is found that most colors change
noticeably in hue as they get farther from the center. A red
becomes yellowish, and so on. But there are four definite
hues which do not alter in this respect. 1 These four ' invari-
able ' hues are called primal colors, and may be regarded ay
the most primitive and representative hues of all; they are a
certain definite blue, green, yellow, and red. Curiously
enough, primal red is not a spectral hue. It is slightly
purplish. The primal colors and the changes which occur in
other hues near the periphery may be observed by means of
the perimeter. [Fig. 33.] Table II shows the wave-lengths
of the primal colors and the wave-lengths of the groups of
hues to which popular names are given.
TABLE II. SPECTRAL LINES AND COLOR RANGE
Spectral Line
A
Primal Red
B
C
D 2
Primal Yellow
Primal Green
F
Primal Blue
Wave-Length
MM
766.1
No. of Vibrations
Trillion per second
391.41
Color
Hue
Range
MM
Red
Orange
Yellow
Green
760-647
647-588
588-550
550-492
Blue 492-455
Violet 455-390
687.0 417.06
656.28 456.91
589.0 509.01
577 521
526.96 569 03
501 599
486.14 616.82
477 629
Gi 432.58 693.19
H 396.84 755.62
Visible Range: 760-390 MM, 399.55-768.87 trillion.
Limits of Color Change: 655-430 MM.
(Wave-lengths from Houstoun, Treatise on Light, p. 473. Primal colors
from Titchener, Exper. Psychol., Vol. I, Part I, p. 4.)
Purkinje Phenomenon and Adaptation, Most of our
color sensations are due to the reflection of light from painted
surfaces. The paint pigments absorb all rays except one
1 At the periphery they become gray, as do all colors; but the hue does not
vary it only fades out.
76 SIGHT [CH. iv
wave-length; the reflected light is of the hue corresponding
to the non-absorbed wave-length.
The brightness of pigment colors varies with the intensity
of the general illumination. In a darkened room all colors
appear darker; but the brightness of different colors changes
at different rates. When the general illumination is very
bright, yellow and red become relatively brighter than other
colors. If the room be made very dark they appear darker
than blue or green. This is especially noticeable if we com-
pare red with blue. [A. red book-cover which appears much
brighter than a blue cover in a well-lighted room, will appear
darker when the light is turned very low. This peculiar
variation in the relative brightness of colors is called the/'
Purkinje phenomenon, from the man who first reported JtJ
The Purkinje phenomenon is part of the process of adapta-
tion to intense and feeble illumination which takes place in
the retina itself, due to changes in the condition of the rods
and cones. When we go suddenly from darkness to bright
daylight the eyes are dazzled. After a time the eyes become
adapted to brightness. In the same way the eyes adapt
themselves to a darkened room. The process of adaptation
is greatly assisted by the iris reflex.
There is also adaptation when the general field of vision is
tinged with some color. If we put on green glasses the whole
landscape at first appears green. After a time this tinge dis-
appears, and our outlook is apparently normal, except that
red objects appear gray.
Complementaries, After-sensations, and Contrast. If a
disk of yellow cardboard and a disk of blue be fitted together
so as to give a surface half yellow and half blue, and this be
rotated rapidly on a color mixer, the two will tend to neu-
tralize each other. If we select a certain hue of each and mix
them in various proportions, at some point we get a mixture
in which no color effect whatever is observed: the disk appears
as a plain gray surface. For a given yellow, a certain blue
CH. iv] AFTER-SENSATIONS, CONTRAST 77
can be found which yields this effect. This yellow and this
blue are called complementaries or complements. 1 For every
color hue in the series, including the purples, one and only
one complementary hue exists.
If we look steadily for about a minute at a very bright
colored object (a red blotter, for instance) and then turn the
eye quickly to a white wall, we see on the wall a patch of the
complementary color (bluish green, in this case). This after-
effect is called &negajjge afi^r-^ansotwn^ It is due to fatigue
of the portion of the retina stimulated by the bright color.
White gives rise to a black after-sensation, and conversely.
For this reason white and black are regarded as complements.
After practice one can get an after-sensation more readily
and hold it longer. If you reach this stage you will observe
another effect also; after the eye is turned toward the white
wall there appears first of all a sensation of the same color as
the object you were looking at. This is a positive after-sensa-
_ twn. It lasts only a very short time and then changes into
the negative. The positive after-sensation is due to inertia
of the retina.
Often a strong negative after-sensation after persisting
some time changes into a second positive, and this again into
a second negative. These effects are obtained only after
great practice and under very favorable conditions; all except
the first positive are due to fatigue and recuperation of the
retina.
Complementary effects may be brought about under cer-
tain conditions without moving the eye. If we place on a
color mixer a disk containing a ring which is partly black and
partly white, surrounded by a uniform color (e.g., blue), when
the disk rotates the black and white ring it not seen as gray,
but is tinged with the complement (yellow) of the surrounding
color. [Fig. 34.] A similar effect is obtained by placing a
1 The latter is a term recently suggested by Christine Ladd- Franklin.
* It is also called an after-image.
78
SIGHT
[CH. rv
FIG. 34. CONTRAST COLOR
Mottled surface represents blue. Ro-
tating the disk, the black and white
ring is tinged with yellow; if instead of
blue tne mottled surface is red, the ring
takes on a greenish tinge.
bit of gray paper on a colored blotter and covering the whole
with white tissue paper. TTip arnpar.np^f A ftrnnflfcnfflit.fl.rv
effect without eye movement is called simultaneous contrast.
The complementary color which
appears around the borders of a
colored figure on a white back-
ground when the eyes wander is
a negative after-sensation. It is
called successive contrast.
Color Blindness. A consider-
able proportion of persons show
striking peculiarities of color sen-
sation. They fail to distinguish
between certain hues which lie
far apart in the spectrum, such as
red and green. This defect is
called color blindness. Ask a color-
blind person to hand you the red
book on the table and he is just as likely to hand you a green
book. You think he is joking; but really he is acting in per-
fectly good faith; he cannot tell the difference between red
and green. Color blindness is due to something in the make-
up of the retina. Just what this is no one has yet been able to
discover. It is not a diseased condition of the eye; for cer-
tain types of color blindness are inherited, like the color of
the hair or shape of the fingers. It seems rather to be the sur-
vival of a primitive, less developed type of eye which may
have been universal in mankind before color vision became
perfected.
The most common form of color blindness is inherited in a
peculiar way. It is found chiefly in males. The sons of such
a color-blind person do not inherit the peculiarity, and his
daughters inherit only the latent possibility. They are not
color blind themselves, but their sons are color blind. In
other words, this form of color blindness is transmitted from
CH. iv] COLOR BLINDNESS 79
a man to his daughter's sons. There are also forms of color
blindness which appear in women as well as men.
Color blindness is either total or partial. A totally color-
blind person sees everything like a photograph; the world
appears to him in black and white and shades of gray, with-
out any color whatever. This form is quite rare.
There are three distinct varieties of partial color blindness,
which are popularly called red, green, and blue blindness.
Blue blindness is rare and is possibly due to some diseased
condition of the retina. In this form the person is unable to
distinguish between blue and yellow.
Red and green blindness are the most common forms. In
each there is confusion between red and green. But the two
forms are distinct. This is demonstrated if we ask the person
to tell us how the spectrum looks to him. A red-blind indi-
vidual sees nothing at all at the red end of the spectrum. The
green-blind person sees something throughout the spectrum,
but he confuses red and green with yellow.
How do we know just what the colors look like to a partially
color-blind man? Our description would seem to be mere
guesswork. But, as it happens, cases have been found in
which one eye is color blind and the other eye normal. Such
persons are able to compare the sensations of their two eyes
and to translate the abnormal eye into terms of the normal.
Color blindness raises certain very practical issues. On
the railroads and at sea the two colors red and green are com-
monly used as signals. It is sometimes a matter of life and
death to distinguish them clearly and immediately. A color-
blind engineer may make a fatal mistake. Many tests have
been devised to determine color blindness. Some of these
are open to serious objection. Color-blind persons can dis-
tinguish differences of shade very accurately. If only a few
standard cards are used in the test, one may learn to dis-
tinguish these particular cards by their shade and so pass
the test.
80 SIGHT [CH. iv
A test devised by Stilling meets this objection. It consists
of a set of cards with a great many round colored spots of
various sizes and shades scattered about promiscuously.
Most of the spots on each card are of one color (say, red), with
a few of the other color (green) interspersed. The green
spots are arranged in the form of numerals, so that a normal
person will see immediately and clearly the number 37 (or
whatever it is) in the pattern. A color-blind person looking
at the card can see only the differences of shade: he cannot
pick out the number, but will trace some entirely different
pattern. It is practically impossible to fool this test.
Color Zones. At the periphery of the eye color qualities
disappear even in normal persons. We are all color blind in
this region. Unless the stimuli are exceptionally bright
everything looks gray, like a photograph, at about 90 degrees
in any direction from the point on which the eye is fixed.
Some colors disappear before others. Green, for instance, is
limited to a much smaller region than blue or red. The
region in which we can see any color is called the zone for that
color. These color zones are determined by means of the
perimeter. 1 A map of the color zones in a typical eye is
shown in Fig. 35.
Visual Intensity. In sight, changes in intensity or bright-
ness are closely related to the gray series of qualities. White
is always very intense: black is of faint intensity. The
Purkinje phenomenon and adaptation may be treated as in-
tensity relations.
Experimental psychology is interested in two problems of
visual intensity: (1) What stimulus produces the least ob-
servable visual intensity, or brightness? (2) What change of
stimulus gives rise to the least observable change in brightness?
These same questions crop up in every one of the senses.
The least observable changes in sensations will be treated to-
gether after we have finished our study of the separate senses. 2
1 See Fig. 33, p. 74. * See p. 146-149.
CH. IV]
VISUAL INTENSITY
81
The least observable visual brightness may be determined
as follows : The observer is placed in a darkroom with black-
FIQ. 35. COLOR ZONES OF THE RETINA
Limits at which four colors disappear in passing from center of eye toward periphery,
determined for radii 30 degrees apart. Right eye.
ened walls. On a dull black surface before him a pencil is
fixed upright. A light of standard brightness is moved slowly
toward the pencil from a distance, till the subject just barely
observes the shadow cast by the pencil. The faint light
bordering on the shadow is called the least observable bright-
ness. Certain visual processes occur in the retina, however,
even when no stimulus is present; we often see dust clouds or
spots of light when our eyes are closed in the dark. So that
this experiment really measures the brightness of the objec-
tive stimulation which is just observably different from the
eye's own retinal light. According to Langley the energy of
82 SIGHT [CH. iv
the light which produces the least observable visual sensation
under most favorable conditions is 0.000,000,03 ergs.
Explanation of Visual Qualities. Many facts in the sense
of sight are peculiar and difficult to explain : Why do the two
extremes of the spectrum, red and violet, look somewhat
alike? How is it that purple, a simple color, is not found in
the spectrum? Why is yellow a distinctive color, though it
is not among the three that are sufficient to produce every
hue by mixture? How can we account for the various sorts
of color blindness, and the wide prevalence of color blindness
in the human race? Why is the periphery of the retina color
blind even in the normal eye?
Most puzzling of all is the sensation of black. Black is as
much a sensation as white or any of the color hues; yet it is
not due to stimulation by light waves at all. It is aroused
when no light stimulates that particular portion of the retina,
though to get a distinct black sensation some nearby region
must be stimulated by light.
These extraordinary facts indicate beyond question that
the processes in the retina are very complicated. Even to-day
they are not understood. The explanations suggested are
only partly satisfactory; they do not cover all the facts.
The penetio theory of sifrht. which was devised by Christine
Ladd-Franklin, seems tofrt the facts best. This explanation
starts with the notion that color vision has evolved gradually
from a more primitive type of eye which could see only shades
of gray. It supposes that there exists in the rods and cones
a certain substance, which when stimulated by light arouses
sensations of gray and white. This substance occurs in the
retina in the form of particles called color molecules. In the
primitive eye only gray and white were distinguished.
In the course of evolution the color molecules in the cones
became differentiated into two components, 1 one of which
1 The color molecules in the rods are not differentiated: they give gray
only.
CH. iv] THEORY OP VISUAL QUALITIES 83
when stimulated yields sensations of blue, while the other
yields sensations of yellow. Later on in history the yellow
component became differentiated in turn into two compo-
nents, one yielding red, the other green. So in the fully
developed eye there are four primal colors : red, yellow, green,
and blue. But since red and green are derived from yellow,
yellow is not essential to color combinations like the other
three. This theory explains why red and green color blind-
ness are comparatively common, and why the normal eye
does not distinguish colors peripherally: in color-blind per-
sons the color molecules are only partly developed; and the
periphery is capable of giving only sensations of gray because
this region has no cones.
The Ladd-Franklin theory seems to cover all the perplexing
phenomena of sight except the sensation of black. The best
plan is to accept this view as a partial explanation, recogniz-
ing that it does not tell the whole truth. 1
One conclusion is forced upon us more and more as we
study the sense of sight: this sense has by a long process of
evolution developed an exceedingly complicated organ, which
has come to fit our needs most admirably. It furnishes us
with a vast number of elementary sensations which give an
incalculable variety to our experiences. We can see very fine
distinctions of color and shade. We can distinguish very fine
lines and points. We can observe objects at a very great
distance from our body by means of sight. Of all the senses,
sight has the greatest practical importance in human life.
PRACTICAL EXERCISES:
16. Describe the after-sensations of color obtained by looking across the
room at a window-sash on a bright day, and then closing the eyes, or
turning them to a dull gray surface.
17. Describe your experience of visual adaptation on going suddenly from
a very light to a very dark room and vice versa. Note especially the
Purkinje phenomenon (p. 76).
1 There are two other important color theories, one devised by Young and
Helmholtz, the other by Hering.
84 SIGHT [CH. iv
18. Test the limits of your color zones for red, yellow, green, and blue.
This requires assistance. The test should be made in a room with
white walls. Cut out small bits of each color and place one at a time
on a black or white strip of cardboard. The assistant brings the color
gradually in from right or left till the color is recognized. Test one
eye at a time, with the other eye bandaged.
19. Make a map of some one's blind spot. Bandage one eye and fix his
head by a head-rest fifteen inches from the wall. Place a sheet of
white paper on the wall, marking a cross in the middle for fixation
point. Make a pointer of white cardboard, with the tip (one-eighth
inch square) blackened, and move it slowly across the paper. Mark
in pencil each spot where the black tip disappears or reappears.
20. Examine various colored objects in your room, including surface of
walls, tables, chairs, and floor. Describe their shade in five grades:
very bright, bright, medium shade, dark, very dark. Describe their
tint (saturation) in three grades: very pure color, medium saturation
(much gray), slight tinge of color (very pale).
21. With eyes closed place the blocks in the form-board (p. 175). Notice
the length of time required and the errors made. Repeat with eyes
open, and compare the two performances.
[Exercise 20 is on visual qualities; 21 is on the relative importance
of sight and touch; the other exercises are self-explanatory.]
REFERENCES:
On the eye: Ladd and Woodworth, Physiological Psychology, pp. 182-196.
On visual sensations, color blindness, etc.: J. H. Parsons, Introduction to
the Study of Color Vision; E. A. Schaefer, Text-book of Physiology, article
on 'Vision'; M. Greenwood, Physiology of the Special Senses; chs. 10-20.
On visual theories: C. Ladd-Franklin, in Mind, N.S. 1893, 2, 473-489;
Parsons, op. cit.; Greenwood, op. cit.
CHAPTER V
THE SENSES: HEARING AND OTHER SENSES
2. HEARING (AUDITION)
The Ear. The human ear is a very complicated organ.
The peculiar-shaped shell to which the name ear is popularly
applied is only an insignificant part of the apparatus for hear-
ing. It merely collects the stimuli and directs them into the
proper channel. The real ear lies inside the head.
The receptor for hearing is divided into the outer ear,
middle ear, and inner ear. [Fig. 36.] The outer ear consists
Shell
FIG. 36. CBOSS-SECTION OP EAB
Vertical section or right ear through meatus and Eustachian tube, viewed from
front of bead.
of the g/tg/j.(concha). together with a tube, about an inch long,
called the meatus, which leads into the head through an open'
86 HEARING [CH. v
ing in the skull and ends in a vibrating membrane called the
ear-drum (tympanic membrane).
Thelmiddle ear lies beyond the drum. It is a small cavity
in the head, containing three small bones which take up and
transmit the vibrations from the drum. The middle-ear
cavity is the end of a passage (the Eustackianju^ which
opens into the back of the mouth. If the drum is pressed
back too far into the middle-ear cavity by a tremendous
sound, we may remedy the trouble by swallowing, which
forces air into the Eustachian tube and pushes the drum
forward into place. In the bony wall of the middle-ear
cavity, opposite the drum, are two apertures, called the qya],
round window. They are not open; but each is
fitted with a vibrating membrane, which permits the sound
waves to pass through, just as the glass in a window-pane
admits light waves.
The three small bones of the middle ear form a chain. The
hammer bone (so called because it is shaped like a rude,
primitive hammer) is attached to the center of the drum at
the handle end, and at the middle is held in place by a tendon.
The head of the hammer fits into the second bone, called
the anvil; and the anvil attaches to the arch of the stirrup
ff ' - ^^~~ ^*^^^* te
bone, whose base is attached to the membrane of the oval
window.
The sound waves gathered by the shell of the ear pass
through the meatus and set the drum in vibration. This
vibration affects the handle of the hammer; the hammer being
pivoted in the center, its head beats on the anvil, which jars
the stirrup, and this sets the membrane of the oval window
vibrating in exact measure with the original sound waves.
But this is not all. The crucial process of hearing takes place
in the inner ear.
The inner ear or labyrinth is a very complicated cavity,
only part of which is concerned with hearing. [Fig. 37.] The
portion toward the back of the head contains the semicircular
CH. V]
THE EAR
87
Ampullae
Ampulla
canals, which are receptors for the static sense; ] they have,
nothing to do with hearing. The front part of the labyrinth
contains a spiral
structure resembling
the shell of a snail,
called the cochlea,
which contains the
real receptor for
hearing. Between
the canals and the
cochlea is a cavity
called the vestibule.
The inside of the
cochlea is divided
into two spiral tubes,
lying side by side,
which run from the
base to the tip of the
cochlea. [Fig. 38.]
They are separated by a membrane, except at the top, where
they unite. Between these two tubes (called the scala tym-
pani and scala vestibuli) is a smaller tube called the cochlear
duct, which is separated from them by membranes. In a
small canal within the cochlear duct is a system of minute
j-ods and hajrjceljs, called the orflranofJTorfr'. [Fig. 39.] These
rods and hair cells connect with the fibers of the auditory
nerve, and are the real receptors for hearing.
. We traced the course of the stimulus through the chain of
bones as far as the oval window. The vibrations of the mem-
brane in this window set up waves in the liquid that fills the
cochlea. These waves pass up the scala vestibuli, which
starts at the oval window; at the apex of the cochlea they go
over into the scala tympani and pass down, finally reaching
the round window at the base. (The round window serves
1 See p. 117.
FIG. 37. LABYRINTH OF THE EAR
Enlarged view of labyrinth in nearly the same plane as
Fig. 36. Semicircular canals at left, cochlea at right; be-
tween them the two windows and vestibule. [From Smith
and Elder.)
88
HEARING
[CH. V
merely as a shock-absorber.) During the passage of
the waves through the cochlea the cells of Corti are set
into sympathetic
vibration. They
are of different
lengths, and each
picks up certain
wn VPS; of
iam. spiral
Canal. Follop.
tan. Ft
FIG. 38. SECTION THROUGH COCHLEA
just as the strings
of a piano rever-
berate to sounds
of their own
length. When a
wave of a given
length passes
through the coch-
lea, it sets in
vibration the ap-
The cochlea cut open from apex to base near the central core
(modiolus) at right angles to plane of Figs. 36 and 37. The apex
or tip of cochlea is at left of the drawing. Section shows three
windings of scala tympani (right) and scala vestibuli (left). prOpriate rod Or
The cocblear duct (not shown) lies between the two scalae away i^ :_ p p ll n >
from the core; it is bounded by two membranes which form a
continuation of the spiral lamina (Lam. spiral, ossea). [From and tills
Smith and Elder.]
lates a certain
fiber of the auditory nerve, which carries a nerve impulse up
to the auditory center in the brain.
There is no muscular apparatus for focusing sounds in the
human ear, such as we have in the eye. A rudimentary
muscle exists for lifting the ear, but it is rarely used and in
most persons is not under control of the will. We can focus
sounds slightly by turning the head so as to make the effect
clearer and more distinct.
Stimuli for Hearing. The stimuli for hearing consist of
vibrations called sound waves. These waves are very much
more sizable than light waves and differ from them in many
other respects. Sound waves travel through the air at the
CH. V]
STIMULI FOR HEARING
uniform rate of 332.4 meters (about 1000 feet) a second. Like
light waves they differ from one another in length. The
longer the sound wave, the fewer waves strike the ear-drum
membrana tectoria
outer hair cell*
limbus
nerve fibres
cells of Deiters
outer rod
b&sil&r membrane
FIG. 39. ORGAN OF CORTI
Section perpendicular to direction of windings of the scalte. Rods of Corti are designated
'inner rod,' 'outer rod.' The rods and hair cells become longer in successive sections toward
apex of cochlea. [From Lickley, after Retzius.]
in a given period of time. It is customary to measure sound
waves in terms of the number per second instead of wave
length. 1 The greatest frequency (rate of vibration) of sound
waves that the average man can hear is about 30,000 per
second; the lower limit is about 12 or 16. The rate of vibra-
tion determines the quality of sensation.
Sound waves may be started in three different ways: (1)
by twanging a tightly stretched violin string, which being
elastic vibrates to and fro; or by tapping a tuning fork or the
membrane of a drum. (2) They may be started by blowing
into a tube, which sets the air into vibration at different rates
according to the length of the tube. (3) A third way of
1 Because the number of waves per second is the same for any given sound,
whether the vibration is of air particles or strings; the wave length would
vary with the density of the medium.
90 HEARING [CH. v
starting sound waves is by tapping a rigid body, such as a
bell or xylophone; here the rate of the sound waves depends
on the size and material of the body, not on its elasticity.
In every case the sound waves are eventually communicated
to the air and so to the ear-drum. The only exception is
where a vibrating fork is pressed against our head; the sound
waves are then transmitted directly through the bones of the
skull to the drum.
Sound waves differ not only in frequency (vibration rate)
but also in intensity. The same sound (e.g., middle C on the
piano) may be faint or loud, depending on the force of the
disturbance in the air. If you pluck a violin string vigor-
ously, the air particles do not move any faster, nor vibrate
more times per second, but they swing more violently back and
forth with each vibration. This results in a louder sound
not in a different quality of tone.
Qualities of Auditory Sensation. Just as in sight, there
are different qualities of auditory sensation for the various
rates of vibration, and there are also sensations due to mixed
rates. A uniform sound vibration gives a tone sensation;
mixed vibrations give a noise.
The parallel between sight and hearing is not complete.
A noise is not pleasant like gray light; and noises do not form
an independent series like the grays every noise is more or
less like some tone whose vibration rate predominates in the
mixture. Strike a table in different places and you will
notice that the resulting noises are somewhat like dull, flat
tones.
Tones and Pitch. If we snap a tuning fork, the prongs
vibrate to and fro uniformly, at a rate which depends on the
length of the fork. This vibration causes uniform sound
waves in the air, and the resulting sensation is not a noise
but a tone. A long fork vibrates at a slow rate that is, few
times per second; it gives a deep tone. A shorter fork vi-
brates at a more rapid rate and the resulting tone is more
CH. v] AUDITORY SENSATIONS 91
shrill. 1 The vibration rates between 12 and 30,000 give a
series of about 11,000 distinguishable tones. The difference
in quality between tones is called difference in pitch, and the
whole series of audible tones is called the auditory scale.
Tones and pitch correspond to colors and hue in the sense o f
sight. We ask, " What is the pitch of that tone? " just as we.
ask, " What is the hue of that color? "
The relations of tones to one another is quite different from
the relations of colors. In the first place tones have not so
much individuality. Take the tone produced by 256 vibra-
tions, which is called middle C on the piano and is used as a
standard. 2 Most persons are quite unable to identify it. If
you ask a man to hum C, he is likely to give something quite
different; if you strike several notes on the piano, he is unable
to tell which is C. Color recognition is much more developed.
No one who is not color blind finds any difficulty in picking
out a green from a red or a yellow. This lack of individuality
in tones is probably the reason why they have never received
distinctive names like the colors. They are called by the
uninspiring names A, B, C, etc.
A few persons are able to recognize tones as accurately as
colors. They can tell whether a piano is tuned slightly above
or below the usual standard. This ability is called recogni-
tion of absolute pitch. It is said that Mozart, when quite
young, went with his father to the house of a musician. He
tried the man's violin and immediately noticed that it was
tuned a quarter tone above his own, which he had left at
home. Even among musicians the ability to recognize abso-
lute pitch is rare.
On the other hand most persons recognize quite accurately
the relation between pairs of tones. When we sing or hum or
whistle a tune the tones are sounded in a certain order; it is
1 Deep and shrill tones are often called low and high respectively. But
these terms suggest differences in intensity faint (or low) and loud.
2 This is the standard in scientific work. Musicians generally use another
standard, called international pitch, in which middle C is 261.
92 HEARING [CH. v
the relation of the successive tones that makes the tune. The
ability to hum a tune or to recognize it depends on your
recognition of pitch relations, or relative pitch, not on abso-
lute pitch; for the tune is the same whether you start with C
or D or any other tone.
The serial relation of tones is also quite different from that
of the color series. If you strike middle C on the piano and
then the next key to the right, and so on, you will observe
that they become continually " more shrill." But if you
compare them in pairs, C : D, C:E, C:F, etc., you will find
that some of these pairs are more closely related than others.
Notice especially C 1 and C 2 . [Fig. 40.] They sound very
much alike, though they are far apart. The vibration rate
of C 2 is just twice that of C 1 . This 1:2 relation is called an
octave. It suggests that tones might be represented by a
diagram shaped like a spiral or corkscrew, in which any tone
lies immediately above (or below) its octave in the next twist
of the spiral.
Suppose we take the tones C 1 and C 2 and all tones lying
between them. A great many tones can be distinguished
within these limits, but only a few are used in music. On a
piano there are seven white keys starting with C 1 ; the eighth 1
key, C 2 , begins a new series. The eight tones included within
the octave, taken in pairs, give the principal relations or
intervals used in tunes and in musical compositions generally.
They are chosen because the numerical proportion of their
vibrations appeals especially to the human ear: C 1 has 256
and G 1 384 vibrations per second; that is, the relation of C 1
to G 1 is 2: 3; the relation of C 1 to F 1 is 3: 4; and so on. If you
examine Fig. 40 you will see that the musical intervals within
the octave are all represented by rather simple numerical
relations the ratio numbers are small; 15:16 is the least
simple ratio. 2 In general, the simpler the numerical ratio of
1 In Latin 'eighth' is 'octavus,' whence the word 'octave.'
2 The black keys on the piano are used when we take some other tone
besides C as standard; we need extra tones to fill in the larger intervals.
CH. V]
AUDITORY SENSATIONS
*
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101-
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Ml-
10|K)
oOllO
0|CVJ
o
<VJ
*>
I 7:
e 9
II
II
o 2
.2 J5
2 I
to e
II
Is
11
1*
B
-
a =
8 U
3 I
s I
g-s
94 HEARING [CH. v
two tones, the ' closer ' or ' more harmonious ' is the relation,
whether the tones are sounded successively or together.
This closeness of relation is something quite different from
nearness of pitch. The smallest pitch difference in music is
the semitone, or minor second, which is the interval between
E and F and between B and C. But this interval, whose
ratio is 15 : 16, is musically the least close relation of all.
It is not easy to explain why these tone intervals affect us
as they do. The effect is probably due in some way to the
hair-cells and rods of Corti; but the full explanation is still
uncertain. However, we shall see why intervals bearing a
simple ratio are pleasanter than those expressed in larger
numbers, when we observe the effects of two or more tones
sounded at the same time.
Overtones and Timbre. When we strike a key on the
piano or blow a cornet, the sound waves are not simple.
Besides the vibrations depending on the length of the string
or tube, there are fainter vibrations corresponding to the
half-length, third-length, etc. When we pluck a violin string
it vibrates not only as a whole, but in half-lengths if it is
plucked one-quarter from the end, and in other part-lengths
according to the place where it is plucked. [Fig. 41.]
I
finDE
am t.*cB^jiriiiQiiiJiiDjiLTii^-^^^^ rQ ^ 1 ^
FIG. 41. How OVERTONES ARE MADE
The solid line is a violin string fastened at A and B. Pluck it 1/6 from the
end (at arrow) and it vibrates in thirds, besides vibrating as a whole. The
part-length vibration is the overtone or harmonic; it is fainter than the funda-
mental. ( The amount of ' waver ' is exaggerated in the figure.)
These lesser tones fuse with the main or fundamental tone,
and give it a richer effect. They are called overtones, because
they overlay the fundamental tone. The fundamental with
its overtones make a single sound, called a simple clang,
Overtones are responsible for our ability to distinguish
CH. v] OVERTONES AND TIMBRE 95
between different musical instruments. In some instruments
one set of overtones are more prominent, in others another
set. This is why we can readily distinguish a wind instru-
ment from a stringed instrument, even if they play the same
tune. This individual effect of each instrument is called its
timbre. The human voice has a great variety of overtones,
and each human voice has a timbre of its own. A well-made
tuning fork has practically no overtones; it gives the nearest
to a pure tone of any instrument.
Differences in timbre correspond roughly to the series of
tints in colors. They give us a variety of additional sensations
over and above the pure tones. If we take into account these
timbre differences, the number of different sounds that we
hear is many times greater than 11,000.
Difference Tones. When two tones are heard at the
same time they combine in such a way that their identity is
partly lost. This combination effect is called fusion. In
tonal fusion the tones do not merge together completely;
with practice either of the components can be picked out
from the total impression. Tonal fusion is due to a different
kind of collection of nerve impulses from that which occurs
in sight. When different colors stimulate neighboring parts
of the retina the sensations are distinct and the only modifica-
tion that occurs in the combination is the contrast effect.
When two tones (such as C and E) are sounded together,
you will be able after practice to distinguish along with them
a third tone, called the difference tone. Difference tones are
produced by the combination of the two sound waves not
by a third stimulus. They arise in this way: Suppose you
start with two tones almost alike say, one of 256, the other
of 257 vibrations. Then, once every second the two sound
waves will reinforce each other and make a louder sound; and
once every second the two forces will be working against
each other one pushing the particles forward, the othes
pushing them backward so that the result will be a softer
96 HEARING [CH. v
sound. This loud-and-soft effect constitutes a beat, and the
number of beats is always equal to the difference between the
vibration rates of the two tones. When a tuning fork of 256
and one of 258 vibrations are sounded together there will be
two beats every second; with forks of 256 and 266 there will
be ten beats every second, and so on. As the difference be-
tween the two tones is increased the beats increase in number,
till at length they become so rapid as to be indistinguishable;
instead of hearing beats we hear a deep tone, which is the
difference tone. The rate of a difference tone is always equal
to the difference of rate between the two tones which are
sounded together.
So then, whenever two tones differing by more than 16
vibrations are sounded together it is possible to hear three
tones two primary and one difference tone; and when three
tones are sounded together we may hear six three primary
tones and the difference tone of each pah*; and so on. The
primary tones and difference tones fuse together into one
complex impression. These complex sensations are called
compound clangs. A noise may be regarded as the limiting
case of a compound clang.
Difference tones help to explain the fact that simple ratios
in tone intervals are more pleasing than ratios expressed in
large numbers. For if the ratio of two tones is simple, the
difference tone will be proportional to the primaries: the dif-
ference tone of 256 and 320 is 64, which is one-quarter of 256.
But if the two tones are not in simple ratio the difference tone
will make beats or secondary difference tones with each tone
of the pair, and these again will make beats with the pri-
maries. In other words, if the ratio between the two is
not simple the result will be a conglomerate mass of jarring
vibrations an unpleasant noise, instead of a clear-cut com-
pound clang.
Intensity and Other Characteristics. Differences in in-
tensity or loudness of sound sensations are due to differences
CH. v] SOUND INTENSITY 97
in the force of the sound waves. The faintest audible sound
is produced by dropping a cork weighing 1 milligram l from a
height of 1 mm., the ear being 91 mm. distant. The upper
limit of intensity has not been determined; loud sounds tend
to become more and more painful, and in the end produce
actual injury to the ear-drum.
Very deep and very shrill sounds are usually not so loud as
those in the ' middle range ' that is, those within the com-
pass of the human voice. Middle-range sounds are also
easier to locate. A deep organ tone seems to fill the air. A
shrill tone, such as the chirp of a cricket, is thin and unex-
tended; it is difficult to determine the source unless we see it.
Sounds in the middle range of pitch can usually be rather
definitely located. The two ears assist considerably in this
determination. Sounds on our right give a louder effect in
the right ear than in the left. A sound in the medial plane
of the body is most difficult to locate correctly. Often a
noise that seems at first to come from in front is afterwards
found to be behind us.
Importance of Hearing. The tone series in hearing corre-
sponds to the series of pure hues in sight, and the timbre
series to the series of tints. There are about 11,000 pure
tones, as compared with only about 160 pure hues, and there
are far more grades of timbre than grades of tint, so that
altogether we receive a greater variety of simple sensations
in hearing than in sight. 2 On the other hand, visual sensa-
tions from different points of the retina do not fuse. They
are put together into all sorts of patterns, corresponding to
the objects which stimulate the eye; while auditory sensa-
tions give one single composite effect at any given instant;
so that the eye furnishes more detailed information of the
world about us than the ear.
1 One milligram (mg.) is about 15 thousandths of a grain avoirdupois.
1 In spite of the great number of shades, which increases the variety of
our visual sensations.
SMELL
[CH. V
The sense of hearing is chiefly important in two ways : (1)
Music adds much to the pleasure of life. The average human
being gets more happiness from singing, humming, and listen-
ing to music than from looking at landscapes and pictures.
(2) Spoken language is received through the ear. It is a
readier means of communication among human beings than
gesture or written language, which stimulate the eye. Be-
cause of this advantage, the evolution of hearing has been a
powerful factor in promoting communication and social life
in the human race and in developing the higher mental
processes (ch. xiii).
3. SMELL (OLFACTION)
Receptor and Stimulus for Smell. The organ for smell is
far simpler than either the eye or the ear. In fact none of
the other sense receptors begin to compare in complexity
FIG. 42. NASAL CAVITY AND OLFACTORY REGION
Vertical section of bead, viewed from front, passing through the rear part of eyeballs. The
olfactory region lies mainly at the upper end of the long narrow passages at each side of the cen-
tral vertical membrane (septum) of the nose. [From Wenzel.]
CH. V]
RECEPTOR AND STIMULUS
99
N
with the eye or the ear, except the receptor for the static
sense (p. 117).
The olfactory receptors consist of a number of spindle-
shaped cells, which are embedded in the lining of the nostrils. 1
They lie far back in the nasal passages. [Figs. 42, 43.] Each
olfactory spindle is connected with a fiber of the olfactory
nerve.
The stimulus for smell consists of very minute odorous
particles which em-
anate from various
objects (especially
organic matter) and
permeate the sur-
rounding air. They
sometimes travel
great distances. In
blossom-time we can
SCent the fragrance
rkf a rpuoh rnvliarrl
from afar. The
odor emanations are drawn into the nose in breathing. As
they pass through the nostrils some strike the olfactory cells
and stimulate them. The stimuli include many varieties of
particles which excite different kinds of nerve impulses in the
olfactory nerve. The process of stimulation is apparently
a chemical action. The neurons of the olfactory nerve start-
ing at the spindles carry the impulses to the olfactory center
in the brain.
Odors. Olfactory sensations are called odors. Although
the receptor for smell is simple, a great number of different
qualities can be distinguished. No complete list of odors
has ever been made, and their total number has not yet
been estimated. New qualities are often discovered when
1 The nose is not a receptor, like the eye or ear; it is part of the organ for
breathing.
FIG. 43. OLFACTORY CELLS
Section of mucous membrane within the nose, showing
olfactor y ^^ ( C ) and nerve fibers < N ) which connect
with them. SC = supporting cell. [Based on Piersol.]
100 SMELL [CH. v
we come across a new fruit or some new chemical com-
pound.
The odors do not form a simple series, like the color hues
or auditory tones. They fall into several groups or series,
and these are mutually related through intermediate odors.
Recent investigation shows that there are six distinct types
of odors: Fragrant, ethereal, foul, aromatic, balsamic, and
empyreumatic. [Table III.] A typical fragrant odor is
heliotropine. From pure fragrance there is a series of odors
becoming more and more ethereal, the odor of geranium being
about midway between. There is also a graded series from
fragrant to foul) and from fragrant to aromatic; and so for
other pairs.
TABLE III. CLASSES OF ODORS
Class Examples
1. Fragrant or flowery Heliotropine, Tonka bean
2. Ethereal or fruity Lemon, oil of bergamot
3. Foul or putrid Rancid cheese, carbon bisulphide
4. Aromatic or spicy Anise, pepper
5. Balsamic or resinous Camphor, turpentine
6. Empyreumatic or smoky Tar, pyridine
[After Henning, Zsch. f. PsychoL, 1915, 73, pp. 240-5257.]
The relations of odors are represented in the form of a
prism [Fig. 44], because the six types can be arranged as
corner points of three surfaces, with cross-series between the
diagonal corners of each. There are cross-series between the
fragrant and empyreumatic, and between the aromatic and
foul; and similarly for the diagonals of the other two surfaces
of the prism. 1 An interesting case is the odor at the inter-
section of diagonals. For example, the odor of parsley is
midway between fragrant and empyreumatic, and it is also
midway between foul and aromatic. The prism diagram
means that if you take samples of every different odor and
1 The prism is hollow there are no odors represented by points in the
inside.
CH. V]
ODORS
101
3.Fovil
arrange them in this way, there will be gradual changes of
odor as you sniff the samples in regular order in no case
will there be an abrupt change.
Intensity differences in smell depend not so much upon the
force with which individual particles strike the olfactory
spindles, as on the density of the
stimuli that is, on the number
of particles drawn into the nos-
trils at a time. With a uniform
rate of breathing the intensity of
the odor is greater according to
the density of the emanation
from the odorous substance. Dif-
ferences in intensity may be
tested by means of a series of
bottles containing some odorous
substance in different degrees of
dilution. The more concentrated
the solution, the more particles
will emanate from it, and hence
the greater will be the intensity of the sensation.
Intensity tests are also made with the olfactometer. [Fig.
45.] This apparatus consists of two parallel tubes, curved at
one end for insertion in the nostrils. Tubes lined with sub-
stances containing odorous particles are drawn over the
straight end of the olfactometer; the intensity of the odor
varies with the amount of exposed surface of odor-bearing
substance that is, with the length of the projecting part
of the odor-tube.
Either of these apparatus may be used to determine the
lower limit of intensity. The least observable intensity
varies widely according to the substance used; for mercaptan
it is about 0.000,000,043 mg. in a liter of air. This is one of
the lowest values : in other words, the smell receptor is more
sensitive to mercaptan than to almost any other substance.
4. Aromatic 5. Balsamic
FIG. 44. ODOH PRISM
Showing relation of the six types of
odors to one another. [Modified after
Henning and Titchener.]
102
SMELL
[CH. V
Importance of Smell. Much remains to round out our
systematic knowledge of smell. The reason for this back-
wardness is that smell plays a relatively small part in human
life. Pleasant odors are
sources of esthetic enjoy-
ment, and unpleasant
odors sometimes serve to
warn us of danger in the
environment. But smell
is not especially impor-
tant, like sight, hearing,
or touch, in extending our
knowledge of the outer
world. Man has not the
capacity for fine discrimi-
nation in this field. In
the dog, the deer, the ant,
and certain other species
the sense of smell is much
highly developed.
more
FIG. 45. OLFACTOMETER
The bent tubes at left are inserted in the nostrils.
Tubes lined with some odorous substance are drawn
over straight part of tubes at right. Amount of QdorS are the dog's chief
exposed surface is indicated on the scale. The up-
right screen conceals position of odor-tubes from clue in following a trail,
observer. , , .,
where men rely on the
sight of footprints, broken twigs, and other visual clues.
With man, smell is a luxury or an ornament, not an essen-
tial part of his life equipment.
Historically this sense arose in connection with the feeding
process. It is an offshoot of a primitive food sense, which at
some point in evolution divided into the two senses of smell
and taste. Like other senses, smell came in the course of
time to acquire new uses. The deer, for example, detects the
presence of enemies by their odors.
The three distant senses sight, hearing, smell fill some-
what the same place in the mental life of animals. So it
happens frequently that where one of these three senses be-
FIG. 46. TONGUE, SHOWING PAPILLA
Taste bulbs are located in the circumvnllate (C) and fungiform (Fu) papillae,
are found in the filiform (Fi) or foliate (Foi. [From Wenzel.]
None
CH. V]
IMPORTANCE OF SMELL
103
comes highly developed in a given species, one of the others
degenerates. This is the case with smell in the human spe-
cies. Sight and hearing overshadow it so completely that
we scarcely ever rely upon it for help in the important affairs
of life.
4. TASTE (GUSTATION)
Receptor and Stimulus for Taste. We come now to the
senses which are stimulated only by objects near our body or
in actual contact with it. These are called contiguous senses,
in distinction from the distant senses. Taste is the most
stay-at-home of all the external senses. The tastable sub-
stance has to get inside the mouth before it can become a
stimulus.
The receptors for taste are certain bodies shaped like bulbs
or flasks, which are inserted in the mucous lining of the tongue
and palate. [Figs. 46, 47.] These bulbs have a small open-
ing or pore at the
neck end, which re-
ceives the stimulus;
the taste cells lie in
the walls of the taste
bulbs. The stimuli
are always in liq-
uid form; solid sub-
stances are tasted
only when dissolved
by action of the sa-
FIG. 47. TASTE BULBS AND TASTE CELLS
Section of lining of papillae of tongue, showing taste bulbs
llVa. Fibers from (TB), with pore (P) at neck anH taste cells (TO forming
. l_ , , , . , part of the bulb; EC = epithelial cells. [Based on Piersol.]
three of the cranial
nerves connect with the cells in the taste bulbs at various
parts of the tongue and convey the impulses furnished by
the stimuli to a taste center in the brain.
Taste Sensations. Tastes and odors are often confused.
We imagine that certain substances have very pronounced
104 TASTE [CH. v
tastes, which in reality have no taste at all. This is because
much of the food which we take into the mouth consists of
odorous substances. We breathe while we are chewing, and
the odor-particles are carried out with our exhaled breath
through the nostrils. Naturally we associate the resulting
sensations with the food in the mouth, and regard them as
sensations of taste. The real nature of these sensations may
be determined by holding the nose while chewing, so that no
odorous particle can stimulate the receptor for smell. Such
a test will cause many surprises. It will be found that an
onion and a potato do not differ in taste at all; their tremen-
dous difference in odor has led us to imagine that there is a
difference in their taste quality also. Usually the sense-
impression which we derive from food is a mixture of various
sensations chiefly smell and taste, partly also touch and
temperature. This mixed sensation is called the flavor of
food. It is by no means easy to pick out its various com-
ponents.
The confusion between taste and smell sensations is respon-
sible for the prevalent belief that taste affords a great number
of different qualities. The most careful examination indi-
cates only four qualities in taste:
Sweet
Sour (or acid)
Saline *
Bitter
Some observers notice two other qualities, metallic and
alkaline; these are probably combinations of taste qualities.
The four simple qualities do not form a series. They bear no
special relation to one another except that sweetness con-
trasts to a certain extent with the other three.
Intensity differences in taste may be tested by means of
bottles containing solutions of some tastable substance in
varying degrees of concentration. The solutions are applied
successively to the tongue by means of a brush. It is rather
CH. v] TASTE SENSATIONS 105
difficult to compare two taste intensities, because the stimuli
tend to persist; it requires some ingenuity to remove a taste-
ful substance from the tongue quickly enough to compare it
accurately with the next stimulus. The least observable in-
tensity of taste differs widely for the four qualities. [Table IV.]
TABLE IV. LEAST OBSERVABLE INTENSITY FOR TASTE
Quality Substance Dilution in Water
Bitter Quinine 1 : 390,000
Saline Salt 1: 2,240
Sour Sulphuric acid 1: 2,080
Sweet Sugar 1: 199
[From Sanford, Exp. Psychol., p. 48, after Bailey and Nichols.]
Significance of Taste. Pleasant tastes or flavors add con-
siderably to the enjoyment of food, and unpleasant flavors
often enable us to reject what is unpalatable. On the other
hand, certain nutritious dishes may acquire an unpleasant
association through taste. If you were fed up with prunes as
a child, the taste of prunes will be disagreeable to you in later
life. Most of us have a distaste of this sort, often a loathing,
for certain articles of food which are by no means harmful
which in fact may be very beneficial. It is also true that
pleasant tastes or flavors are sometimes obtained from
unwholesome foodstuffs. Savages and civilized men alike
are prone to overeat of delicious substances which injure the
digestive organs.
The information about the outer world which this sense
gives us is of some value in life. Yet we cannot but imagine
that the taste sense would have been more useful if pleasant
and unpleasant tastes corresponded more closely to the
nutritious and harmful. On the whole, taste is probably the
least valuable of all the senses.
57. CUTANEOUS SENSES: TOUCH, WARMTH, COLD
Cutaneous Receptors and Stimuli. The outer surface of
the body is susceptible to several kinds of stimulation which
106 TOUCH, WARMTH, COLD [CH. v
are grouped together in popular language under the name of
' touch.' In reality there are different receptors for the
various stimuli, so that we are bound to treat the skin sensa-
tions as forming several distinct senses.
In addition to the touch sense, there are senses of warmth
and cold. These two are not merely different qualities but
separate senses, as is shown by a simple experiment. Mark
off an area 20 mm. square on some one's arm. Take a knit-
ting needle which has been chilled in ice-cold water, and
explore this area systematically, marking in ink each spot
which the observer reports as feeling ' cold.' When a com-
plete map of the cold spots has been made, explore the same
area with a needle warmed in hot water, and mark the warm
spots with a different-colored ink. The arrangement of the
cold and warm spots is found to be very different.
Every spot on the skin is stimulated by contact and gives a
touch sensation. But we find that certain spots give also a
pressure sensation distinct from contact. The arrangement of
pressure spots does not correspond to either the warm or the
cold spots. [Fig. 48.] This indicates that the three are
different senses.
If we examine the structure of the skin with a microscope,
we find several different kinds of corpuscles embedded in it
and connected with nerve endings. The most noticeable of
these in man are the corpuscles of Vater-Pacini, Meissner,
Krause, and Merkel. [Fig. 49.] Some of these types lie near
the surface; others lie deeper in the skin. It is believed that
these several types are receptors for different cutaneous
senses.
The receptors for touch, warmth, and cold are distributed
over the entire outer surface of the body. There are touch
corpuscles at the roots of the body-hairs; they are found also
in the eyeball, tongue, and other special organs. Some of the
inner organs are sensitive to contact and pressure but not to
temperature stimuli.
CH. V]
RECEPTORS AND STIMULI
107
The stimulus for touch is the con-
tact of any substance with the skin.
The stimulus acts mechanically
(not chemically) on the touch cor-
puscles. The warmth stimuli are
heat waves that penetrate the skin
and act on the receptors for the
warmth sense; in order to affect
these receptors the temperature of
the stimulus must be somewhat
higher than the temperature of the
skin. The cold receptors are af-
fected by stimuli that are colder
than the skin. The cold receptors
lie nearer the surface than the
warmth receptors and are more
readily stimulated.
Cutaneous Sensations. Each
of the two temperature senses has
one characteristic quality, called
warmth and cold respectively. When
the warmth and cold receptors are
stimulated together the result is a
sensation known as heat sensation.
The sense of touch has two ele-
mentary qualities, contact and pres-
sure; under special conditions of
stimulation touch gives rise to cer-
tain other quality effects. We
distinguish between sensations of
roughness, smoothness, moving con-
tact, moisture, and stickiness. The
sensations of tingling and itching
appear to be touch qualities; but
they are caused by stimuli within
FIG. 48. PRESSURE AND
TEMPERATURE SPOTS
Map of palm of left hand, showing
relative distribution of sensitivity to
pressure (A), warmth (B), and cold
(C). Same area is represented in all
three cases. In A the regions marked
black are relatively insemitire to
pressure. In B and C the areas
most sentilite (to warmth and cold
respectively) are marked in black,
less sensitive in lighter shading, etc.
[From Schaefer, after Goldscheider.]
108
TOUCH, WARMTH, COLD
[CH. V
the body and are possibly organic sensations. The peculiar
sensation known as tickle differs strikingly from most sensa-
tions, in that a very faint stimulus produces a very intense
sensation. The tickle sensation is probably due to a definite
s w.j n
FIG. 49. CUTANEOUS RECEPTORS
A. Vater-Pacini corpuscle.
B. Transverse section of same.
C. Meissner corpuscle.
D. Merkel cells in interpapillary epithelium.
E. Krause end-bulbs from human conjunctiva.
F. Free nerve endings in epidermis of rabbit.
N = nerve fibers.
touch stimulus applied to a very small area. The other
special touch qualities are due to spatial and temporal varia-
tions of the stimulus.
Differences of intensity may be examined in touch, warmth,
and cold by methods similar to those used in the higher
senses. The least observable intensity in touch is stated to be
CH. v] CUTANEOUS SENSATIONS 109
the contact of a cork weight of 2 mg. on the tip of the finger.
For the temperature senses the least observable sensation is
produced by a stimulus about one-eighth degree warmer or
colder than the temperature of the skin.
Importance of the Skin Senses. While the cutaneous
sensations furnish no great variety of quality, the fact that
their receptors are spread over the entire body gives them
great importance in life. Touch sensations inform us of the
location of things which press against the skin. They help
us considerably in acquiring knowledge of the shape and size
of objects, and in perceiving motion and other space rela-
tions (ch. vii).
Warmth and cold are far less significant than touch. They
rarely occur apart from touch sensations, and usually com-
bine with these, just as taste and smell sensations combine
together. The information which the temperature senses
give is useful so far as it goes; these senses are undoubtedly
more important for life than taste. It is interesting to notice
that warmth (and to a lesser degree cold) is in a rudimentary
way a distant sense. We feel the warmth of a glowing stove
at some distance, and we can sense the cold of ice before the
hand quite touches it.
8. ORGANIC SENSES (CCENESTHESIA, VISCERAL SENSES)
The Systemic Senses. We have examined the ' five
senses ' recognized by popular tradition, and in doing so we
have discovered two more warmth and cold which were
improperly identified with touch. All these seven senses are
stimulated by external objects and forces. They give us
information concerning situations and occurrences outside
our own body.
There are also two senses which inform us of conditions
within the body and of what is taking place there: (1) The
organic senses report the general condition and workings of
our organs of digestion and other internal organs. (2) The
110 ORGANIC SENSES [CH. v
pain sense reports injuries which happen to our body and
which may be due to either internal or external causes. The
two, taken together, are called systemic senses, because
they report events that occur in our bodily system.
Information about our bodily processes is quite as impor-
tant a factor in life as knowledge of the outer world. The
organic and pain senses do not deserve to be ignored as they
used to be. The student of psychology who insists on recog-
nizing only the traditional five senses ought to be inflicted
with a jumping toothache till he admits at least a sense of
pain.
Organic Sensations. The organic senses are extremely
difficult to investigate, because then- receptors lie buried so
deep within the body that they are generally inaccessible to
examination. Our knowledge of them is very imperfect.
Not only is it difficult to determine exactly the number of
different sensation-qualities that they furnish, but it is
uncertain how many of them have different kinds of recep-
tors and are really separate senses.
There are at least four important sorts of organic sensa-
tions: (1) digestive sensations, (2) vascular and respiratory
sensations, (3) generative sensations, and (4) feeling tone.
The first three are connected with the operation of the great
systems of life functions after which they are named. Feel-
ing or hedonic tone is apparently due to metabolic l conditions
within the body.
Among our digestive sensations the most easily distinguished
are hunger and thirst. Under careful examination the sensa-
tion of hunger proves to be a complex affair. It includes
hunger pangs, due to muscular contractions in the stomach;
appetite or craving for food, which sometimes occurs even
when the stomach is filled; general discomfort due to starva-
tion and depletion of the tissues. A distinct sensation quality
1 Metabolism includes various chemical changes, especially the destruc-
tion and restoration of tissue.
CH. v] VARIETY OF ORGANIC SENSATIONS 111
accompanies the satisfaction of hunger. Thirst is probably
due to drying of the mucous membrane in the mouth and
throat. Another digestive sensation is nausea, which has a
very pronounced quality. There is also a special sensation
in the digestive tracts due to distension of the stomach and
other cavities. Less definite sensations accompany the later
digestive processes in the intestines, bladder, etc. There are
also sensations connected with urination and defecation.
Associated with the digestive sensations is a sensation local-
ized in the abdominal region, which is stimulated under
emotional conditions of fright, anger, affection, etc. Al-
though the various sensations just described are all associated
with the digestive processes, they are due to distinct stimuli
and in some cases probably involve different kinds of recep-
tors.
The vascular and respiratory sensations are less varied and
much more obscure. The circulation of the blood is accom-
panied at times by distinctive sensations such as flushing,
heart quavers, throbbing, and tingling of the blood. Breath-
ing is often accompanied by an unnamed sensation of ' expan-
sion/ or its opposite, ' stuffiness.' Sensations from circula-
tion and respiration are present in states of trepidation,
anxiety, and panic. But for the most part the autonomic
bodily processes go on without any sensations except a
feeling tone.
The reproductive organs furnish a number of distinctive
generative sensations. These include the sensations of sexual
craving, sexual excitement, orgasmic sensations, and sexual
satisfaction. The generative system also contributes to the
general feeling tone of the body.
Feeling tone is a vague sensation which often accompanies
other sensations. It includes two opposite qualities, pleas-
antness and unpleasantness. It probably has no special
receptor of its own, but is due to certain characteristics com-
mon to all the stimuli which act upon the organic receptors.
112 ORGANIC SENSES [CH. v
The chemical (metabolic) changes which take place in the
body are of two opposite sorts constructive and destruc-
tive processes. New cells are built up and the wastage of
cells is restored; this process is called anabolism. Cells are
destroyed or impaired by use, giving the opposite process,
catabolism. The organic sense receptors are affected by
these two kinds of life processes as well as by their own
special stimuli. That is, organic stimuli, whatever else they
may be, are either anabolic or catabolic; so that any organic
sensation, besides having its own quality (hunger, heart
throb, craving, and the like), has also a, feeling tone, which is
pleasant if the stimulation is anabolic and unpleasant if it is
catabolic. Draw a series of slow, deep breaths and you will
notice a growing feeling of pleasantness in the region of the
lungs. Notice the gradual onset of unpleasantness which
accompanies nausea. In each case the feeling tone is differ-
ent from the special quality of the sensation.
The external sensations have a certain degree of feeling
tone also. Many sounds and tastes are noticeably agreeable
or disagreeable. A man will almost sell his soul for a lus-
cious peach, and sometimes he is quite ready to murder an
ear-racking organ-grinder. But in the external senses the
special quality of the sensation is so pronounced that the
feeling factor is usually of secondary importance. On the
other hand, most of our digestive and other organic sensa-
tions are observed chiefly as a feeling tone of pleasantness or
unpleasantness; their own special qualities are subordinate.
Besides the feeling tone connected with various senses,
we experience a feeling of general sensibility, or general feeling
tone, in the body as a whole. This general feeling varies from
time to time. It gives sensations of well-being, vigor, buoy-
ancy, repletion, drowsiness, discomfort, fatigue, weakness,
and the like. Our general feeling tone at any time is a highly
important factor in our mental life. The dyspeptic and the
athlete live in two very different worlds, even though they
CH. v] VARIETY OF ORGANIC SENSATIONS 113
room together. Our actions are not merely responses to the
' midst ' in which we are placed; they reflect our own organic
condition as well. We shall notice this especially when we
examine emotion and emotional attitudes (chs. ix, xv).
9. PAIN (ALGESTHESIA)
Pain Sensations. The pain sense is like the organic
senses in that it gives us information concerning the state
of our own bodily tissues and organs. But it is an independ-
ent sense; its receptors are different and it gives a quality
of sensation very different from the organic or any other
sense.
The pain nerves form an exception to sensory nerves gen-
erally, in that they are not provided with any special recep-
tors. Their endings in the skin are unattached and are
called free nerve endings. [See Fig. 49 F.] One might say
that they keep open house for any stray stimuli that are
wandering about in the body. This is true in a way, but it
needs qualification. There are no stray stimuli in the body,
except the overflow of very intense stimuli which are too
powerful for their proper receptors to manage. Very bright
light, very intense heat, give more energy than the receptor
for sight or warmth can absorb; the surplus energy spreads
destruction through the neighboring tissues. The free end-
ings of the pain nerves take up these vagabond stimuli and
the resulting nerve impulses travel up to special pain centers
in the brain.
Pain sensations have a distinctive quality of their own;
pain is pain, whatever its source. But there are many sorts
of pain, each of which bears the mark of its origin. We dis-
tinguish between scratches, pricks, stings, and sores (touch) ;
burns (temperature); stomach pains, nausea, intestinal
pains (organic); bruises and muscular soreness (muscle
sense). Certain eye pains are tactile; others are due to strain
of the eye muscles (muscle sense); occasionally eye pain is
114 PAIN [CH. v
due to intense light. Toothache is due to stimulation of
certain nerves which originate in the teeth. Shooting
neuralgic pains are apparently due to internal stimuli which
affect the nerves at some point in their course.
There is always a marked feeling tone of unpleasantness in
the pain sensation. The fact that pain stimuli are destructive
to the bodily tissues (catabolic) would account for this.
The connection between the pain quality and the unpleasant-
ness quality is so universal that we find difficulty in dis-
tinguishing them. It is much like the confusion between
tastes and odors, except that in the latter case we can readily
bring out the distinction by holding the nostrils closed. The
discrimination between pain sensation and unpleasant feeling
is not so easy. It requires considerable practice in observing
our sensations carefully before we can say, " This sensation is
unpleasant, but it is not a pain."
However disagreeable the pain sensations may be, the
sense itself is useful. It serves to warn us of dangers, both
outside and inside the body; it often enables us to avoid or
remedy harmful situations. In the course of animal evolu-
tion an elaborate system for receiving pain impressions has
been built up. In the higher species the pain sense is an
important factor in life. Far from making the responses of
dogs and other animals less suitable to the general situation,
pain sensations usually help the creature to do the best thing
in the circumstances. The same is true of man. It is a
mistaken psychological attitude to regard pain as an evil or
mental error. Pain is part of our equipment for meeting the
situations that confront us in life. It is an important factor
in adjusting our behavior to unfavorable conditions in the
environment.
10. MUSCLE SENSE (KINESTHESIA, KINESTHETIC SENSE)
The Motor Senses. We have examined the two great
groups of senses: those which give information concerning
CH. v] THE MOTOR SENSES 115
external objects, and those which report conditions within our
own body. We now come to a third group : the senses which
give information regarding our bodily movements and which
indicate the position of our body in space and the relative
position of its various members. For want of a better term
this group is called the motor senses, although they indicate
position as well as movement. The motor senses include (1)
the kinesthetic sense or senses, usually known as the muscle
sense, and (2) the static or equilibrium sense.
Muscle Sensations. Kinesthetic or muscle sensations are
obtained through sensory nerves which start in the muscles,
tendons, and joints. These nerves are provided with special
receptors which are stimulated by contractions of the volun-
tary (striate) muscles. The muscle sensations may be ob-
served by moving the finger, elbow, knee, eyelid, eyeball, or
tongue, and noticing how the movement feels; the sensation
is quite different in quality from the sensation of contact or
pressure. In certain diseases the patient is unable to feel
pressure, but has distinct sensations of movement; in other
cases the opposite is true. 1 This establishes the existence of
' kinesthesia ' as a separate sense or senses. It has not been
determined whether the tendons and joints yield different
kinds of sensations from the muscles. The term muscle sense
is commonly applied to the whole group of kinesthetic sensa-
tions.
These sensations give information not merely of bodily
movements, but of the position of our members in space, of
how they are bent, etc. When a member is held rigid in any
position, each of the antagonistic muscles is subject to a
certain amount of contraction; the two resulting sensations
taken together indicate the relative amount of muscular
contraction and hence the position of the member. This may
be observed if you close your eyes and hold your bare arm in
1 If you wake up at night with your arm numb, try to move it, and then
touch it. Is it the muscle sense that is benumbed, or touch?
116 MUSCLE SENSE [CH. v
some position where it does not touch the body, or if you twist
your neck to the right or left and keep it in this position; the
muscle sensations tell you what its position is.
Muscle sensations are usually reinforced by touch sensa-
tions, such as the scraping of the clothes against the skin, and
by indications from other external senses. When the eyes
are turned from side to side, the motion of the whole field of
objects across the retina brings about a general change of
visual sensations; in walking we have a visual picture of the
moving scene. These auxiliary motor indications from the
external senses (touch, sight, hearing) are not really kines-
thetic sensations, but they assist materially in the perception
of our posture and movements; they may be termed second-
ary motor sensations.
There are few differences of quality in the muscle sense.
When we are actively pushing or lifting a heavy object, we
obtain a sensation called effort; when a member is resisting
external pressure there is a sensation of strain. These sensa-
tions are assigned to the tendons. When the muscles have
been active for a long time there arises a sensation of muscu-
lar fatigue; this is possibly a form of feeling tone.
The intensity differences of muscle sensations are very pro-
nounced and are finely discriminated. A slight movement of
the finger or arm is readily observed; the movements of our
limbs are regulated very accurately by means of these indica-
tions. This may be easily tested by observing how many
different positions of one of your fingers you can discriminate
when your eyes are closed. The least observable difference of
position for the middle finger is found to be 1.
The muscle sense not only serves to inform us of our various
postures and movements, but it also gives information regard-
ing the weight of external objects. If we start to lift a heavy
suitcase or push a piano, the resistance which it offers checks
the speed of our muscular contraction; the intensity of the
muscle sensation is greater than when we merely raise the arm.
STATIC RECEPTOR
11. STATIC SENSE (EQUILIBRIUM SENSE)
117
B
Static Receptor and Sensations. The static sense is
another source of information concerning the position and
movements of our
body. It has noth-
ing to do with the
muscles and is en-
tirely distinct from
the muscle sense,
though the two
work together. The
static receptor is a
complicated struc-
ture in the inner
ear, consisting of
the semicircular ca-
nals and sacs. The
canals are three in
number, and are
placed at right an-
gles to one another
in three different
planes. [Fig. 50;
cf. Figs. 36, 37.]
They are bony in
substance, and in
shape resemble a
horseshoe. The ca-
nals are situated in
the labyrinth of the
ear, lying slightly
above and to the
rear of the cochlea.
K
FIG. 50. SEMICIRCULAR CANALS AND SACS
Section through vestibule of left ear. (Compare Fig. 37
for right ear.) Canals are shown above, the sacs in middle,
beginning of cochlea below. A = superior canal; B = pos-
terior canal; C = horizontal canal; D, E, F, = ampulla: of
three canals; G = utricle; H = saccule; I = oval window;
J = beginning of scala vestibuli; K = cochlear duct; L =
scala tympani, ending in round window beneath. [From
Wenzel.J
Each canal is filled with a liquid called
endolymph. Receptor cells with long projecting hairs line
118 STATIC SENSE (CH. v
the walls of the canals. The two sacs, the utricle and saccule,
are rounded protuberances situated in the vestibule near the
canals. They contain minute crystals called otoliths. The
canals open into the utricle; at the base they enlarge and form
the ampulla. The saccule lies just below the utricle.
The stimuli for static sensations are the flow or pressure of
the endolymph inside the canals, due to changes in the posi-
tion of the head. The otoliths in the sacs are also affected by
changes in the endolymph. The relation between the canals
and the sacs is not clear, but it is probable that the canals
give us information of motion and rotation, while the sacs
indicate the position of the head in relation to gravity.
Since the canals lie in three different planes, any angular
change whatsoever in the position of the head involves rota-
tion of at least one canal. When the head is turned horizon-
tally to the right, inertia causes the liquid in the horizontal
canal to circulate toward the left; when we turn the head
to the left the direction of circulation is reversed. If the
whole head is moved forward, backward, or to one side, as in
walking, the pressure at both ends of some canal is increased
or diminished. These changes in the endolymph stimulate
the sensitive projecting hairs and this excites the neurons
of one branch of the eighth cranial nerve the same nerve
whose main branch is used for hearing; the nerve impulses
are carried to the static center of the brain.
The canals were formerly supposed to be connected with
the sense of hearing. But it is found that when a pigeon's
canals are removed the bird is unable to maintain his balance
or regulate his flight. Tracing back the evolution of the two
organs in the animal scale, it is found that the static organ
arose before there was any sense of hearing; curious though it
may seem, hearing is an outgrowth or offshoot of the static
sense. In man and other high species hearing has developed
much further than the static sense and has far outstripped it
in importance.
The static sense gives sensations of position and sensations
CH. v] RECEPTOR AND SENSATIONS
of motion. In both cases the static sensation is so closely
bound up with muscle sensations and other motor informa-
tion that it is difficult to distinguish its own particular qual-
ity. The sensation of motion apparently differs in quality
from the sensation of position. The sensations from the
three canals may differ slightly in quality also. Nausea is
an organic sensation due to some connection between the
digestive organs and the static nerves. Dizziness is, in part
at least, due to eye movement.
The differences of intensity in static sensations may be
observed by lying flat upon a rotation table, with eyes closed,
while the table is turned at various rates of speed. The least
observable motion is a rate of about 2 per second, starting
from a standstill. The stimulus for static sensation is the
acceleration of motion, not its velocity. If we are rotated on
the table at a uniform rate, the sensation gradually dies away;
then if we twist the head in any direction the sensation im-
mediately starts up again.
Static sensations, muscle sensations, and the perception of
movements through sight and other external senses combine
to give us information of our bodily postures and movements.
This mass of motor information is the basis of our motor
adjustments and plays an important part in the formation of
our motor habits.
Significance of Sensation in Mental Life. It cannot be
too strongly impressed upon the student of psychology that
all eleven senses must be reckoned with. Of the five tradi-
tional senses, taste and smell are far less important in life
than the two motor senses and pain. It is especially useful
to keep in mind the three great groups of senses external,
systemic, and motor. 1 These three types of sensation bear
essentially different relations to mental life. They are the
basis of three different sorts of mental activity.
(1) The external senses furnish information which leads to
perception, remembering, and thinking; the sensations from
1 See Table 1. p. 58.
120 THE SENSES [CH. v
these seven senses make up our cognitive experiences, or
intellect the knowledge side of our mental life. (2) The
systemic senses furnish information concerning our internal
organic processes and bodily condition; they are the source
of our affective experiences our feelings. (3) The motor
senses furnish information as to the position of the various
parts and members of our body in space, and the direction and
rate of our movements; they are the basis of our active
experiences our will.
The separate sensations are not experiences; they are the
elementary bits of information which combine to make up our
experiences. Any conscious experience perceiving a land-
scape, the feeling of happiness, the sense of making a sweeping
arm-movement is composed of a number of separate sen-
sations which are combined together by the collecting of sep-
arate nerve impulses in the brain centers. Our various ex-
periences, taken together, make up our conscious mental life.
PRACTICAL EXERCISES:
22. Listen for difference tones and overtones on the piano (or some other
musical instrument) and describe the experience.
28. Observe the sensations of taste from various common foods while
holding the nose, and compare with the usual sensations.
24. Make a map of warmth and cold spots as described on page 109.
25. Compare three different sorts of systemic sensations, e.g., hunger,
general bodily fatigue, toothache.
26. Observe your muscle sensations (a) in bending the elbow and fingers,
and (6) in lifting a weight. Compare these with the accompanying
touch and pressure sensations.
27. Test your static sensations on a rotation table or in a swivel chair.
Spin on your heel (a) with head erect, (6) with head inclined to right,
left, or forward; observe the resulting sensations. Look in a mirror
on a moving train, shutting out direct sight of the landscape; observe
especially your sensations when the train starts or stops, and when
it goes round a curve. Report the results of these observations.
REFERENCES:
On the receptors: Ladd and Wood worth, Physiological Psychology, Part I,
ch. 8.
On sensations: E. A. Schaeffer, Textbook of Physiology, articles 'Cutane-
ous Sensations,' 'Muscular Sense,' 'The Ear,' 'Sense of Taste,' 'Sense
of Smell'; M. Greenwood, Physiology of the Special Senses, chs. 2-9.
CHAPTER VI
CONSCIOUS LIFE
Review. This is a good place to stop and glance back over
the ground so far covered. We started with the notion of
psychology as the science which investigates the responses of
living creatures to the stimuli that affect them. It includes
the study of the entire chain of events beginning with stimu-
lation and ending with responsive activity. These processes
are carried out by means of the nervous system and the recep-
tors and effectors which lie at either end of the nervous arc.
The whole series of events make up our mental life.
Any single episode in our mental life may be divided into
three successive stages: (1) We receive piecemeal impressions
from the outer world or from our own body. (2) We put these
detached pieces of information together and prepare to re-
spond in an orderly and appropriate way. (3) We send out
nerve impulses to the muscles and glands, which thereupon
perform the proper movements or reactions. 1 These three
parts of the process are called stimulation (or reception), ad-
justment (or integration), and response.
The first stage, receiving the separate bits of material
(sensations), was examined in the two preceding chapters.
The senses are the means by which all our impressions are
originally obtained. (There are also some secondary impres-
sions, memories, which are only indirectly due to the senses.)
The sense organs or receptors are stimulated by light waves,
sound waves, pressure, and other physical forces, and the
1 This sounds somewhat mechanical and artificial, because it attempts
to describe moving, flowing events in a piecemeal way. If you examine any
one of the pictures of a galloping horse which enter into a motion picture
scene, the horse's position appears ridiculous each momentary attitud*
u very different from your total impression of galloping.
122 CONSCIOUS LIFE [ce. vj
sensory nerves conduct the resulting nerve impulse to a
center in most cases to a brain center. In this way we
receive sensations.
Sensations would be detached, piecemeal experiences, if
the sensory impulses which cause them were not collected and
integrated in the brain centers. This is the second stage of
the mental process. In the next few chapters we shall see
how the separate elementary sensations are put together so as
to make actual conscious experiences. 1 Perceptions, memo-
ries, emotions, thoughts, and other experiences are such inte-
grations; they are due to the orderly combination of separate
sensations, and to various changes which take place in con-
nection with the combining process. We shall examine these
different sorts of experience in turn. But they will be easier
to understand if we explain first of all what is meant by con-
sciousness and how our conscious life is related to the working
of our brain.
Consciousness and Subconsciousness. Consciousness is
one of those notions that are perfectly plain to everyone, and
yet are not easy to explain. It is like the idea of beauty in
this respect. You know that a certain statue or painting or
symphony is beautiful; but you cannot describe precisely
what ' beauty ' is. One cannot inject beauty into a thing
with a syringe. Something in the make-up of the work of art
gives it the quality of beauty. Add a line, take out a line,
change a line in a drawing, and its beauty is gone; and yet
beauty is not a line or a group of lines.
Like beauty, consciousness is a quality or characteristic of
things it is not itself a concrete thing. Consciousness is
not something poured into the mind; it is a characteristic of
mental life. Given the proper conditions and there is con-
sciousness. Alter the conditions and there is no conscious-
ness just as in the case of beauty.
1 The third stage, the process of acting and responding, is treated in chs.
x-zil
CH. vi] NATURE OF CONSCIOUSNESS
Nothing has given more trouble to the beginner in psychol-
ogy than the notion of consciousness. The word itself is
mysterious and forbidding. 1 It is well to recognize this diffi-
culty at the start and try to get better acquainted with the
term.
To be conscious, means simply to have sensations and any
sort of experiences. You are conscious when you are receiving
impressions and putting them together into perceptions,
thoughts, and the like. When you are in a swoon or a dream-
less sleep and are getting no impressions, you are not con-
scious. In other words, consciousness is merely a shorthand
term used to express the fact that perceptions, thoughts, and
the like are part of one's personal mental life.
We are conscious only when stimuli start nerve impulses
and these impulses reach the brain. There are cases where
stimuli excite nerve impulses which do not reach the cortex;
in such cases we are not conscious, though the stimuli produce
important reflex results and consequently belong to the realm
of psychology. The reflex eye-wink is an example of this.
In many cases the sensory nerve impulses are integrated in
the brain centers and cause coordinated responses, yet the
impressions are not joined up with our general train of
conscious experiences. When we are walking with a friend
and are busy talking, we do not notice the objects about us;
yet we step up and down and avoid obstacles quite as well as
if we were fully aware of our surroundings.
Experiences which form part of our life of stimulation and
response, yet do not enter into our personal mental life, are
called subconscious. Our subconscious mental life is quite as
important for psychology as consciousness. The lower brain
centers are constantly receiving sensory impressions and
1 Some psychologists get around the difficulty by dropping the notion of
consciousness altogether and studying behavior. The result is a rather
fragmentary science. It is like trying to study art and ignoring the notion
of beauty.
124 CONSCIOUS LIFE [CH. vi
sending out motor impulses that are never associated with
our conscious life. Many of our thoughts and decisions are
determined in large measure by previous subconscious experi-
ences. All the activities of the nerve centers, whether con-
scious or subconscious, must be reckoned with in psychology;
they are all factors in determining our responses.
The Brain and Consciousness. The really difficult prob-
lem is not what consciousness is, but how it is related to
brain activity. In discussing each of the senses we traced the
course of the nerve impulse from the receptor to the center.
When an impulse in the optic nerve reaches the visual center,
we see. When an impulse in the auditory nerve reaches the
auditory center, we hear. And so for each of the other nine
senses. But just how the brain activity produces sensations,
memories, and other experiences is not known. 1
This much seems certain: Every single perception and
every step in our thinking means some definite nervous activity.
Our thoughts never for an instant proceed without brain
activity. If the brain is in any way impaired, thinking or
memory or perception or some other mental process is dis-
turbed. Insanity is caused by some injury to the brain.
Lapses of memory, swooning, sleep, are brought about by
temporary changes in the condition of the brain.
Psychology need not be tied to any special theory of how
brain and consciousness are related. But the facts just men-
tioned point to the conclusion that whenever we think or per-
ceive, our brain is acting in certain corresponding ways.
In other words, the psychologist can study his thoughts and
memories, his perceptions and emotions, in place of the cen-
tral nerve processes which accompany them. We have no
means of measuring brain processes as we can measure light
1 There are several theories which attempt to explain the relation. The
older view is that the mind is in the brain, and that mind and brain interact.
A newer theory is that thought and brain activity are really the same event,
observed in two different ways.
CH. vi] BRAIN AND CONSCIOUSNESS 125
waves or muscular contraction. The investigation of our
own experiences supplies this lack.
Self -observation. One of the most important things in
studying psychology is to examine your own experiences, or
states of mind. The basal facts of psychology were discov-
ered by men observing their own thoughts and perceptions,
and reporting what they observed. This method of study is
called self-observation, or introspection.
At first glance it seems simple enough to observe our own
experiences. We have them with us constantly and need
only direct our attention toward them. Yet when we try it
out we find that it is not easy to attend to our experiences
carefully and faithfully or to report our observations accu-
rately. The old error about the five senses persisted through
many generations. It was kept alive because men did not
examine their experiences carefully. They reported not
what they observed for themselves but what they had read
and heard.
Just as bad mistakes have been made in other sciences and
have retarded their development. In physics men persisted
in believing that heavy bodies fall faster than light ones;
in chemistry they stuck to the idea that there are only four
elements earth, air, fire, and water. These notions seemed
so self-evident that for a long time no one took the trouble
to put them to actual test.
In psychology the material is so very accessible that the
student is slow to realize that training is needed before he
can observe it properly. Some of the most absurd mistakes
in psychology examinations occur in answering questions for
which the student has the material right with him: for
instance, he has only to wink his eyes to observe after-
sensations. Casual or haphazard noticing of our own experi-
ences is not scientific psychology. Self-observation, as a
scientific method, means careful and often minute attention
to the flow of conscious experiences; it means also giving
126 CONSCIOUS LIFE [CH. vi
exact reports of our observations. Both demand considerable
training before the results are accurate. If the student has
carefully performed the practical exercises in the previous
chapters, he will already have advanced a considerable way
in the art of self-observation.
How Conscious Experiences are Formed. When sensory
nerve impulses reach the brain centers, they are combined
and altered in many ways before the motor nerve impulses
are ready to start a coordinated movement. When we enter
a shop our eyes are stimulated by many objects which give
us a great mass of color sensations. These elementary bits
of sensation are combined at once into vivid perceptions of
the various objects in the shop; the perceptions start a train
of thoughts and memories which continue until we decide
which way to turn and what things to examine and purchase.
Sensations are merely the bits of material out of which our
experiences are constructed. The quality and intensity of
the separate sensations depend on the nature of the objects
which stimulate the receptor organs, and on the nature of
the receptor organs themselves, far more than on the nervous
system and its activity. Certain visual sensations are ' red '
because red-giving light waves strike the eye and because the
retina is capable of distinguishing these rays from others.
Certain sensations are ' loud ' because intense sound waves
strike the ear and make the ear-drum vibrate vigorously.
This is true of all sensations.
But when we examine the experiences built up out of these
sensation elements the opposite is true. Their composition
depends far more on nervous processes than on the stimuli.
The nervous operations which result from the various
properties of nerve substance, 1 are the principal agencies in
forming our experiences. For instance, conscious attention
varies with nervous fatigue : fatigue of the nerve substance in
the brain means inattention; restoration of this substance
1 These were described in ch. iii; see pp. 44-48.
CH. vi] FORMATION OF EXPERIENCES 127
means attention. Memory or revival of old experiences
varies with the nervous operation of retention. Association
of ideas depends on nervous conduction. There are impor-
tant conscious operations, or mental processes, corresponding
to each of the principal properties of nerve substance (ch. iii).
Mental Processes: Impression and Suggestion. The
two most prominent mental processes are that we are im-
pressed by objects and events, and that one experience sug-
gests another. Impression corresponds to nervous excitation
and suggestion corresponds to nervous conduction.
Impression means that a sensation or some other experience
is aroused. It occurs when the central neurons are excited by
nerve impulses. You see this book you get a visual im-
pression of it. The impression is due to nerve impulses from
the eye which excite the visual center in your brain. Anger
is an experience that arises when nerve impulses from your
bodily organs and motor organs excite some of your brain
centers. And similarly for other experiences.
Suggestion is a form of mental association: one thought
passes over into another. The thought of peaches suggests to
me the island of Corfu, where I tasted specially delicious
peaches. The peach thought and the Corfu thought are
associated together; that is, the thought of peaches passes
over into the thought of Corfu. In terms of nervous activity
what happens is that the nerve impulses pass from one center
to another, where they assume a different form.
Revival and Attention. Revival and attention are two
other mental processes. Revival or memory corresponds to
the nervous process of retention. The set or trace left by
previous nerve impulses in the brain centers makes it possible
for these centers to be aroused later in the same way; the
form of the earlier impulse is reproduced because of the trace
which it leaves behind. Memory images are the conscious
experiences which arise as a result of this revival; they are
reproductions of earlier impressions. You remember a cer-
128 CONSCIOUS LIFE [CH. vi
tain birthday party because the brain centers which retain
traces of that group of experiences have been excited again,
renewing the experience to a certain extent.
Attention is related (inversely) to the nervous process of
fatigue. Some parts of an experience are more vivid than
others. When you are reading, the printed words are vivid.
Sounds that occur at the same time are not attended to;
the stimuli may be quite intense, but the experiences are not
vivid. The rubbing of your clothes and other incidental
stimuli are generally unnoticed. In reading you attend to
only a few words at a time; the rest of the page is scarcely
noticed. All this means that out of the many stimuli which
occur at any moment, only a few send impulses straight
through to your brain centers without hindrance; the others
are blocked by resistance due in part to fatigue or exhaustion
of certain synapses they are not attended to. The greater
the fatigue, the greater is the degree of inattention.
Attention means the focusing of certain impressions.
Other impressions that occur at the same time are out of
focus; they are said to be in the margin or fringe of conscious-
ness. The different degrees of vividness or focusing that
characterize the several portions of our total experience at
any given moment depend on variations in the chemical
conditions of the several neurons concerned. In other
words, the vividness of an experience depends not so much
on the strength of the stimulus, as on the condition of our
brain. Attention is partly involuntary and partly under
our own control. A very loud sound will force itself upon us
and drive all else out of the focus; on the other hand a faint
impression may be brought voluntarily to the focus if it is
of special interest; the football player sees distinctly certain
slight movements on the part of his opponents, which give a
clue to the play.
Composition and Discrimination. The third pair of
mental processes are composition and discrimination; they
CH. vi] MENTAL PROCESSES 129
correspond to the collection and distribution of nerve im-
pulses. The composition of sensations into larger experiences
occurs when the impulses from several distinct nerve paths
are collected together in a single center.
There are two different sorts of mental composition:
fusion and colligation. In fusion the elementary sensations
are so merged together that it is difficult to pick them apart.
The experience is a total consolidated effect. A typical case
of fusion occurs in musical chords. The stimuli for the chord
C-E-G are three separate tones. When they are all struck
together, the resulting sensation is a single, compound clang,
in which the three tones are so fused together that only a
practiced musician can pick out any one of them from the
harmony.
Colligation is another sort of composition, in which the
individual components keep their identity. It occurs notably
in sight. A painting does not appear to be a patchwork of
separate colors on a canvas; we see it as a single picture,
representing some definite scene. In colligation it is easy
to distinguish the different parts; they do not merge, as in
fusion, but appear side by side, as a pattern or picture.
Touch impressions generally unite by colligation; taste and
smell by fusion. Sensations from different senses, due to the
same object, fuse together. Fried mushrooms are round and
brown, odorous, sweet, warm, and soft; it is not easy to sepa-
rate any one of these sensations from the total effect of
a * luscious food.' A crowbar always looks heavy to you if you
have once tried to lift one. The fusion is so strong that the
visual and muscle-sense elements stick together even when
you look at it without lifting it.
Discrimination occurs when a nerve impulse in the central
region is distributed into two or more different paths. The
mental process is a separation of two or more elements in a
given experience. It is the opposite of composition. In
looking at a person's face we first see it as a single object.
130 CONSCIOUS LIFE [CH. vi
By the process of discrimination we pick oui the eyes, nose,
mouth, and other features. 1
All our experiences are made up of elementary sensations
which have been ' whipped into shape ' by these mental
processes. In examining the various sorts of experience we
shall have to refer constantly to these operations. They are
brought together in Table V, with the corresponding nervous
processes.
TABLE V. FUNDAMENTAL CONSCIOUS OPERATIONS
Conscious Operation Nervous Operation
Impression (sensibility) Excitation
Suggestion (successive association) Conduction
Revival (memory) Retention
Attention (vividness, focusing) Fatigue
Composition (simultaneous association) Collection
Discrimination Distribution
Transformation (mental chemistry) Modification
Kinds of Experience. Any definite state of mind or con-
sciousness is called an experience. When we look around the
room we get a distinct visual impression of the table and
chairs and floor and walls and various objects about us. This
composite experience is known as a perception; we perceive
the world as presented to us by the visual receptors 2 and
nerves. When we are ill at ease or in pain, the experience is
of a very different sort : it is called & feeling. Our motor senses
tell us how we move and how our body is placed; this type of
experience has no familiar name, because it is popularly con-
fused with volition.- Psychologists call it a conation.
Perceptions, feelings, and conations are three fundamental
sorts of experience. In each case the state of mind is made
1 Besides these six mental processes there is another called transformation
or mental chemistry. When several impressions combine together the result
is often quite unlike any of the components, just as the properties of water
are unlike those of the oxygen and hydrogen which compose it. Mental
transformation depends on the modification of nerve impulses.
2 Sounds are perceived through the auditory receptors. All the external
senses yield perceptions.
CH. vi] VARIETIES OF EXPERIENCES 131
up largely of sensations from one of the three great groups of
senses. Perceptions are composed chiefly of external sen-
sations; feelings, of systemic sensations; conations, of motor
sensations. There is another fundamental kind of experi-
ence called imagery, which is made up largely of memories
and other ideas. Memories are revivals of past sensations.
They are not directly due to present stimuli. When you
remember the scene at your last Thanksgiving dinner, the
experience is not a visual impression. The memory is
aroused by some sensory stimulus, but you do not at this
present moment se^ the table and cooked turkey and mince
pie which gave you the original experience. 1
Besides these four fundamental types there are several
important secondary kinds of experiences which are com-
posed of elements from two or more different sources. For
instance, an emotion is composed of sensations coming from
both the systemic and motor senses. When we are very
angry we have very intense organic sensations and very
intense muscle sensations. The experience of anger is a
combination of these two elements. The various funda-
mental and secondary experiences which occur in our mental
life, and the elements of which they are composed, are shown
TABLE VI. CLASSES OF EXPERIENCES
FUNDAMENTAL
Experience Dominating Component
Perception External Sensations
Imagery External Ideas
Feeling Systemic Sensations
Conation Motor Sensations
SECOND ABT
Experience Dominating Components
Emotion Systemic and Motor Sensations
Sentiment Ideas and Systemic Sensations
Volition Ideas and Motor Sensations
Thought and Language (Social) .... Ideas and Motor Sensations
Ideals Ideas; Systemic and Motor Sensations
1 Memory is discussed in ch. viii.
132 CONSCIOUS LIFE [CH. vi
in Table VI. We shall take them up one by one in the next
few chapters.
One thing should be constantly borne in mind when we
examine our experiences : our state of mind at any moment is
rarely a pure experience of a single sort. When we look at
the objects around us, our perceptions are always tinged with
memory or feeling; the paper-weight looks heavy, the razor-
blade looks painfully sharp. Our feelings are usually ac-
companied by some external impressions; and so on. But
every experience is composed largely of a certain type of
sensation (or ideas) or else largely of two types. A percep-
tion is an experience whose prominent elements are external
sensations; and so of other experiences. In every case certain
prominent ingredients fix the character of the experience
state; they are its dominant components.
Subconscious Experience. Many nerve impulses do not
reach the higher centers in the brain and do not give con-
scious experiences. Yet these subconscious processes may
be essential factors in our responses. When you are riding a
bicycle you are not aware of the static sensations from the
semicircular canals ; but these sensations of balance are occur-
ring all the time in the center for the static sense. They
start a constant succession of motor impulses to the muscles
of the arms and hands, which produce slight movements of
the handle-bar to right or left; these movements keep you
balanced and prevent the machine from falling over. How
you learn to make these adjustive movements need not be
discussed here. 1 The point is that you do make them with-
out being conscious of the action.
Sometimes we are confronted with a difficult mathematical
problem which we cannot solve. After puzzling over it for a
long time we drop it and go about some other business.
Then all of a sudden, without any apparent reason, the solu-
tion of the problem flashes before us when we are thinking of
1 See ch. xi.
CH. vi] SUBCONSCIOUS EXPERIENCE 133
something entirely different. The problem seems to have
been worked out subconsciously.
A clock strikes when you are reading and you do not
notice it. A minute or two later you recall that it struck
four times.
You meet a man a perfect stranger in some gather-
ing, and at once take a dislike to him. You cannot explain
this dislike for a long time. Finally you realize that he re-
minds you strongly of some one you know, whose person-
ality is distasteful to you.
You go out for a walk and take a certain path because of
the interesting scenery it offers. That is, you believe this
to be the reason for your choice. You return disappointed,
and suddenly become aware that you subconsciously expected
to encounter a certain attractive damsel on the way.
Sometimes immediately after waking in the morning I can
think of nothing but annoying blunders made by members of
the family or others perhaps months ago. This fault-
finding attitude is due to subconscious systemic sensations
of indigestion, not to anything in the external situation. On
first waking, the digestive conditions overweigh the objective
facts, and unwittingly control my thoughts, till I realize the
reason and see the absurdity of this attitude.
Instances of subconscious factors in mental life might be
multiplied indefinitely. Reasoning, memory, emotion, motor
coordination all proceed at times subconsciously. Often
these subconscious attitudes or processes are valuable
adjuncts to our conscious processes, as in the first example
given. In other cases they interfere with the normal opera-
tion of our mental life. This is particularly true of unpleas-
ant experiences or thoughts which we are ashamed of and
wish to ignore. We try to forget them, and we succeed so
far as our personal consciousness is concerned. But their
traces may persist in the subconscious framework of our
being. They crop out in unexpected and annoying ways;
134 CONSCIOUS LIFE [CH. vi
sometimes they are betrayed by slips of the tongue, disquiet-
ing dreams, or inexplicable actions.
Psychoanalysis. Attention has recently been called to
> this subconscious phase of mental life by the investigations of
Sigmund Freud and others who have followed his method of
investigation. These observers find that if you let your
thoughts proceed naturally, without repression or guidance,
frequently you will bring into the field of consciousness some
subconscious memories or tendencies of whose existence you
were not aware.
A certain man has an unconquerable repugnance to the
contact of fur. He is unable to explain it. Under expert
handling, a train of thought is started, beginning with the
idea of fur. He is led through quite a succession of memo-
ries, and finally recalls an incident of early childhood, long
forgotten, of being attacked by a shaggy dog.
This method of bringing the subconscious into the fore-
ground is called psychoanalysis. It has been used with good
effect by physicians to enable patients to conquer unreason-
ing fears and obsessions. Psychoanalysis is based on sound
psychological principles; for our mental life depends largely
on subconscious memory traces and on the attitudes which
they have developed. It is also a fact that when we dis-
cover the real origin of a baseless fear we can often over-
come it.
We must be cautious, however, in interpreting the results
obtained by this method. There is danger of carrying our
conclusions too far, as the followers of Freud have done re-
peatedly. Three great faults are found in the books which
treat of subconscious life from this standpoint:
(1) They convey the idea that the subconscious part of our
being is a very highly organized personality. Freudians speak
as if there were a subconscious person (the ' censor ') inside
us, who forces us to repress certain thoughts and desires.
As a matter of fact, the subconscious part of our personality
CH. vi] PSYCHOANALYSIS 135
is not nearly so well organized as the conscious. It is rather
a lot of independent, partly organized attitudes and tenden-
cies, which enter separately into our life. The ' fear of fur '
is one such tendency; the desire to meet a certain attractive
girl is an entirely separate tendency. Each of- these sub-
conscious motives works independently, not through a gen-
eral ' subconscious self.'
(2) There is danger also of forcing the interpretation.
Some writers become so fascinated with the notion of sub-
consciousness that they use it to explain everything. A lady
says to her physician, " Please do not give me big bills "
meaning ' big pills.' Immediately it is assumed that she was
thinking subconsciously of his high charges. It is more
likely that the letter ' b ' in ' big ' was carried over to the
next word and happened to make sense. Had she said ' pig
pills ' or ' pig bills ' the purely vocal nature of the blunder
would have been obvious.
We must be especially careful not to attach importance to
the symbolic interpretation which psychoanalysts assign to
dreams and trains of thought. They are usually far-fetched
or fanciful. In interpreting dreams they say that the sun
stands symbolically for the dreamer's father; a woman
dreamed of is symbolic of his mother or wife. A number
symbolism has been worked out which is as fantastic as that
of the fortune-tellers.
(3) Writers on the subconscious assign too much sexual
significance to the hidden motives of action. The generative
processes undoubtedly play a large part in human life far
more than we usually recognize. Civilized man has been
taught to repress his sexual feelings, and the result is to mag-
nify their importance in our silent thinking. But there are
other important factors in our subconscious life. Nutrition
is a powerful motive. The nutritive function dates back to
the very dawn of life long before there were two sexes.
Avoidance of pain and the urge toward general activity are
CONSCIOUS LIFE [CH. vi
also important motives of conduct. In studying mental life
we should not be prudish and ignore the sex factor; on the
other hand we must not be carried away by the zeal of uni-
form interpretation so far as to attribute every subconscious
motive to this one source.
These cautions are needed to-day because the method of
psychoanalysis has recently received considerable attention
and has been exaggerated and distorted. The method itself
is perfectly correct. By its use we can often arrive at a
knowledge of many factors in our subconscious life which
without it remain hidden: motives become clear which are
otherwise incomprehensible. The danger lies merely in
interpreting the results unscientifically. If the above cau-
tions are observed there is little danger of misusing psycho-
analysis. 1
Varieties of Subconsciousness. The term subconscious
experiences may be applied to several different sorts of events
in mental life. These fall into two classes: Subliminal con-
sciousness and subordinate consciousness.
. (1) SUBLIMINAL EXPERIENCES: These are due to stimuli
which are so Faint that the result falls below the threshold or
limit of consciousness; there is no conscious impression at all.
Or two stimuli may differ so slightly that we do not con-
sciously discriminate between them.
A laboratory experiment illustrates this. The Jastrow
cylinders are hollow cylinders of hard rubber with removable
ends, which can be readily grasped and lifted. [Fig. 51.]
In this experiment we take two of them and put weights
inside so that one is slightly heavier than the other, say 150
and 153 grams. If you lift first one, then the other, they
seem about the same weight.
1 An amusing satire on the method is contained in one of the Provincetown
Plays called ' Suppressed Desires.' One character dreams of a hen stepping
about; the interpreter declares she was subconsciously thinking of a certain
man named Stephen.
CH. vi] TYPES OF SUBCONSCIOUSNESS
137
FIG. 51. JASTROW CYLINDERS
Used to test the ability to discriminate
small differences in weight, by lifting or
by pressure on the skin. Shot is poured
into each cylinder till the desired weight
is obtained. When the ends are screwed
Now let the subject close his eyes and let the experimenter
give him one cylinder after the other to lift and compare;
let him judge (or guess) which
is the heavier. Repeat this a
large number of times, giving
him the two cylinders now in
one order, now in the other. If
the subject were merely guess-
ing, half of his answers would
be right and half wrong. But
it is found that in the long run
the subject will give decidedly
more than fifty per cent of right
answers, even though he may . the cyliBders look and feel alike.
believe he is only guessing. In other words, the slight differ-
ence between the two stimuli, even though it is so small as
not to be consciously noticed, has a real effect on our experi-
ences. It influences OUT judgments to the extent which the
percentage indicates.
Similar experiments may be made with pairs of lines that
are nearly equal, or with other pairs of slightly different
stimuli. The results indicate the presence of subliminal ele-
ments in our experiences.
Somewhat the same sort of elements occur in the ' margi-
nal ' portions of our ordinary experiences. When you look
attentively at any object the things at the far end of the
visual field are hazy and almost unnoticed. They may not
be quite subliminal, yet they do not enter into the general
picture as conscious factors. Or again, if you are reading,
the conversation and other noises about you are marginal.
In such cases the second stimulus is not necessarily very
faint, but the nerve impulses which it starts do not pene-
trate to the higher centers except in a faint degree. Their
passage is hindered by fatigue of the synapses, which is
equivalent to ' inattention.' Consequently the resulting
sensations in the higher, conscious centers are marginal
138 CONSCIOUS LIFE [CH. vi
(2) SUBORDINATE LEVELS OF EXPERIENCE: Here the
sensory impulse does not connect up with our present per-
sonal experience at all. Its effects are inhibited at the lower
center. The case of the clock striking without your noticing
it illustrates this; the original experience did not form part
of your personal field of consciousness, but it did belong to a
subordinate field of consciousness, as shown by the fact that
you recalled it afterwards.
In other cases the experience never gets to our personal
consciousness, and we are inclined to doubt whether the
effect is not purely ' physiological ' and unconscious. Some
morning when I am in my laboratory it begins to rain. I
wonder whether I closed my bedroom window before leaving
the house. Hard as I try, I cannot recall closing it. On
returning to the house I find the window closed. I did close
it, for no one else has been in the room. Did I close the
window consciously or not?
We may treat all such dissociated experiences as ' sub-con-
scious '; that is, they are of the same sort as our conscious
experiences, except that they are not part of our personal
conscious life ; they are experiences of our lower centers
not of the cortically organized self. It is helpful to regard
even pure reflexes, such as winking, as subconscious. This
view enables us to bring all experiences and all mental life
into one general notion. 1
Hyperesthesia and Anesthesia. Stimuli sometimes have
a more TntensiveTeffect than usual. This is called hyperes-
thesia. When we are in a high-strung nervous state we can
hear faint sounds which ordinarily would not be detected;
the sense of hearing is ' hyperesthetic.' Visual hyperesthesia
occurs frequently. A hypnotized person is able to distinguish
between blank sheets of paper, which look alike to the ordi-
1 In many text-books the reflexes and instincts are treated as purely
physiological activity and are not regarded as mental acts. This view is
admissible, but it limits the field of psychology unduly.
CH. vi] DEGREES OF SENSITIVITY 139
nary eye. Tell him that one sheet is a photograph of X,
another a picture of Y, a third of Z, and he will pick them
out correctly after they have been shuffled. This abnormal
discrimination is due to hyperesthesia: the hypnotic subject
is unusually sensitive to differences of texture in the blank
sheets. Certain persons can distinguish odors much better
than others. They are hyperesthetic in the sense of smell
as compared with the average man. When we are more sen-
sitive to touch or cold in some special locality of the skin
than elsewhere, it is called local hyperesthesia. A high-strung
person is apt to have hyperesthesia of all the senses that
is, general hyperesthesia. Both local and general hyperes-
thesia may be induced by stimulants.
The opposite of this condition is undersensitivity or hypes-
thesia. It occurs especially in fatigue. When the air is
laden with perfume in the blossom season we notice at first
the overpowering odor; gradually the odor becomes less vivid
and at length it may appear very faint indeed. In eating a
sweet dessert we find that the sweet taste becomes gradually
less noticeable. The same is true of other senses. These are
instances of temporary undersensitivity of the receptor. In
the same way the nerves may be temporarily impaired by
fatigue of the synapses.
The limiting case of undersensitivity is anesthesia, where
there is no sensation whatever. This occurs when a sensory
nerve is cut or a receptor destroyed. Anesthesia may also be
brought about by the action of certain drugs on the receptors.
Cocaine applied to the skin deadens the pain sense tempo-
rarily. We have practical demonstrations of this in the
dentist's chair. This condition is local anesthesia. The
numbness of the arm when we lie on it in bed is not a sensa-
tion but the absence of usual sensations; it is local tactile
anesthesia. Narcotic drugs, which act upon the nerves di-
rectly, produce general undersensitivity and sometimes gen-
eral anesthesia. There is general anesthesia in dreamless sleep.
140 CONSCIOUS LIFE [CH. vi
Hyperesthesia, normal sensitivity, undersensitivity, and
anesthesia really form a continuous series containing all the
various grades of sensitivity. Our degree of consciousness
and the tone of our experiences depend very largely on the
general condition and chemical changes of our body. Ill-
health, bad nourishment, drugs, impure air, result in unfa-
vorable physiological conditions of the bodily organs and
unhealthy chemical products in the tissues. These harm-
ful influences affect the nervous system and impair its ac-
tivities, so that the entire aspect of the world may appear
changed.
Relation of Sensitivity to Consciousness. The intensity
and vividness of our experiences depend on the nervous proc-
esses in the brain centers. These brain processes are deter-
mined by two separate factors: the activity of the receptors
and sensory nerves, and the conditions of the brain itself.
Suppose some one knocks on your door. In order to hear
the sound as the average person hears it, your ear and audi-
tory nerve must be in normal condition. You may be deaf
or hard of hearing; or you may have an unusually keen ear
or be keyed up. The way you hear the sound depends on
the condition of the ear and sensory nerves. The difference
in sensitivity of the receptors is the basis of the series from
anesthesia to hyperesthesia.
Now suppose your sense of hearing is normal and the
auditory impression reaches the center. Ordinarily you hear
the sound and say " Come in." But you may be busy read-
ing and not notice the sound. Or you may be drowsy or
asleep. If you hear the knocking plainly, you are conscious.
If you are inattentive, the experience is marginal. If the
knocking is loud and you do not hear it at the time, its effect
is subconscious it is an experience of your lower centers.
If the sound is very faint, the effect may be subliminal. That
is, your experience of the knocking depends not only on your
receptors but on the condition of your brain. This is the
CH. vi] SENSITIVITY AND CONSCIOUSNESS 141
basis of the difference between vivid consciousness, marginal
consciousness, and subconsciousness.
Summary. In the two preceding chapters we examined
the process of receiving information (sensation) and the
nature of the sensations in man. This chapter takes up
the question: "What happens when the sensory material
reaches the brain centers? "
One important result is that we receive the information.
That is, the man in whose brain the nerve impulses are going
on is conscious and has sensations and various experiences.
Consciousness means that the man is alive to his surround-
ings.
Still more important is the fact that the sensations do not
remain detached and unrelated. They are put together into
definite experiences. The piecemeal sensations are worked
into shape by a number of mental processes: impression,
suggestion, revival, attention, composition, and discrimina-
tion. As a result of this working over we have a number of
different sorts of experience perception, memory, etc.
which will be discussed in the following chapters.
In addition to our conscious or personal experiences there
are certain brain effects of which we are not aware. These
are called subconscious experiences. They are either (1)
subliminal, that is, too faint to be noticed; or (2) subordinate,
that is, they occur on a lower brain level and not in the
cortex. Our conscious experiences are also subject to changes
of vividness due to the condition of our receptors: hyperes-
thesia means a high degree of consciousness; undersensitivity
(hypesthesia) means a faint degree of experience, the limit
being anesthesia, or entire absence of sensation.
With practice we can learn to observe our own experiences
and note their characteristics. This method of studying
mental facts is called self-observation or introspection.
142 CONSCIOUS LIFE [CH. vi
PRACTICAL EXERCISES:
28. Examine your experience in trying to read when an interesting con-
versation is going on in the room. Describe the changes of attention
from one group of impressions to the other, and the marginal elements
of the experience.
29. Report your experiences in trying to listen to a lecture when you are
very sleepy. Note especially any fluctuations of attention, diffusion
of attention, snatches of anesthesia.
30. Describe some recent experience in which you have worked out a
problem subconsciously or performed some rather complex act sub-
consciously.
81. Describe any notable experience of anesthesia or hyperesthesia in
your recent life.
82. Examine one of your well-formed habits (e.g., dressing, eating with
table implements, taking a customary walk) ; what factors seem to be
(1) conscious, (2) subconscious, (3) absolutely unconscious?
REFERENCES:
On attention: W. B. Pillsbury, Attention.
On subconsciousness: M. Prince, The Unconscious.
On psychoanalysis: S. Freud, Psychopathology of Everyday Life.
CHAPTER VH
PERCEPTION
Nature of Perception. Perceptions are experiences due to
direct impressions from the external senses. This is slightly
narrower than the ordinary use of the term. It is all right in
offhand conversation to speak of ' perceiving a pain ' or
' perceiving the truth.' But when we study mental states
systematically, it is important to call different sorts of experi-
ences by different names: We perceive what is outside the
body, we feel what takes place within the body, and we
believe the truth of propositions.
Perception is the grouping together of various external
sensations 1 into a single, united experience. Your percep-
tion of this book involves putting together a large number of
sensations obtained through your eye and optic nerve. Each
letter on the page stimulates your retina at some point and
starts a nerve impulse along some of the optic nerve fibers
toward your brain. Hundreds of these impulses reach the
visual center at the same time and give separate sensations.
In the center the separate impulses are brought together by
the nervous process of collection, and the complex impulse
which ensues arouses a complex experience of the whole
printed page. The combining process is called perception;
the experience is a perception.
Our perceptions correspond very closely to the objects
which cause them. If your eyesight is good, the shape and
markings of the perceived book are very similar to the shape
and markings of the real book which lies beyond your eyes
1 An 'external sensation' is a sensation coming from one of the 'external
senses,' such as sight (see Table I, p. 58). The stimulus is outside our body.
The expression external sensation is short for externally stimulated sensation.
144
PERCEPTION
[CH. VII
FIG. 52. FILLED-IN
PEKCEPTION
Hold the book at a distance and the
outline of the letters appears complete.
The missing lines are supplied in per-
ception.
and furnishes the visual stimuli. This is true also of per-
ception by touch. We perceive the roughness of sandpaper
or of a gravel walk. Our experiences resemble the situation
in the world outside our body.
The correspondence between perception and reality is not
always perfect. We often have illusions in perception,
that is, things do not always appear as they really are. Some
of these illusions are very striking. In Fig. 52 we see per-
fectly clearly the entire outline
of the letters; we see lines where
there are no lines at all.
The lack of complete harmony
between the perception and the
thing perceived is not remark-
able when we consider the chain
of processes involved light
waves, retinal activity, nerve
impulses, central collection, and
other operations. It is like transmitting a telegram. You
write out the message in pencil, the telegrapher clicks it off,
the receiving operator hears a succession of dots and dashes
and typewrites the words in Roman letters. It is really
surprising that more mistakes do not occur in perception.
The exactness with which our experiences correspond ' to
reality is evidence of the high precision of our receptors and
nervous system.
Often our perceptions are more like the real object than the
sensations which compose the experience would lead us to
expect. For instance, if we tilt a book at an angle (like the
book shown in Fig. 56 J ) the four corners still appear as
rectangles, though the sensations taken by themselves would
make the page look diamond-shaped. The reason why the
corners look rectangular is that our perceptions include not
merely sensations but memories of other books we have seen
*P. 151.
CH. vn] NATURE OF PERCEPTION
145
FIG. 53. ILLUSION OF THE
CROSSES
The rectangular cross-lines either look
oblique or seem to swing into the paper ;
the oblique cross-lines look rectangular.
and handled in the past. These memory elements combine
with the present sensations, and since all books are made with
square corners the resulting per-
ception takes that form. This
tendency to interpret according
to*past experience is so strong
that in Fig. 53 the rectangular
cross-lines look tilted, and the
tilted lines look rectangular.
There are certain errors in
perception due to defects of the
receptors. If you are astig-
matic, everything looks some-
what distorted; if you are near-
sighted, objects at a distance
are blurred. You are quite
aware in such cases that your
perception is faulty. But there
are also errors in perception which one does not appreciate.
Certain objects are colored with ultra-violet or infra-red
light; we cannot see these colors because the retina does not
receive such rays. Ordinarily we see nothing of what is
going on inside our own body; but the X-ray penetrates
the tissues, and if our eyes were sensitive to the X-ray, we
could see through a human body almost as readily as
through a glass window. There are sounds in the world
about us which perhaps an insect can perceive plainly, but
which man cannot hear. The dog's perception of his master
by smell is incomprehensible to the human nose. We do
not perceive the earth's magnetic current directly at all.
It follows that our perceptions of the world about us are
not exactly like the real world. We are limited to material
that our receptors can take in. So far as we can perceive,
we generally perceive things in their real relations ; we inter-
pret our sensations truly, except for certain illusions based on
146 PERCEPTION [CH. vn
habit. The piecing together and interpretation of sensations
is due to the mental processes of composition, attention, etc.
(ch. vi). It takes place after the nerve impulses have
reached the brain centers.
There are quite a number of different ways of working over
the sensory material in perception. We shall discuss them in
the following order:
Discrimination
Perception of surfaces
Perception of depth
Perception of objects
Perception of time and events
a. Bigflfcflinfltinn | Weber's Law. Discrimination of two
things does not always mean that we consciously perceive
their difference. A very small difference between two sensa-
tions may lead to subconscious discrimination. When we
compare two lifted cylinders that are nearly equal in weight
there is some discrimination, as shown by the fact that con-
siderably more than half our judgments are correct, though
they seem mere guesses. 1 Our automatic balancing move-
ments when we ride a bicycle are based on subconscious dis-
crimination.
Conscious discrimination occurs when the nerve impulses
reach the higher brain centers in the cortex. We perceive a
difference of quality or intensity between two sensations
when the two sensory impulses are brought together in a
perception center of the brain, and the central impulse is dis-
tributed on the basis of this difference. Suppose you lift
two cylinders which are noticeably different in weight. The
two sensations are different, and this difference starts a motor
impulse in the proper channel, so that you point to the
heavier, or say, " the first is heavier," or respond in some
other discriminative way. You react discriminatively be-
cause you have arranged to do so beforehand, and because
1 Seech.vi,p. 137.
CH. vn] WEBER'S LAW 147
the motor paths from the brain centers are prepared to send
the impulses down to the motor organs. But whether you
will point to the first or to the second cylinder is deter-
mined by the difference between the two sensations and by
the central process of discrimination.
Considerable work has been done hi the psychological
laboratory on the perception of very small differences.
There is no special problem in distinguishing large differences :
when a thick cloud passes over the sun, we notice the darken-
ing effect at once. But if we are reading in the late afternoon
it often happens that we do not notice the growing dusk till
suddenly the strain of reading brings us to a realization that
the light has greatly diminished.
How much difference must there be between two things in
order that we may be able to consciously distinguish them?
This is an important problem in psychology, since it deter-
mines the number of different impressions we are capable of
experiencing. In the laboratory this is investigated by
taking two stimuli of the same sort and varying the inten-
sity of one (the other remaining constant) till we no longer
observe any difference between the two. Or, starting with the
two alike, we gradually vary the intensity of one till it is just
observably different from the other. This can readily be done
with any of the external senses; we can compare the bright-
ness of two lights, the loudness of noises, the intensity of
tastes and odors, the heaviness of pressure or lifting. 1
Experimental investigations show that the intensity of a
stimulus must be increased by a certain proportion of itself
in order to give a just observably different sensation. For
example, whatever the intensity of a light, it must be in-
creased by 1/100 of itself to appear brighter; pressure on the
skin (without lifting) must be increased by 1/20 to be dis-
tinguished; a lifted weight must be 1/40 heavier in order to
be noticeably heavier. This law of discrimination was first
1 The muscle sense belongs among the external senses in this respect.
148
PERCEPTION
[CH. VII
formulated by E. H. Weber in 1834, on the basis of his own
experiments, and is called Weber's Law. Weber's Law may
be stated in a simple form: Sensations increase in arithmetical
progression as the stimuli increase in geometrical progression.
Weber's Law as applied to sound intensity is represented
by the curve shown in Fig. 54. Here the fraction of increase
is 1/3 . For pressure and bright-
ness the curve is of the same
form, but it is much flatter:
each step requires less increase
in these senses than in hearing.
When two stimuli are nearly
alike our discrimination is often
influenced by inattention, dis-
tracting stimuli, and other fac-
tors; so that a large number of
experiments are needed to de-
termine the fraction of increase
exactly. But the fundamental
principle can easily be verified.
Compare the difference of
brightness in a darkroom lighted
first with one candle, then with
two; now compare daylight,
with daylight increased by
one candle. In the darkroom
comparison the difference ap-
pears very great, in the daylight
it is not noticeable. The differ-
ence between 3 oz. and 4 oz. is
very noticeable, while the difference between 4 Ib. and 4 Ib.
1 oz. is imperceptible. It is always the relative difference
not the absolute difference that we distinguish.
The fraction of least observable difference is called the
Weber Constant. The constant for various senses is shown
FIG. 54. CURVE OF WEBER'S
LAW
Form of the curve for intensity of
sound; the Weber fraction is 1/3. Just
observable increases of sensation are in-
dicated by equal distances along the X
axis at points Si, S 2 , 83, etc. Correspond-
ing values of stimuli are represented by
the lines Si R,, S 2 Ri, etc. For pres-
sure the Weber fraction is 1/20; the curve
it much flatter.
CH. VII ]
WEBER'S LAW
149
in Table VII. Weber's Law holds to some extent for dis-
crimination of duration and size as well as intensity. It does
not hold for least observable differences in qualities, such as
color hues and auditory tones.
TABLE VII. VALUES OF THE WEBER CONSTANT
Sensation
L.P.D. Intensity
Individual range
Visual (light)
0.01
0.015 to 0.005
Auditory (noise) ....
33i
(tones)
0.15
0.20 to 0.125
Olfactory
0.25
0.33 to 0.25
Gustatory
25
33 to 0.25
Tactile
05
0.10 to 033
Warmth
036
Cold
0.036
Kinesthetic
0.025
0.05 to 0.013
Each fraction denotes the proportion of the original stimulus which must be added to it in
order that the sensation may be just noticeably greater.
b. Perception of Surfaces. The perception of space rela-
tions includes two very different processes. One is perception
of the size and shape of objects that we see or touch. The other
is the perception of distance of objects from our body. The
former is called surface perception, the other is depth per-
ception.
Surface perception is much the simpler process. Objects
which we see, stimulate a great number of rods arid cones in
the retina, and the things which touch our skin stimulate
many different touch receptors. When the separate visual
(or tactile) impressions from all parts of the object are com-
bined together in the brain centers we get a perception of
something spread out before us. The question is, how we
come to perceive the various parts of any object in the same
relations to one another that they really bear. This really
involves three distinct problems. Take, for instance, touch
perception [Fig. 55]:
150
PERCEPTION
[CH. vn
(1) How do we distinguish two points A and B on the skin at all? Why do
they not fuse, like sounds?
(2) How do we perceive that a given point A on the skin is farther distant
from C than from B?
(8) How do we perceive that C and X are in different directions from A?
The same three questions come up in visual perception:
How do we distinguish different points, perceive their dis-
tance apart, and appreciate direction? Sight and touch are
the two chief sources of surface perception.
(1) First as to discriminatwn^Q^d^erent points. This is
due tosfighl dillerellL-cs Inthe receptors themselves. Each
rod and cone in the retina, each
touch corpuscle in the skin,
is slightly different from every
other and gives slightly differ-
ent sensations. These slight
differences are local signs (that
is, indications of locality) which
enable us to distinguish one
point from another. We can
think of them as the ' personal
touch ' which each receptor
gives to its stimuli, just as the
timbre of each man's voice has
its own individuality, which
enables us to recognize who it
is that is talking regardless of
what he is saying.
(2) The second question is
how we come to perceive cor-
rectly the size of objects and
their distance apart. Two fac-
tors assist us in getting our clue
to surface distances, (i) When objects move over the body or
before the eye, or the skin or eye is moved over stationary
FIG. 55. SPACE PERCEPTION
IN TOUCH
Arrows indicate direction in which
timulus moves over the skin. (See dis-
cussion in text.)
CH. vn] SURFACE PERCEPTION 151
objects, any given point on the object stimulates a number
of receptors in regular order. On the skin the points ABC...
K L [Fig. 55] are stimulated in succession, or else some other
series A W X Y Z L. We never get the sensations in a
Direction of Eye movement
FIG. 56. VISUAL SPACE PEBCEPTION
Dotted lines show paths of light waves from a point P on the book-cover toward the eye,
first spreading out, then brought together by the lens and focused at A on the retina. When
the eye moves counter-clockwise (in direction of lower arrow), the picture of P on the retina
moves clockwise (left-hand arrow) from A to B, C, D. (See discussion in text)
random, jumbly order, A K B L C. The same is true in
sight. The eye moves regularly; any given point (say, the
letter P in Fig. 56) stimulates the rods and cones of the retina
in some regular order, such as A B C D, never in random
order.
This means that any given point K on the skin or D on
the retina, which is situated far from the starting-point A, is
not stimulated by a given object immediately after A, but
only after a number of other points have been stimulated.
The same series ABCKorABCD occurs over and over
again, and this enables us to appreciate that B and C are
nearer A than are any of the points which are stimulated
afterwards.
(ii) The muscle sense aids greatly in building up our per-
ception of size. When we move the hand or the eye we get
muscle sensations. If the movement is quick, the muscle
sensations are more intense; the unusual muscular exertion
informs us that the starting and stopping points are farther
distant than the mere time would indicate. If the move-
152 PERCEPTION [CH. vn
ment is very slow, the muscle sensations are faint and the
distance is perceived to be small.
Our perception of the length of a line or the size of an
object, then, is due to these two factors : (i) the orderly suc-
cession of points on the skin or retina, with their distinguish-
ing local signs, and (ii) the intensity of the muscle sensations
which accompany the movements of our limbs or eyes.
(3) Finally the question arises, how we come to appreciate
difference in direction. Muscle sensations furnish the chief
information regarding the direction of lines and their curva-
ture, which is an important element in surface perception.
In Fig. 55 the points C and X are equally distant from A.
But the hand moves differently in the two cases, so that the
muscle sensations when we move from A to C are different
from the muscle sensations which accompany a movement
from A to X.
In sight this factor is even more evident. When we turn
the eyes upward the superior muscles do most of the con-
tracting; when we turn them toward the right it is one of
the horizontal muscles of each eye. The muscle sensations
in the two cases are different, and this difference of sensation
enables us to distinguish the direction of the two movements
readily. For diagonal movements one horizontal and one
vertical muscle come into play; we perceive the direction
according to the proportion of sensation from each muscle.
To sum up, surface perception includes three independent
mental acts: (1) We distinguish between different points and
parts of objects by means of local signs. (2) We perceive
their distance apart by means of the orderly succession of local
signs and by the varying intensity of the accompanying muscle
sensations. (3) We appreciate differences of direction by
means of the different muscle sensations which accompany
movements of the eye, hand, or other members. When we
look at things or touch them, we get these clues in addition
to the touch and visual sensations. They give us information
CH. vn] SURFACE PERCEPTION 153
which enables us to perceive objects as spread out in space
before us.
c. Visual Depth (Projection and Perspective). The dis-
tant senses give us information about things that are more
or less distant from the body. The stimuli come in contact
with the receptors, but the objects themselves do not.
When we see and smell a rose, stimuli from the rose affect
our visual and olfactory receptors; but the rose remains out
there on the stalk, some distance off. In such cases we per-
ceive the object " where it is " the rose does not seem to be
in contact with our eyes or inside our nostrils.
How is it that we see the rose projected out at a distance
from the eye, although our sensations are due to stimuli on
the retina? Perception of depth (that is, distance straight
away from the eye toward the horizon) is not due to local
signs; for the stimuli from all distances in the same line from
the eye strike the same point on the retina and bear the same
local sign. The same is true of hearing and smell.
Sight is far more developed in its space relations than the
other senses. We are able to distinguish very accurately the
distance of objects from the eye. We see a statue ' in per-
spective ' that is, the perception rounds out toward us in
curves like the real statue. What factors in the sensation
enable us to project our visual perceptions in this way?
Depth perception in sight is due to a combination of cer-
tain non-visual information with the visual sensations, just
as surface perception is due to the combination of local signs
and muscle sensations with the sensations of sight. Some of
the clues for perceiving depth accompany the visual sensa-
tions from each eye separately; we get them as readily when
one eye is closed. Other clues are due to the two eyes work-
ing together. There are six uniocular, and two binocular
factors.
(1) ACCOMMODATION SENSATIONS: The lens of the eye
bulges out when we look at objects close by, and flattens when
154 PERCEPTION [CH. vn
we look at distant objects. 1 Muscle sensations accompany
these changes of the accommodation muscle; the sensations
vary with the amount of muscular contraction. These
accommodation sensations are an important clue for percep-
tion of depth or distance away from the eye. When we focus
the eye for a given distance we get a certain muscle sensation
which tells us how far off we are focusing.
Accommodation sensations assist us only in determining a
limited range of depth distances. The lens of the normal
human eye is completely relaxed when we focus for about 6
to 10 meters (20 to 33 feet). There is also a near-by limit,
normally about 10 cm. (4 inches); we cannot squeeze the
lens sufficiently to get a clear picture of nearer objects.
Within these limits the changes of accommodation sensations
furnish clues which enable us to perceive rather exactly the
depth of objects. For perception of greater distances other
factors are needed.
(2) DISTINCTNESS: Owing to the dust in the atmosphere,
objects at a distance are not so distinct as those near by.
Objects seem close to us if their outlines are sharp and their
details are clearly marked off; they appear farther off as the
outlines and details grow more vague. Distinctness is an
important clue for depth perception, but it often gives mis-
leading information. We misinterpret distances when the
atmosphere is unusually clear or unusually dense. In Colo-
rado mountains thirty or forty miles away seem only a half-
hour walk. On a misty day objects look larger and farther
away than they really are. These mistakes of perception are
called illusions.
(3) SHADING : When light strikes the human face from the
right, the nose casts a shadow on the left cheek, the mouth is
in shadow, etc. Shading is a clue to the different distance of
various parts of an object from the observer. This factor
1 Stand close to some one, at his side, and observe the changes as he looks
near by and far away.
CH. vn] DEPTH AND PROJECTION 155
gives the finest of all depth distinctions. It enables us to see
objects in perspective and in relief. So powerful is its in-
fluence that we tend to interpret the flat surface of a painting
or photograph in terms of depth. Some objects in the pic-
ture stand out and others recede back from the canvas or
paper. In the theater, we perceive a cottage in the back-
ground at least two or three miles away, though we know
perfectly well that it is really painted on a stage curtain.
The illusion is irresistible if the curtain is seen through a glass
window; the glass makes the imperfections of the painted
curtain less apparent.
(4) SUPERPOSITION : If two objects lie in the same straight
line, the nearer one will hide part of the farther one. When
we see the outline of a house broken by a tree, the house
looks farther away than the tree. This effect, called super-
position, is of great use in perceiving the relative distance of
different objects from us. The illusion of perspective in
photographs and paintings depends largely on this factor.
(5) SIZE AND SHAPE OF FAMILIAR OBJECTS: Many of the
familiar creatures and objects around us are of a ' standard
size,' with only slight variations. Grown-up human beings
vary in height only a few inches from the average. When we
see a man, the size of the impression on our retina is a clue to
his distance. If the retinal picture is small the man looks
far away, if it is large he looks- near by. Houses differ
considerably in size, but the windows and the height of
the stories are fairly uniform; we appreciate the distance
of a house by means of this factor. And so of any familiar
thing.
This factor may give rise to illusions. A miniature house
on the stage is perceived as a full-sized house in the distance.
The shape of a familiar object also gives us a clue to its
position. Book covers are usually rectangular; when we see
a book lying before us whose cover has two acute and two
obtuse angles we project one of the acute corners farther
156 PERCEPTION [CH. vn
away from us than the other. [Fig. 56.] In paintings and
pictures the perspective effect is enhanced by this factor.
(6) RELATIVE MOTION: When we look out of the window
of a moving train, objects near at hand pass by much more
rapidly than distant objects. If we are standing still and
move the head to right and left the same thing happens. In
either case we get a clue of the distance of various objects
from their relative rate of motion across the field of vision.
For one-eyed persons this is the most important factor in
giving perspective to the landscape.
(7) CONVERGENCE: Focusing the two eyes upon a single
point is called convergence. When we look first at an object
some distance off and then at a nearer object in the same
direction, the eyes do not turn both together, as in ordinary
N
FIG. 57. CONVERGENCE OF THE EYES
When the eyes are fixed on a distant point F botli pupils are slightly converged
toward the nose, as shown in the upper figure. When we look from F to a point
N near by in the same direction, both eyes turn in toward the nose (converge
more), as shown in the lower figure.
movements. Either one eye remains fixed and the other
turns slightly inward (toward the nose); or else both turn
inward they converge. [Fig. 57.] Since the eye move-
ments in convergence are different from ordinary eye move-
CH. vn] DEPTH AND PROJECTION 157
ments, the accompanying muscle sensations are different.
They give us a clue as to the distance from us of the point
upon which the eyes are converged. This factor supplements
the various uniocular indications described above; but its
value is limited to distances of not more than one hundred
feet; beyond this there is practically no change in the angle
of convergence.
(8) BINOCULAR DIFFERENCES: If you hold a piece of card-
board between the two eyes with one edge toward you, the
left eye sees only one side of the cardboard while the right
eye sees the other; your two visual fields are different. If
you hold a ball near the eyes, the right eye sees a little farther
around it to the right than the left eye. Any rounded object
which is near your body presents a slightly different picture
to the two eyes. These two different pictures do not clash
as one would think; they combine into a single definite per-
ception, so that the object ' stands out in relief.' It looks
rounded out and solid.
The combination of binocular pictures may be studied by
means of the stereoscope. [Fig. 58.] In the holder of the
stereoscope, several inches from the eyes, is placed a card with
two pictures. The pictures are nearly alike, but not quite;
the left picture is the way a solid object or scene would look
to the left eye if it were some distance off the right is the
scene as it would appear to the right eye. By means of
prism lenses the two pictures are brought together in the
middle of the field of vision. One is seen by the right eye
and the other by the left, but we see only a single picture.
Examine a pair of stereoscopic photographs without the
instrument and notice how different some of the details are.
Yet when the two are combined in a stereoscope they give
one distinct picture, just as we would see a similar scene with
the two eyes in reahlife/
.
Howtfiese Clues are' tTsecf. Of the various sorts of clues
that enable us to see at a distance, only one (binocular differ-
158
PERCEPTION
[CH. VII
ence) is really a visual sensation. Some of the clues are
muscle sensations that occur at the same time as the visual
sensations and combine with them; and some are not even
sensations, they are memories of past sensations. The size
FIG. 58. STEREOSCOPE
Above, a stereoscope. Left eye looks through A at left-hand picture of card G in card -holder
F; right eye looks through B at right-hand picture. Prisms C, C' bring the two pictures to-
gether into a single view in the middle of the visual field. E = rod for sliding the holder to
and from the eyes. D = handle to hold stereoscope.
Below, a card with pair of stereoscopic pictures. Looking at the card through the stereo-
scope we see a single picture of a pyramid. (The two pictures in the_upper card G also com-
bine into a solid-looking picture.)
of familiar objects is a memory of many former perceptions
of these objects. When we perceive a tilted book as having
right-angled corners, the experience involves previous per-^
ceptions of books in many tilted positions. The memory
clues and muscle-sense clues are combined with the visual
sensations derived from the objects and the total effect is a
perception of things at a distance. The scene is projected.
It would be wrong to say that we first see things flat and
CH. vn] DEPTH AND PROJECTION 159
then correct this impression. The protective process is
immediate it is not an inference. We perceive the size and
tilt and depth of things at once. This is proved by experi-
ments with instantaneous or very short exposures. 1
It is difficult to understand how we come to have one single
perception, and not two, when each of the eyes has a retinal
picture of the entire field. This is partly explained by the
course of the optic nerve. At the optic chiasm [Fig. 27 2 ] the
fibers from the inner (nasal) half of each retina cross to the
opposite side of the brain; those from the outer half do not.
The fibers from the left half of each retina go to the left side
of the brain, those from the right half go to the right side;
so that two similar stimuli from corresponding points in the
two retinas arrive at neighboring points in the visual center
of the brain at the same time. Just how these pairs of cor-
responding central points are connected is not known. It is
a case of fusion, and is similar to the fusion of identical sound
impressions from the two ears.
It is also puzzling to understand how we see objects " off
at a distance " when the perception process actually takes
place in the brain. This much can be said about it: Pro-
jection is one of many ways in which the raw material of
experience is worked over and transformed. A ' projected
out ' quality is added to the various sensations that enter
into our experience of distant objects, just as a ' spread-out '
quality is added to the experience of visual surface. Our
projection of visual experiences means only that we project
most of these visual pictures beyond the visual picture of our
own body, which forms part of our visual world.
Projection in Other Senses. Depth perception and pro-
jection occur to a considerable extent in smell and hearing.
Odors are perceived not in our nostrils but in the rose or
1 Accommodation and convergence require time; these factors would not
occur in instantaneous exposures.
1 P. 66.
160 PERCEPTION [CH. vii
other outside object which is the real source of the stimulus.
Sounds are localized outside the head, often at a considerable
distance.
The actual distance of odorous objects or sounds is not
perceived so precisely as in sight. If we possess the sense
of sight we usually project odors into the objects that we see
and measure the distance of the source visually. The pro-
jection of sounds is assisted by training. Certain sounds
are ordinarily limited to a certain range of intensity. If
they are softer or louder than usual, we localize them far off
or near by.
The cutaneous senses (warmth, cold, touch) furnish a few
independent indications of depth and projection. If we hold
our hands near a hot stove we locate the sensation of warmth
outside the body toward the stove. Cold is similarly pro-
jected when we hold our hand near a cake of ice. Ordinarily
our eyes are open and there is visual projection also. But
even with closed eyes some temperature projection takes
place. In touch, which is well developed for surface percep-
tion, there is only slight projection.
Projection in touch usually occurs when a rigid object con-
nects the source of stimulation with our touch receptors.
When we write with a pen we feel the point of the pen touch-
ing the paper. When we cut with scissors the touch sensa-
tion is projected to the place where the cutting occurs. When
we walk we feel the soles of our shoes pressing on the ground,
and in using a cane we feel the tip of the cane where it touches
the pavement. Most singular of all, when we dig with a
spade we feel the impact of the spade underground when it
strikes a stone. 1
All this indicates that we have a general tendency in per-
ception to project a sensation as far out from the body toward
the source as the data warrant. Even our systemic sensa-
tions are projected from the brain centers to their source in
1 In these illustrations the word 'feel' means to 'have a perception.'
CH. vn] DEPTH AND PROJECTION 161
the receptors within the body; muscle sensations of effort
are often projected into objects, so that we are apt to endow
inanimate things (such as the wind) with muscular power
and strength.
The space perception of the blind is quite different from
that of normal men. Blind persons perceive lines and sur-
faces just as we do, except that they do not discriminate
nearly so finely. But (1) they perceive all sides of a solid at
once the back as well as the front; and (2) they do not
perceive objects in perspective.
A blind man perceives the shape of a ball by putting his
hands around it; his perception includes every part of the
spherical surface with equal vividness. To us, the farther
side is hidden and does not enter into the perception except
through memory images or touch, so that usually we perceive
only half the ball at a time. And so of objects generally;
the blind perceive them all around at the same time; ordi-
narily we do not. It is not easy for us to picture what this
means, because our space perception is so largely visual.
But if you close your eyes and examine objects by touch, you
can appreciate the blind man's kind of perception somewhat
better; when you handle a book or a ball you get as clear an
impression of the far side as of the side nearest you.
On the other hand, a blind person has no idea how anyone
can get perceptions of near and remote objects all at once.
Accommodation, shading, convergence, mean nothing to him.
To the blind, perception is largely an exploring process,
which takes time.
d. Perception of Objects. When a whole group of stimuli
affect our receptors at once, some of the resulting sensations
enter into the perception more clearly and vividly than others.
Usually there is a ' focus of attention ' comprising certain
elements that are especially clear; other parts of the percep-
tion are fairly vivid, while others are indistinct or quite un-
noticed. This unevenness in the perception is partly due to
162 PERCEPTION [CH. vn
differences in the intensity of the stimuli. A loud sound
usually occupies the focus of attention, while very faint
sounds which accompany it pass unnoticed. A bright-colored
pattern stands out prominent, while the dimmer background
is scarcely observed at all.
There are also differences of vividness in our perceptions
which do not depend on the intensity of stimulation. When
we look at a human face we do not observe each individual
feature distinctly. Usually the eyes, nose, and mouth are
most prominent, the ears and chin and the arrangement of
hair are noticed somewhat, while the curves and shading of
the cheeks may escape notice altogether. These differences
are due to attention and inattention that is, to the focus-
ing of certain nerve impulses and inhibition of others at the
brain centers, where sensations are combined into percep-
tions. The focusing process enables us to perceive objects
as units. The human face is seen as ' a face,' not as a mass of
separate features. In looking about the room you perceive a
number of objects chairs, tables, books, etc. each one of
which is focused as a distinct thing, with its individual fea-
tures more or less merged in the total perception.
The visual perception of objects is strengthened by im-
pressions from other senses. Usually objects about us stimu-
late several senses at once. An orange may affect the eyes,
the skin, the muscles, the nostrils, and the taste receptors.
We see, touch (or ' palp '), heft, smell, and taste the orange,
all at the same time. The various sensations combine into
one single perception a perception of the orange with its
many characteristics. This is object perception in its most
developed form.
Even when some of the characteristic sensations are lack-
ing we supply them through memory elements. In looking at
an orange we get an impression of its taste and heaviness.
An iron crowbar ' looks heavy ' ; an aluminium dish ' looks
light.' All our perceptions of objects in adult life are tinged
CH. vn] OBJECT PERCEPTION 163
with such memory elements, due to many past experi-
ences. 1
The practical importance of the non-visual elements in per-
ception is greater than we are apt to realize. We only
appreciate this when some of these elements are missing. In
certain abnormal mental conditions the muscle sensations are
cut off; the patient does not feel the resistance of objects that
he lifts or pushes. Nothing seems to have weight. In such
cases the patient declares that the things he sees do not ' look
real.' The whole world about him seems an illusion, because
his object perception is incomplete: the muscular sensation of
resistance is absent.
The way in which habit influences our perception of things
is brought out if we look at the landscape with the head upside
down. The horizon seems much farther off ; the sky coloring
near the horizon is more vivid. In a wrong-side printing of a
photograph the right-and-left reversal of buildings or animals
does not look strange because we are accustomed to see build-
ings and animals turned either way. But if printed letters
(especially handwriting) are reversed, they look very strange.
The script in Fig. 76 2 is almost impossible to decipher unless
you look at it in a mirror. This is because words are always
written in a left-to-right direction never from right to left.
The reversal of white and black also plays havoc with per-
ception it makes a familiar face quite unrecognizable.
[Fig. 59.]
A special problem in connection with object perception is
the number of objects that can be perceived distinctly at once;
not the total number of details noticed at one time (which may
be indefinitely great), but the number of vivid groups which
are marked off as separate objects. This is called the span of
attention. Experimental investigations indicate that the span
depends upon several factors. It is increased by voluntary
1 In perceiving Fig. 52 (p. 144) certain visual memories are added.
2 P. 290.
164
PERCEPTION
[CH. vn
PIG. 59. WHO is THIS?
Fix the white dot in the center stead-
ily for 60 seconds. Then look away
quickly to a white surface; a negative
after-sensation will appear, and there
should be no difficulty in recognizing the
portrait [From The Farm Journal.}
attention and diminished by fatigue. Under ordinary con-
ditions from six to eight objects are clearly distinguished
simultaneously. The number
may be increased with practice
to about fifteen.
Objects and Space. The
space" relullohs 61 our several
senses coincide. We feel (palp)
our hand in the same place as
that in which we see it. The
taste, touch, and warmth of the
steak we are chewing are all
localized in the mouth. Our
field of perception consists of
only one space, not of separate
spaces for sight, touch, and other
sensations. This is brought out
strikingly when the normal rela-
tionship of the senses is disturbed. If you look at your
hand through a reversing lens you feel the fingers in a dif-
ferent place from where you see them. In using a micro-
scope you push the slide in one direction to move the visual
field in the opposite direction.
The oldest recorded contribution to experimental psychol-
ogy, Aristotle's experiment, illustrates this. Aristotle noted
that if the middle fingers are crossed and a stick or marble is
placed between them (the eyes being closed), the object
appears double. This is because in ordinary experience the
far sides of these two fingers lie some distance apart and are
never touched by the same object.
Our integration of the clues from various senses into a
perception of one general ' space ' is the result of habit.
This can readily be verified. When we become accustomed
to using the microscope the direction of the slide's motion as
we see it, tallies with our sensation of muscular pull. One
CH. vii] DEPTH AND PROJECTION 165
who wears near-sight glasses has no difficulty in touching
objects in the exact place where he sees them, though when
he first wore glasses everything appeared slightly displaced.
That we can learn to combine properly our various space
perceptions even under most exceptional conditions, is proved
by Stratton's experiment.
Stratton wore a large reversing lens continuously for seven
days, removing the apparatus only at night, when his eyes
were kept bandaged. Seen through this lens the whole field
of vision was turned completely around, like the picture on
a camera plate. With respect to touch and muscle sense
his left hand was seen at the right side, his feet were above his
head, the lintel of a door was where the threshold ought to be.
At the end of the week he found that the space relations were
almost completely reintegrated to meet the new conditions.
He reached for things where he saw them and manipulated
implements properly. He felt his hands, feet, and body in
the same place and in the same relations as their visual pic-
tures. Only the position of the head, which had not been
seen during the experiment, tended to remain in its old
relations its localization was confused and vacillating.
e. Perception of Time and Events. Most stimuli persist
for some time, and the sensations which they produce persist
too. When you are looking at an object and it moves or disap-
pears or changes, the nerve impulses in the brain centers do
not immediately cease or alter all at once. There is usually a
certain period during which the old perception is fading away
and the new perception is beginning. In other words, suc-
cessive perceptions dovetail together; we perceive at one and
the same instant both the incoming and the outgoing events.
The ' now ' of perception is not the same as the physicist's
idea of ' the present.' It is not a thin knife-edge separating
the past from the future, but a fair-sized period of time.
The perceptual present, as it is called, 1 may cover as much as
1 It is also called the 'specious present.'
166 PERCEPTION [CH. VH
six seconds. All impressions within this period of time may be
present to you at once. This is what makes it possible for you
to perceive changes and events as well as stationary objects.
When you see a man running you get a series of visual sen-
sations of his various positions. These successive sensations
are all embraced in one perceptual moment, and they com-
bine into a perception of running. Examine the instanta-
neous photographs of a man walking. No one of them is
specially characteristic, and some look absurd. Your per-
ception of walking is an integration of the whole series; the
absurd positions are not noticed. The pictures of a man
jumping or of a horse galloping show this even more strik-
ingly. You have a very definite visual perception of the
act as an event, though every one of the instantaneous poses
looks unreal and ridiculous. The same is true of other com-
mon actions. Many activities of inanimate nature are per-
ceived as events rather than as a succession of situations;
the lashing of surf on the beach, the fall of a leaf, the flapping
of a sail, and the waving of a tree in the wind are perceived as
' happenings.'
In the sense of hearing, successive sounds tend to combine
into definite groups, particularly in music. A tune is com-
posed of a series of groups, each consisting usually of 3 or 4
successive tones. One tone in each group is accentuated in
some way : the accented tone may be louder than the others,
or it may be slightly prolonged, or the effect may be due to an
accompanying pattern (dum-da-da-dum-da-da) in the bass.
This grouping of sounds by accentuation is called rhythm.
Rhythm occurs in poetry as well as in music. Even when
there is nothing in the stimuli to cause it, we tend to perceive
sound successions in a rhythmic way. We weave a rhythm
pattern into the ticking of a clock and into the clicks of the
wheels on a moving train. We do not have to make an effort
to get the effect; it is difficult not to get it.
A musical tune is perceived as an event, just as visual acts
CH. vii] TIME PERCEPTION 167
are perceived as events. The rhythmic pattern is the basis
of the grouping, and the tone differences complete the effect.
The development of tune-perception may be observed in the
army bugle calls. When you first hear them, they appear as
mere tone-successions; one call seems scarcely different from
another. After a time the tattoo, reveille, taps, and other
calls acquire individuality, like the familiar visual objects
of every-day life.
Illusions. Our perception of the qualities and relations of
objects is remarkably exact. It tallies very closely with the
qualities and relations of the objects themselves far more
closely, indeed, than would be expected from a study of the
senses. The fact that the visual receptors are located in one
place, the auditory receptors in another, the taste bulbs in a
third, might lead one to suppose, if he had no senses of his
own, that a human being would see things in one place, hear
them in another, and so on. The fact that separate nerve
paths lead from each rod and cone in the eye and from each
touch corpuscle in the skin to the brain, and that the various
sense centers are some distance apart in the cortex, would
confirm this supposition. Yet the opposite is true. We tend
to group our sensations into relations just like those of the
objects which arouse them, and we project all our various
sensations visual, auditory, and the rest from any given
object into one and the same set of space relations. We
perceive it as one object.
Considering the intricacy of the perception process and the
number of factors involved, it is certainly not remarkable that
our perceptions are sometimes inexact that they do not
always show us the true relations of objects in the environ-
ment. Perception depends largely on habit, and when our
present sensations conflict with some firmly established habit
of receiving experiences, an ' untrue ' perception arises.
A perception which does not correspond to the actual situa-
tion in the environment is called an illusion.
168 PERCEPTION [CH. vn
The illusions that occur in connection with space per-
ception are especially interesting to psychologists. Some of
these have already been described. There are many others
which we notice constantly in daily life. If we look at a
motion picture taken from the front of a moving train, it is
difficult not to get the impression that we ourselves are
rushing forward. This is because ordinarily we get the
relative motion of objects only when we move. When we look
down from a tall building the people below seem very small,
because the superposition of nearer objects to which we are
accustomed is lacking, and this counterbalances the factor of
their known size. The objects seen in the stereoscope appear
large and distant, because the convergence sensations are like
those that we ordinarily get in looking at distant objects.
The bits of memory and imagination that enter into our
perceptions are often powerful factors in producing illusions.
How many readers on first looking over chapter v of this
book, read systematic instead of systemic^ sensations? You
imagined you saw the more familiar word. Mistakes in
printing are due to this principle. The printer's perception
of words in the copy is influenced by his memory pictures;
or accidental errors in composition are overlooked by the
proof-reader. Such mistakes occur in the most carefully
printed books. Fig. 52 is another variety of the same illusion.
It is almost impossible not to see the outlines of the letter
COME, even where they are actually missing.
Another class of illusions occur in pictures that can be
perceived in two different ways. This double interpretation
often occurs in geometrical patterns. Take the common oil-
cloth patterns in two colors. At times you see a figure of one
color on a background of the other. Then it changes about;
the second color becomes the pattern and the first is the back-
ground. Fig. 60 is a whimsical case of double interpretation.
Does the picture represent a rabbit or a duck?
Often this- sort of illusion results in, reversible perspective.
CH. vn]
ILLUSIONS
169
In Fig. 61 you can perceive the black faces either as under
surfaces or as upper surfaces of the cubes; in one case you see
seven cubes, in the other six. The cube in Fig. 62 appears
FIG. 60. DOUBLE INTER-
PRETATION
Is this a rabbit or a duck? [From
Jastrow, after Harper's.]
readily in two positions
either the lower or the upper
central point looks nearer.
With practice one can make the cube shift back and forth
FIG. 61. THE ILLUSORY
CUBES
How many cubes do you see 6 or 7?
[From Jastrow.]
FIG. 62. THE
REVERSIBLE
CUBE
Is the lower mid-
point nearer you, or
the upper?
FIG. 63. THE REVERSIBLE STAIRCASE
At first this looks like an ordinary flight of stairs.
By focusing on the upper jagged line (and pulling it
toward you) the staircase turns over and looks like
cellar stairs seen from underneath.
at will. The staircase [Fig. 63] is not so easy to shift. We
are more accustomed to see the upper surface of stairs than
170
PERCEPTION
[CH. vn
their under side. If we lived in cellars the reversal would
be easier. By recalling how cellar stairs look from under-
neath we are greatly aided in reversing the perspective; but
most observers report that the upper-side effect lasts much
longer than the other, even after practice.
Certain illusions are due to eye movements that are not
properly taken into account Jn perception. The muscle
MULLER-LYER ILLUSION
The distance between apex of left and apex of central figure appears longer
than that between central and right. The two distances are equal.
sensations report to us the actual movements of the eyes (or
their tendencies to movement), which may be greater or less
than the distances they are supposed to cover; and our per-
ceptions overestimate or underestimate the distances accord-
Fio. 65. HERING ILLUSION
The horizontal lines appear to bend apart in the middle. They are parallel.
ingly. In the Miiller-Lyer illusion [Fig. 64] the distance from
the left point to the middle point looks considerably longer
than that from the middle to the right; the two distances are
really equal. In the Bering illusion [Fig. 65] the two hori-
CH. vn] ILLUSIONS 171
zontal lines look ' bow-legged,' though they are really parallel.
The Zb'llner and Poggendorff patterns are illusions of the same
sort. [Figs. 66 and 67.]
When we look at the Miiller-Lyer figure, the eye does not
travel from apex to apex as we suppose, but from some point
FIG. 66. ZOLLNER ILLUSION
The horizontal lines appear to be slightly tilted the upper one slanting down to the right,
next slanting up, etc. They are all parallel.
inside the first angle to a corresponding point inside the
second, and then to a point inside the third. This makes the
left distance appear longer, because the eye travels farther,
with greater muscle sensations. (The eyes may not make the
actual movements, but there is always a tendency to the move-
ment and this is accompanied by muscle sensations, which
determine our appreciation of the distance.) In the Zollner
figure the cross-lines divert the eye slightly from the hori-
zontal path, so that the horizontal lines seem to tilt upward
or downward, as the case may be. The other illusions depend
on similar muscle-sense factors.
Relation of the Brain to Perception. Perception is a
higher mental process than sensation. Sensation is merely
the reception in the brain centers of nerve impulses from
the sense organs. Perception works this sensation material
into shape. It includes composition of sensations, focusing
172
PERCEPTION
[CH. vn
(attention to parts), revival of memory elements, and dis-
crimination.
The elements which make up our perceptual experiences
are chiefly sensations from the external senses, reinforced by
muscle sensations and memory ele-
ments. This material is put together
and modified by central nervous ac-
tivities, so that the perception cor-
responds more nearly to the general
situation in the outer world than the
separate stimuli dp.
The way in which the elementary
sensations combine into perceptions
depends largely upon the inherited
structure of our central nervous sys-
tem. Sensory neurons which lie near
together in the brain and readily
connect with a single higher path-
way, tend to furnish group impres-
sions. For instance, the optic nerve
fibers connect together in the visual
centers, so that all visual sensations
which occur simultaneously tend to
unite into a single experience. The
same is true of auditory impressions and other types. The
sight of a red disk, or the sound of a complex chord, belongs
to the simplest type of perception; this simple grouping of
sensations probably takes place in the primary centers. Per-
ceptions which bring various senses together, such as the im-
pression of a cold, heavy, glittering cake of ice, involve the
use of association fibers which gather the sensory material
from several primary centers into a higher center. This
results in perception of objects.
The natural grouping of impressions due to inherited
nervous pathways is supplemented by the retention of past
FlG. 67. POGGENDORFF
ILLUSION
The upper cross-line appears
to be the continuation of the line
starting at B. It is really the con-
tinuation of A.
CH. vn] SIGNIFICANCE OF THE BRAIN 173
effects and previous connections in the brain. Our percep-
tion of familiar objects and common events involves some-
thing more than present sensations; it includes the memory
of similar past experiences. Our perception of a friend's
face when we see it in full front, includes a vague impression
of his profile and the back of his head, due to memory. The
more frequently we observe the same object or occurrence,
with slight variations, the fuller and richer does our percep-
tion of it become. The absence of these memory elements
interferes with perception, as in the case of reversed hand-
writing.
The highest development of perception, then, depends (1)
upon the presence of a mass of inherited association fibers
connecting the various sensory centers in the brain, and (2)
upon the formation of definite nerve connections and paths
by means of these fibers, and the retention of such effects.
Training of Perception. The development of perception
proceeds in two opposite directions composition and dis-
crimination. (1) Perception enables us to grasp objects and
events as a whole. Common experiences are soon consoli-
dated in this way. We see a house as a single object. It is
something to live in. The front path is the means of reach-
ing the house; the steps are for climbing, the door is for enter-
ing the house. Each of these perceptions is associated with
some idea of possible action on our part. These associated
ideas make up the meaning of the perception. The impor-
tance of ' meaning ' is brought out strikingly in our experi-
ences with unfamiliar objects. The countryman tries to pull
or twist the door-bell button instead of pushing it. He does
not perceive its meaning.
(2) The second direction in which perception develops is in
giving emphasis to certain features at the expense of others.
We pick out this or that detail which relates to OUT own gen-
eral experience. The artist perceives at a glance some tech-
nical blunder in a painting which most of us never notice.
174 PERCEPTION [CH. vn
The ornithologist sees the nest in a high fork of a tree. The
expert proof-reader's eye sometimes catches an error on the
printed page before he has read a single word.
As our field of experience enlarges, our perceptions develop
in both these directions even without special training. We
learn naturally to see the things which bear on our own
interests, and to pick out details which have special signifi-
cance for us. The guide in the wilderness sees trail signs
which the ordinary traveler cannot detect even when they
are pointed out to him.
The need for training is rather in lines outside our own
interests. The child at the outset needs to be trained espe-
cially in the phases of perception which do not develop readily
under ordinary conditions. Sight is the dominant sense;
it needs less cultivation than any of the other senses. If you
compare a child's performances on the form-board [Fig. 68]
with that of a grown person, you will find that the child takes
much longer to fit the pieces into the right holes. Blindfold
the adult and you will find that he makes the very same errors
that the child makes with eyes open, and takes as long a time.
The touch perception of the adult remains immature, while
his visual perception has developed far beyond the child's.
This means that the average man's touch perception has not
been properly trained.
An important task in primary education should be to train
perception in touch, muscle sense, hearing, and other senses.
The child should be taught to discriminate and to build up
object-perceptions in these fields. The special problem is to
accomplish this without boring the child to train him
through play activities which keep his interest aroused. This
is the underlying principle of all kindergarten methods. The
Montessori system of primary education has been especially
successful here.
Systematic training of perception would benefit almost
every one in later life. Some of us are naturally slovenly
176 PERCEPTION [CH. vn
observers. If we realize this fault, the very realization is an
incentive to train ourselves in careful observation. Perhaps
we do not notice the color of people's eyes ; this is not impor-
tant, but it is often useful for identification. Make it a point
to note the color of every one's eyes for a while; once the
habit is formed it will be kept up automatically. And so of
any other detail. It is impossible to observe every detail in
the things about us and too great minuteness of observa-
tion is a waste of attention. But most of us err in the other
direction.
A noted conjuror tells how he and his brother made a
practice of running past a show window, and then trying to
describe as many as possible of the things displayed. Train-
ing of this sort would be useful to most persons. It fosters
habits of more precise observation and better retention.
Summary. In this chapter we begin the study of different
kinds of experiences. Perceptions are composed of a great
number of external sensations, put together so as to show us
objects and events in the world around us. The most impor-
tant process in perception is to get the spatial relations of
things to one another (surface) and to our body (depth or
projection). Perceptions are usually ' true to life,' but we
sometimes misinterpret the evidence, and this gives rise to
certain striking illusions.
PRACTICAL EXERCISES:
33. Examine how far your depth perception depends upon each of the
eight factors mentioned in the text.
34. Place several upright rods at various distances from your eyes. Close
each eye separately and observe the different effects; compare these
with the effect when both eyes are open.
35. Study a pair of stereoscopic pictures with and without the instrument.
Report the stereoscopic experience and its relation to the two separate
pictures.
86. Observe the motions of your hand when seen only in a mirror, e.g.,
in shaving, hair-brushing, or writing; report the nature of your diffi-
culties, and whether you can 'feel' your hand where you see it.
87. Test the 'staircase illusion'; note the eye movement, use of volition,
time, etc., in changing from one perspective to the other.
CH. vn] SUMMARY 177
38. Glance for one second at a shop window as you walk by. Write down
what objects you perceived. Repeat for several shops and note the
number of perceptions obtained for each.
REFERENCES:
On space perception and illusions: W. James, Principles of Psychology, chs.
19, 20; E. Mach, Analysis of the Sensations.
On Stratum's experiment: G. M. Stratton, in Psychological Renew, 1897,
4, 341-360, 463-481.
On illusions: E. C. Sanford, Course in Experimental Psychology, ch. 7;
J. E. W. Wallin, Optical Illusions of Reversible Perspective.
CHAPTER VIII
MEMORY AND IMAGINATION
Imagery. Human experiences consist largely of percep-
tions of the things around us and reproductions of these per-
ceptions. Our perceptions may be reproduced in the form of
ideas, when the external objects are absent. There are. tseo
stages in the growth of ideas: imagery and thought. 1 Images
appear earlier in evolution than thoughts and bear a closer
resemblance to the original perceptions. Mankind is capable
of several kinds of imagery:
Memory images
Imagination images
Anticipation images
Composite images
General images
Memory and imagination occur the most frequently and
are' very important in human life, especially among civilized
peoples. A memory reproduces more or less exactly some
former experience, while an imagination is unlike any previ-
ous perception. You remember what actually happened to
you; you imagine things that never happened to you before.
But imagination images are not composed of new material:
every part of the experience is the reproduction of some
earlier sensation; the originality consists merely in working
these bits together in a new way.
Some of our memories are also imaginations. We may
remember something we have already imagined, instead of
what we have already perceived. As children my chums and
I imagined a weird, fantastic vehicle called a Gobblestraw, in
which we fancied ourselves riding. To-day I can remember
1 Thought is a higher type and will be treated later (ch. xiii).
CH. vm] IMAGERY 179
this imaginary coach as well as any real carriage; the experi-
ence is a memory image of an imagination image, because
the vehicle never existed.
Anjmage is not *jftgyily , visual experience it may
belongto any of the senses or to several. We remember
tunes and odors. We can imagine hearing a friend say things
which he never actually said. In popular language the word
image isjisually applied to something visualized; in psychol-
ogy it is used in a broader way, tq include reproduced senaogy
The chief distinction between images and perceptions,
when we compare them as actual experiences, is a differgnce
in intensity. Memories are like the original perceptions so
far as qualities are concerned but they are ordinarily
much fainter. Compare your memory of a thunder-clap
with the real thing; or compare your memory of how your
room looks with the actual perception. The feeble intensity
of the image in each case is striking. We usually know at
once and without question, from the very nature of the
experience, whether it is a perception of something outside
our body, or merely a mental reproduction.
Images of systemic and motor sensations may occur as well
as images of external things. At times we have experiences
of this sort, but they do not count for much. This is because
we can usually arouse systemic and motor sensations, so that
we do not need to imagine or remember them. When you
imagine yourself getting angry you assume a certain bodily
attitude which arouses actual sensations of anger. If you
remember making a certain movement your muscles tend to
contract slightly and you get muscle sensations instead of
muscular memories. So it comes about that systemic and
muscular memories and images do not often develop into
important experiences. External stimuli cannot be so easily
controlled as our own bodily processes and muscular move-
ments; we cannot see or hear things unless the objects are
180 MEMORY AND IMAGINATION [CH. vin
there to stimulate our senses. This lack is met by the devel-
opment of imagery, which supplements our perceptions.
Nature of Memory. If some one asks you what you had
for breakfast this morning, you at once get a mental picture
of the dining-room with the table spread for the meal. At
each seat is a napkin in front, a fork and small plate to the
left, a knife, spoons, and a tumbler to the right. You picture
other definite details of the meal, including the taste of the
prunes, and the uncomfortable warmth of the coffee-pot
handle. All these items are part of your present experience;
but they are not perceptions. No such stimuli strike your
eyes or mouth at the present moment.
What causes the memory experience? It is started by the
question that was asked you. You heard the word breakfast.
The nerve impulse which brought up this word in your center
for hearing finds a path open into another center in your
brain, in which there are deep traces left by your breakfast
experience this morning. Because of these traces the nerve
impulse, when it passes into that center, takes a form similar
to that during the previous experience, when you were actu-
ally breakfasting; so that you have memory images like the
r perceptions which occurred at breakfast time.
Every memory, or at least every actual recollection, is due
(1) to traces left in the brain substance by past experiences,
and (2) to some new nerve impulse which enters the region
where these traces have been left, and causes activity of the
same sort as before. The two essential Jactors-in memory
(and in imagination as well} are relent ion and revival.
The popular notion of memory is that the image itself is
stored away in the mind or brain. This is not true, though
one can readily see how the notion arose; it is merely attribut-
ing to memory what actually occurs in perception. Objects
in the world about you continue to exist even when you do
not perceive them. You see the breakfast table, you go out
of the room, and when you return you see the table again;
CH. vin] NATURE OF MEMORY 181
it is there all the time. Men naturally assumed that mental
images continue to exist when we are not observing them,
just like objects.
The truth of the matter is that th jpcmnrv image does not
persist, but only the traces in the nerve substance. What
remains within the brain is not a picture of the object or event,
but a record. This lasting record does not resemble the object,
nor is it like the original sensation. It is analogous to a phono-
graph record, where the traces are not at all like the words or
music which they represent, but are capable of bringing about
a repetition of the words or music under proper treatment.
Like all analogies this is not quite exact. The memory image
is not produced by a needle or anything like a needle. The
truth is that the present nerve impulse is shaped by the traces
into the same form as the previous nerve impulse.
Besides (1) retention and (2) revival, there are two other
factors in memory: (3) location in time and space, and (4)
familiarity. These belong to memory alone, and distinguish it
from imagination and other sorts of imagery.
Location means that a memory is always given a more or
less definite setting in time and space. In the case of the
breakfast memory, your image is projected out from this room
into the dining-room of a certain building in this town (spatial
setting) and is projected back to this morning (temporal
setting). The recollection of my first trousers is definitely lo-
cated in a certain New Jersey village and in May or June of a
certain year.
The projection of memories is neither so definite nor so
instantaneous as the projection of perceptions. Often you
recall that you ' have seen this person before ' without any
clear idea of where or when it happened. In projecting a
memory image we fill in the intervening space and time
between ourselves ' here now ' and the original occurrence
* there then ' by means of clues, just as we use clues in
depth perception ; but memory projection is not so vivid nor so
189 MEMORY AND IMAGINATION [CH. vm
convincing as perceptual projection. When you look out of
the window, the tall tree you see is unmistakably just across
the street. When you look back at a certain conversation with
your best friend the time and space projection may be uncer-
tain it may have two or more possible locations.
The space location of memories is determined by several
clues, such as prior location, verbal associations, and accompany-
ing details. When you recall some incident of childhood you
locate the experience in your home town, because you have
already built up a set of memories in which your childhood
experiences are located in this place. Central Park is well
known to the New Yorker. He has assimilated it to a lot of
memory images. So when he recalls some event in a Central
Park setting, the prior localization enables him at once to
project the event into that place.
The memory itself may include some name which identifies
the localization. The word 'home' and the name 'Wool worth
Building ' are clues that enable us at once to project certain
occurrences into definite locations. These are verbal associa-
tions.
If we recall a town with picturesquely colored houses, the
coloring may at once locate the scene in Italy. If the houses
have curved roofs we project the memory to Japan or China.
The memory of salt, sea-weedy odors will place the scene on
the sea coast. Any such accompanying detail may serve to
locate the memory image in space.
The time location of memory is also determined by a num-
ber of clues. Among civilized races verbal associations are
usually the most important indication. The calendar, with
its system of days, months, and years, assists us to project a
memory back to the proper time. If I recall the conference of
psychologists when America entered the World War, I can
easily fix the time by the calendar date, April 6, 1917.
Often we have a succession of memories connected together.
They occur in a certain order and the series appears in a time
CH. vin] NATURE OF MEMORY 183
'perspective which is not unlike the space perspective of percep-
tions. We recall the progress of a Presidential campaign in
this way the discussion of possible candidates, the nomina-
tions, the principal addresses, and finally the election. The
natural sequence of these events enables us to arrange the
memories in perspective.
X ^ Even where there is no chain of memories, the change of
conditions in the world is frequently a decisive clue. Your
memory of a conversation with some one who has died, is
projected back to a time earlier than the date of his death.
When you recall some childish question of an old friend, the
memory of his piping voice or his knickerbockers fixes the
incident in boyhood days. My memory of a visit to the
Windsor Hotel in New York jumps back at once to a tune
before that hotel burned down, though it seems much more
recent.
A sense of familiarity is the mark that distinguishes memory
most clearly from other kinds of imagery. There is a ' sense
of realness ' about a memory which is lacking in a mere thought
or imagination. In picturing the breakfast incident there is a
feeling that it really happened that the situation actually
existed in the physical world and is not imaginary. This
feeling can be readily observed in any memory a lecture you
heard last week, a street scene some tune ago, an incident of
your childhood.
The feeling of familiarity may be explained in terms of
nerve activity. It is due to the traces retained in the brain
substance. When a nerve impulse enters the brain centers it
encounters less resistance if there are definite traces in these
centers than if it has to make a new path. This ease of
passage through the synapses is what gives us the feeling of
familiarity.
There are also feelings of familiarity associated with our
perceptions: they occur when the same thing is seen or heard
repeatedly. On returning to a town after an absence the
184 MEMORY AND IMAGINATION [CH. vin
place looks familiar. We recognize our friends because we
are familiar with their features. Certain tunes are familiar
because we have heard them over and over again. Even a
stranger may look familiar to us because he resembles some
one we know. In all such cases the feeling of familiarity is
due to the traces of similar past experiences which unite
with the present impression. The perception process is
easier because of these traces. Recognition depends on ease
ofjngxvous ^ conduction. In recognizing persons we may not
recall definitely any incident connected with them; the
familiarity feeling in perception is merely a vague memory
element added to the sensations which make up the percep-
tion.
Recollection. Memory images are aroused by nerve
impulses passing into some brain center and taking the form
of the traces which have been left in that center. The result
is that we have an experience resembling a former perception;
we remember or recall the past experience. The question
remains, why we recall one incident rather than another.
A little while ago some one spoke of Paris, and I immedi-
ately remembered standing on the corner of the Rue de la
Paix last summer looking at the Vendome Column. Why
was that particular scene recalled, rather than some other
part of the city?
The real explanation is that the nerve impulse which
arouses the recollection passes into one center rather than
another because the resistance is less in that direction; and
the degree of resistance is determined by the amount of
retention, fatigue, and other nervous conditions. We can-
not study these nervous conditions in the brain directly, but
we can observe their results by examining our own experiences.
We can notice what sorts of memories are aroused by various
sorts of perceptions and other memories. This study has led
to the formulation of certain fundamental principles which
are called the laws of association, because the most impor-
CH. vm] RECOLLECTION 185
tant thing in recollection is successive association or sug-
gestion.
The discovery of the laws of association was one of the
earliest accomplishments of psychology. Aristotle, the
father of the human sciences, took up the problem nearly
2300 years ago and concluded that association proceeds
according to three principles : Similarity, Contrast, and Con-
tiguity; that is to say, a perception or idea calls up an idea of
something which either resembles it, or is in striking contrast
with it, or was formerly near it in time or space. Since Aris-
totle's time it has become evident that contrast is not a real
principle of association. Black does not suggest white much
more readily than it does blue; any color may suggest any
other through general similarity because they are all colors.
A giant does not suggest a dwarf unless we have seen a giant
and a dwarf together, and this is a case of contiguity.
The two remaining principles, Similarity and Contiguity,
have been confirmed as fundamental laws of association.
Memories, imaginations, and thoughts are aroused either (1)
through their resemblance to what we are perceiving or think-
ing about at the time, or (2) through having been previously
a part of some similar experience or closely connected with it.
When you see a stranger and are reminded of some one you
know, it is because the stranger looks like your friend or acts
like him similarity. When you hear the name of Abraham
Lincoln and think of the Emancipation Proclamation it is
because the two ideas have been closely connected together
before. The thought of Paris led me immediately to remem-
ber the Vendome Column, because the Column was part of
my former experiences of Paris.
Contiguity and similarity are not independent principles:
they work together. The stranger resembles your friend; but
when you recall your friend, your memory picture includes
some features in which he is unlike the stranger. These are
recalled by contiguity. It is more exact, then, to regard the
186 MEMORY AND IMAGINATION [CH. vm
law of similarity and contiguity as a single principle, though
usually one of the two factors is more prominent than the
other.
LAW OF SIMILARITY AND CONTIGUITY: An experience tends
to recall another experience which resembles it in part, the
dissimilar elements being such as were closely connected
with that other experience in space and time.
We have still not answered fully the question raised at the
outset why this particular memory or thought is aroused
rather than one of a dozen others. Many persons you know
are more or less like the stranger why do you recall just
this one of your friends? You have heard of many things
connected with Lincoln. Why do you recall the Proclama-
tion? The law of similarity and contiguity does not explain
the facts completely. It must be supplemented by certain
other principles, which are called quantitative laws of associa-
tion. There are three important quantitative laws which
determine the selection of ideas: frequency, vividness, and
recency.
(1) LAW OF FREQUENCY: An experience which has been
repeated many times tends to be recalled as a memory or
thought more readily than an experience which has occurred
in the past only once or a few times.
We recall the name or looks of a friend much more readily
than we recall a stranger. The same law holds for verbal
memory; we tend to recall far more readily phrases we have
memorized than those we have heard only a few times. The
law may be explained in terms of nerve activity: Repetition
improves the synaptic connections between neurons, and
this facilitates thereafter the passage of nerve impulses along
the same path.
(2) LAW OF ORIGINAL VIVIDNESS: Among alternative ideas,
any one of which might be recalled, that particular one tends
to be suggested which was more intense or vivid when it
occurred originally as a perception or thought.
CH. vm] RECOLLECTION 187
We tend to recall more readily an important or thrilling
experience than one which we did not attend to; vivid
thoughts and clean-cut phrases are most apt to be recalled.
The explanation is that an intense nerve impulse tends to
leave a deeper trace in the neurons through which it passes,
and this makes these neurons more fit to receive future
impulses.
(3) LAW OF RECENCY: A recent experience is more ap^to be
recalled than an experience which occurred some time ago.
We recall many more events of the past week than occur-
rences dating back a year or ten years. This is because a
nervous path which has recently been used is more passable
than paths which have not been used for a long period of time.
Connections in the central nervous system tend to become
more resistant through disuse.
The factors of frequency, vividness, and recency often con-
flict. A vivid experience which occurred many years ago may
be recalled more readily than a recent experience of lesser
vividness. Frequent repetition may strengthen a remote
experience. On the other hand an experience which has
never been attended to which lacks vividness may not
be recalled even though it has been repeated many times. We
all know how hard it is to remember a set of instructions on a
subject which is entirely outside our interests, no matter
how often they are drummed into us.
Forgetting. Why do we fail to remember certain things
especially proper names though we try our best to recall
them? Often when you start to speak about some one whom
you know perfectly well, you suddenly find you are unable to
recollect his name. You cannot recall whether you locked
the door or turned off the light downstairs. You put a paper
away very carefully for future use; and now you have not the
slightest idea where you put it. You make a dinner engage-
ment two days ahead: when the time comes you forget it.
In the case of proper names there is often a vain struggle to
188 MEMORY AND IMAGINATION [CH. vra
remember. We think of several names one after the other,
and reject each in turn, recognizing at once that it is not the
right one; it lacks the feeling of familiarity. Sometimes
we go down the alphabet systematically, trying out each
letter in turn, and perhaps strike the right word as a matter of
chance. The attempt to recall a man's name by picturing
how he looks is generally futile. If we dismiss the subject
completely it often happens that the desired name suddenly
' jumps up in consciousness ' it may be in a minute or
within an hour, or perhaps only after several days.
The subject of forgetfulness has not been studied so thor-
oughly as memory and recollection. But the following prin-
ciples have been noticed : they apply not merely to names but
to memory lapses of all sorts.
(1) CONFLICTING ASSOCIATIONS: If another thought, simi-
lar to the one we are trying to recall, is present, it tends to fix
the attention and exclude the desired thought. This ac-
counts for most cases of inability to recall names. I cannot
recall the name of my Latin professor, Dr. Packard. The
name of Dr. Patton has come up first and holds the field,
preventing the other association. I meet an old acquaint-
ance after several years and am at a loss for his name; I can
only think of Lamson not because the name sounds like
Lamson but because the man looks like Lamson, whom I
have seen more recently.
(2) FAINTNESS: If an experience was not originally at-
tended to, or is not recent, or has not been repeated, it is
difficult to recall it. You do not remember whether you have
locked the door because the action was quite automatic;
you did not pay attention to it. You forget where the paper
was laid away, because the occurrence took place some time
ago. In a city we pass many people daily on the street; if
we chance to pass one of them a second time we fail to recog-
nize him unless there is something striking about his appear-
ance that is, unless the original impression was vivid.
CH. viii ] FORGETTING 189
This law of faintness is simply the negative side of our three
laws of recall.
(3) INHIBITION: If an experience is painful or is accom-
panied by some unpleasant emotion, the recollection tends to
be inhibited. If you have done something you are ashamed
of, every time you recall it you dismiss it from thought by
passing as quickly as possible to something else. In this way
the tendency to recall this particular thing is continually
weakened till at last the association may be entirely inhib-
ited. Some writers describe this as a ' repression ' of un-
pleasant ideas into the subconscious field. The process is
really not a repression but a weakening or inhibition of
associations.
The influence of frequency and recency on the rate of for-
getting may be studied experimentally by committing to
memory several series of nonsense syllables. Meaningless
syllables do not differ in vividness like words, so that one
series makes the same impression on you as another. If you
take two different nonsense series, and repeat one a great
many times and the other only two or three times, you find
that very much more of the former is retained. If you repeat
several nonsense series the same number of times and try
to recall one after one day, another after two days, and so
on, you can determine how much you forget as time goes
on. This is shown in Fig. 69. The curves (which repre-
sent the amount retained) drop decidedly at first, and less
and less thereafter. In other words, the amount of loss is
greatest at first; and there is less additional loss as time
goes on.
It is often asked whether any experience is really forgot-
ten whether all traces in the brain substance persist
indefinitely, or if some wear away completely in the course
of time. Instances are cited of events in early life which are
recalled after an interval of many years. In two cases
recently reported, men of ninety repeated orations which
190
MEMORY AND IMAGINATION [CH. vm
they had learned in boyhood and had apparently not recalled
meanwhile. In both these cases the lines were originally
fixed in memory by repetition (and interest), so that the
FIG. 69. CURVE OF FORGETTING
The curves show the results of experiments on learning and forgetting by
three different investigators. A and B memorized nonsense syllables. C used
series of jumbled letters. The curves show the percentage recalled after various
time intervals. [After Starch.)
recollection was not the revival of an isolated experience.
James cites the case of a very young woman who could
neither read nor write, who during a fever uttered sentences
in Latin, Greek, and Hebrew languages with which she
was wholly unfamiliar. It was found that during her child-
hood she lived in the family of an old clergyman, who was
accustomed to walk up and down reading aloud in these Ian-
CH. vra] FORGETTING 191
guages. Passages repeated by the woman were found in
books from his library. The impressions had been retained
many years without either repetition or original vividness.
Whether any memory is utterly lost is uncertain. 1 It is
safe to say that far more is retained than we ever actually
recall. It may be that in the normal brain every trace per-
sists indefinitely. Or it may be that the traces wear away, or
are gradually effaced by other traces. Too little is known at
present about the nature of memory traces to answer the
question definitely.
Training the Memory. The practical value of a good
memory is too obvious to need discussion. One of the most
frequent questions put to the psychologist by outsiders is:
Can you help me to improve my memory? A good memory
means ability to recall what we want when we want it. This
depends on several different factors: (1) perception; (2) the
learning process; (3) verbal association.
(1) PERCEPTION: Certain sorts of memory depend essen-
tially on accurate perception, and the obvious way to improve
them is to train our perceptions. The memory for faces is a
good example of this. Contrast the man who recognizes at a
glance a person whom he has not seen for years, with the man
who is always in doubt as to the identity of the people he
meets. The one has been accustomed from childhood to
perceive faces accurately; recollection takes place automati-
cally. The other has never trained himself to observe faces
carefully. Often the deficiency is due to defective eyesight.
Near-sighted and astigmatic persons do not see faces clearly;
they cannot recall them because they have never registered
the distinguishing marks. Such persons may recognize a
man instantly by the tone of his voice.
Another sort is the memory for scenes and incidents. We
often wish to describe scenes or events to friends some-
1 If one of the brain centers is destroyed by disease or accident, the traces
in that center are gone, and with them the possibility of certain recollections.
192 MEMORY AND IMAGINATION [CH. vm
times we are asked to testify about them in court. Accurate
testimony depends on accurate perception. The witness who
told of a man " pacing to and fro, his hands behind his back,
reading a newspaper," must have observed rather carelessly.
It may be of life-and-death importance to recall which of two
shots was fired first. In thrilling moments accurate percep-
tion is difficult. The discrepancies between the testimony of
witnesses is often due to the disturbances of perception
wrought by the excitement of the moment; it is no reflection
on their sincerity or mental ability. Nevertheless a careful
training of perception will prevent many errors.
(2) LEAKNING PROCESS: Memorizing poetry and speeches
so that we can repeat them accurately depends on the learn-
ing process (ch. xi). It is not a matter of accurate perception,
but of repeating the words over and over so as to strengthen
the retention traces in the brain centers. The ability to
memorize quickly is largely a matter of inheritance; that is to
say, the inherited nervous system of some persons is such that
they readily retain long series of impressions and reproduce
them in the right order. But our inherited capacity may be
strengthened by training and impaired by disuse. Self-
confidence is an important factor here. If you feel sure you
will succeed, many slips are avoided which would occur if you
distrust your own ability to repeat a speech.
(3) VERBAL ASSOCIATION: The ability to recall names
depends largely on verbal associations. The names of com-
mon objects are learned early in life; through constant repeti-
tion the word table becomes an integral part of our perception
and thought of a table. The normal man finds no difficulty
here. It is the memory for proper names that troubles him.
Henry Brown may have light hair or black hair the associ-
ation of the word brown with the man Brown is arbitrary.
We meet the same difficulty in learning a foreign language
unless the words are similar to our own. The French word
fromage is difficult to associate with cheese.
CH. vni] TRAINING THE MEMORY 193
than perception and
The understanding of words involves brain
centers at a higher nervous level than the perception centers.
The act of associating words with perceptions (or with mental
images) is different from ordinary association; it follows much
the same principles, but it is a more specialized process.
Verbal memory may be improved to some extent by training.
In old age it is the first to deteriorate; witness the struggles of
elderly persons to recall the names of then* best friends and
even of their own children.
Statistical data belong in the same class. The date of the
discovery of America, the rate at which sound travels through
the air, the population of Chicago, are arbitrary associations
of numbers with events or objects. Much of our scientific
knowledge is of this sort. There are certain facts that " every
educated man ought to know." How far to insist on such
knowledge is a serious problem. Teachers are inclined to
attach undue importance to this kind of memory. Ency-
clopedias and reference books are generally available, and it
seems useless to burden the child's memory unnecessarily.
He should of course be taught the addition and multiplication
tables, weights and measures, and other fundamental statisti-
cal matters. But in the higher education it seems more im-
portant to teach the student where to look for information than
to take up his time in memorizing arbitrary number associa-
tions.
Certain devices have been invented to assist this sort of
memory. The figures are associated with letters of the alpha-
bet (consonants), and a catch-phrase is made up which brings
together the number and the fact. Let b=l, g=4, r = 9,
d = 2; then the number 1492 is represented by b, g, r, d. We
invent the phrase, " Columbus made a big raid on America,"
and thus remember the date. Many persons find such a
system useful; others find they get on quite as well without it.
1 See ch. xiii.
194 MEMORY AND IMAGINATION [CH. vm
There is danger of course that the phrase may be twisted,
If we think that Columbus made a ' bad raid,' the discovery
of America would be shifted to 1292.
Imagination (Fancy). An imagination image or fancy is
an image composed of elements from two or more separate
experiences. A typical example is our mental picture of a
centaur, which combines the head and arms of a man with the
body and legs of a horse. This image is a combination of two
separate perceptions unless it happens to be the memory
of some picture or statue we have seen. The scenes in a novel
or history, as we mentally picture them, are imagination
images. We piece together bits from familiar experiences
suggested by the narrative, and construct scenes which may
be quite different from anything we have ever witnessed.
The plans of an inventor in the earlier stages are imagination
images; they are pictures based on real experiences, but are
unlike anything the inventor has actually perceived.
Some of our fancies are so fantastic that we are apt to
regard them as absolutely different from our perceptions.
This is not the case. The elements composing the image are
often much transformed from the original, but they are
always derived from former sensations of some sort. On the
other hand it does not follow that every fancy represents
some reality or possible reality. An imagination image is
novel in just the same way that an invention is novel. The
finished product is new, but not the materials.
The practical working of imagination will be better under-
stood if we study its manifestations in children, before it has
been overlaid with higher processes of thought and molded
into definite lines by our interests in life. The child is natur-
ally imaginative. He pictures the fairies and monsters of
his story books vividly. He hears animals talk, he sees inani-
mate things acting like living creatures all this as dis-
tinctly as though the experiences were actually remembered.
There seems, in fact, to be no sharp distinction in early liff
CH. vm] NATURE OF IMAGINATION 195
between memory and imagination. The child tells of imagi-
nary adventures with the same sense of reality that he feels in
describing real occurrences. Many of the child's lies have no
ethical significance whatsoever, though then* psychological
significance may be most important, as indicating the nature
of his mental processes.
These facts indicate that in early childhood imagination is
as fundamental as memory. Both depend on retention and
revival. Memory is revival of definite groups of retention
traces, while imagination is the revival of separate traces
which are grouped together into new experiences. It appears
that imagination is really not distinguished from memory in
early childhood. This is probably because memory traces
are not yet deeply fixed, so that the revival is not accom-
panied by a strong familiarity feeling.
As the child's mind develops, the distinction between
memory and imagination grows more definite. Memory
images are recognized as such by the accompanying familiar-
ity feeling and by their setting in space and time. The dis-
tinction is fostered socially by the punishment or disapproval
which follows when the child tells as fact what really belongs
to the realm of imagination. The outer world becomes to
him more and more an independent reality; his memories
represent that real world, and his fancies do not.
As we pass out of childhood the imagination tends to
become more restricted. Instead of being free and desultory
it falls into certain definite grooves. In one person it tends
toward artistic creation, in another toward invention; one
man seeks to explain the mysteries of nature, another pro-
poses to reorganize society. In this way various types of
imagination arise, based on the special life interests of the
individual. Esthetic, creative, scientific, and social or ethical
imagination are broad general types; under them we find
many subordinate types, such as pictorial, musical, and
graphic imagination.
196 MEMORY AND IMAGINATION [CH. vra
Other Kinds of Imagery. Besides memory and fancy
there are several other sorts of images. Anticipations are
images which picture our future actions and lead to some
appropriate activity on our part. Both voluntary and invol-
untary acts may be preceded by anticipation images. My
mental picture of a ball game scheduled for this afternoon
leads me to walk down to the field. The nerve impulses
concerned in this image are part of the set of operations in the
nervous system which start the appropriate movements.
Anticipation images are similar to fancies except for their
' prospective reference.' A fancy may suddenly blossom into
an anticipation when the painter starts to paint or the
inventor begins to build his machine; an anticipation image
withers into mere fancy when our plans fail.
There are two reasons for emphasizing anticipation as a
distinct sort of image. First, because it is intimately con-
nected with our active life. Anticipation, or purpose, is more
efficient than imagination in bringing about suitable re-
sponses; and this after all is the vital point in mental life.
Second, the anticipation image arose earlier in animal evolu-
tion and appears earlier in the human child than fancy.
Image experiences seem to have arisen in the first place as a
method of reaching into the future, not as a means of bring-
ing back the past or of picturing novelties. When a baby
cries for milk, he has probably a faint anticipation of getting
it. The dog who jumps about when his master appears in
hunting costume would seem to have a rather vivid anticipa-
tion of what is going to happen.
A composite image x is built up through frequent repetitions
of substantially the same experience. It is a more perfect
reproduction of past experiences than an imagination, but it
is less definite than a memory. The effect of this repetition
is to weaken the general setting, which is different in each
case. The image represents some object we have actually
1 Also called a free image.
CH. vra] OTHER KINDS OF IMAGERY 197
perceived, but it shows the object without any definite loca-
tion in time and space and with no fixed surroundings or
background. You often picture the face of a friend or a
familiar tune without special reference to time or place or
circumstances; the image is a composite effect of many past
experiences. The repetition strengthens the accompanying
feeling of familiarity, and usually adds something to the image
itself. The composite image of your friend's face usually
includes both profile and full front views, and the composite
image of a house may include both inside and out, which we
never perceive or recall in the same picture.
A general image is due to the fusion of many similar images
into a single experience. It arises from the perception of a
number of objects which are partly similar and partly unlike.
When the child has seen a number of men whose general
appearance is the same, but with certain differences, he
begins to form a mental image which embraces their common
features. These common points are vivid, and make up the
focus of the image; the details in which men differ appear
only indistinctly in the margin of the conscious field. In the
same way the child forms a general image of a horse and of
various other sorts of creatures and objects.
Our general image of horse in adult life is probably based
on memories of a certain horse it may be an old bay mare
we knew in childhood. Attached to this memory are a
variety of different characteristics, such as gray and black,
long-tailed and bobtail, stocky and slim, derived from our
experiences of other horses. These points of difference be-
tween horses are only faintly pictured in the general image,
while the characteristics common to all horses are empha-
sized. In other words, our general image of the horse, though
based upon some particular animal, is not stocky nor slim,
it has no distinctive color, no special trim of the tail; many
of the features and outlines are vague. The prominent
elements in the general image are those details in which all
198 MEMORY AND IMAGINATION [CH. vm
horses agree, and which distinguish horses from other crea-
tures.
In adult life the general image rarely occurs in a pure form;
almost always a word or symbol of some sort attaches to it,
and it becomes a thought (ch. xiii). Thought is a higher type
of experience than the general image.
Illusions of Memory and Hallucinations. We often make
mistakes in interpreting our image experiences, just as we
make mistakes in perception. Two different sorts of errors
occur in connection with imagery : illusions of memory, and
hallucinations.
Illusions of memory are due to our misinterpreting some
factor in the experience. The most common illusion is based
on the ' location ' factor. If the memory of an event includes
only a few details it is easy to refer it to the wrong time or
place. I recall a conversation with a friend; the surround-
ings are not definitely recalled, and I imagine it occurred when
we met in New York; actually the discussion took place at
another meeting elsewhere.
It often happens that the memory of a certain event re-
mains unusually vivid, so that we place it much too near the
present time. The opposite is true when we move to a new
town and quickly grow familiar with our surroundings. We
soon get the feeling that we have lived there a long time;
the older background tends to fade into the distance.
Another illusion consists in mistaking an imagination for a
memory. I remember distinctly posting a certain letter, and
assure my wife I did so. When the letter turns up later in my
overcoat pocket the ' memory ' proves to have been merely a
vivid imagination. Usually this sort of illusion is due to the
mingling of imagination elements in a memory picture. I
remembered taking the letter but I imagined the post-box
part. The inaccuracies of court testimony are often to be
explained in this way. You describe a man in a brown suit
and a derby hat. Your description is correct except that the
CH. vm] ILLUSIONS OF MEMORY 199
suit was gray and he wore no hat. These details were added
(quite innocently) from the imagination.
Such illusions are often due to the fact that you first
imagine certain details and then remember your imagination.
Who has not related incidents of family history that have
been handed down through the years, and felt certain he
witnessed them? only to discover that they occurred some
time before he was born. They are memories indeed, but
memories of narratives that have been told him memories
of the vivid fancies which he formed on hearing the stories in
childhood.
An illusion is the wrong interpretation of certain factors or
elements in the experience. An hallucination is the confusion
of images or thoughts with perceptions.
We have usually no difficulty in distinguishing images and
thoughts from perceptions. One distinguishing mark is
intensity. Most mental images are far less intense than any
perception. You know that the table before you is real;
the experience is too intense to be due to anything but an
external stimulus, and consequently the experience is a per-
ception; you know just as certainly that the tune ' running
through your head ' is imagined; it is far weaker than real
music.
Another factor which enables us to distinguish perceptions
from fancies is that perceptions are independent of our control.
They come and go according to their own sweet will not as
we wish. If we can call up or alter a certain experience at
will, we class it as a memory or fancy.
These two factors, intensity and controllability, generally
cooperate, and prevent hallucinations. But they are not
infallible tests. Some perceptions are faint and some fancies
are vivid. On dark nights we are not certain what we actu-
ally perceive and what we merely imagine. Dreams are vivid
fancies; for the time being they appear to be perceptions,
since we have no external sensations to compare them with.
200 MEMORY AND IMAGINATION [CH. vin
In states of high-strung tension one sees a specter, or hears
voices warning him, though the experiences are mere fancies.
If the object seems to act independently of our control, the
error may be reinforced, or our uncertainty may be greater.
In such cases the normal individual falls back upon a third
test, the uniformity and general consistency of experience.
We convince ourselves that the ' specter ' is imagined, that
the ' voice ' is within us, because such experiences do not
conform to the general scheme of things. Even in dreams we
sometimes notice the inconsistency of the experience with
other circumstances and realize that we are asleep.
The characteristics by which we distinguish imagination
from perception are merely practical tests, based upon the
general run of our experiences. In most cases there is a sharp
dividing line between them, and the bulk of our experiences
fall naturally into one class or the other. But neither the
experience itself nor its elements furnish a decisive indication
of the original source. Both imagination and perception are
due to brain processes; either may readily be mistaken for the
other if its general characteristics fall within the border-line
territory.
In certain mental diseases the patient ignores the test of
consistency, and systematically mistakes his fancies for
objective reality. These pathological states are delusions;
they are a stage beyond hallucinations.
Importance and Training of Imagery. Memory and imag-
ination are of varying importance in human life. As we
advance in civilization the use of imagery develops more and
more into verbal thinking and the use of image pictures tends
to become less active. In certain occupations imagination is
especially serviceable and deserves cultivation. The ' crea-
tor ' of every sort whether artist, writer, or inventor
is helped by the cultivation of exact and vivid imagina-
tion ; the professional man, the scientist, and the business man
usually find verbal thinking more useful.
CH. viiij CULTIVATION OF IMAGERY 201
Nikola Tesla, the inventor, attributes much of his success
to his power of visualizing distinctly, and in detail, the
machine which he wishes to devise. The whole idea is
worked out mentally before ever a sketch is put on paper.
" In my mind I change the construction, make improvements,
and even operate the device." 1
The exactness and vividness of imagery depends largely on
our ability to observe our perceptions exactly. The training
of perception is essential to accurate memory and vivid
imagination. This must be supplemented by practice in
recalling events in detail and by constant exercise of the
imagination. The cultivation of imagination is useful only in
certain lines of work; but memory training is of general
utility.
It is a matter of great social importance to be able to
distinguish clearly between true memories of objective events
and mere fancies. Lying has an ethical significance. It is
more than a ' psychological phenomenon ' in the adult. For
this reason it is important for every man to learn to distin-
guish clearly between truth and fiction. Fancy as fancy has a
legitimate place in mental life. Like play and jesting it
relieves the strain of our more serious occupations. The most
earnest mental worker finds relaxation in pure horse-play,
and the most rigid logician heartily enjoys a pun. The atti-
tude to be cultivated is one of absolute sincerity in matters
of fact; we should discriminate clearly between objective
facts or truths and the constructions of our own imagination.
The more completely we separate these two spheres, the
better can we appreciate the fantastic tales of Wells and the
subtle exaggerations of Mark Twain.
Summary. In this chapter we have examined imagery,
an experience which owes its characteristics to brain traces of
former experiences not to the present stimulus. Most
images are revivals of external sensations; though occasion-
1 Quoted in American Mag., April, 1921, p. 62.
202 MEMORY AND IMAGINATION [CH. vra
ally other kinds of sensations are revived. The most impor-
tant sorts of imagery are memory images and imagination
images (fancies). Memory reproduces some perception we
have actually experienced; an imagination is made up of
bits of former perceptions, gathered here and there and put
together into a definite image.
PRACTICAL EXERCISES:
89. Take at random some date between six months and a year ago. Try
to recall as many incidents as possible that occurred on that day.
40. Take some notable event in your recent life (over six months ago) and
describe the scene and the succession of occurrences as minutely and
accurately as possible.
41. Lying in bed at night with closed eyes, try to picture imaginary scenes
or stories. Describe the experiences; compare their vividness with
real scenes; how far are they due to retinal stimulation?
42. Read a description of a scene or event from some novel or history,
and note the images which are aroused. Classify them as visual,
auditory, etc. Grade them according to vividness.
43. Describe any experience you can recall where you have mistaken an
imagination for a perception or vice versa, or where you were unable
to judge its real nature.
REFERENCES:
On memory: H. J. Watt, Economy and Training of Memory.
On the rate of forgetting: H. Ebbinghaus, Memory (trans.).
On cases of unusual recall: W. James, Principles of Psychology, I, p. 681;
H. C. Warren, in Psychological Bulletin, 1918, 5, p. 207.
On imagination: F. Galton, Inquiries into Human Faculty (cb. on 'Mental
Imagery '); T. Ribot, Essay on the Creative Imagination (trans.).
CHAPTER IX
FEELING AND EMOTION
Affective Experiences. The experiences we have exam-
ined so far have to do with objects and conditions outside our
own body. Perceptions are made up for the most part of
sensations which come from the outer world. Memories,
imaginations, and other images are made up chiefly of repro-
ductions of these same external sensations. Perceptions,
images of all sorts, and thoughts (which we shall discuss
later) all belong to the same class of experiences, which are
usually called cognitions or intellectual experiences. The
responses that we make when we perceive or remember or
think are movements which have to do with conditions
outside us, in our environment not inside our own body.
We now come to a different kind of experience experi-
ences which are made up chiefly of systemic sensations or in
which systemic sensations are especially prominent. These
experiences are concerned, first and foremost, with the condi-
tion of our bodily organism not with events in the surround-
ing world; though our body and our environment are too
closely related to make the distinction complete. They are
called affective experiences, and include the following sorts:
Feelings
Emotions
Sentiments
FEELING
Nature of Feeling. A feeling js^ aji_ experience in which
systemic sensations are the main elements. 1 Feelings are
1 Feeling is also used to denote any indefinite sensation. This is an older
meaning of the term. It is still kept, because the expression 'I sense' has
204 FEELING [CH. ix
made up of organic or pain sensations or both. The feeling
of hunger which we experience before a meal is due to organic
sensations; a toothache is a very pronounced feeling derived
from the pain sense. The feeling of general well-being which
pervades our body after a hearty meal is base'd on our ' gen-
eral sensibility ' on the condition of the body as a whole.
Systemic sensations have not only their own special
qualities like the external senses, but also a common feeling
tone: they are either pleasant or unpleasant. When sys-
temic sensations combine into feelings, their special qualities
usually fade away and the prominent feature is their pleas-
antness or unpleasantness.
This is the opposite of perception. When you look at a
picture you perceive and discriminate its various parts; they
do not merge together. In a feeling, the greater the number
of sensations entering into the experience, the less distinct are
their details; you feel more and more an indefinite pleasant-
ness or unpleasantness within you. A pin-prick is definitely
localized and stands out sharply. When you fall and are
bruised, the feeling of hurt seems to spread over a large part of
the body in an indefinite way. When you have a certain
pain in the region of the teeth, you are not always sure
whether it is merely toothache, or toothache combined with
earache. It is localized now in one place, now in another.
The most prominent feature of these experiences is the ' hurt,'
or sense of discomfort not the kind of hurt or its location.
The same is true of pleasant feelings. It is difficult to locate
the feeling of ' thrill * or to analyze its quality.
Our mental life at any moment is generally tinged with a
pervasive feeling of some sort. If the general tone is pleasant
the feeling is one of happiness or euphoria; if it is unpleasant
the feeling is despondency. We rarely have two conflicting
never come into general use; but we must be careful not to confuse the two
meanings. It is advisable not to use feeling for the sense of touch; this is too
confusing. The old English word 'to palp' is better.
GH. DC] NATURE OF FEELING 205
feelings at the same time. In fact, it is sometimes stated that
pleasantness and unpleasantness cannot be experienced
together at the same time. This is one of those popular
generalizations which we must learn to challenge. Under
some conditions it is certainly possible to experience two con-
flicting feelings at once. We are pleased when a friend sym-
pathizes with us over our toothache; but this does not alto-
gether obliterate the discomfort of the ache. In cases of
this sort we do experience both the unpleasant and the pleas-
ant together sometimes with equal vividness.
Systemic sensations frequently form part of our percep-
tions of external things. Some odors are unpleasant; most
musical chords are pleasant. The feeling tone in such cases
does not come directly from the external stimulus, but from
some organic change which the stimulus brings about. The
sharp edge of a knife is not pain-/w/ but pain-inducing; the
pain is due to the laceration of the skin and the consequent
organic injury. Odors are unpleasant when they produce
destructive changes of tissue within the organism. The
pleasure we get from listening to music is due to certain
chemical changes (anabolic processes) wrought in our bodily
system by the music.
We may grow to like certain odors that were once unpleas-
ant or to dislike tones or colors that were formerly pleasing.
The change from pleasantness to unpleasantness is due to the
body becoming accustomed (' hardened ') to the stimuli, so
that they no longer produce destructive effects. The oppo-
site change is probably due to some idea which works through
the motor nerves on the bodily processes. If " the very
thought of that fellow nauseates you," the nausea is due to
nerve impulses from your brain centers to the glands of your
stomach.
Many of our affectiye experiences come about in this
indirect way. The glands which secrete the substances used
in digestion, and various other internal glands (including
206 FEELING [CH. ix
those of the reproductive organs), are operated by the auto-
nomic nervous system. The autonomic and cerebrospinal
systems work together. Consequently our feelings often
modify our ideas and thoughts very decidedly ; and our ideas
often influence our bodily processes and produce very intense
feelings. When a man is despondent it is sometimes difficult
to determine whether his feeling of despondency is due to
certain disturbing thoughts, or his thoughts of impending
disaster were started by despondent feelings.
Appetite and Aversion. Our feelings are not so well
developed as our perceptions and ideas. They have com-
paratively few different qualities. There are several reasons
for this. Systemic sensations are not so clear-cut and
definite as the sensations of sight, hearing, touch, or smell.
They are produced (except in the case of pain) by internal
stimuli which are constantly changing and are difficult to
hold. They are not so intimately connected with conditions
in the environment, which are of supreme importance in the
life of man.
Our internal bodily experiences are usually subordinate to
our experiences of the world about us. But there are times
when the organic or pain stimuli are so intense or so insistent
that our experience is largely and unmistakably a feeling,
with everything else in the background. These definite
states of feeling are of two opposite sorts, appetites and aver-
sions, according as their general toning is pleasant or un-
pleasant.
Feelings of appetite result most frequently from digestive
and generative sensations, while feelings of aversion are made
up of pain sensations and sensations arising from disturbed
digestive conditions. In many cases the tone of a feeling is
not pure. The feeling of digestive appetite, for instance,
includes both unpleasant hunger sensations and pleasant
satisfaction. A pain may be accompanied by pleasant sensa-
tions due to the healing process. ^Sometimes the feeling
CH. ix] APPETITE AND AVERSION 207
tone is indefinite it is recognized neither as pleasant nor as
unpleasant. Here there is apparently a balance between the
destructive and restorative chemical processes in the body.
These neutral feelings are called excitement.
Intense feelings of any sort are apt to arouse activity of
the muscles, which gives muscle sensations. When this
occurs the feeling passes into another kind of experience,
called emotion. In other cases the feeling arouses activity of
the glands, which stimulates additional organic sensations
and these keep the feelings alive.
Intensity of Feeling. The intensity of feeling is difficult
to measure. We do not discriminate differences of intensity
among systemic sensations as exactly as we distinguish
brightness or loudness. It is difficult to get at the stimuli and
experiment on their changes.
Some attempts have been made to measure the changes of
intensity of the feeling tone which accompanies external
sensations. When the intensity of a light or sound or pres-
sure is increased continuously, the intensity of the accom-
panying feeling varies at the same time. But this change
does not follow Weber's Law, because feelings have two
opposite phases, pleasantness and unpleasantness, while per-
ceptions have only one. The experiments bring out the fol-
lowing relations:
(1) With slight intensity of stimulation the intensity of the
accompanying feeling is zero.
(2) As the intensity of the stimulus increases there is at
first a slight degree of pleasantness.
(3) With further increase in the intensity of stimula-
tion the pleasantness increases to a maximum and then de-
creases.
(4) At a certain point the pleasantness disappears entirely.
(5) With further increase in the intensity of stimulation
unpleasantness appears and thereafter increases steadily.
(6) With great intensity of stimulation a maximum degree
208
FEELING
[CH. IX
of unpleasantness occurs; this marks the beginning of actual
destruction of some of the tissues. [Fig. 70.]
Importance of Feeling. We are apt to underestimate the
importance of the feelings in mental life because they are so
overshadowed by our perceptions
and other intellectual experiences.
The knowledge of our bodily con-
dition may not be so essential to
us as knowledge of the outer
world, but it is too important to
be ignored. The influence of feel-
ing in determining a man's atti-
tude toward the outer world is
seen if we compare the responses
of different individuals under simi-
lar conditions; or if we observe
how differently the same person
acts in two cases where the ex-
ternal situation is similar but his
own internal condition is radically
different.
Some men apparently can never be disheartened or in-
sulted; others will collapse at the slightest misfortune, or
bristle at the most trivial remark. The same man who meets
difficulties energetically and cheerfully when he is in good
health, may refuse to face danger or perplexity when affected
by indigestion, malaria, or other weakening influences. The
external stimuli are alike; the difference lies in the internal
bodily condition.
We can only appreciate the real significance of feeling in
man's mental life when we consider its influence on the evolu-
tion of animal species. Destruction of tissue is harmful to
any creature. It follows that any species or creature that
develops a means of avoiding the destruction of its tissues
will stand a better chance of surviving. Those creatures and
FIG. 70. INTENSITY OP
FEELING
The curve shows how the feeling ac-
companying a perception varies with
increase of stimulation. Distance
above the base-line represents degree
of pleasantness, distance below repre-
sents degree of unpleasantness; hori-
zontal distance represents intensity of
stimulation. The numbers correspond
to the six laws given in the text.
CH. ix] SIGNIFICANCE OF FEELING 209
species which are able (1) to avoid harmful stimuli, and (2)
to react positively to beneficial stimuli, are most likely to
survive in the long run. These two opposite types of response
are determined by the two opposite phases of feeling. So
that any species which evolves a set of receptors and nerves
for feeling has gained an additional and important means of
getting along in life.
EMOTION
Nature of Emotion. Mental life is especially concerned
with the interaction between the body and the outer world.
Accordingly, the most important development of feeling is in
connection with the motor activities which it arouses. The
most significant affective experiences are not pure feelings,
but feelings combined with powerful motor sensations.
These experiences are called emotions.
An emotion is an experience made up of both systemic and
motor sensations. It is a condition of mental excitement,
either pleasurable or the opposite (usually with definite
organic or pain qualities), accompanied by great muscular
activity or tension, which gives rise to intense muscle sensa-
tions.
When the fire alarm is sounded your heart beats faster and
your legs almost irresistibly carry you toward the scene.
After a thunderbolt your heart stops beating for an instant
and your muscles are tense. When you come home after a
long absence, you feel a thrill of happiness and wave your
arms or shout for joy. These are emotions; they consist of
systemic and motor sensations both very vivid.
Emotion is the only secondary experience in which ideas do
not play a prominent part. An emotion is usually aroused by
external stimuli or by ideas which represent things in the
external world; but the perception or idea is not part of the
emotion it fades into the margin when the emotion surges
into prominence. The sight of the smile on the subway
210 EMOTION [CH. ix
guard's face as he slams the gate on you, makes you boiling
mad. But your anger is the bubbling up of inner feeling and
the clenching of your teeth and shaking your fist not the
sight of the guard. The anger experience is composed of
sensations stimulated by your intense physiological and mus-
cular activity.
According to popular notions the essential ingredient of
emotion is the feeling the motor display is an after-effect.
We speak of " emotion and its expression." This interpreta-
tion of emotion was generally accepted by psychologists till
about thirty years ago. It assumes that we first experience
the feeling of anger, then clench our teeth and fists, scowl, and
assume the general anger attitude.
William James and Carl Lange independently suggested
that the factors really arise in the opposite order : We first of
all assume the anger attitude clench our teeth and fists, and
strain the tension of our muscles; these movements in turn
stimulate the anger feeling. That is, according to these
writers, the motor sensations generate the feeling sensations
which compose the experience. Many psychologists now
accept the James-Lange theory of emotion. This theory
finds some confirmation in the fact that if we artificially
assume the anger attitude with all its motor accompaniments
(for instance, when we act a part in a play), our feelings are
aroused very strongly; and on the other hand when we are
really angry, if we succeed in relaxing our muscles and so
rid ourselves of the motor sensations, the feeling of anger
diminishes and the entire emotion tends to disappear.
However, the facts seem to indicate that neither of the two
factors has precedence in emotion. Both systemic and
muscle sensations are aroused by some perception or thought;
both arise together, and both are integral parts of the emo-
tion. If we succeed in relaxing the muscles, the emotion
vanishes it passes over into a simple state of feeling. If
we succeed in removing the systemic sensations the emotion
CH. EC] NATURE OF EMOTION 211
also disappears it is reduced to a simple motor experience
called conation (ch. xii). Most persons are able to control
their motor expressions more readily than their organic
processes. This is why the motor factor seems to be the
crucial factor when we test emotions experimentally. We
conclude, then, that neither the popular view nor the James-
Lange theory is correct. Emotion is the joint product of
nerve impulses from the systemic and motor senses. Emo-
tional feeling and emotional expression are equally important
parts of the experience.
The glands are even more important in emotion than in
feeling. It is found that in some emotional conditions certain
chemical products, such as adrenalin, are formed in great
quantity and diffuse themselves among the neighboring
organs. These compounds are apparently the stimuli which
arouse the systemic elements in the emotion. Muscular con-
traction and muscular tension serve as stimuli for the motor
elements.
Primitive Emotions. Comparative studies on animals
indicate that emotion is present in many species below man.
This is particularly true of warm-blooded animals, including
mammals and birds. 1 Their reactions and expressions cor-
respond so closelj* to the manifestations of human emotion
that we are justified in attributing real emotional experiences
to these animals. The fundamental kinds of emotion may be
studied to advantage in subhuman species, where they are not
complicated by shadings which depend on thought and com-
plex social relations.
In popular books the study of animal emotion consists too
often in attributing to pet dogs and cats various shades of
human emotion which depend on thought and reasoning.
This reading of human experiences into lower species does
1 In cold-blooded species the circulation is sluggish and there is not that
quickening and violent agitation which is characteristic of human emotion.
Their emotions, if they have any, are essentially different from ours.
212 EMOTION [CH. DC
not help us to understand the actual facts. The mental
processes of subhuman species are far simpler than in man.
The emotional display in the dog or cat is not the result of
thought it occurs without thought or reasoning; it shows,
rather, to what extent emotion is independent of thought and
more primitive than thought. What will help us, is to study
carefully the manifestations of emotions in various animal
species and read them into man. When a cat struts away
from a growling dog with an air of offended dignity she has a
pride emotion of some sort, but no thought of dignity. The
inciting cause of the emotion is a perception, not an idea.
This suggests that even in man the pride emotion depends
perhaps more on perceptions and less on ideas than is gen-
erally supposed.
This method of studying emotion is helpful, but the con-
clusions should not be carried too far. Human emotion
differs from animal emotion in the prominent part which
memories and thoughts play in producing it. A child cries
when we scowl at him, or exhibits fear at the sight of a snake
or some other strange creature. His emotion is aroused by a
perception, like the anger of the bull at the sight of red. But
in the human adult, emotions are determined by ideas rather
than by perceptions. We are angry when we see a big boy
beating a small boy; we are not angry when we see a strong
man beating a rug.
The most primitive emotions in man are those based on
certain fundamental conditions of life, which led to the evo-
lution of certain types of reaction in animals long before the
human species appeared. The three most fundamental
types of emotion are fear, anger, and love.
The feeling tone of fear is unpleasantness, which is usually
very intense. The organic sensations which form part of the
fear experiences are stimulated through receptors in the lower
viscera and in the region of the lungs and heart. The char-
acteristic motor expressions of fear are certain definite mus-
CH. ix] PRIMITIVE EMOTIONS 213
cular contractions, which produce trembling, shrinking
movements, raising of the eyebrows, etc. These motor ac-
tivities furnish muscle sensations which form an important
part of the emotional experience.
In anger the feeling tone is also unpleasant, but the feeling
tone is not so prominent as in fear. The special systemic
sensations are derived from the upper digestive tract, the
heart and lungs, and the circulatory system. An outburst
of anger is accompanied by vigorous heart activity and
breathing, which usually causes intense flushing of the face
and sometimes a choking sensation and suffusion of the eyes.
The characteristic motor activities of anger are clenching of
the fists and teeth, strained tension of the face muscles, and
rigidity of the lower limbs. These motor activities are accom-
panied by very intense muscle sensations. The expression
of anger is generally movement toward the object in fear
the movement is away from its object.
Love is the third type of primitive emotion. Its character-
istic feeling tone is pleasantness. The special systemic sen-
sations are less prominent than in fear or anger; they arise
from the region of the lungs and from the generative organs.
The popular notion which associates the emotion of love with
the heart is not so far wrong; careful observation shows that
the characteristic sensation is located somewhat above the
heart, but that it is due to the circulation and not to breath-
ing. There are various motor accompaniments of this emo-
tion, and the muscle sensations which these arouse enter
prominently into the experience. A somewhat less intense
variety of this emotion is sympathy. Here the general
feeling tone (pleasantness) is most prominent, and the special
systemic sensations are less definite than in love. The motor
expressions of sympathy and love are generally movement
toward the object. In sympathy a common form of expres-
sion is activity of the tear glands.
This is the way the psychologist describes the three great
214 EMOTION [CH. ix
emotions of life. It sounds very different from the descrip-
tion of the poet or story-teller. The psychologist and the
poet have something quite different in view. The poet uses
language which will thrill his readers and arouse the same
emotions in them. The psychologist tries to show what sen-
sations make up the emotional experience. It is like the
attitude of the cook and the chemist toward the soup. The
cook wants to make a soup that will tickle the palate; the
chemist wants to know what is in the soup. Most men would
prefer to see love through the poet's eye and fear or anger
through the psychologist's.
Kinds of Emotion in Man. Human emotions have been
classified in various ways according as one characteristic or
another is selected as the starting-point. The objection to
most classifications is that they try to show all possible
varieties instead of those that are really significant. Some
types of emotion have developed tremendously and show
many different shades, while others that we might expect to
find scarcely appear at all. We can only discover what are
the really important emotions in human life by actual obser-
vation and experiment.
An important aid in this study is to notice the various
names used to distinguish emotions in the languages of
civilized and uncivilized races. If a large number of different
names for a certain kind of emotion are found in a given lan-
guage, we infer that a great many shades of that emotion are
present in the race using that language.
The list of emotions in Table VIII is based on the different
kinds of behavior that man exhibits with reference to his
surroundings. 1 For our present purpose five great classes of
responses may be distinguished: nutritive, reproductive,
defensive, aggressive, and social.
Strictly speaking, the nutritive functions do not lead to
emotions: eating and its various accompaniments are usually
1 See ch. x, p. 237.
CH. DC] TYPES OF HUMAN EMOTION
TABLE VDI. HUMAN EMOTIONS
215
1. Ex^essmJ^Nutriti
ve)
2. Reproductive
Emotion
Expression
Emotion Expression
+Joy (Enthusiasm)
Diffused
+Love Mating
Grief (Despair)
+Lust
Shock
Jealousy
H-Mirth
Coyness " (female)
+Ecstasy
+Tenderness Maternal
Restiveness
Exuberance
Play
+Wonder
Curiosity
3. Defensive
4. Aggressive
-Fear
Flight and Hiding
-Anger (Rage) Fighting
Disgust
Avoiding
Hatred Resenting
Timidity
Shyness
-Envy Rivalry
(Embarrassment)
+Pride Domineering
Shame
Covering
+Exultation
+Awe
Submission
5. Social
6. With Temporal Projection
+ Affect ion
Family relations
Retrospective Reference:
+Cordiality
Herding
-Regret (Remorse)
-Pity
Sympathetic
+Satisfaction (Elation)
+Gratitude
Surprise
+Admiration
Prospective Reference:
Detestation
Antipathetic
+Hope
Revenge
-Dread
Suspicion
f
Anxiety
-Scorn
**
unemotional acts. But there are certain expressive emotions
of an indefinite or diffused sort which depend indirectly on
the nutritive life. Joy, grief, and the like are expressive
emotions, made up of diffused feelings.
The defensive, aggressive, and reproductive emotions are
represented by the emotions of fear, anger, and love, which we
have already examined. These are the original forms; the
table shows a number of other well-known emotions that have
developed out of them.
216 EMOTION [CH. ix
The social life of man in relation to his fellows develops
special emotions. Some social emotions are defensive or
aggressive, but others do not belong in either of these groups.
The fifth class in the table includes the social emotions that
are not connected with other sorts of behavior.
There are also emotions that are essentially connected with
ideas of the past or the future. The prospective emotion of
hope, and the retrospective emotion of satisfaction are similar
to joy apart from the time reference.
In the table the kind of feeling tone that is characteristic
of each emotion is shown at the left and the kind of motor
expression at the right. In most emotions the feeling tone is
definitely pleasant (-J-) or unpleasant ( ). Certain sorts,
such as restiveness and surprise, may be either pleasant or
unpleasant. Frequently they alternate between one quality
and the other.
In many cases we may readily notice several different
shades of emotion under the same general type. It is easy to
distinguish, for example, between anger and rage. Some of
these varieties are of considerable importance in mental life;
remorse, for example, has very different consequences from
regret. Some of the less important distinctions are interest-
ing to study. Notice the difference between ' feeling
slighted,' 'pique,' 'feeling insulted,' 'feeling outraged';
or between various degrees of mirth.
Adapting Emotions to Civilized Life. The emotional life
has not kept pace with the other phases of mental evolution.
Perception, memory, and other types of experience have
adapted themselves to changing conditions, but our emo-
tional experiences continue in almost primitive form. Many
of the more important emotions seem like echoes of our
prehuman ancestors; they do not fit into the social life of
to-day.
The emotion of anger is well adapted to the food-getting
activities of carnivorous animals. It stimulates them to
i
CH. ix] TRAINING THE EMOTIONS 217
greater exertions and seems really to help them in overcoming
their prey. Even in primitive man strength is more impor-
tant than skill. But under modern conditions of civilized life
intellectual adjustment and motor coordination are far more
valuable than mere strength. A Foch or a Hindenburg is
the brains of the army, not its fist. The man who gives way
to blind rage in the presence of an adversary is usually at a
disadvantage. We look upon unbridled emotion of any sort
as childish or brutish; one who has not learned to control
the display of emotion is held more or less in contempt.
People are even apt to regard the shell-shocked veteran as a
coward, though really his disability should arouse the same
feeling as the loss of a leg in battle.
Since our emotional inheritance is unsuitable to present
conditions, the obvious course is to direct this phase of mental
We into more suitable paths by systematic training. This is
one of the most important tasks of education, socially speak-
ing. Emotional training is not so prominent a feature of
our present-day educational systems as intellectual training;
it is generally accomplished indirectly or incidentally.
School discipline and home discipline, especially through
punishment and admonition, teach the child to repress or
suppress violent displays of emotion. Social tradition and
example help considerably. The child finds that he makes
himself ridiculous by giving free vent to his emotions. The
'cry-baby' is an object of contempt among children; the
stolid child or youth is admired by his playmates.
The ideal of a calm, passionless life may perhaps be socially
desirable, but it does not take into account the innate pro-
pensities of the individual. No boiler is strong enough to
resist every pressure, and the engineer who clamps down the
safety-valve is heedless of the best interests of his machine.
Expression is the_safety-yalve of emotion.^ The emotional
tendencies are part of our mental inheritance. It is not
possible to eradicate them entirely. Freud has shown that
218 EMOTION [CH. ix
the struggle to suppress them often results in nervous dis-
organization. On the moral side it fosters deceit and
hypocrisy. A rational training of the emotions would con-
sist in modifying their feeling elements and directing their
motor expression into useful channels.
The various classes of emotions differ considerably in
value. The defensive emotions refer back to prehistoric
modes of defense, and for the most part hamper us under
modern conditions. The same is true of the aggressive emo-
tions. On the other hand, the social emotions harmonize
well with modern social conditions, excepting those which
are distinctly antipathetic. The reproductive emotions
(especially love and tenderness) are by no means anachro-
nistic, but they require careful training to fit them into the
social life of civilized man. In some communities this train-
ing has gone to extreme lengths.
The expressive emotions and the retrospective and pro-
spective types are socially neutral. Extreme manifestations
of joy, grief, mirth, regret, hope, and the like, do not fit in
with modern life; but a moderate display of these emotions
is not socially detrimental and is of some benefit to the bio-
logical life of the individual.
In short, psychology and pedagogy should recognize that
the emotional side of our mental life is to some extent behind
the times. Uncontrolled emotion hampers the proper inter-
action between the individual of to-day and his environment.
It is only when our primitive, inherited emotions are trained
into socially acceptable modes of expression that this phase
of mental life is brought into harmony with the rest of our
experiences and actions.
SENTIMENT
Nature of Sentiment. Besides feeling and emotion, there
is another, less important experience connected with our
inner bodily processes, called sentiment. A sentiment is
CH. ix] NATURE OF SENTIMENT 219
an experience which is made up of systemic sensations and
ideas. 1
Sentiments may be aroused by any external sensation or
idea, but the experience itself is essentially different from
either. Your " sense of beauty " is not a sensation nor a
perception, but a sentiment. It may be aroused by seeing
the Venus de Milo, or by listening to Beethoven's Fifth
Symphony, or by the memory of one of these experiences;
but the sentiment of beauty is not the perception of the
object. The perception suggests the sentiment, and then
fades into the background of the new experience. The promi-
nent elements in the sentiment of beauty are a feeling and
an idea of value (ch. xiii).
When something has aroused a sentiment, and the same
situation continues to affect us, we connect the sentiment
with the perception and read it into the objective situation.
The statue ' looks beautiful.' The world about us ' looks
real.' A locomotive appears powerful. An action appears
good.
Are the beauty, reality, and power in the objects them-
selves? Is the ' goodness ' in the action or in the actor? In
discussing feeling we noticed that pain is not a quality of the
sharp knife, though we experience pain when the knife cuts
us, and the pain is stimulated by the sharp edge. In much
the same way the sentiment of beauty is stimulated by cer-
tain combinations of tones in music or by certain curves or
color combinations in a painting; but it is not a quality of the
music or painting. And the same is true of power and good-
ness. Our sentiments are generated within us; they are
intimately personal, like pain, and yet they are excited by
something in the external stimulus.
1 The term sentiment has a special meaning in psychology. It is not pre-
cisely what we mean by 'a sentiment' in ordinary language, and it does
not correspond to the adjective 'sentimental'; but it carries a trace of each
notion the imagery of 'a sentiment' and the feeling tone of 'sentimental.'
220 SENTIMENT [CH. ix
Kinds of Sentiments. Sentiments are classified according
to the kind of experience that arouses them. [Table IX.]
TABLE IX. CLASSIFICATION OF SENTIMENTS
Sentiments Source
Reality Feelings Perceptions
Beliefs Ideas
Esthetic Sentiments Systemic Experiences
Dynamic Sentiments Motor Experiences
Moral Sentiments Social Situations
The sentiment of real ness, or reality feeling, attaches to per-
ceptions of the outer world. We are sure that the objects
which we see, palp, heft, hear, etc., really exist. Usually this
sureness or conviction is marginal. Like the familiarity feel-
ing, it is only a subordinate element in the perception. In
adult life the reality feeling rarely occurs as an independent
experience. It takes something unexpected, or something
that does not fit in with our general scheme of things to bring
it out vividly. If we meet a friend who was supposed to be
a thousand miles away, the reality of his presence bursts
through into prominence. The other extreme occurs in day-
dreaming, or when we are dazed by a sudden blow or a loud
noise: then the reality element is quite lacking things about
us do not impress us as real. In certain pathological condi-
tions the sense of reality disappears completely: the patient
declares that the world does not seem real.
Belief is very much like reality feeling, except that it is
associated with ideas. We are sure that certain of our images
and thoughts are true. Two opposite varieties of belief have
developed : affirmative belief, and negative belief or disbelief.
We may either believe in the existence of the object we are
thinking of; or we may believe that no such object exists.
When you picture a mermaid, your sentiment is belief in its
falsity, while if you have a mental picture of Vesuvius the
sentiment takes the form of belief that this volcano actually
exists. In the two cases the sentiment is of the same type
CH. EX] TYPES OF SENTIMENT 221
belief but our attitude is different (ch. xv). The 'not'
attitude gives a special tinge to the sentiment. The true
opposite of belief is not disbelief, but doubt. Doubt is a
sentiment which arises from alternation of belief and dis-
belief.
Esthetic sentiments arise when the feeling tone of an experi-
ence is especially intense and combines with an idea of value.
This produces a sentiment of beauty or harmony if the feeling
is pleasant, and a sentiment of ugliness or discord if the feeling
is unpleasant. The intensity of the esthetic sentiments
varies considerably with the individual and with training.
In some persons an appreciation of beauty and harmony
appears early in life and develops without any special train-
ing; in others it is only attained gradually, through education
and imitation. Esthetic sentiments are especially character-
istic of the ' artistic ' type of personality.
Dynamic sentiments arise when vivid motor sensations are
associated with our perceptions. These motor sensations are
stimulated by the activity of our own muscles; but their
intensity depends upon the weight or resistance of objects
that we try to move. In connection with our voluntary
movements there is a sense of power or abilily to act. If the
resistance is strong, we have a sense of opposition, of being
thwarted, of force or power in the environment. These are
dynamic sentiments. A tornado, a great factory machine in
action, arouse a sentiment of the power of inanimate nature.
The religious sentiment is due to an idea of some mighty
power in the universe. Dynamic and esthetic sentiments
combine to form the sentiment of the sublime.
Moral sentiments come from feelings which attach to our
perceptions of social acts usually the actions of other per-
sons. The ' traffic cop ' who goes over and leads a blind man
across the street arouses your approval; the youngster who
hurls a stone through a shop window arouses a feeling of dis-
approval. In each instance the feeling combined with the
SENTIMENT [CH. ix
idea of social value forms a moral sentiment, in one case a
sentiment of right, in the other a sentiment of wrong.
Sentiments are the least important kind of experience. If
a sentiment is weak it becomes an element in some other state
of mind. If it grows intense, it tends to bring about some
motor expression; this arouses muscle sensations and the
experience is no longer a mere sentiment. Esthetic senti-
ments pass readily into emotions; dynamic sentiments arouse
an impulse to overcome resistance or to exert our own power.
Moral sentiments, if they are vivid, are likely to pass over
into voluntary actions. We are not content with merely con-
demning or approving the actions of others. If a wrong
appeals to us deeply, we are apt to start in to remedy it. We
' push along ' a good thing literally as well as figuratively.
In a word, sentiments lack stable equilibrium; if they are
weak they are crowded out of focus by other experiences; if
they are intense this very strength transforms them into
something else. Beliefs are the most stable of all sentiments.
Our belief in the multiplication table and other fundamental
truths persists unaltered throughout life. Other underlying
beliefs undergo certain changes from time to time, but still
remain as enduring sentiments.
Summary. In this chapter we have examined three sorts
of experience in which systemic sensations are prominent.
Feelings are experiences consisting almost wholly of (1)
organic sensations that is, sensations from the internal
organs of digestion, reproduction, circulation, respiration,
and other bodily processes, or (2) pain sensations, or (3)
feeling tone and general sensibility. Feelings are experiences
of our own bodily condition, and may be contrasted with
perceptions, which are experiences of the outer world.
Emotions are experiences in which both systemic and motor
sensations are prominent. They combine feeling and action.
In general they are more intense and vivid than simple feel-
ings and occupy a specially prominent place in mental life.
CH. EX] SUMMARY 223
Emotional experiences belong to primitive conditions of life
and do not fit in especially well with man's higher mental
evolution.
Sentiments are experiences which combine systemic sensa-
tions with ideas. They are generally weak and unimportant
in mental life. Belief is the most hardy of all the sentiments.
The others tend to fade into the background, or they lead to
action and so are transformed into some other kind of
experience.
PRACTICAL EXERCISES:
44. Analyze your general state of feeling at three different times; e.g. on
waking, after a hearty meal, after a brisk walk.
45. Describe the expression of three different emotions, in cases you
have witnessed recently.
46. Analyze some powerful emotion of your own at the time or soon after
the outburst has subsided.
47. Mention some fact which you believe thoroughly; also some statement
which you are sure is false; also something about which you are in real
doubt. Now examine the sentiment you have in each case the
belief, the disbelief, and the doubt; describe them as far as possible.
48. Describe the expression of anger (or fear) in a child.
REFERENCES:
On feeling: E. B. Titchener, Psychology of Feeling and Attention, chs. 2-4.
On classes of emotion: W. McDougall, Social Psychology, chs. S-6.
On theory of emotion: W. James, Principles of Psychology, ch. 25;
C. Darwin, Expression of the Emotions in Man and Animals.
On the physiology of emotions: C. W. Crile, Origin and Nature of the Emo-
tions; W. B. Cannon, Bodily Changes in Pain, Hunger, Fear and Rage.
CHAPTER X
INSTINCT
Motor Experiences and Response. The experiences so
far examined belong to two separate groups: (1) Perceptions,
memories, and their kindred are based on the information we
receive from the outer world. (2) Feelings and emotions are
concerned with internal conditions and are stimulated by the
physiological processes which go on within our own body.
There is still a third class called motor experiences, which are
composed largely of motor sensations. The muscle sense and
static sense furnish information about our movements and
responses, and about our bodily postures with reference to the
outer world. These sensations are organized into experiences
called conations, and when joined to images and thoughts
they develop into secondary experiences called volitions and
language.
Motor experiences differ from other experiences in one
important respect: We perceive, we imagine, we feel, before we
act. Motor experiences, on the other hand, are the result of
our motor activity; they arise after the motor nerve impulses
have begun to affect our muscles. When we walk, we sense
each movement of our limbs as it takes place. In other
words, whereas perceptions, images, and feelings keep us in
touch with the stimuli that affect us, conations and other
motor experiences are concerned chiefly with our responses.
Before taking up these motor experiences, 1 we must examine
the motor side of the nervous operation and see how it is
related to stimulation.
Every stimulus starts an impulse in the sensory nerves,
which proceeds to some center in the spinal cord or brain.
1 See chs. xii, xiii.
CH. x] EXPERIENCE AND RESPONSE 225
In these central neurons there is a certain amount of latent
nerve energy, so that the incoming impulses, instead of being
' absorbed,' actually arouse a greater amount of nervous activity
at the centers, and this activity seeks an outlet into other
neurons. The nervous activity aroused in the brain by visual
stimuli results first in our perceiving the scenes around us,
and this perception may be followed by a series of memories
and fancies. But this succession of events in the brain does
not continue indefinitely. In the end the central impulse
finds an outlet into some motor path and passes out of the
brain and down to some muscle, where its energy is expended
in producing muscular contraction. The final result of the
nerve impulse in this case is movement^ In other cases the
outlet is into a path leading to some gland, and the final result
is the chemical process_of j gecre<ion. Our notion of nervous
activity will be incomplete, then, if we stop at the central
processes of perception, feeling, and the like. Every stimulus
tends in the end to bring about some response. The most signif-
icant feature of the entire nervous and mental process is not
the information it furnishes, but the way we act upon this
information. Action by a creature in response to stimula-
tion is called behavior.
Kinds of Behavior. Behavior may be grouped into the
following classes:
Diffused movements
Reflexes
Autonomic functions
Instinctive behavior
Intelligent behavior
(1) DIFFUSED MOVEMENTS: Nerve impulses always follow
the path of least resistance. If the neurons were not arranged
in definite groups and chains, the nerve impulses might follow
all sorts of paths and our responses would be largely a matter
of chance. The same stimulus would lead now to this move-
ment, now to that, at random, without any appropriateness
226 BEHAVIOR [CH. x
whatever. Impulses would tend to spread into several chan-
nels at once and cause diffused movements.
Diffused movements occur in the new-born child. When
he is affected at the same time by several stimuli none of
which is especially intense, his responses are uncoordinated;
they bear no significant relation to the stimuli. Observe a
child lying on his back when nothing in particular is affecting
him. He wriggles his arms, gurgles, winks, kicks about,
moves his toes, his lips, his eyes, his head. These diffused
random movements are the result of general stimulation by
light, pressure, warmth, and sounds. The incoming impulses
are weak and diffused; they find outlets here and there
through various motor channels.
(2) REFLEXES: Diffused response is not the only form of
behavior in the new-born child. Our nervous system is
arranged at the start by heredity in an orderly way. The
sensory and motor centers are placed in very definite rela-
tions to one another. From the very beginning certain sen-
sory paths are closely connected with certain motor paths, so
that stimuli which affect a given receptor are bound to bring
about certain definite responses. If an infant's palm is
touched with a stick he grasps it; if a milk bottle is put to his
mouth his lips close around it; certain stimuli produce
coughing, others produce sneezing. These are immediate
responses, brought about by inherited connections between
sensory and motor nerve paths. A definite response to a
definite stimulus, due to an inherited arrangement of the
nerve paths, is called a reflex, or reflex action.
(3) AUTONOMIC FUNCTIONS: The earliest reflexes that occur
in a child's life are due to systemic stimuli. Long before birth
the heart begins to beat through stimuli which arouse activity
of the heart muscles. Immediately after birth the lungs are
stimulated and the result is muscular activity which draws the
air into the lungs and expels it again. These responses,
which control the bodily processes of circulation and respira-
CH. x] KINDS OF BEHAVIOR 227
tion, are so arranged that each response furnishes a stimulus
for another reflex of the same sort. They form a chain of
reflexes, which continue in endless series during the entire life
of the individual. Regardless of the environment (except
in a general way), the lungs expand and contract, the heart
pumps blood into the arteries continuously till death.
These chains of reflexes which govern the life processes are
called autonomic functions. They are of the utmost impor-
tance to life; but since they are only indirectly concerned with
the individual's relations to his environment, they do not
interest psychologists especially. Their special bearing on
psychology lies in the fact that the autonomic nervous system
is connected with the main cerebrospinal nervous system
(ch. ii). By reason of this connection the autonomic func-
tions may be modified by motor impulses from the brain and
spinal centers. This occurs, for example, in voluntary
changes of respiration and in the changes in heart activity
that accompany the emotions.
The digestive processes are controlled by the autonomic
system also. But they do not form a single continuous series
of reflexes like respiration and circulation. Digestion de-
pends upon stimulation by food in the stomach or intestines;
in the absence of food the digestive organs are comparatively
inactive. When food is taken into the mouth the digestive
organs are stimulated and the autonomic processes begin to
act at once; they include a whole series of digestive activities
ending in the excretion of the waste products. All these
processes are subject to some control by the cerebrospinal
system, and often serve to stimulate and modify its activities.
Apart from this connection, psychology is not particularly
concerned with the autonomic functions.
(4-) INSTINCTIVE BEHAVIOR: The nervous connections
within the cerebrospinal system are not so close as those of
the autonomic nerves. There is more branching of neurons
and consequently more possibility of alternative motor dis-
228 BEHAVIOR [CH. x
charges. But the various nerve paths and centers are so
arranged by inheritance that certain connections are inevi-
table, especially in early life. Not only are there from the
beginning certain definite reflexes to external stimulation, but
some of these reflexes cause stimuli which produce other
reflexes, so that when a given stimulus occurs a definite chain
of reflexes inevitably follows. This is best illustrated in the
feeding activity of the infant. The contact of the lips with
the breast or bottle causes the lip-grasping reflex. This
serves as stimulus to the sucking reflex. The milk in turn
stimulates the swallowing reflex. Any succession of cerebro-
spinal reflexes like this, in which one response provides the
stimulus for the next, is called an instinct, or instinctive
behavior.
In subhuman species, where the branching connections are
not so numerous as in man, a large part of behavior is of the
instinctive type. Remember that in any instinctive act the
successive steps follow in natural order each is caused by
the preceding. There is no delay; no thinking and deciding
what to do. The progress of the action is automatic ! unless
checked by some interfering stimulus. Instinctive behavior
generally brings about some result that is useful to the crea-
ture ; that is, it is adaptive. This is because the nervous struc-
ture, like the rest of the body, has grown up in the course of
long ages of time through the natural selection of useful
arrangements of the neurons and centers.
(5) INTELLIGENT BEHAVIOR: The branching connections in
the nervous system make possible still another type of behav-
ior. Reflexes that are not so closely connected as to form
instincts, may come in time to be grouped into hard and fast
series of actions which are of the utmost importance to life.
A series of useful movements whose connection is not based
on heredity, but is acquired by the individual, is called intelli-
gent behavior. If the act becomes so fixed that it proceeds as
1 Not to be confused with autonomic.
CH. x] KINDS OF BEHAVIOR 229
automatically as an instinct, it is called a habit. Speaking
and writing are instances of human habits.
The human adult finds it difficult to draw a sharp line
between instinctive and intelligent behavior in the case of his
own actions. Early in life our instincts begin to be modified,
and these new modes of action are often so quick and auto-
matic that they seem to be inborn. Most of our actions have
marked instinctive elements and equally marked intelligent
elements. Walking is especially hard to classify. When the
child starts to walk his movements are uncertain, and they
seem to improve by practice; but the fact that walking always
develops at about the same age indicates that it depends
fundamentally on certain inherited factors. On the whole the
act of walking seems to be mainly instinctive in man.
REFLEX BEHAVIOR
Nature of the Reflex. The reflex is the simplest form of
response in creatures possessing a nervous system. It in-
volves the operation of a single nervous arc or a number of
arcs acting together.
The characteristic feature of reflex activity is that the
response is definite, not diffuse. This makes it a suitable type
of activity for response. It accomplishes something. The
infant's diffuse movements are responses to stimulation, but
they are not especially adaptive they do not answer the
problems which the stimuli set before the child. Definite
reactions of the reflex type do this. Winking protects the
eyes; swallowing assists the nourishment process. Even
glandular reflexes may solve some of the minor problems of
life, weeping may remove a cinder from the eye.
While reflex activity is definite, it is by no means invariable :
the response usually varies with the intensity of the stimulus.
Very intense stimulation generally causes violent muscular
contraction, and the effect is apt to be widespread. The
shudder reflex extends over a larger part of the body when the
230 REFLEX BEHAVIOR [CH. x
stimulus is more intense. The tickle reflex is an exception to
this rule: the tickle stimulus is less intense than the ordinary
touch stimulation, but its peculiar quality brings about a
much more violent response than ordinary contact.
Varieties of Reflex Action. In reflex action the stimulus
starts a nerve impulse along the sensory nerve toward the
central part of the nervous system; at the center the impulse
passes over to a motor path and descends to a muscle or
gland, causing responsive activity. This process may be
complicated in two ways: (1) The impulse may either cross to
the motor path and pass out at the first opportunity; or it
may proceed to a higher center and then pass out. On this
basis reflexes are divided into lower and higher. (2) The
sensory impulse may produce a single response; or the motor
impulse may divide and go out to two or more effectors at
once. On this basis we distinguish between simple and com-
pound reflexes.
In lower reflexes the adjustment takes place in the spinal
cord or in the lower centers of the brain. When you touch a
hot stove, the sensory impulse upon reaching the spinal cord
immediately passes over to the motor side and a motor im-
pulse goes out directly to the hand, so that you withdraw the
hand before you feel the heat or pain.
In higher reflexes the sensory impulse travels to a higher
brain center and the adjustment takes place there. A sudden
loud noise often produces violent beating of the heart. The
sensory impulse goes first to the primary center of hearing,
then to a higher center, and from there part of the impulses
passes out through a motor pathway to the cardiac muscles.
A simple reflex involves a single nervous arc; the sensory
impulses all travel up through a single sensory nerve and the
outgoing impulses all proceed along one motor nerve and
affect a single muscle. 1 When we hear a sound and auto-
1 A number of parallel neurons in the nerve usually carry the impulse
inward or outward.
CH. X]
VARIETIES OF REFLEX
231
matically turn the eyes in that direction, the action is a simple
reflex. [Fig. 71; cf. Fig. 16, p. 41.]
A compound reflex involves two or more separate motor
nerves. The hand-grasping reflex is a compound reflex,
FIG. 71. SIMPLE REFLEX
Simple cranial reflex from the ear to the eye muscles. A sound stimulates
the ear (A) and starts a sensory nerve impulse along the 8th cranial nerve to
lower auditory center (C) in the brain. The impulse travels to the center for
eye movement (D). Thence a motor impulse passes along the 6th cranial
nerve (E) to the eye muscles (F); the muscles contract and the eye is turned
toward the sound. (A simple spinal reflex is shown in Fig. 16.) [After Her-
rick.1
because it involves the muscles of all the fingers and several
joints in each finger.
In nearly all reflex actions there is a certain compounding
of impulses in the sensory part of the nervous arc. The eye-
wink is a response to stimulation of the whole field of vision,
or at least a large area; the withdrawal of the hand from a hot
surface is usually in response to a temperature stimulus that
affects many warmth receptors covering quite an area of the
skin. This compounding of sensory impulses is not especially
significant; it serves to intensify the response, but seldom
changes its character.
The simplest sort of compounding occurs in reflexes which
have two or more motor effects. This is called a distributed
reflex, because the outgoing impulse is distributed into
232
REFLEX BEHAVIOR
[CH. X
(Kin
several motor paths. The operation of a distributed reflex is
shown in Fig. 72. This diagram represents what happens, for
example, in the pain reflex.
A simple reflex may form part of a distributed reflex. For
example, in the knee-jerk, when the nerve impulse reaches the
cord it may divide; a por-
tion may cross over di-
rectly into the cord or the
motor path and cause the
leg to fly up, while part
may travel up to the brain
and produce some other
type of activity, such as
grunting or flinching.
If the entire impulse
reaches a higher center it
may result in a coordinated
compound reflex. Grasp-
ing, sucking, and certain
vocal reflexes are exam-
ples of this. In the grasp-
ing reflex of the hand all
the fingers are bent at
once; the sucking reflex sends motor impulses to several dif<
ferent muscles in the lips, cheeks, and tongue. If the highei
centers come into play the response may be on the opposite
side of the body from the stimulus ; frequently it is bilateral.
This is due to the fact that the motor pathways to the two
sides of the body are connected by transverse paths in the
brain.
Among compound reflexes considerable importance at-
taches to the way in which the different muscles are related.
We distinguish between antagonistic reflexes, in which the
impulses lead to opposing or antagonistic muscles, and allied
reflexes, where the various muscles assist one another. In
FIG. 72. DISTRIBUTED REFLEX
Showing how stimulation of a receptor in the
skin leads to contraction of several different mus-
cles Ml, M2, M3. [From Herrick.l
CH. x] VARIETIES OF REFLEX 233
TABLE X. HUMAN REFLEXES
A. Purest least subject to central modification in adult
'Pupillary ' or iris reflex Shuddering
Ear twitching (controlled in some Starting (to sudden noise, etc.)
individuals) Shivering
Hand withdrawal (to heat and pain) Trembling
Digestive reflexes (autonomic) Rhythmic contractions (in epilepsy,
paralysis agitans, etc.)
B. Largely pure subject to inhibition or reinforcement
Winking Hand twitching (to dermal pain)
Accommodation, ciliary reflex Plantar reflex (to stimulus on sole of
Eye-fixation and convergence foot)
Hiccoughing Great toe reflex
Sneezing Vasomotor changes (blushing, paling)
Patellar reflex (knee-jerk) Breathing changes (to specific stimuli
Dizziness reflexes and to onset of sleep)
Yawning Sudorific reflexes
Vomiting Groaning
Facial reflexes (to bitter taste, etc.) Laughing
Salivation Cramp movements
Tickle reflexes Squirming
C. Occasionally pure, more often centrally modified
Coughing Smiling
Swallowing and gulping Wincing, etc.
Visceral discharge, etc. Scowling
Generative reflexes Stretching
Reflexes to odors Convulsive contractions (to deep pres-
Gasping sure and heat, to pricking and other
Weeping dermal pains, and to visceral pain)
Sobbing
D. Pure in infancy, centrally modified in adult
Sucking Tugging (wrist reflexes)
Biting and grinding Clasping (elbow reflexes)
Spitting Reaching (shoulder reflexes)
Hunger and thirst reflexes Kicking (knee reflexes)
Lip and tongue reflexes Stepping (gluteal reflexes)
Vocal reflexes Jumping (ankle reflexes)
Turning the head Sitting up
Tossing Bending forward
Grasping (finger reflexes) Rising
E. Posture reflexes
Holding head erect Standing
Sitting Equilibration
234 REFLEX BEHAVIOR AND INSTINCT [CH. x
some cases the actions of different muscles tend partly to
neutralize, partly to reinforce one another; these are called
allied and antagonistic reflexes. Where several reflexes follow
in succession, they may be alternating, as the two legs in walk-
ing, or supplementary, as the flexing of the several finger
joints in grasping.
These relations emphasize the fact that a reflex is not a
mere muscular contraction; it is a response to the stimulus
it accomplishes something. An isolated reflex, such as the
knee-jerk, may not be particularly useful; but compound
reflexes generally tend to bring about some result which
makes life a bit easier.
Human Reflexes. In human adults comparatively few
activities belong to the pure reflex type. Even such a reflex
as winking may be reinforced or partly inhibited by volun-
tary control; and the same motor paths that carry impulses
for the winking reflex also carry impulses for voluntary
winking and for closing the eye.
Table X shows the most important human reflexes that
have received familiar names. There are many others with
technical Latin names which involve single muscles or whose
connections are somewhat obscure. In some cases a number
of similar reflexes have been grouped together under one name
in the Table (e.g., the facial reflexes). The list is chiefly
interesting as showing the great variety of comparatively
simple motor activities, and how much more voluntary con-
trol we have acquired over some than over others.
INSTINCTIVE BEHAVIOR
Nature of Instinct. The term instinct has been variously
defined. Earlier writers treated it as a mysterious innate
power possessed by subhuman animals, which enables them
to do the right thing in the right way, without consciousness
or deliberation. This notion still prevails in popular psychol-
ogy. To-day we know that instinctive behavior is the result
CH. x] NATURE OF INSTINCT 235
of integration and coordination of nerve impulses, and that
this ' central adjustment ' is due to inherited nervous con-
nections.
Following out this notion, instinct is defined as any sort of
complex behavior that involves a set of reflex activities, in
which (a) one reflex furnishes the stimulus that leads to the
next, and in which (6) the connections depend upon inherited
structure, not upon gradual learning by the individual. In
walking, for example, each movement serves as a stimulus
for the next. When the left foot touches the ground the
touch stimulus, together with the muscle-sense stimulus
from the muscles of the left leg, starts the motor impulse for
lifting the right leg, and so on. This succession of response
and stimulation is characteristic of instinctive behavior
generally.
In most instincts each act in the series involves a different
kind of reflex from the preceding. A typical example is the
suckling instinct in the human infant. This involves a suc-
cession of different reflexes : bending the head, grasping with
the lips, sucking, and swallowing. Each reflex in the series
furnishes a stimulus which causes the next reflex, as already
pointed out. l In later life the series is broken up, but the last
link in the chain still holds: when you take food into the
mouth, especially if it reaches the back of the tongue, it stimu-
lates your swallowing reflex so powerfully that you can
scarcely avoid making the swallowing contractions.
Instinctive action takes place because each reflex that com-
poses it follows an inherited path of least resistance, and
because the motor response of one reflex provides the appro-
priate stimulus for the next. The development of an instinct
may be thwarted if at any stage the movement does not lead
to the proper stimulus for the next stage. As a general rule
the same fundamental instincts appear in every individual of
the species at about the same period of life, because they all
236 INSTINCTIVE BEHAVIOR [CH. x
inherit the same fundamental nerve structure and live in sub-
stantially the same environment.
Origin of New Instincts. Every species of animal, man-
kind among the rest, has evolved certain typical kinds of
instinctive behavior. Some instincts belong to a large num-
ber of species; others to a single species. The origin of wide-
spread instincts and their special varieties is explained on the
basis of natural selection in the following way:
Each separate reflex appears in the first place in connection
with some chance variation of nerve structure. The varia-
tions that are useful to a species are selected; that is, because a
given reflex is useful in keeping the creature alive, more and
more individuals having this reflex live to maturity; those
without it are at a disadvantage and die young.
The combination of reflexes into instincts is due to chance
variations in the position of nerves, which bring certain
pathways close together. Suppose some new combination of
reflex paths, brought about by chance variation and capable
of inheritance, is especially fitted to preserve the animal's life;
then the creature possessing this new combination is more
likely to survive and transmit the instinct to his offspring.
Not every new combination is advantageous. If a variation
should occur in the feeding instinct of such a sort that the
sucking reflex was not stimulated by lip-grasping, the result
would be disastrous to the infant: he would starve to death.
Detrimental variations tend to weed themselves out by the
very same selection that promotes the survival of advan-
tageous variations.
Human Instincts. The human adult seldom behaves in a
purely instinctive way. His activities are largely modified
and controlled by individual experiences. Even the deep,
underlying instincts are partly suppressed and reduced to
conventional forms. As we pass from infancy the feeding
instinct is greatly modified by the use of our hands and vari-
ous implements for eating. It ceases to be a pure instinct.
H. x] HUMAN INSTINCTS 237
Many innate tendencies never get a chance to develop into
instincts; they are modified by habits which are already
formed when the tendency appears; so that what we get is a
form of behavior that is partly instinctive, partly intelligent.
The tendency to prefer the right hand over the left, for
instance, does not appear till after the child has learned to
use his hands in various ways. In later life it is difficult to
say how much of our right-handedness is innate and how
much is due to training.
There have been wide differences of opinion among psy-
chologists as to the number of human instincts. James and
others insist that man possesses a great variety of instincts
as many, in fact, as any of the lower species. Other writers
restrict human instincts to a few kinds. Both views are
partly correct. The human adult has few pure instincts, but
he has a great number of modified instincts. When we speak
of human instincts, it is to be understood that the behavior
described is not wholly inherited, like most animal instincts,
but only that it is very largely determined by inheritance.
In this sense walking is a human instinct, though a child may
be aided in developing it by teaching and imitation.
It is convenient to classify human instincts according to the
kind of results they bring about. What objects in life do our
various movements and actions accomplish? What purposes
do they serve? Looking over the field broadly, we find that
man tries to attain one or other of the following results by his
activities :
Nutrition: maintenance of bodily organization
Reproduction: perpetuation of the species
Defense: prevention of injury by the environment
Aggression: destruction of enemies
Social organization : cooperation with his fellows
Individual development: his own improvement
Most of these great objectives in life give rise to emotional
expression, as we noticed in the last chapter. 1 They are, in
1 P, 214.
238 INSTINCTIVE BEHAVIOR [CH. x
fact, the motives for all our complex actions, whether emo-
tional or not; they determine both instinctive and intelligent
behavior. These six kinds of biological purposes serve as a
basis for classifying human instincts. Human beings, by
their inherited nervous make-up, perform actions which
result in their getting food, reproducing their kind, warding
off destruction, overcoming their enemies, cooperating with
other men, and improving their own condition.
TABLE XI. HUMAN INSTINCTS
1. Nutritive 2. Reproductive
Walking Mating (sexual attraction. court-
Feeding ship)
Wandering [Hunting] Maternal
Acquiring [Hoarding] Filial (of infancy)
Cleanliness
Diffused expression
3. Defensive 4. Aggressive
Fighting Fighting
Submission Resenting
Hiding Domineering
Avoiding Rivalry
Modesty [Shyness]
Clothing [Covering]
Constructing [Home-making]
5. Social 6. Individual Development
Family (parental and filial) Imitativeness
Tribal [Herding] Playfulness
'Apopathetic* Curiosity
Sympathetic Dextrality (right-handedness)
Antipathetic Communicativeness
Cooperative Esthetic expression
[Note: Names in square brackets denote a more primitive form of the
same instinct.]
The principal human instincts are shown in Table XI.
Looking over the list we recognize many familiar kinds of
actions which need no comment. The meaning of some-of the
others is not so clear. The wandering instinct, which to-day
finds expression in exploration and globe-trotting, seems to be
CH. x] HUMAN INSTINCTS 239
derived from a more primitive hunting instinct; and the tend-
ency to acquire property harks back to a hoarding instinct in
the days when life depended on storing away supplies for the
winter.
Often a single instinct includes several different kinds of
behavior. For example, fighting may be performed with the
fists or the feet or even with the teeth. Part of this diver-
sity of expression is due to the fact that our inherited tend-
ency to fight is developed this way or that by intelligent learn-
ing. Diffused expression is the emotional display of general
systemic conditions; it includes the natural expression of
joy, grief, and the like. These diffused instinctive expres-
sions are the only instincts in the nutritive group that are
distinctly emotional.
The instincts belonging to the reproductive group develop
somewhat later than the others, due to the slow maturing of
the generative organs. Yet rudimentary expressions often
appear at an early age. Symptoms of courtship are seen even
in young children. Filial instincts determine the child's be-
havior toward his parents. A child may manifest the same
devotion toward adopted parents; it is not a question of
actual relationship, but of an instinctive tendency on the
child's part to behave in certain ways toward those who
foster him. After the fostering age is past, family ties rest
more and more on a social basis.
The defensive and aggressive instincts are not always
opposite alternatives, as one might suppose. Fighting and
fleeing are alternative ways of responding to the same stimu-
lus; but many defensive instincts have no counterpart in the
aggressive group. The covering and home-making instincts
in primitive man are instances of this; they arose because
man needed protection from rain and cold. In civilized man
these instincts have developed into clothing and constructing
tendencies. The constructing instinct has had far-reaching
results in the sphere of invention.
240 INSTINCTIVE BEHAVIOR [CH. x
The clothing instinct and the modesty instinct are apt to be
confused. If we trace them back to their primitive forms,
covering and shyness, the distinction is more obvious. Shy-
ness is connected with our personality; covering has to do
with our body. In civilized life modesty is a defense measure
against the attacks on our mental privacy, while clothing is
a means of protecting the body.
In the list of social instincts are included only those forms
of behavior that are essentially social actions which are
neither defensive nor aggressive but have to do chiefly with
social organization. The family instincts are closely related
to the mating instincts tribal instincts only remotely so.
Family life may exist without community life, as we find in
many primitive races.
The instincts called apopathetic (for want of a better name)
are responses to the attitudes of others. We tend to act
differently when others are present, even though they pay no
attention to us; the bare fact of their being around has an
effect on our behavior. We respond in special ways to the
approval of others, and in other special ways to their expres-
sions of disapproval.
The distinction between sympathetic and antipathetic be-
havior is too obvious to need discussion. We see instances of
each almost daily. The only question is whether this distinc-
tion is innate, or whether the two opposing types of behavior
are acquired through social intercourse. There is reason to
believe that the distinction rests on inheritance. Certain
people please us from the start, and others are repugnant. In
each case the person arouses & feeling in us. What stimulates
this feeling? Usually some sensation from sight, hearing,
smell, etc. This man has an attractive face or manner; that
man's voice pleases us. The external senses may also
arouse dislike consciously or subconsciously. The scarcely
perceptible human body odor often arouses an indefinable
antipathy; race antagonisms are probably due to this cause.
CH. x] HUMAN INSTINCTS 241
The cooperative instincts are similar to the tribal instincts.
Division of labor to produce ' community results ' is instinc-
tive in the ants, where certain classes of individuals perform
various duties. In man cooperation is largely an acquired
trait; but it probably rests upon an instinctive basis.
Instinctive Tendencies. The types of behavior connected
with individual development (Table XI) are not instinctive
responses, strictly speaking: they do not represent definite
ways of acting. Imitation, for instance, may be observed in
any one of a hundred different actions; an action is imitative
if it reproduces some other person's act, or if it brings about a
result which resembles some other result. Generally the
ability to imitate anything is acquired by a process of learn-
ing it is not inherited. But there are distinct inherited
paths in the nervous system which enable us to try to imitate,
instead of responding in some entirely different way. An
inherited tendency to imitate is found in some subhuman spe-
cies; the parrot tends to imitate speech and the monkey to
imitate gestures. But the parrot has no arrangement of
nerve paths for reproducing gestures, nor the monkey for
reproducing articulate expression.
Imitation, then, is not an instinct; but there is in certain
species an instinctive tendency to imitate. 1 The same is true
of play and curiosity. They are definite inherited tendencies,
which find expression in various sorts of acts. The actions
themselves are not inherited, but they are learned more
quickly on account of the innate tendency.
The imitative tendency is much stronger and more extensive
in man than in any other species. This is due to the vast
system of connections between the various centers in the
human brain. We are able to imitate not only vocal expres-
sions (like the parrot) and gestures (like the monkey), but
muscular movements of almost every sort which we see others
perform. We copy handwriting, where we see only the result
1 The tendency is imitativeness; the act is imitation.
242 INSTINCTIVE BEHAVIOR [CH. x
and not the movements made in writing : we can reproduce the
form of objects in nature by gestures or by drawing. Often
the imitation succeeds only after a more or less elaborate
course of training; but the tendency to imitate is inherited;
it is based on man's nervous make-up.
Play is partly an imitative phenomenon. Children learn
to play games by imitating other children; when they play at
being grown up, they imitate (often grotesquely) the actions
of older people. But the play behavior has also a distinctive
character of its own; play means a tendency to perform acts
which are not directly concerned with our bodily or mental
welfare, but which serve as an outlet for our nervous energy.
This is characteristic of all play, whether imitative or spon-
taneous, social or solitary. Such widely different activities as
' playing telephone,' the game of football, a solitary game of
. qards, a ramble in the woods, have one common feature : they
represent relaxation from the serious business of life.
Curiosity is the innate tendency to seek information. It is
deep-rooted human trait, and distinguishes man from other
cies. The curiosity of dogs and other animals is probably
merely involuntary attention to very vivid stimuli. The dog
is not curious to explore the burrow in the ground; he is held
there by the odor which indicates the presence of a rabbit.
Curiosity manifests itself in mankind in a variety of ways,
which differ according to the individual's tastes and habits of
life. It may take the form of exploration, study of nature,
delving into history, listening to gossip, and other kinds of
behavior.
Right-handedness, more properly called dextrality, is the
preference of one hand over the other in performing acts; in a
majority of cases the right hand is preferred (dextro-dextral-
ity), though in many individuals it is the left (sinistro-
dextrality). The tendency is supposed to rest on a greater
development of certain motor centers in one hemisphere of
the brain and is apparently connected with the formation of
CH. x] INSTINCTIVE TENDENCIES 243
the language centers, which are usually in the left hemisphere.
The left side of the brain controls the right side of the body,
and vice versa.
The tendency to communicate is not peculiar to man; it is
found in gregarious animals and others. But in man it is
unusually strong. It manifests itself in many ways, such as
gesture and speech, which are developed into systematic
modes of expression by intelligence through the influence of
the social environment (ch. xiii). Communicative behavior
is greatly assisted by the development of the language centers
in the brain, and by man's upright posture, which leaves his
hands free to practice gesturing and writing.
Esthetic expression, the artistic touch which many human
actions exhibit, has not as yet received a satisfactory expla-
nation. Its early manifestation in childhood and among
primitive races seems to indicate that it is a real inherited
tendency.
Besides these special instinctive tendencies, there seems to
be a general innate tendency underlying each class of instincts.
We may regard walking, feeding, and the like, as indicating a
fundamental nutritive tendency. In the same way we note a
reproductive, a defensive, an aggressive, and a social tendency
in human behavior. These are not acquired. They belong
to human nature; they are based on something in our inher-
ited nervous constitution.
Popular writers speak of an ' instinct of self-preservation.'
Strictly speaking there is no such instinct. But we have
inborn tendencies to nourish ourselves, to defend ourselves,
and to perpetuate the species. Taking all these as a part of
our general inherited bodily organization, it is correct to say
that man has a very fundamental instinctive tendency to
keep himself alive and to preserve his species.
Development of Instincts in the Individual. Instincts and
instinctive tendencies, like reflexes, belong to the inborn con-
stitution of each individual. The nerve structure through
244 INSTINCTIVE BEHAVIOR [CH. x
which they operate is provided for in the original germ cell
from which the individual grows, and is derived directly from
one parent or both. This does not mean that a given instinct
is present at birth, nor that the appropriate nerve connec-
tions are already formed at birth. The nervous structure
needed for many of the instincts is practically ready at birth,
and in some cases it develops long before: but no instinctive
action can take place till there is some actual stimulation and
until the several reflexes which compose it are linked into a
series. The welding of separate reflexes into an instinct is
often not completed till a considerable time after birth.
Human walking, for example, is usually not completely ad-
justed till some time in the second year of life. This is
because the muscles of the legs are not sufficiently developed
till then. The reproductive instincts are not fully developed
till somewhere between the tenth and fifteenth years.
In short, any given instinct begins to manifest itself at a
certain period of life, and the period at which it appears
depends not so much upon the chance occurrence of appro-
priate stimuli as upon the perfection of the nerve connections
and effector organs. If the proper stimuli do not occur at the
right season, the appearance of the instinct is delayed, and in
some cases it may never be perfected. But since we all live
in the same general environment the appropriate stimuli
usually do occur, so that the instinct appears sooner or later.
It is sometimes stated that instincts are invariable. This
is not absolutely true. Instinctive movements are greatly
influenced by various stimuli that occur while the act is
being performed. In the act of walking we adjust our move-
ments in different ways when we step up or down or walk on a
slope, or if we encounter a stone in the path. Some of these
variations are due to differences of pressure on the sole of the
foot, others are due to visual stimuli from the objects we see
ahead. Nor is this altogether a matter of consciousness.
We adjust our walking movements to slopes and obstacles
245
quite as well when we are absorbed in conversation as when
we are paying strict attention to the path in front. We step
down from the curb or walk around a tree, often without
being aware that we are doing so. There are similar varia-
tions in the instinctive actions of animals where there is no
question of intelligence. They are due to variations in the
stimuli.
The chief difference between the variations which occur in
instinctive and intelligent behavior is that instinctive modes
of expression are not altered by past experience, while intelli-
gent expression depends essentially upon the effects of reten-
tion.
If instinctive expression is not modified by experience,
how is it that walking and feeding and other instincts show
the effect of learning? The explanation is that in such cases
some of the inherited paths or lines of conduction in the nerv-
ous system are broken up and other pathways are substituted.
To the extent that this occurs the behavior loses its instinctive
character. In the complex cortex of the human brain the
higher centers gather in and send out impulses which inhibit
certain reflexes and reinforce others. The effect of this, as
time goes on, is to transform our actions little by little from
the instinctive to the intelligent type. In the human adult
there are no pure instincts. Our behavior consists largely
of intelligent actions which rest on an instinctive basis.
The instinctive tendencies persist and develop along intel-
ligent lines. The nearest we come to purely instinctive
behavior is in walking, feeding, fighting, and other modified
instincts.
Summary. Before examining motor experiences (ch. xii),
we must study the relation of responses to stimulation.
Some responses are inherited, others are acquired by each
individual. By inherited is meant that certain definite
arrangements of nerves in the body are determined from
the start; their natural connections are such that if a cer-
246 INSTINCTIVE BEHAVIOR [CH. x
tain stimulus is given a certain definite response always
follows.
The simplest inherited response is the reflex. A reflex is not
learned it is innate. Coughing, winking, etc., are reflex
responses; they are the automatic outcome of certain stimuli;
their nervous paths are inherited.
An instinct is a complicated form of response made up of
a succession of reflexes. It is also innate. Instincts do not
necessarily appear at birth. Any given instinct appears
when the bodily conditions for it are ripe. Besides instinc-
tive responses or movements we have certain instinctive
tendencies. Imitation and other inherited tendencies express
themselves in actions that are not inherited; but the tendency
itself is innate.
Man has few pure instincts. Most of his inherited behav-
ior is modified by learning. Nearly all our activities are
partly instinctive and partly intelligent. .
PRACTICAL EXERCISES:
49. Describe (or name) all the different sorts of muscular movements
which you can observe in your face and head.
50. Examine a number of the most familiar reflexes given in Table X.
Test in your case and report how far each is under voluntary control.
51. Analyze the motor processes included in three different human in-
stincts, e.g., eating, walking, fighting.
52. Examine why you have the following tendencies: (a) to sympathize
with your friends; (b) to collect objects of some kind; (c) to find out
things you do not know.
53. Report all noticeable right and left preferences in your actions; e.g.,
which arm or leg acts first in putting on or removing your various
garments.
REFERENCES:
On reflexes of infants: M. G. Blanton, in Psychological Review, 1917, 24,
456-483.
On instinct: W. James, Principles of Psychology, ch. 4; W. McDougall,
Social Psychology, chs. 2-4, 10-15; E. L. Thorndike, Educational
Psychology (briefer course), chs. 3, 5; J. Drever, Instinct in Man. chs.
7. 8: J. B. Watson, Psychology, ch. 7.
CHAPTER XI
INTELLIGENCE
Individual Adaptation. If the same stimulus bp applied t
to the same individual time after time, his responses n^ay,"
change. These differences in the effect when the external
causes are the same do not throw doubt upon the uniformity
of nature; they mean simply that conditions within the organ-
ism have changed. There are two distinct kinds of individual
modifications in responses : fatigue and adaptation.
(a) The fatigue change occurs in instinctive actions and
reflexes as well as in intelligent actions. Constant repetition
of the same stimulus causes wear and tear in the receptors,
synapses, and muscles. There are destructive chemical
changes in the tissues which tend to weaken or inhibit the
usual response, so that the outcome is different. If the knee
be tapped repeatedly, the knee-jerk gradually becomes
weaker. Fatigue is a condition of diminished efficiency. In
ordinary cases fatigue disappears after a period of rest, when
the exhausted tissue is restored by the building up of new
chemical compounds.
(6) Adaptation acts in the opposite way. It is not an im-
pairment of the response, but a distinct improvement due to
more perfect adjustment. It is due not to destruction of
tissue, but to the formation of new paths in the nervous
system, or to gradual improvement of the old paths by
cutting out useless movements. If you are unfamiliar
with shooting, and practice firing at a target, you find after
awhile that you begin to get better results. Your responses
become better adapted to the situation; you make more
hits.
The adaptation effect does not wear away when we rest;
248 INTELLIGENCE [CH. xi
it tends to persist. Increased adaptation of response is the
most notable characteristic of intelligent behavior, and dis-
tinguishes it from instinct.
CONDITIONED REFLEXES
Nature of Conditioned Reflexes. The simplest form of
acquired adaptation occurs in reflex actions. Under certain
conditions a response which in the beginning was called forth
by a certain stimulus, may become the response to a totally
different stimulus. The new reflex acquired in this way is
called a conditioned reflex.
Conditioned reflexes are built up when two stimuli occur
repeatedly at the same time, one of which (A) leads to a defi-
nite and characteristic response, while the second (B) does
not. After a number of repetitions of the two stimuli to-
gether, if B occur alone, it may bring about the response
which originally belonged to A.
An example of this is the conditioned knee-jerk. If you
tap a certain spot just below the knee-cap, the leg flies up.
This is the natural knee-jerk reflex. In certain experiments
it was arranged to strike the knee with a hammer held and
operated by mechanical devices so as to insure uniform force
and location of the blow. A bell was sounded each time be-
fore the hammer fell. During the experiment something
went wrong with the apparatus. The hammer fell part way
but did not strike. Yet the leg flew up, just as it was accus-
tomed to respond to the blow. The auditory stimulus (B)
brought about the response which belonged originally to the
contact stimulus (A). The subject had formed a conditioned
reflex.
This is a specially good example because there is no ques-
tion of association of ideas. The knee-jerk is not under
voluntary control; you cannot produce it by suggestion. In
other cases there might be some doubt whether the new con-
nection was automatically acquired; here there is not, and
CH. xi] CONDITIONED REFLEXES 249
we may assume that other simple conditioned reflexes are
established in the same automatic way.
A dog sees a box containing food and smells the food; the
smell stimulus causes a response in his salivary gland
saliva accumulates in his mouth. If the same box be brought
in daily, a conditioned salivary reflex will after awhile be
aroused by the mere sight of the box. If a bell be struck every
time the box is brought in, after awhile a conditioned sali-
vary reflex will be brought about by the mere sound of the
bell, before the box is seen.
This has been definitely proved by Pawlow's experiment.
Pawlow made an incision in the dog's salivary gland and
inserted a glass tube which passed through the corner of his
mouth and hung down. The saliva passed out through the
tube and could be observed by the experimenter as it dropped.
The strength of the conditioned reflex was measured by the
number of drops per second.
Conditioned reflexes are found in man just as in lower ani-
mals. It is probable that the ' watering of the mouth ' at the
sight of a juicy peach is a conditioned reflex and is not due
to an association of ideas. Our response to the dinner bell
involves a more complex mental process and is not quite
analogous to the dog's conditioned response.
The formation of conditioned reflexes depends upon the
existence of branching connections in the nervous system.
When two stimuli occur simultaneously their nerve impulses
may come together in one of the centers. If the sensory
nerve bearing one of these impulses has a definite motor path,
the combined impulses will tend to follow that path. Sup-
pose that at the outset the sensory nerve bearing the other
impulse has no definite motor connections but its stimuli
produce diffuse movements through one motor path or an-
other according to the condition of its various synapses.
Then, by repetition the synapses connecting this sensory
nerve with the definite motor path of the other will be
250 CONDITIONED REFLEXES [CH. xi
strengthened. Eventually the connection becomes so firmly
established that when the ' diffuse ' stimulus occurs alone, its
nerve impulse will follow the motor path of the ' reflex '
stimulus and will bring about the response originally belong-
ing to the latter.
The conditioned reflex is the simplest type of individual
modification of behavior. It will readily be seen that the
changes which it brings about in the animal's (or the man's)
actions tend to be adaptive that is, to be suitable or fitted
to the general situation. For, if two stimuli occur together,
a response suitable to both is likely to be suitable to either.
INTELLIGENT BEHAVIOR
Intelligence. When reflexes are altered, there are changes
in the complex actions of which they form part. Instinctive
behavior is modified by the acquisition of conditioned reflexes,
and by other changes to be described later. In so far as our
behavior is not fully determined by inherited paths in the
nervous system it ceases to be instinctive. 1 Complex actions
which are due to individually acquired connections of nerve
paths are termed intelligent actions.
The words intelligence and intelligent are used in psychology
in nearly (but not quite) the same sense as in popular lan-
guage. Popularly the expressions intelligent actions and
intelligent behavior imply that we realize that the actions in
question are the proper thing to do. Psychology shows that
individually acquired behavior tends to be suitable though
it is not always so. It also finds that we are usually aware to
some extent of the fitness, but not always : when we have once
learned to perform a suitable act it may be carried out just as
automatically and unthinkingly as an instinct. It is best,
then, not to lay stress on the ' awareness.' In psychology,
intelligent behavior is defined as any complex action which is
not inherited, but is acquired by the individual, provided the
1 Instinctive means inherited, innate, inborn.
CH. xi] NATURE OF INTELLIGENCE 251
response be in any way suitable to the situation. 1 Intelli-
gence means the capacity of an individual to break away from
instinctive behavior and acquire new modes of action. In-
telligence is often used as a shorthand term for intelligent
behavior, just as instinct is used for instinctive behavior.
Although instinct is the usual form of behavior in sub-
human species, there is a certain amount of intelligent adap-
tation in all animals except those low down in the scale of life.
This is shown by experiments with the maze. [Fig. 73.] An
animal is released at the entrance (A) of a maze, food having
been placed at the far end or center (B). The hunger stimu-
lus, reinforced by the odor stimulus, arouses him to action.
He starts off and after a certain number of hesitations, false
moves, and retracings reaches the food and satisfies his
hunger. The same program is repeated on the same or suc-
cessive days. It is found that after a number of trials the
animal succeeds in reaching the food-box in a shorter time,
and with fewer false moves as indicated by the total distance
traversed. In an experiment with 27 white rats the average
time was reduced from 467 seconds in the first trial to 40.3
in the eleventh, and the average distance from 4216.1 to
1029.8 centimeters. Even in species as low as the cray-
fish and other Crustacea there is a slight reduction in time and
distance after many trials in a simple maze.
The animal's behavior in the maze experiments consists of a
long series of reflexes which, taken together, form a complex
action. The action at first is instinctive, but it becomes mod-
ified in the course of time. The rate of improvement serves
as a measure of the animal's intelligence. 2
Adaptive changes in behavior are not limited to improving
the efficiency of responses. The most important changes are
those that bring about new kinds of response. Human be-
1 This excludes movements that are entirely irrelevant, but includes errors,
large and small, that occur during the process of learning.
1 Compare Table XII, p. 260.
252
INTELLIGENT BEHAVIOR
CH. XI
havior is far more subject to this kind of modification than
the behavior of any subhuman species. In the human child
4>
FIG. 73. MAZES FOR INVESTIGATING HABIT FORMATION
Two mazes used to determine the rate at which an animal learns the right path from A to B.
Upper figure is a simple maze used by Yerkes with frogs. One choice of paths at start, one
choice near end. [From Harvard Psychological Studies.]
Lower figure is a maze used by Hubbert with rats. Heavy line shows actual path of one rat
on 62d trial. See Table XII for results of this experiment. [From Jour, of Animal Behavior.}
we observe any number of instances in which new forms of
response are developed through individual experience: talk-
CH. xi] NATURE OF INTELLIGENCE 253
ing, manipulating knife, fork, and spoon, buttoning the
clothes, opening the door, climbing stairs, folding the napkin,
writing, swimming, riding a bicycle, and many others. Adult
acquisitions are generally concerned with more complex
processes, such as steering a sail-boat or motor-car, type-
writing, telegraphing, and shooting.
Habit Formation. Learning, or habit formation, is the
process of forming new connections in the nervous arc and
perfecting these connections through repetition. There are
two rather different sorts of learning: (1) The formation of
motor habits, through coordination of muscular movements
as, for example, learning to typewrite. (2) The formation of
mental habits; this means establishing new connections in the
brain, connections which have no immediate motor ex-
pression. When we learn to notice weather signs or to
observe things ' out of the corner of the eye ' or to think
logically, or when we memorize a poem or the multiplication
table, the acquisition is chiefly the forming of new paths in
the brain centers; there is eventually some motor result,
but this is incidental.
The learning process is substantially the same in motor and
mental habits, though the results differ. Both kinds of habit-
formation involve two steps or stages of progress: (a) Acquisi-
tion, making new connections in the nervous system; and
(6) Fixation, strengthening these newly acquired connec-
tions. These two processes supplement each other.
a. Acquisition. A baseball pitcher finds a way to deliver
a new curve one that he has never pitched before. A
billiard player makes a new kind of shot. A recruit in the
training camp gains the ability to respond by the proper
movements to each command in the drill manual. In every
case the first time the new movement is made, or whenever
it is altered, the man has acquired something. The acquisi-
tion is not a change in the muscles but a change in the nervt
ous paths that operate the muscles. Intelligent acquisi-
254
INTELLIGENT BEHAVIOR
[CH. XI
Bl
tion ' of new movements is the process of forming new paths
of conduction in the central part of the nervous arc.
Acquisition does not involve the growth of new neurons nor
the projection of new collaterals. The neurons and then*
branches have already been formed in pre-natal life. It is
only the course of the impulse that is changed. The acquisi-
tion of new responses means that the nerve impulse is
shunted from the usual path to some new path. This means
that the impulse in some part of its course passes through a
synapse which has not hitherto been used, instead of through
the commonly used synapse. In Fig. 74, suppose the usual
path of the impulse be
along the neuron A and
out into the neuron Bl;
then if on some occasion
for any reason the im-
pulse passes over into
B2, a new path of dis-
charge is opened and a
new response is ac-
quired.
How do these changes
of path come about?
They are made possible
in the first place by the
existence of manifold
connections in the nervous system. There can be no acquisi-
tion unless the central neurons are provided with a number of
collaterals or branches, each connecting with a different lower
or higher neuron. The several synapses leading out from a
given neuron must vary in their degree of resistance, and
they must be capable of varying independently, so that at one
time a certain synapse (connecting with Bl) will be less
1 Instinctive acquisition is a racial product and depends upon the evolu-
tion of the nervous system from generation to generation.
Fie. 74. CHANGES OF PATH IN HABIT
FORMATION
Diagram to illustrate the acquisition of new nerve
paths. Nerve impulses travel along A in direction of
arrows to synapses connecting with Bl, B2, BS, B4,
which are alternative pathways. (See text.)
CH. xi] HABIT FORMATION 255
resistant than any of the others, at other times another
synapse (connecting with B2 or B3). If there are no
branches the nerve impulse will always follow the same path;
and if there are several branches but a certain one of the
synapses is always the path of least resistance, then the im-
pulse will always follow that path.
Man has inherited an intricate system of multiple connec-
tions in the brain centers and particularly in the cortex. His
central nervous system includes a vast number of alternative
paths capable of being brought into connection. This is the
real cause of man's superior intelligence as compared with
other species.
But this only means that acquisition is possible. The ques-
tion still remains, How is it actually brought about? The
actual change of path in every case depends upon changes in
the conditions of the synapses. There are at least three ways
in which we form new paths: (1) One synapse may become
less resistant to the passage of impulse than it was before;
or (2) the synapse that usually carries the impulse may
become very resistant, so that this pathway is blocked and the
impulse passes over into the next best path; or (3) a very
intense impulse may succeed in breaking through several
synapses at once, just as a powerful stream of water not only
fills the usual channel but trickles over into other channels
as well. It is likely that the degree of resistance at synapses is
determined by the quality as well as the intensity of the im-
pulse, and that it depends also on conditions in the next higher
neuron the neuron into which the impulse seeks to pass.
These three ways of altering the nerve paths give three
kinds of acquisition: (1) Accommodation occurs when a new
path is opened. In reading aloud, when we see a new word
the nerve impulses are shunted into new paths according
to our retention and memory of the several letters or sylla-
bles composing the word; there is an accommodation of
response. (2) Inhibition occurs when the old pathway is
256 INTELLIGENT BEHAVIOR [CH. xi
blocked. When we see some one coming who looks like a
friend we prepare to greet him in one of the usual ways; if
when he comes closer he proves to be a stranger, the path
of response is closed and the bow or greeting is inhibited.
(3) Diffusion; the impulse may spread into several paths si-
multaneously into new paths as well as old. When we
are walking to the station to catch a train, if we hear the loco-
motive whistle, there arises a very powerful nerve current, due
to a combination of the sound sensation and the muscle sen-
sations concerned in walking; this causes the motor impulse
to spread into several paths; the result is a much livelier
response.
Sometimes these forms occur together. Inhibition is com-
bined with accommodation when we start to wind a clock the
wrong way. If the key does not turn (inhibition), we there-
upon alter the course of the motor impulse and twist it in the
opposite direction (accommodation).
Most examples of acquisition drawn from every-day life
involve complicated actions. To study the process system-
atically we must start with the simple reflexes which compose
our actions and observe how these are modified. The con-
ditioned reflex is a typical case of accommodation. When
you learn to check the eye-wink, or the cough, you are inhibit-
ing these reflexes. Diffusion may be studied by attempting
to twitch the ear voluntarily if you have never done so before.
The effort to raise the ear causes the motor impulse to spread
to various regions near by. You raise your eyebrows, move
your scalp, etc. If the effort is finally successful, it means
that the impulse, in spreading, has forced its way into the
hitherto unused pathway leading to the levator muscle of
your ear.
b. Fixation. Fixation is the process of strengthening the
connection in the newly acquired path. The passage of the
nerve impulse through a new synapse tends to ' set ' the
structure of that synapse so that it offers less resistance in
CH. xi] HABIT FORMATION 257
future. If only one impulse of the sort occurs the effect tends
to wear away; the acquisition is lost and the old response
returns. But if another impulse of a similar sort occurs soon
after, it is more likely to pass through the new than through
the old channel. An acquisition becomes permanently fixed
when the new pathway is finally established.
The rate of progress in fixing a new path depends upon four
factors: repetition, intensity, recency, and conflict. The new
path is more firmly established in proportion to the number of
times the given stimulus is repeated. Fewer repetitions are
needed when the nerve impulses are very intense. The repe-
tition is more effective if the original acquisition occurred
recently. These conditions of habit-fixation correspond to
the three laws of recollection. 1 Recollection, in fact, is just a
special case of fixation. The connection between visual
impressions and verbal memories becomes fixed in the same
way as motor habits, so that the sight of a certain face leads
to the recollection of the man's name.
The remaining condition of fixation, the principle of con-
flict, corresponds to the first law of forgetting. 2 The progress
of fixation is hindered if, meanwhile, impulses of a different
sort occur, which use the old pathways. In such cases the
old connection is maintained along with the new, and fixa-
tion takes longer. Suppose when we start to learn typewrit-
ing we use two machines with slightly different key-boards or
with the shift-key in different places. Here we have to learn
two different responses to similar stimuli. The two responses
conflict, and this retards the progress of fixation. If we
attempt to memorize a poem in which each stanza begins
with the same line and then runs on differently, there is the
same sort of conflict.
As the process of fixing a habit goes on, two different
changes in the behavior take place our actions are im-
proved in two different ways:
1 See ch. viii. pp. 186-187. * P. 188,
258 INTELLIGENT BEHAVIOR [CH. xi
(1) As the new connections grow stronger there is less hesi-
tation, so that less time is needed for performing the action.
This effect is called facilitation of the act.
(2) As the new connections become stronger there are fewer
diffused impulses along alternative paths, so that various
useless and erroneous movements gradually drop out. This
is called elimination.
LAW OF FACILITATION OR SPEED: As the newly acquired
path is strengthened, the new response tends to proceed more
rapidly.
LAW OF ELIMINATION OB ACCURACY: As the new connec-
tions improve, there are fewer useless and erroneous move-
ments; the response becomes more precise and more accurate.
These two types of improvement may readily be observed
in the progress of any complicated habit, such as typewriting.
After you have used the machine some time you find that the
movements follow more rapidly. At the same time you will
find that you strike fewer wrong keys, and make fewer useless
movements, such as wrinkling the brows, puckering the h'ps,
exploring the keyboard with the eyes to find a letter.
If you work methodically at learning a new habit your
progress may be measured quite exactly in terms of speed and
precision. The speed of performance is reckoned either by
the amount accomplished in a given time or by the time re-
quired to perform a stated task. In learning to typewrite, if
you practice an hour a day, your improvement in speed may
be measured either by the number of words typed in five min-
utes, or by the time required for typing a single page day after
day. Accuracy is measured by the number (or percentage) of
errors; in learning to typewrite you compare the number of
mistakes made from day to day in typing one page.
Experiments on the rate of learning have been made in
many common habits, such as telegraphing, juggling three
balls, shorthand, and mirror-writing. Fig. 75 shows the
progress of a novice in learning to telegraph. The ' curve '
CH. XI ]
HABIT FORMATION
259
100
90
80
70
60
50
40
30
20
10
10 15 20 25 30
FIG. 75. CURVE OF LEARNING
40
Shows the progress of facilitation (speed) during the fixing of a habit: learning to telegraph.
Vertical numbers denote the number of words which the learner was able to telegraph in 5
minutes after SO minutes of practice. Horizontal numbers denote successive days. The ex-
perimenter was entirely unfamiliar with the habit at the start [From Swift, in Ptychological
Bulletin.]
260 INTELLIGENT BEHAVIOR [CH. xi
(which is really a jagged line) represents the number of words
tapped off in 5 minutes on successive days with the same
amount of daily practice. It shows the gain in speed, not in
accuracy.
TABLE XII. PROGRESS OF LEARNING
A. Habit Formation in Man:
Day Av. Time (sec.) Ac. No. of Errors
1 79 29
2 72 27
3 63 14
4 60 10
5 66 7
6 54 4
7 53 2.5
8 49 2
9 47 0.25
Average attainment of 4 human subjects learning to typewrite nonsense
groupings of 7 different letters, arranged in a series of 55 letters. The series
was performed 3 times daily. Table shows average time and average number
of errors per series. (J. H. Bair, Psychol. Monographs.No. 19, p. 17.)
B. Habit Formation in the Rat:
Trial Av. Time (sec.) Av. Dist. (cm.)
I 467.0 4216.1
6 186.6 1719.2
11 40.3 1029.8
16 25.5 868.4
21 24.2 739.9
26 26.1 756.5
31 31.8 593.2
Average attainment of 27 white rats in maze experiment. Two trials each
day; animal allowed to feed after second trial. (H. B. Hubbert, J. of Animal
Behavior, 1914, 4, p. 63.)
Progress in both speed and accuracy are shown in Table
XII. The upper table (A) shows the average progress of four
men in typewriting nonsense groups of letters. Their speed is
measured by the time required to typewrite fifty-five letters
and their accuracy by the number of errors. The same sort of
measurements may be applied to animal learning, though the
habits involved are much simpler. Table XII B shows the
CH. xi} HABIT FORMATION 261
average progress of twenty-seven white rats in learning to
thread a maze. The speed is measured by the time required;
in this experiment the accuracy is measured, not by the num-
ber of errors, but by the distance covered by the rat in his
wanderings, which indicates the amount of unnecessary move-
ment.
In some experiments on human learning an interesting fact
is brought out. After a certain amount of practice the prog-
ress appears to cease; there is virtually no improvement.
Then if practice is continued, after a time the man takes a new
spurt. If the progress is represented by a curve, the period of
. no-progress is a flat stretch between two slopes. This flat
part is called a plateau. In Fig. 75 there is a plateau between
the 19th and 30th days. Plateaus are pmlmhly fat* tn nnr
having about reached theTTIniit of improvement through
facilitation and elimination. The new rise in the curve indi-
cates that another acquisition has taken place, which in turn
becomes gradually fixed.
An interesting practical problem in learning is whether
progress in fixation is more rapid when the repetitions are
crowded into a short period of time or when they are spread
over a longer period interspersed with intervals of rest.
Contrary to the general impression, it has been found that
progress in memorizing is faster (in the long run) with shorter
practice periods, interrupted by rather long rest intervals.
But the progress in memorizing a speech is more rapid if we
learn it as a whole than if we split it up into parts and learn
each part separately. __
-CL Relation between Acquisition and Fixation. Our world
i presents many constant and many variable features. Cer-
tain situations occur over and over again with no significant
changes. Each morning we have to dress, we breakfast under
much the same conditions, we pursue our regular occupa-
tions in much the same way, we are constantly meeting the
same people, we walk the same streets. On the other hand
262 INTELLIGENT BEHAVIOR [CH. xi
we vary our dress according to the weather or the occasion,
we travel, we indulge in a variety of recreations, we meet new
people, we find new tasks to perform. Most of the situations
in human life are too complex and varied to be solved by
instinctive behavior. Our inherited nervous connections are
not sufficiently elaborate to enable us to perform the duties
of civilized human beings. 1 Even the simple act of putting
on our clothes and buttoning them must be learned.
The variable situations in life require acquisition of new
modes of behavior, and the constant situations need fixation
of responses. We must (1) adapt ourselves continually to
new situations by new acquisitions, and we must (2) autom-
atize many acts by fixation, in order not to waste time over
details that are always the same. One process is just as
important as the other; and both are phases of intelligence.
Most situations in life contain both old and new elements.
When we write a letter, we hold the pen and manipulate it in a
stereotyped way, but we write different words and sentences.
We learn in childhood how to write that is, how to wield
the pen. This becomes a fixed habit, so that finally the act
of writing becomes as automatic as any instinctive act.
Because fixed habits proceed automatically, some writers
regard them as cases of lapsed intelligence. This is a wrong
notion. Intelligence means capacity for adaptation. Habits
are individually acquired modes of behavior, and are just as
suitable to the permanent factors in the environment as new
reactions are suitable to new conditions. A habit is as much a
display of intelligence as a new response. There is no lapse of
intelligence in fixed habits only a decrease in the vividness
of the impressions. New responses (acquisitions) are accom-
panied by vivid consciousness, while habits (fixations) are not.
A deeply rooted habit, such as operating a pen in writing, is a
case of lapsed consciousness but not of lapsed intelligence.
1 Ants have an elaborate inherited nervous equipment, and can meet
some very intricate situations instinctively.
CH. xi] ACQUISITION AND FIXATION 263
It cannot be emphasized too strongly that the all-important
fact in psychology is the creature's response to the situation
which confronts him. Consciousness, awareness of the situa-
tion, is only one factor in the process. If the best results are
reached by making the brain connections more automatic and
reducing the vividness of consciousness to a minimum, such a
condition marks a higher degree of intelligence than the con-
scious planning of every detail. The dressing habits formed
in childhood enable us to prepare for the day's work more
rapidly. We are able to think out some other problem at the
same time. Notice how much time and effort is spent by a
child who is just learning to dress. Notice that in your own
case the performance of these stereotyped actions may be
actually impeded if you attend to each movement. In all
fixed habits subconscious behavior is more effective, more
adaptive, more intelligent, than conscious behavior.
Fixed habits always tend to be adaptive (or suitable),
because none but suitable actions are likely to be repeated
constantly and become fixed. But does a new acquisition
tend to be adaptive? Yes and no. If by an acquisition we
mean every new variation that occurs in our movements and
expression, then a large part of our acquisitions are by no
means an improvement. We may try a dozen times before
we hit on the right movement to accomplish what we are
after. But most of these failures drop out at once; they do
not count as acquisitions. The real acquisitions are those
that get us somewhere. These suitable acquisitions are
selected, and tend to persist. The selection of suitable new
responses comes about in two different ways: (1) through
trial and error and (2) through associative memory.
i. Trial and Error Learning. Trial and error is a process
which includes (a) persistent trials with wrong responses, and
in the end (6) accidental success. This type of adaptation is
found in subhuman species as well as in man. Suppose a dog
is confined in a yard with a latched gate. He sees a cat out-
264 INTELLIGENT BEHAVIOR [CH. xi
side and jumps at the gate time after time, pawing it and
barking vigorously. The gate holds despite his pawing and
barking. By chance his paw touches the latch-bar and
releases the latch; the gate flies open, and the dog gets out.
The jumping and pawing are persistent trials with misfit
responses; they do not bring him to the cat. Pressing the
latch-bar is an accidental variation of response which brings
success. For the very reason that it solves the difficulty it is
the last to be tried; and because it was the most recent of the
series, it is more likely to recur than any of the other responses
the next time the same situation is presented.
Many human habits are the result of trial and error learn-
ing. In first learning to ride a bicycle we make a lot of useless
movements, which wabble us zigzag along the road and bring
about numerous falls. These are all responses to our visual
and static sensations. They are not successful at first; but
we persist and try all sorts of variations. Certain twists and
body movements keep us upright and steer the wheel in a
straight course; these responses are successful and gradually
supplant the rest. In a word, persistent trial is likely to meet
final success by sheer chance, and the successful response,
being the last in the series, is more likely than any other to
recur in future. Acquisition by trial and error, then, does
tend to be adaptive.
What goes on in the nervous system during the trial and
error process? The key to the explanation is the persistence
of the stimulus. In the case of the dog at the gate, the dog
sees and smells the cat all the time. The cat-stimuli keep
sending nerve impulses to the dog's brain and lead to a con-
tinuous series of movements. The gate prevents the com-
pletion of his usual response to pounce on the cat; the
motor response is inhibited and finds some other channel.
The jumping and pawing movements are accommodations of
response due to the increased resistance of certain synapses
and the lowered resistance of others. When the new response
CH. an] TRIAL AND ERROR 265
succeeds, the synapse through which the impulse passes
remains a path of lesser resistance because the situation is
solved and the bothersome stimulus is removed; therefore, the
next time a similar situation occurs this channel is more likely
to prove the path of least resistance than the pathway through
other synapses.
2. Associative Memory. Learning by means of associa-
tive memory is a higher type of acquisition. The stimuli do
not result in trial responses. Instead, the nerve impulses
pass from center to center in the brain, arousing a succession of
images and thoughts. We picture to ourselves various ways
of acting; if one course of action does not solve the difficulty,
we picture another, and so on till we picture some action
which brings about the suitable result. Then at last the
nerve impulse passes out into the appropriate motor channel
and we act.
An example of learning through associative memory is the
attempt to solve a chess problem or a mathematical puzzle.
We think over the various ways of proceeding, one after the
other. As long as our thoughts fail to present a satisfactory
solution, the nerve impulses continue their course in the brain,
arousing one thought after another. When the thought of
the correct solution arises, a motor impulse is started and
results in action; the bothersome situation is gone and ceases
to stimulate our thinking.
This method of learning is called associative memory
because our thoughts depend altogether on the revival of
retention traces in the brain, which arouses memory and
mental pictures. Instead of actually making the chess
moves we picture them mentally, and these pictures form
trains of association (ch. xiv). The thought of the problem
keeps the impulse going rather than the sight of the chess-
board. Associative memory involves higher centers in the
brain and better connections of the neurons than trial and
error acquisition. It resembles trial and error in one respect:
266 INTELLIGENT BEHAVIOR [ca. xi
the last thought, which is the successful one, is most likely to
recur the next time a similar situation is presented. So that
acquisition by the associative memory method tends to be
adaptive also.
Growth of Intelligence. Intelligence, like instinct, is a
racial growth. The capacity to acquire new responses evolves
gradually from lower to higher species of animals as the
nervous system becomes more complex. But unlike instinct
it is also an individual growth. In the human species intelli-
gent behavior develops gradually in each individual and may
continue to progress until far beyond middle life.
Every intelligent act depends upon the perfection of cer-
tain simpler acts which compose it. The act of writing
depends upon our ability to move the fingers and wrist so as
to trace each letter properly. This in turn depends upon our
ability to hold a pen or pencil. After we have learned to
form the letters by means of certain wrist and finger move-
ments we extend the same act to other muscles, when we write
large upon the blackboard. 1 Certain elements in the act of
writing are utilized in typewriting and typesetting, while
other elements in handwriting are lacking in both of these
acts. Owing to the intricate interconnection of the various
brain centers in man an almost infinite number of new motor
combinations are possible. These new actions are due not
merely to differences in the stimuli, as in the case of instinct,
but to the manifold connections in the brain.
Human habits are so complex that it is difficult to classify
them satisfactorily. Some of them fit into the same general
types as the emotions and instincts. Our table habits are
obviously nutritive; dressing and house-building are defensive;
warfare is aggressive behavior; educational acquisitions are
habits of individual development. But most habits belong to
several different classes. Games are social; they are also
nutritive if they give us bodily exercise; or developmental if
1 See Fig. 80, p. 368.
CH. xi] GROWTH OF INTELLIGENCE 267
they exercise our thought processes. Boxing is both aggres-
sive and defensive; and it is nutritive when used as a mode of
exercise or if we adopt boxing as a profession to gain our
livelihood; a friendly bout is social behavior.
The difficulty of classification is due to the fact that intelli-
gent behavior represents a response to the entire situation
which confronts the creature, rather than a reaction to this or
that particular stimulus. Intelligence tends to express the
organism as a whole, not merely some special phase of organi-
zation. There seems to be no natural scheme of classifica-
tion, except the very practical division into useful and detri-
mental habits.
Training of Habits. Given a sudden emergency, some
men generally do the right thing, while others always seem to
fall down. The latter individuals need special training.
Readiness to meet unforeseen situations depends upon train-
ing in several phases of mental life. In the first place, we
must train our perceptions we must learn to observe
quickly and exactly. If we perceive instantly the real mean-
ing of the situation, we are in a better position to act properly.
If we can pick out the significant details, we are more likely
to see where to direct our efforts. Memory training is also
important in meeting new situations. Few situations are
wholly new; the organization of our memories will assist us in
coping with situations that are partly familiar. The training
of our thought processes (ch. xiii) is one of the most important
factors in adaptation. And finally, training in the fixation of
habits is essential even in connection with new situations.
From the very nature of the case there can be no special
training in the ' acquiring process ' itself. The unexpected is
unexpected. We can only train the underlying processes
of observation, memory, and thought, which will render any
new situation less strange. When we are not confronted with
an emergency but with a general problem of action, the
nature of the acquisition process itself offers a helpful sugges-
268 INTELLIGENT BEHAVIOR [CH. xi
tion. The trial and error method is fundamental, and the
only way to insure success is to stick to the task to perse-
vere. The copy-book motto, " Try, try again," represents a
real principle of mental activity.
The other side of intelligence, the fixation process, admits
of much more systematic training. The process of strength-
ening habits has been investigated in the laboratory and some
definite quantitative results have been obtained which have
a practical value. We have already noticed that, in certain
kinds of learning, progress is quicker if the practice periods
are comparatively short, with periods of rest in between.
These results bear directly on the length of study periods in
schools. How much time should be devoted to one subject
at a stretch? How long should the recreation periods be, and
how should they be distributed? In recent years, much has
been accomplished in the psychology of pedagogy, which it
would take too long to describe here.
The importance of cultivating useful habits can scarcely be
overestimated. The habits involved in dressing, writing,
table manners, and general social intercourse are essential to
a well-ordered life. We cannot respond to new features in
the environment unless we have developed habits which meet
the permanent phases of life.
A habit tends to become detrimental to our welfare when it
is too firmly fixed to admit of modification, or when it usurps
the place of other, more useful responses. If we are so wedded
to smoking that we must drop work for a cigarette at impor-
tant junctures, or if we are so fond of telling anecdotes that we
cannot readily listen to others, we are likely time and again
to lose certain business or social advantages. There are also
mannerisms and stereotyped actions which waste time and
energy, or which are disturbing to others. Nervous move-
ments, drumming with the fingers or tapping with the foot,
hemming, coughing, and giggling are useless habits; a shrill
tone of voice, uncouth table manners, whistling in public, and
CH. xi] TRAINING OF HABITS 269
the like are socially annoying. All these may be classed as
' bad habits ' from the social standpoint. Biologically and
psychologically bad are such habits as intoxication or the
habitual use of drugs, which impair the vital processes and
weaken our mental lifei
The practical problem in such cases is how to break the
habit how to modify it into a useful form or suppress it
entirely. This is one of the hardest problems of life. In
extreme cases the individual seems powerless to break the
habit by himself. Drug habits are especially masterful
because they produce a physiological state which acts as a
powerful stimulus to repeat the action; drastic measures by
others seem necessary to check this class of habits.
Some habits can be checked by substitution. Nervous
drumming with the fingers may be broken off if each time we
catch ourselves at it we begin some other hand-and-finger
movement; or if we turn to some useful occupation involving
the use of the fingers. Day-dreaming may be repressed by
reading or by trying to solve some useful problem. A man
who smoked to excess broke the habit by taking a long trip
where no tobacco was available.
Some habits can be broken by interposing an irrelevant
stimulus. A sudden shock will sometimes shunt the motor
impulse into other paths. This explains how a bad habit is
often cured by punishment or through the shock of being
caught in the act. Mutual assistance is extremely useful
here. If friends agree to cooperate in the proper spirit
progress is more rapid. Reprimanding and ridiculing are apt
to produce bad effects even though they break up the habit.
Habit-breaking is such a vital matter that a systematic study
of its principles is well worth while. The schoolmaster
should know how to unteach as well as to teach.
Summary. Intelligence means the ability to acquire new
and suitable forms of response by individual modification.
It means changing our modes of behavior from the inherited
270 INTELLIGENT BEHAVIOR [CH. xi
ways of acting to something new. The simplest type of modi-
fication occurs in the conditioned reflex. A higher type is the
transformation of instinctive behavior into intelligent behavior.
This requires a complex nervous system with manifold con-
nections.
The learning process, or habit-formation, includes two
steps : acquisition and fixation. Acquisition means the per-
formance of some new response; in fixation we improve a new
response by making it more exact and more rapid. These
two processes go together.
There are two methods of learning: trial and error, and
associative memory. In the former we persist in making
various wrong responses till at last we happen upon the right
one which tends to supplant the rest. In associative-
memory learning we think over various solutions till we hap-
pen to strike the right one; this supplants the other thoughts.
A fixed habit is just as intelligent as a new acquisition if it
enables us to meet the situations in life. New acquisitions
depend on our having certain fixed habits as their foundation.
A habit is ' bad ' only to the extent that it prevents new ac-
quisitions or interferes with our individual or social welfare.
PRACTICAL EXERCISES:
54. Experiment with the formation of some new habit. Practice a certain
amount daily and record your progress in speed and accuracy. [This
should be started two weeks ahead.]
55. Make a list of 'useless' and 'annoying' habits observed in those
around you, including some of your own.
56. Take some trivial useless habit and try to break it. Report the
methods used and the degree of success.
57. Practice mirror-writing, looking in the mirror attentively, with your
hand concealed from direct view. Report any notable feature of the
experience.
58. Try to twitch your ears. Observe and report what movements you
make in your efforts, and what success you attain.
REFERENCES:
On conditioned reflexes: J. B. Watson, Psychology, pp. 2&-3S.
On learning and breaking habits: S. H. Rowe, Habit Formation.
On experimental investigations of learning: E. L. Thorndike, Educational
Psychology, vol. 2; E. T. Swift, MincFinJhe Making, ch. 6.
\ ' V -c
\ * *..
CHAPTER XII
VOLITION
Motor Experiences. In chapters x and xi we have exam-
ined the different kinds of behavior. All behavior of what-
ever sort is response to some stimulus. In all complicated
behavior there is a central process of adjustment between the
stimulation and the man's response; and in connection with
this central nerve activity there arise sensations, perceptions,
and other experiences. When you see a ball coming swiftly
toward you, and you step aside to avoid it, your perception of
the ball is an experience which arises in connection with the
adjustment process in your brain; the perception takes place
after the stimulus (the light from the ball) strikes your eye
and before you move. You perceive the ball, and then you
side-step.
But this is not all. We know not only what stimuli are
affecting us at a given moment, but how we are responding
to them. You are aware that you are moving out of the path
of the ball. You get this information through muscle sensa-
tions which arise after the response has begun. Your experi-
ence of making the movements is a very different sort of
experience from your perception of the ball. Motor experi-
ences are experiences of our own movements. They are
stimulated by the contractions of our muscles when we are
actually making the response; they inform us about our own
responses and not about the stimulus which started the
response. This information helps us to guide and control
the progress of the movement.
Motor experiences are composed of kinesthetic or muscle
sensations. Every movement, whether reflex, instinctive,
or intelligent, which involves muscular contraction, gives
272 CONATION [CH. xn
rise to muscle sensations. 1 In the case of reflexes these sen-
sations are generally weak; they do not form independent
experiences, but enter as marginal elements into some other
experience that is present at the time. We know we are
winking or coughing. But the chief experience when we wink
is a darkening of the visual field; when we cough the experi-
ence is partly of hearing the sound of the cougb.
In instinctive and intelligent acts the muscle sensations are
more apt to combine into definite experiences; they form
special sorts of experience, which are different from any of
the kinds so far considered.
CONATION
Nature of Conation. Our simple motor experiences are
usually not vivid and have never received a popular name.
Psychologists have adopted the term conation for this kind of
experience. A conation is an experience made up largely of
motor sensations. It gives us direct knowledge of our own
bodily attitudes and movements.
There are frequently other elements in a conation besides
muscle sensations. If the head or whole body is moved, we
have static sensations from the semicircular canals. These
are motor sensations, though they do not come from the
muscles. The external senses also contribute to the experi-
ence. You see your arm moving; these visual sensations
form part of your conation. In certain diseases where the
muscle sense is destroyed, the patient is not aware of his
movements unless he sees them; he can move his arms and
legs if they are visible, but is unable to do so with his eyes
shut. Touch also furnishes information of our movements,
through the rubbing of our clothing on the skin.
The special qualities of conation are effort, strain, and
resistance; where the static sensations enter in, there is also
a nameless quality which may be called whirl. The external
1 Glandular reflexes may produce systemic sensations.
SH. xn] NATURE OF CONATION 273
senses add no special quality to the experience, but they tend
to arouse slight muscle sensations or images. We notice this
on a train when it starts smoothly, or if our own train is
standing still and a train close by starts to move. The sight
of the motion leads to an impression of motor effort on our
part.
Conations occur in connection with reflex actions, instinc-
tive movements, and habits. We have reflex conations occa-
sionally, when a reflex action causes vivid muscle sensations.
When we start at a sudden noise, the movement arouses a
conative experience. Coughing and sneezing are accom-
panied by conation. Usually the sensations arising from
simple reflexes do not give definite conations, but are inci-
dental elements in our perceptions or feelings.
Instinctive conations most frequently accompany the so-
called ' nutritive ' instincts, such as wandering, acquiring,
cleanliness. In other classes of instincts the systemic sen-
sations are apt to be more vivid than the motor; in fighting,
sympathizing, mating, and even in modesty reactions, the
experience is an emotion and not a conation.
Habit conations are motor experiences which accompany
the performance of well-established habits. We are vaguely
aware of our activity when we are dressing; there is no vivid
experience of the various movements unless we meet some
difficulty, such as a misplaced shoe or the loss of a collar but-
ton. Then all at once the response ceases to be automatic
and the motor experience is no longer a conation, but a
volition.
Conations are neither so vivid nor so important in life as
perceptions, memories, or feelings. The motor sensations of
instinctive movements are usually overshadowed by other
elements, so that the experience is not a true conation. If
the systemic sensations are strong the experience becomes
an emotion; if vivid images or thoughts are present it be-
comes a volition. Intelligent actions, except automatic hab-
274 VOLITION [CH. xn
its, usually require thought, and their experiences rise to a
higher level than conation.
VOLITION
Will and Ideomotor Activity. In man, responses to stimu-
lation are frequently delayed. The intricate system of con-
nections between our various centers permit the nerve im-
pulse to travel from center to center before it discharges into a
motor pathway. As the impulse passes through each center,
ideas are aroused corresponding to the memory traces re-
tained in that region. When at length the nerve impulse
discharges, our action is as much an outcome of these ideas
as a response to the original stimulus. Such responses are
called ideomotor actions, in contrast to sensorimotor actions,
which are responses to sensory stimuli. If you stop to think,
even for an instant, before you act, your action is ideomotor.
If you are lying in bed in the morning, vegetating comfort-
ably, and you suddenly remember an engagement at 8:30,
you jump up like a flash. The movement is started by the
thought not by a direct sensory stimulus; it is ideomotor.
If the alarm-clock wakens you and you jump out of bed, the
act is sensorimotor the stimulus is a sensation, not a
thought.
The distinction between sensorimotor and ideomotor action
is not quite the same as between instinctive and intelligent
action. All reflex and instinctive acts are sensorimotor, but
not all intelligent acts are ideomotor. Many of our habitual
acts are quite automatic; they are sensorimotor, though they
have been acquired by a learning process and are therefore
intelligent. Your response to the thought of lateness is
ideomotor and intelligent. If some one douses you with
water or pricks you with a pin and you jump out of bed, the
act is sensorimotor and probably instinctive. The man who
starts to change his collar for dinner and finds he has un-
dressed completely and is turning down the bed, is acting in a
CH. xn] roEOMOTOR VS. SENSORIMOTOR 275
sensorimotor way, but the act is not instinctive; it is a series
of actions which he has learned acquired individually
and has reduced to a perfect habit; in fact, the habit is alto-
gether too perfect.
The kind of experience which accompanies ideomotor
actions is called volition or will. 1 A volition is a complex
experience made up chiefly of two sorts of elements: motor
sensations and ideas. When we will to do a certain thing, we
have a thought of the action, together with certain muscle
sensations of effort or memories of such sensations. Voli-
tions are generally more vivid than conations.
Volition is especially important in life because the idea
which starts the action is an anticipatory image or purpose;
it represents what we are going to do. Suppose you plan a trip
to the mountains and afterwards take the trip. When you
make the journey you produce actual movements and receive
sensations which correspond to the image experiences that
you had in making your plans beforehand. Just so far as you
accomplish what you planned to do you bring the events of
the outer world under your own control. You think of a
certain situation, and as a result of your actions this situa-
tion, which you previously thought of, is finally brought
about. Your will has changed the course of events in the
outer world.
The actual working of ideomotor activity is often misunder-
stood. It is commonly supposed that the idea of a movement
tends to produce that very movement that the idea directs
the nerve impulse into the proper motor path. 2 This is not
the case. There is no inherited or natural connection between
the idea of a given movement and its execution. Every idea
tends toward some expression ; but the exact tort of expression
is in the beginning a matter of chance. It may be any sort
I Strictly speaking, 'will' is the capacity for ideomotor activity; 'volition'
is the experience which accompanies the action; the act itself is 'voluntary.'
1 Even so acute an observer as James held this view.
276 VOLITION [CH. xn
of movement. There is no inherited adaptive connection
in volition as there is in reflexes.
When you will to pick up a book, you grasp it at once.
But this is the result of a habit; there is no inherited tendency
to pick up a book when you will to do so. This is evident if
you watch a very young child trying to pick something up.
He fumbles about, and even if he finally succeeds, the act is
performed awkwardly; he has not yet learned to connect up
the idea with the proper motor impulse. Watch a child try-
ing to copy the letters of the alphabet or trying to draw a
picture. Or try yourself to perform some action which you
have never learned to do, such as twitching your ears. The
idea is vivid, and it results in various movements, but it
does not issue in the movement which you willed.
All ideomotor responses must be learned; the proper con-
nections between brain centers and motor paths are acquired
by trial and error. In adult life all our ideas of action lead to
the appropriate movements except in rare cases, such as ear-
twitching. This is because the right response has already been
selected. If the child thinks of picking up a book, and the
right movement happens to follow, the muscle sensations
reinforce the idea and make this particular nervous connec-
tion stronger than others, so that the next time the proper
motor impulse is more likely to follow the idea. In this way
our volitions come to be followed by just the movements we
want to make. The ability is not inherited, but acquired.
Volition is a distinct advance over the kinds of experiences
which we have so far examined. It anticipates what is going
to happen. The will is not (like perception, memory, and
emotion) concerned chiefly with the reception of information
from the outer world or from our own bodies, but with action
by the individual upon the environment. The volition experi-
ence leads to voluntary activity, which is a great step toward
control of the physical world by living beings. 1
1 Instinctive behavior involves some control over nature. Volition
increases this control tremendously.
CH. xii] VOLUNTARY ACTIVITY 277
Voluntary Activity. Voluntary activity is distinguished
from other activity by deliberation and choice. The latent
period between the stimulus and response is longer. The
delay is due to the fact that the motor expression is checked
and a train of ideas take place before the action begins.
The deliberation which precedes voluntary acts is not al-
ways long. The length of the latent period depends on the
nature of the situation. An intricate course of action, such
as the choice of your career in life, generally requires a long
time to think out. But such situations are comparatively
rare. Most of our voluntary acts are decided quickly. The
latent period is often very short. When you are reading a
book and the dusk gathers, you suddenly notice that it is too
dark to read without great effort. Immediately you get up
and turn on the light. There is no apparent delay. Yet the
act does take longer than a simple sensory response. The
sensory response to this situation would be to drop the book
and close the eyes; in voluntary action this immediate re-
sponse is checked and the idea of lighting follows; there is a
slight delay before you act.
The choice which takes place in voluntary actions is due to
the complexity of the nerve impulses. When our motor
expression is checked or inhibited, various ideas follow in
succession, each representing some different course of action.
When at length one of these becomes so strong that it leads
to nervous discharge along some motor path, the result is a
voluntary movement. On a holiday morning my first ' plan '
is to spend the day reading in the library. The bright spring
weather suggests a motor trip through the country. The
motive of duty suggests finishing a half-written article.
Finally, the thought of a long, brisk walk, combining pleas-
ure with exercise, proves the most powerful impulse, and my
voluntary activity proceeds along this line.
Volition is selective, not because it determines events which
are otherwise indeterminate, but because it tends to bring
278 VOLITION [CH. xn
about the fittest actions, instead of the most obvious. 1 In any
response the path of motor discharge is along the line of least
resistance, but in voluntary action the nerve impulses in the
brain pass from center to center before the motor impulse
starts; and during this period of suspense we think of the
various alternatives. As a result of the delay and of the
changes in the central nerve impulses, the action when it does
start tends to be more suitable than an immediate response
would be.
Relation of Volition to Intelligence. We have distin-
guished two sorts of motor experiences: (1) Simple motor
experiences or conations, which are made up chiefly of muscle
sensations; and (2) Volitions, composed of muscle sensations
and ideas. These two are alike in that they give us informa-
tion about our motor attitudes and the movements we are
making, and so enable us to guide the course of our move-
ments and control our actions. You keep on walking or
steering your bicycle or tying your necktie because you are
kept informed every instant as to how your movements are
progressing. Motor experiences have a different meaning in
our lives from perceptions and memories of external objects
or from feelings of our own systemic conditions. These
other experiences are chiefly receptive; motor experiences
not only tell us what we are doing but suggest the way we
shall act.
Leaving out of account simple reflexes and autonomic
activities, human behavior is mainly of two sorts : instinctive
acts and intelligent acts. Instinctive behavior is inherited;
that is, we inherit nervous paths and connecting synapses
which enable us to perform these actions without a course of
learning. Intelligent behavior is not inherited; we do not
inherit definite paths and connections for this type of action,
1 The question whether the will is free has been debated for ages and has
not yet been finally settled. It is not so important a problem if we empha-
size the delay factor and the notion of fitness.
CH. xii] RELATION TO INTELLIGENCE 279
but merely the possibility of making these new connections
(among others) by acquisition and fixation.
A distinction must be made between the way we acquire the
ability to perform an act and the way we perform it. Instinct
and intelligence are two different ways of acquiring motor
ability. Instincts are racially acquired; habits are individu-
ally acquired that is, they are learned. But once a habit is
acquired, the way we actually perform the act may be just
like an instinct. In other words, not all of our intelligent acts
are performed voluntarily. Some highly intelligent, adaptive
actions are sensorimotor; the motor experience which accom-
panies them is a conation, not a volition. This is the case
when the action has been completely fixed or established.
Most of our actions in every-day life are a mixture of old
and new movements. We rarely meet an entirely new situa-
tion, nor yet a situation without some new element. Most
situations are partly a repetition of familiar circumstances,
but with something in them which is quite different from
anything we have experienced before in the same connection.
So our responses are largely automatic. But if they are to
suit the situation they must be partly voluntary also. Re-
moving the collar is a fixed habit; but whether we shall put
on a fresh collar or continue undressing depends on other
factors in the situation. This requires thought and voli-
tion if our response is to be suitable.
Volition is useful only so far as the situation is new or
ambiguous. It impedes the performance of a stereotyped
habit to attend to each movement closely. Intelligence
means attention to the branch-points and alternatives of
behavior, with voluntary control of behavior at these points;
intelligence also means inattention to stereotyped actions
and letting them proceed automatically, without voluntary
control.
Training the Will. Voluntary actions are most effective
when we act after the proper amount of deliberation. In
280 VOLITION [CH. xn
childhood we must learn to inhibit too hasty action. " Think
before you act," is the maxim commonly taught to children,
and with good reason. The child tends to act at once, on
the mere perception of the situation. He must be taught to
avoid impulsive action that is, action in which the motor
impulse follows immediately upon stimulation. Emotional
expression (weeping, kicking, etc.) is restrained and con-
trolled by admonition and punishment. The will to refrain
is taught first; the will to act comes later.
In adult life, if restraint has been properly cultivated, the
emphasis is on the other side. Too much deliberation leads
to a vacillating attitude. We should cultivate the habit of
sizing, up the possibilities quickly and then acting without
neeo*|ess delay. The ordinary situations of life are clear
enough for quick decision. Long deliberation is apt to lead to
a habit of day-dreaming of living in a fictitious world.
Its pathological manifestation is aboulia, a condition where
the patient is unable to reach any decision at all.
In popular psychology ' will power ' means the capacity to
go ahead and keep going ahead in a motor way. The strong-
willed man is one who pushes his purposes to completion
regardless of obstacles. He is not discouraged, whatever
happens. Even physical pain, the greatest deterrent, will
not turn him aside. We read of the Spartan boy who was
gnawed by a fox which he had brought to school concealed in
his clothing, and yet by sheer strength of will kept a passive
countenance and showed no signs of his agony. As a modern
parallel might be cited the American governor of Cuba, who
stuck to his post and fulfilled his administrative duties faith-
fully for days, despite a raging fever.
These instances show the power of vivid thought (the pur-
pose idea) to keep one steadfast in vigorous action or in self-
restraint. He who is trained to control his actions by steady
purpose and grit is best able to cultivate useful habits and
to break bad habits. If the thoughts ' I will ' or ' I will not '
CH. xii] TRAINING THE WILL 281
find strict motor obedience, one need not fear being over-
mastered by any habit.
Training the will gives us greater ability to resist sugges-
tion. This does not mean that if some one advises us to do
a thing we should promptly refuse. The majority of sug-
gestions from those about us are probably reasonable and
deserve consideration. But neither should we promptly
acquiesce. Voluntary decision requires at least an instant
of deliberation. If we fall into the habit of following a
certain person's suggestion without hesitation, we become the
agents of his will, not our own. This may have no bad effect
on us if this particular person is conscientious and competent,
so long as he is there to guide us. But when the master-mind
is removed we are in sore difficulty if we have lost our self-
reliance and power of self-guidance.
This is especially to be remembered in the home training of
children. Parents who insist upon immediate, unreasoning
obedience, are fitting their children to be the slaves of others.
If the training is effective if it makes the child perfectly
docile he will develop into a type of which his parents will
not be proud. If he inherits the same ' masterful ' traits
which prompts them to treat him this way, he will rebel and
the attempt will fail. Training in obedience, in conforming
to social conventions, is an essential part of the child's educa-
tion. But when he reaches the reasoning age, parents and
teachers should not expect unreasoning obedience. It is the
parent's duty to show the why and the wherefore of his com-
mands, and to cultivate in the child the spirit of challenge,
This seems the only way to avoid one of two unfortunate out-
comes : either a hopeless obedience to suggestion, with a min-
imum of will-power, or an unsocial obstinacy.
IDEALS
Nature of Ideals. An ideal is a very complex experience
in which ideas, systemic sensations, and motor sensations
282 IDEALS [CH. xii
are all prominent. It consists of a vivid image or thought,
together with an intense feeling and a strong tendency to act.
If one's ideal is to become a physician, he has a general image
or thought of the various characteristics of the medical pro-
fession; he is stirred by a noticeable feeling when he thinks of
what a doctor can accomplish; and his acts, with their accom-
panying motor sensations, are such as will tend to fit him to
become a capable physician. In other words, an ideal in-
volves thinking a thing, feeling it, and doing it.
Ideals generally grow up by degrees out of particular expe-
riences in which one or other of these different elements pre-
dominates. Our deepest-rooted ideals are usually formed
slowly and are related to a host of separate experiences.
The experiences which develop into ideals are due largely to
social stimulation. We are told that we are fitted for a cer-
tain career; or the ideal may be aroused by contact with some
one who has been successful in this particular line of work, or
it may be strengthened by meeting some one who has made
a conspicuous failure in some other line that appealed to us
as an alternative.
Ideals are of the utmost importance in human life; but
their importance consists in their persistence and pervasive-
ness rather than in their vividness. They stick to us through
thick and thin, but we rarely experience them as distinct and
vivid states of mind. Usually they are marginal or subcon-
scious. They are underlying motives of actions, and are usu-
ally noticeable only in the attitudes which we assume (ch. xv).
Summary. The various kinds of behavior discussed in the
two preceding chapters give rise to motor experiences. Mus-
cular contractions stimulate muscle sensations; these and
our static sensations are combined into experiences of our
own activity. Motor experiences are divided into conations
and volitions. A conation is a simple experience which accom-
panies reflexes, instincts, and fixed habits. It is usually vague
and unimportant.
CH. xii] SUMMARY 283
A volition is an experience composed of motor sensations
and ideas; the ideas are anticipation images or purposes,
which in the course of time are put into effect. The con-
nections in the nervous system between the will-impulse and
the appropriate movements are not inherited, but acquired.
The special features of will are the delay (with deliberation)
and choice. The actions which follow a volition are called
ideomotor actions.
An ideal is a composite experience which includes ideas,
feelings, and motor sensations. Ideals are rarely vivid;
they usually form underlying attitudes, which are of prime
importance in life.
PRACTICAL EXERCISES:
59. Analyze the motor experiences of laughter.
60. Describe the chain of experiences involved in picking up a book,
especially the muscle sensations.
61. Test your ability to inhibit each of the reflexes in lists A and B, of
Table X (p. 233). Also try which of them can be brought about
voluntarily.
62. Examine your experiences when you are planning some course of
action, such as how to spend a holiday.
63. Trace the development of your ideal of what your career should be.
REFERENCES:
On volition: W. James, Principles of Psychology, ch. 26; W. McDougall,
Social Psychology, chs. 9, 16.
On ideas and movements: M. F. Washburn, Movement and Mental Imag-
ery; E. L. Thorndike, in Psychological Review, 1913, 20, 91-106.
CHAPTER XIII
LANGUAGE AND THOUGHT
Communication. So far we have considered a man's
experiences as something belonging to himself alone, and as
having no connection with the experiences of other human
beings. As a matter of fact, the experiences of one member
of the community frequently affect others very decidedly.
Ideas are passed along from one individual to another. The
communication of impressions has an important bearing on
our mental development. In many cases we can shorten the
process of learning considerably by the simple expedient of
having some one else tell us what to do. " Keep your mouth
closed and hold your head lower," says the swimming
teacher, and the process of learning to swim is much simpli-
fied by the communication of these ideas.
There is a popular notion that one mind sometimes in-
fluences another directly, without the medium of the nerv-
ous system and receptors. There is at present no satisfactory
evidence that this direct communication ever takes place.
We get ideas from other persons by means of indications
which they express in words or gestures ; and these indications
are always received through our ears or eyes or some other
sense receptor. What one reads in popular magazines and
novels about telepathy can be dismissed as highly improbable.
Communication is an important factor in mental life. It
not only enables us to learn rapidly, but it furnishes us with
a great store of ideas which no single individual could gather
during his limited life-time by his own unaided efforts.
Besides all this, communication and social intercourse are the
means of building up two new sorts of experience: language
and thought.
CH. xm] COMMUNICATION 285
Language is an experience made up of the same kind of ele-
ments as volition. Both volition and language are composed
of ideas and motor sensations. But language leads to a very
different kind of response from volition. In the case of
volition the response is some direct effect on the general
environment; in language the response is some gesture or
vocal expression which arouses an idea in some other person
and brings him into relation with the speaker. Voluntary
action enables you to open a closed door by turning the knob
with your hand. But if the knob does not work, you call
out, " Open the door," and this language response on your
part may induce some one inside the room to turn the key
and let you in. Language responses often bring about indi-
rectly the same result that volitional responses bring about
directly.
A thought is a special kind of idea which developed in the
first place as an aid to communication. You may have a
vivid memory of some event in your life; but unless you are
an artist you cannot reproduce this in picture form for the
benefit of others. You can only communicate it by means of
arbitrary, conventional symbols. If you have seen the
Natural Bridge and wish to describe it to a friend, you do so
by means of visible symbols (by writing a series of words)
or audible symbols by saying ' bridge ' and uttering other
conventional sounds which call up corresponding ideas in his
mind. Your friend reads your letter or listens to your de-
scription, and this arouses in him an idea of the Natural
Bridge which is more or less like your own idea.
The sound of the word ' bridge ' in no way resembles a real
bridge; and the written word BRIDGE does not look like a
bridge. But by repeated association between the spoken or
written word and the object, the word calls up the memory
image of the object, and in the course of time the word tends
to replace the image, so that we represent the bridge in terms
of words instead of by a mental picture of the thing itself.
286 LANGUAGE AND THOUGHT [CH. xin
Ideas whose prominent elements are words, instead of images,
are called thoughts. Thoughts are arbitrary, conventional
representations which take the place of mental pictures
(images) of objects and events.
Language and thought belong to a higher level than other
experiences. They involve the growth of several new adjust-
ing centers in the cortex of the brain. These two types of
experience, language and thought, grow up together. Speak-
ing and thinking in words depend on the accumulation of
traces in one or more of these special centers. If you speak
a word you hear the sound of your own utterance, so that the
spoken word is intimately connected with the thought-word.
The greater the number of words in a language, the more
acute is the thinking in the community using that language.
We find, then, that language and thought are composed of
ideas and motor sensations; and that they have a number of
peculiar characteristics, which are not found in the experi-
ences noticed in previous chapters. (1) Language and
thought depend on communication between individuals.
Primitive man speaks with reference to some listener: he
learns to think in words through repeatedly uttering words for
social purposes. (2) Language and thought form a higher
grade of experience than perception, memory, emotion, and
the rest; they involve the development of special centers in the
brain. (3) Language and thought are symbolic; that is, they
are arbitrary, conventional signs not mental copies of what
they represent. Except in rare cases the sound and the
written letter do not resemble the thing for which they stand.
Symbolic Experiences. The last-mentioned character-
istic distinguishes thought from other sorts of ideas. A
memory is virtually a reproduction of some definite percep-
tion. Fancies and general images consist of bits gathered
together from various perceptions. The distinguishing mark
of a general image is that it reproduces in a sketchy way the
appearance of some class of objects.
CH. xin] SYMBOLIC EXPERIENCES 287
It would not be easy to draw pictures similar to our general
ideas every time we wished to communicate with others; so
instead we make some arbitrary sound or gesture which takes
the place of the picture. A certain sound or gesture comes to
be habitually associated with the idea of a tree, another with
the idea of a man, and so on; through constant association the
conventional sound or gesture tends to become more and
more a part of the idea. Among civilized men this associa-
tion is so strong that the arbitrary sound produced by utter-
ing the word tree, for instance, becomes the chief element in
our general idea of a tree. We think of trees chiefly in terms
of the sound or vocal utterance of that word; the mental
picture of the tree tends to become more and more vague.
In this way thoughts tend to displace general ideas in our
mental experience. Thinking is largely a series of word-
pictures not of object-pictures. We think in terms of
words and sentences, which do not resemble the things we are
thinking about. Words are arbitrary signs or symbols which
we use instead of calling up the ' copy ' every time.
Thought is an outgrowth of language. One can readily
call up memories and general images of the things he has
experienced. In all ordinary situations of life we could prob-
ably work out our ideas by means of mental pictures without
using any symbolic terms. There seems no reason why a
solitary man should have devised the words tree and cow to
help him in thinking about trees and cows. The fact that
some of us think aloud when alone is no argument; we are
simply exercising a firmly established habit. There is evi-
dence that castaways gradually lose the power of ready
speech ; their thinking probably reverts more and more to the
' image ' type. It is social situations that lead to the inven-
tion of words, and to their use as ideas in place of imagery.
The Different Kinds of Language. The principal kinds of
language are gesture, speech, and writing. Each finds expres-
sion in a special type of behavior: gesturing makes use princi-
LANGUAGE AND THOUGHT [CH. xra
pally of the hands and head; speaking uses the mouth and
throat; writing uses the hands and some instrument which
leaves a permanent mark on stone, paper, etc. Facial expres-
sion is a more primitive type than any of these, but it is
generally an expression of emotional states and is rarely used
for communication. Winking an eye r smiling at some one
may be treated as facial gesturing.
Gesture language probably arose earlier than speech. It
came from the practice of pointing to objects or waving the
arms to arouse attention. In time many of these gestures
assumed a conventional form. Certain movements of the
hand and head came to denote fish, fruit, meat, fire, cooking;
pairs of opposite movements came to signify assent or dis-
sent, or ' come here ' and ' go away.' Gesture language is
still used among the deaf. Otherwise it has been almost
wholly superseded by speech.
Vocal language is much more convenient than gesturing.
One can easily speak when engaged in fishing or plowing,
while gestures are apt to interfere with these occupations.
One can listen to oral conversation without turning the head;
it is not easy to watch the plow and a companion's gestures at
the same time. The ears are always open; we can secure a
man's attention to what we say without stepping in front of
him or seizing hold of him, though some people do not seem
to realize this. In the sick room gesturing may be more
effective; but in ordinary situations speech has all the
advantages.
The various languages or tongues which have grown up
among mankind Greek, English, French, etc. all belong
to the same mental type: vocal expression. They differ only
in the special words that are arbitrarily associated with each
object or meaning. Associations of ideas formed in early
childhood are most likely to persist; so that if one starts life
in an English-speaking community, the English word-associa-
tions are deeper rooted than those acquired later. A young
CH. xni] VARIETIES OF LANGUAGE 289
child may easily be taught three or more languages and
remain master of them all. Later in life, verbal associations
are more difficult to form ; languages learned after the adoles-
cent period are rarely so well organized or so thoroughly
assimilated. It is not known whether each tongue develops
a special center in the* speech region; but we know that the
associations between words of the same tongue are closer
than between those of different tongues.
Written (graphic) language is used in civilized communities
to supplement speech. It consists in making permanent
marks or impressions upon stone, bricks, papyrus, or paper.
In the older graphic languages the records were rude pictures
of objects; later these pictures became conventionalized, as in
Chinese, or each graphic unit came to symbolize a syllabic
sound, as in syllabary Japanese. In the graphic language of
modern western races each symbol represents an elementary
vocal sound, either consonant or vowel. The letters of our
alphabet are symbols for vocal sounds which are themselves
arbitrary symbols for objects. 1
There are several varieties of graphic language. Besides
ordinary handwriting may be mentioned printing, typewrit-
ing, telegraphy, and phonography. In all these forms the
characteristic feature is the permanent record, which makes
it possible for one person to communicate with others at great
distances or after long intervals of time. In fact the chief use
of graphic language is to extend the range of communication
in space and time. Graphic language, like gesture language,
is received visually, except the phonographic variety, which
is auditory. 2
Nearly all graphic languages are asymmetrical. In the
Greek and Latin alphabets the record always runs from left to
1 Our numerals are not vocal symbols, but ' ideographs.' The number 1492
conveys the same meaning to all men, whatever their tongue.
1 Books for the blind, printed in raised letters, are perceived by the sense
of touch.
290 LANGUAGE AND THOUGHT [CH. xm
right, in Hebrew and Arabic from right to left, in Chinese
from top to bottom. The order is practically never reversed,
nor are individual letters turned around. ' Mirror-script ' is
unintelligible to most persons, and it is usually difficult to
write. [Fig. 76.] This is due to long fixation of habit; if you
FIG. 76. READING MIRROR SCRIPT
Unless one is practiced in reading reversed writing it is difficult to recognize and
read a single word of this. Hold it before a mirror and the writing is plain.
practice sufficiently you can learn to write and read reversed
script quite readily. The direction in which we write may
possibly be due to the sort of instrument originally used by
our ancestors in handwriting: a quill is more easily pulled
along; a chisel is more effective when pushed; a brush is more
naturally swept down toward you.
Understanding and Reading. Communication is a two-
sided affair. It is not completed, like other types of behavior,
when the response is made; after the first person A speaks,
CH. xin] UNDERSTANDING; READING 291
there is a receptive process on the part of another person B.
The spoken words produce complex sound-waves, which
stimulate B's ear. The effect of these verbal stimuli is very
different from that of other sounds. There is first a sound-
perception process in B's auditory center; then the nerve
impulse passes into his auditory-speech (word-hearing)
center, where word-perception occurs. This arouses in B a
thought similar to the thought experienced by A as he utters
the words.
The arousing of thought in a second person by speech or
writing is called understanding. When B gets A's thought, he
understands what A is trying to communicate. There is no
special English term for receiving and understanding spoken
words and gestures; 1 but the process of receiving and under-
standing written language is known as reading. Reading is
more under our own control than the reception of spoken
words. We can move the eyes slowly or rapidly so as to
regulate the speed of receiving the stimuli; we can glance
back and read a sentence over again.
In reading, the sensory elements are not prominent. We
perceive the total word, not the individual letters. If there
is an imperfection in one of the letters, we usually do not
notice it, and often a wrong letter in a word passes unnoticed.
Even the most expert proofreader may overlook these errors.
The general meaning of the sentence suggests the thought,
and if some letter or trivial word is omitted the imagination
supplies the gap. The same is true in speech, though not to
the same extent.
Our failure to detect such errors is due to the fact that
understanding involves a double mental process, which almost
smudges out the individual sensations. A word-stimulus is a
sound or a visual effect. It is perceived like other stimuli;
and just as in every kind of perception the piecemeal sensa-
tions merge into a general total effect. But after this there is
1 It may be called comprehension or listening.
292 LANGUAGE AND THOUGHT [CH. xnl
a further working over of the material in the higher verbal
centers, which transforms it still more. This effect is noticed
if we listen to some one speaking alternately in English and an
unknown tongue. We get the same effect in reading if we
come across some unknown foreign word or phrase. The
unfamiliar words are heard or seen plainly, but they do not
arouse ideas; they are merely sounds, or marks on the page.
Reading aloud is a further complication of the communica-
tion process. The reader acts as a relay between the author
who expressed the thought originally, and the persons who
receive it. It is quite possible for you to transmit thought
without understanding it yourself, if you read aloud in an
unknown tongue. You can even learn to read aloud mechan-
ically in your own tongue, thinking of other things all the
while, but giving the right accent and intonation to the sen-
tences.
j Brain Centers for Language and Thought. There are four
special brain centers concerned in language and thought:
(1) a word-uttering or speaking center for vocal language;
(2) a word- writing center for written language; l (3) a word-
hearing center for understanding word-sounds and for audi-
tory thought; and (4) a word-seeing center for reading and
for visual thought.
These centers are found in only one side of the brain
usually the left side whereas the other centers are found in
both hemispheres. 2 The location of these four higher centers
is shown in Fig. 77. 3 The word-hearing center lies near the
auditory center in the left temporal lobe of the cortex; the
word-uttering (speaking) center lies in the left frontal lobe
1 It is possible that the ' gesture ' center is distinct from this.
8 In cases of paralysis, if the left side of the body is paralyzed the indi-
vidual's capacity for thinking and speaking are usually quite normal; but if
the right side is affected some of the language functions are apt to be im-
paired. The right side of the body is controlled by the left side of the brain.
1 Cf. Figs. 13, 14. Recent investigation indicates considerable individual
differences in the location of these centers.
CH. XIII
SPECIAL BRAIN CENTERS
293
near the region which controls movements of the tongue, lips,
and throat. These two regions are connected together by
association tracts. Vocal language ordinarily involves co-
operation of the two. If the word-hearing region is destroyed
the patient is unable to understand the meaning of words, 1
Fio. 77. LANGUAGE CENTERS IN THE CORTEX
Diagram of cortex of the left hemisphere; front of the head is at left of the
drawing. Speaking or word-uttering center is in frontal lobe near centers
for moving tongue, lips, and jaws. Writing center is near centers for mov-
ing fingers. Word-bearing or auditory language center is in temporal lobe
near the center for hearing. Reading or word-seeing center is in occipital
lobe near the visual center. (Cf. Figs. 13, 14.)
though not deaf to sounds in general. He may be able to
utter words through other connections. If the word-uttering
center is destroyed the patient is unable to speak, though he
may understand the meaning of words. This disorder is
called motor aphasia.
In the case of deaf persons who have been taught to speak
and to 'read the lips,' a connection is developed between the
word-uttering center and some center in the visual region.
The popular term deaf-mute is incorrect. A deaf man is mute
merely because the connections between lip-word seeing and
word uttering have not been trained. These connections
are harder to form than between hearing and uttering
1 This disorder is called sensory aphasia.
294 LANGUAGE AND THOUGHT [CH. xm
words, but under proper treatment they can be readily de-
veloped.
The word-seeing (reading) center lies near the visual region
in the occipital lobe of the left hemisphere. Destruction of
this area causes inability to read (alexia). The patient sees
the letters, but they do not convey any meaning to him,
just as an Arabic or Chinese inscription appears to us only as
a miscellaneous collection of marks. The word-writing center
lies in the frontal lobe near the center which controls hand
and finger movements. Its destruction causes inability to
write (agraphid). These two centers are not so closely con-
nected as the two vocal-speech centers. Destruction of one
function is not so likely to involve disturbance of the other.
In fact the word-seeing center is more closely connected with
the word-uttering center than with the word-writing center.
The Different Kinds of Thought. The ideas of civilized
man consist largely of verbal thoughts. For most of us the
word ' horse' is the main feature of our idea of a horse. We
picture vaguely the appearance of horses, their movements,
the sounds they make in galloping or neighing; but the focus
of the idea is the word.
For some persons a word is chiefly a sound. For others it is
the muscle sensations from the lips, tongue, and throat in
speaking, For others it is the looks of the printed word. In a
few cases it may be the muscle sensations from the hand in
writing. So there are these four different kinds of thinking:
auditory, vocal-motor, visual, and hand-motor. We classify
people according as their thinking belongs to one or other of
these types. But in many cases a man's thinking may com-
bine two or more of these elements : your thought of a horse
may include both the sound of the word and the motor sen-
sations of uttering it.
When you think in terms of the sounds, the word- hearing
center is the seat of the nerve activity; if you form the words
in your throat, the nerve activity is in the word-uttering
CH. xin] KINDS OF THOUGHT 295
center. In the vocal type of thinking, the thought is usually
not expressed aloud; there is merely a slight muscular adjust-
ment which is not detected except by very delicate instru-
ments. 1 Individuals of the 'visual* type, who think in
terms of the looks of printed words, use the reading center in
thinking. The destruction of any one of the four special
centers leads to disturbances of thought as well as of lan-
guage. This is why aphasic patients of certain types often
break off in a sentence and seem to lose track of their thoughts.
Meaning and Value. Although thoughts are symbols,
every thought contains certain elements which resemble the
object or situation we are thinking about. These " bits of the
real thing " make up the meaning of the thought. When we
think of man, the arbitrary word ' man ' is the central feature
or focus of the experience. But at the same time there is
somewhere in the background or margin of the thought a
fleeting image of some particular man or of certain human
characteristics. These faint images constitute the meaning.
In other words, the meaning of a thought comprises those
elements in the experience which correspond to the object or
situation, as distinguished from the mere verbal or symbolic
elements. When you try to examine the meaning of a word,
by observing it closely, what happens is that these marginal
elements become prominent. This occurs very notably in
scientific and logical thinking, where the meaning is especially
important. On the other hand, if you take a familiar word
and repeat it over and over again (man-man-man-man )
it finally loses all meaning: the sound becomes so insistent
that the image elements disappear altogether.
The value experience is the same sort of thing as the experi-
ence of meaning, except that it has to do with intensity and
quantity. Your thought of a book is usually tinged with
some idea of its being thick, long, heavy, difficult to read,
true or the opposite of these. In most cases these ideas
1 These slight vocal adjustments are called implicit responses.
296 LANGUAGE AND THOUGHT [CH. xm
are vague and only form part of the margin of the thought.
They make up its value tinge. But if we attend closely to
some quantitative characteristic of an object, this value ele-
ment comes to the foreground; we get a rather new sort of
experience the idea of value. The value idea is especially
prominent in sentiments (ch. ix) ; a belief is partly an idea of
the worth of some statement, partly a feeling.
The same experience may have very different values
attached to it at different times. When Newton saw the
apple fall, it probably seemed a trivial occurrence. After-
wards, as he thought about it more carefully and formulated
the law of gravitation, the experience acquired a meaning
and a value hitherto undreamed of.
Psychology investigates the nature of our experience of
value, but it has nothing to do with finding out the real value
of things. Logic determines what is true; esthetics shows
what is beautiful; ethics teaches what is good. These
sciences enable us to adjust our valuation of situations and
events to the ' objective values ' of the world about us. One
might almost regard them as instances of applied psychology.
This distinction brings out an interesting peculiarity of the
psychologist's attitude toward social relations. Psychology
is just as much concerned with faulty logic and bad conduct
as with their opposites. The psychologist knows that in
each case the error is due to something in the man's nature.
He does not approve of immorality, but he treats it as a fact
to be studied carefully and dispassionately. When he comes
across an instance of wrong-doing he does not proceed at once
to reprove or punish; his first duty is to determine where the
trouble lies. Often this suggests a remedy which avoids the
need of punishment. A child may lie because he does not
appreciate the distinction between memory and imagination;
he may be disobedient because his attention has not been
trained to listen to what you tell him; he may be quarrelsome
or obstreperous on account of digestive disorders. In short,
CH. xni] MEANING AND VALUE 297
it is the business of the psychologist to try first of all to
understand the situation which led to these breaches of ethics.
The practical result of this attitude is seen in the recent im-
provement of the methods of handling delinquents and
criminals, which is attributable in no small degree to the
work of psychologists.
Rational Thought and Rational Behavior. As human
thinking progresses, the meaning and value elements in
thought become more prominent and at the same time the
meaning of familiar words tends to become stereotyped.
When you think of a horse, the meaning of your thought
includes certain definite characteristics common to all horses.
When you try to make your thought correspond as nearly as
possible to what horses really are, the more trivial associations
fade away; only those remain which are characteristic or sig-
nificant. In the same way the value elements in your
thoughts tend to conform to the real values of the objects. A
horse is larger than a man, smaller than an elephant. A
thought which includes, besides the word, only the really
characteristic elements of meaning or value, is called a concept.
A concept is a special type of thought which tends to be " true
to life."
A judgment is a thought which combines two concepts. If
we combine the concept of a horse with the concept of a
vertebrate, we obtain the judgment, " Horse vertebrate,"
or, as it is expressed in language, " A horse is a vertebrate,"
or, " All horses are vertebrates." When we think of a certain
light and of its intensity, and combine the meaning with the
value, the resulting thought is the judgment, " This light is
bright."
Concepts and judgments are rational thoughts. They are
distinguished from ordinary thoughts by their greater pre-
cision and by their close correspondence with real things.
Our ordinary thoughts grow up in haphazard fashion. They
contain irrelevant elements tacked on from casual associa-
298 LANGUAGE AND THOUGHT [CH. xm
tions. Your casual thought of a harbor may be associated
with docks and your thought of a lake with islands. Neither
of these associations is characteristic. As your experience
broadens they fade away; your concept (rational thought) of a
harbor does not include docks, and your concept of a lake does
not include islands.
Since thought is closely bound up with language, rational
thought has led to special sorts of verbal expression. The
language equivalent of a concept is a term; the equivalent of
a judgment is a proposition. The judgment ' horse black '
may be instantaneous, but the proposition takes time; it
starts with one term and the other term comes afterwards.
This involves a succession of experiences (ch. xiv).
Rational thought assists us tremendously in handling real
situations. Pure fancy, as aroused by fairy-tales for instance,
is a source of enjoyment in our leisure hours ; but it does not
help us to meet the problems of real life. The more closely our
thoughts correspond to actual situations in the world about
us, the more appropriate our responses are likely to be.
Behavior based on rational thought is rational behavior, which
is a stage higher than ordinary intelligent behavior. Any
action that is brought about by individual acquisition is
intelligent behavior; an action is rational only if it is brought
about by rational thought. The higher animals act intelli-
gently, but they do not act rationally, because their behavior
is not guided by thought. A human child begins to act
rationally as soon as he acquires thoughts with definite mean-
ings. Rational thought and rational behavior are often
called reason.
The popular notion of reason is wrong in making it a special
faculty of the human mind. It is not a brand-new mental
endowment, but an outgrowth of more fundamental experi-
ences. Mental development is one single continuous process
from the simplest type of stimulation and response to ra-
tional behavior. There is no break, no sudden jump.
CH. xm] RATIONAL THOUGHT 299
There is also a popular notion that human reason is infalli-
ble. As a matter of fact it is quite liable to make mistakes.
Our direct information concerning the world is obtained
through our senses. This information is put together (inte-
grated) by combining sensations into perceptions, memories,
and thoughts. Any misinformation may be corrected even
apart from reason by cutting out chance associations and
broadening our outlook on the world. Rational thought is
merely the final focusing of the picture.
On the other hand, if our perceptions are wrong, even
reason may be unable to correct the impression. In ancient
times the most rational concept of the earth was of a flat, solid
body, surmounted by a transparent dome, in which the stars
were fixed. The rational judgment of matter was that it con-
sisted of four elements earth, air, fire, and water. Many
of the rational thoughts of antiquity have been found not to
correspond to actual conditions; and many concepts and
judgments accepted to-day are doubtless just as false. Ra-
tional thought furnishes merely our nearest approach to the
truth.
Importance of Language and Thought. It is scarcely pos-
sible to exaggerate the importance of language and thought
in the mental life of man. They lead to two new kinds of
behavior, communication and rational behavior, which carry us
to a higher stage of mental life than the trial-and-error way of
learning. Taken together, language and thought provide a
tremendously effective means for adapting our responses to
the general conditions of the environment.
More than any other type of experience, except perhaps
emotion, language and thought must be studied in the light
of then* history. But emotion is a survival from ancestral
conditions, while language and thought are recent human
acquisitions. They are still in the making still improving.
A noticeable feature in the growth of language is its slow
evolution in the race and its rapid development in the indi-
300 LANGUAGE AND THOUGHT [CH. xm
vidual. New words are invented gradually, as the sphere of
thought in the race enlarges. Once adopted they are trans-
mitted rapidly to the bulk of individuals in the community;
each child acquires a large vocabulary at an early age.
Much the same is true in regard to thought. The growth of
thought depends upon the existence of words. If the vocabu-
lary of a community is scanty, the range of thought is limited.
Given a rich vocabulary, the mentally well-developed indi-
viduals in the community quickly attain a wide range of
thought.
The development of language and thought in the individual
depends not only upon the social environment, but upon
inherited nerve structure. In order to speak (to use vocal
language) we must possess inherited pathways between the
word-hearing center and the word-uttering center. Writing
involves countless pathways between the word-seeing or
word-hearing center and the word-writing center. It is
because of the great masses of association fibers present from
birth in the human cortex, that man's intellect is so vastly
superior to that of any other species. Within the human
species it is the sphere of thought, more than any other de-
partment of mental life, that reveals the greatest individual
differences in capacity and attainment. This is especially
true of rational thought.
Training of Thought and Language. The highest stage of
general education is largely a training of thought and of the
rational processes that grow out of it. If primary education
teaches us to perceive, and secondary education teaches us to
remember, college education should teach us to think. This
special objective is often overlooked by both instructor and
student. Too much emphasis is laid on imparting mere facts,
and on retaining them till after the final examination. It
is far more useful to know how to think about the facts, to
understand the principles of whatever branch we are study-
ing. You can readily find the value of the gravity factor g in
CH. xni] TRAINING OF THOUGHT 301
your physics book. It is more useful to understand such
principles as the elliptical motion of planets. In psychology
it is much more important to get the right notion about the
' learning process ' than to memorize any of the tables or
definitions in this book.
The training of thought means especially the cultivation of
rational thought of clear thinking, as it might be called.
The best way to accomplish this is to ponder; not to memo-
rize, in an effort to retain, but to seek out the connections
between the facts. Try to picture the relations step by step.
Practice makes the process continually easier.
A practical problem in education is whether to cultivate
' visual ' or ' auditory ' thinking. Some students master a
subject better by reading, and others by listening to lectures.
(So-called mental arithmetic is really auditory arithmetic.)
Both methods should be cultivated, because both methods of
imparting knowledge are constantly used in modern educa-
tion. Text-books give the main principles; the difficulties
that strike any individual student are better overcome by
word of mouth. An important point is to learn to suppress
the motor type of thinking. You will read more quickly
and understand quite as well if you learn to suppress the
incipient tendencies to utter the words or to form them with
the lips and throat. Such motor accompaniments act as a
drag in reading, and they rarely make the thought more clear.
Their only real use is to focus your wandering attention when
you are tired or the subject is uninteresting.
Psychology is not especially concerned with vocal enuncia-
tion, except that stuttering and faulty pronunciation often
indicate faulty coordination in the brain centers. Psychol-
ogy is more interested in diction. Certain types of sentence,
the use of certain words, indicate clear thinking. Faulty
grammatical construction and the use of incorrect words or
vague phrases indicate slovenly habits of thought. It is
often a help to the student for the teacher to ask, " What do
302 LANGUAGE AND THOUGHT [CH. xra
you mean by this sentence (or word)?" The very challenge
may lead to clearer conception.
An important problem in education is to teach the child to
maintain a proper balance between language and thought.
The contemplative, silent man overemphasizes the thought
side and is inclined to be unsociable. The voluble man
dresses his thoughts in public, instead of within the private
chambers of his own mind. It is the task of the educator to
subdue the chatterer and draw out the reticent one. To suc-
cessfully attain a happy mean, this training must be begun
early in life.
Higher and Lower Levels of Behavior. Language and
thought, as we have seen, involve a higher sort of behavior
than other types of experience. Their relation to the two
lower levels of mental life is shown in the accompanying
diagram. [Fig. 78.]
(1) LOWEST NERVOUS ARC: From the various receptors the
sensory nerves lead first of all to the 'primary centers. There
are numerous primary centers in the cord and in the lower
part of the brain; but in the diagram, for simplicity, they are
grouped into three headings: external, systemic, and motor-
sense centers. From these primary sensory centers the nerve
impulse may pass over directly into one of the primary motor
centers (shown at the right of the figure), and from there
pass down directly to some muscle or gland or over into the
autonomic system. This lowest nervous arc gives reflex
actions, the simplest type of behavior.
(2) INTERMEDIATE NERVOUS ARC: From the primary sen-,
sory centers, paths lead up to the cortex, and to the various
centers there. These secondary or intermediate centers are
active in our experiences of perception and imagery, feeling,
emotion, and volition. They are closely interconnected, so
that a whole chain of experiences may succeed one another
before any important motor impulse is started (ch. xiv).
But sooner or later the nerve impulse passes over to some
CH. XIII
LEVELS OF BEHAVIOR
303
secondary motor center, and from there an outbound impulse
goes out to the lower motor centers and thence to the effect-
3* ARC
Reason
3* ARC
ton muni cation
and
Rational Action
Effe<aora
(Motor
f 1 Organs)
riff
I* si
PrcpoocefiUrs
FIG. 78. MENTAL LEVELS
Diagram showing the three levels of nervous arcs and the grade of mental life corresponding
to each level. Arrows indicate direction of nerve current. Broken lines (below at right) indi-
cate that motor expression stimulates muscle sensations. The centers are shown very sche-
matically; e.g., many separate centers are included in square labeled "external sense centers."
ore. The movements resulting from these second-level motor
impulses are coordinated; they differ in this respect from
304 LANGUAGE AND THOUGHT [CH. xin
simple reflexes. The operation of the secondary nervous arc
gives instinctive and intelligent behavior usually a combi-
nation of the two.
(3) HIGHEST NERVOUS ARC: In man a third set of centers
and a tertiary nervous arc have developed. Impulses from
the second-level experience centers, instead of going over to
the motor centers directly, may pass up to the centers for
thought and language. From these centers the nerve im-
pulse passes over into the verbal and rational motor centers
and then down through motor paths to the lower motor
centers and out to the effectors. This highest level of be-
havior has two different forms: communication and rational^
action^.
The development of the two higher levels of the nervous arc
is accompanied by more perfect adjustment of the responses.
The behavior is more controlled, and more suited to the
' entire situation' than the simple reflexes. Rational behav-
ior is much more adaptive and controlled than ordinary
intelligent or instinctive behavior.
Summary. In chapters vii to xiii we have examined the
various kinds of experiences which are found in man. Per-
ception, memory, and imagination are built out of sensations
which we receive from the world around us; feelings come from
systemic sensations; and conations from motor sensations.
There are also experiences derived from two sources: emo-
tions are built up out of systemic and motor sensations,
sentiments out of systemic sensations and ideas, volitions
out of motor sensations and ideas. There are also experi-
ences called ideals, which are derived from all three sources.
The highest types of human experience are language and
thought, which are brought about by a third level of nervous
arc and involve four special centers in the brain.
All these kinds of experience are different ways of putting
together (integrating) the information brought in over the
sensory nerves. Their real significance in psychology is their
CH. xm] SUMMARY 305
relation to behavior. Our responses are more suitable accord-
ing as the stimuli are more completely integrated that is,
as our sensations are organized into definite experiences.
PRACTICAL EXERCISES:
64. What constitutes your thought of school, idiot, orchestra, Egypt,
steamboat, thunder-storm, medicine, penitence?
65. Ask some one to read aloud, and at the same time to think of other
things; note how far the distraction interferes with his pronunciation
and especially with the vocal inflections which "give the sense."
66. Take two similar problems in physics, geometry, or some other
science. Read one to yourself and have a friend read the other aloud
to you. Compare your experiences in "understanding the problem"
by the two methods.
67. Ask some one to prepare a typewritten page with many typographical
errors. Read the page rapidly, checking the errors noticed. Read
again carefully and observe what mistakes have escaped you. Do you
notice errors better if they look like the right word but sound different
(e.g. though and thought) or if they sound like the right word and
look different (e.g. right and write)?
68. Observe the speech of a two or three year old child. Report any not-
able mistakes in pronunciation, grammar, misuse of words, and sug-
gest the explanation of these errors.
REFERENCES:
On language: C. H. Judd, Psychology, rev. ed., ch. 10; J. London, Before
Adam, ch. 4.
On writing: J. E. Downey, Graphology and the Psychology of Handwriting.
On relation of language to thought: G. F. Stout, Analytic Psychology,
ch. 10; Max MUller, Science of Thought.
On meaning and value: W. M. Urban, Valuation, chs. 2-5.
CHAPTER XIV
MENTAL SUCCESSION
The Stream of Consciousness. Thus far we have consid-
ered detached, isolated experiences and responses. But this
is only part of the story. In reality our states of mind are not
completely separated from one another. Mental life is not a
series of independent happenings. Each experience and each
act is affected by our past experiences and actions.
Human actions are rarely instantaneous. The response to
a given situation often involves a long series of actions, one
step leading to the next. If one step is cut out or if the order
of procedure is inverted, the action may be quite ineffective
and even absurd. You must load your gun before you press
the trigger, and thread your needle before you begin to sew.
For the most part behavior is a continuous process, not a series
of detached reflexes. Each step passes gradually into the next.
Our mental life, with its various experiences and actions,
may be likened to a stream which flows steadily onward,
moment by moment, day by day, year by year, bearing on
its bosom ships and cargoes of various sorts. We often speak
of the ' flow of thought ' and the ' flow of language.' It is not
so common to speak of the flow of perceptions or feelings, but
these and all other experiences flow along in much the same
way. James calls this general flow of experiences the stream
of consciousness. Our conscious life at any instant is a cross-
section of the stream. The present cannot be fully under-
stood except by reference to what has gone before. Under-
lying the thoughts and perceptions of conscious life is the
stream of nerve impulses which course through the brain, rous-
ing now one experience, now another, in endless succession.
The simile of the stream helps us to picture the ' flow '
CH. xiv] STREAM OF CONSCIOUSNESS 307
of life. In other respects it is imperfect. Our experiences
are not uniform like a stream of water. Perceptions are quite
different from thoughts; and these two types of experience
flow along in very different ways. The flow of perceptions is
controlled largely by the succession of stimuli that happen to
affect us, while the flow of thoughts, memories, and images is
determined almost wholly by conditions in the brain. There
are really two different currents in our mental life, or (better)
two separate strands which interweave to form the texture of
experience.
Speed of Thought; Reaction Time. How rapidly do our
experiences flow? Popular notions on this point are quite
vague. Fanciful stories are told of drowning men who live
over their entire lives in a few minutes. We hear of dreams
which involve a long succession of events lasting a year or
more, ending with the crashing of a real mirror which wakens
the sleeper the whole dream having presumably been
started by the crash itself. Such stories lead to wrong ideas
of the duration of our experiences. The terror of drowning
may arouse many memories which had lain dormant for
years, and may speed up the flow of thought considerably,
but there is a limit to the speeding-up process. In the mirror
dream the experiences probably came in the form of an
instantaneous picture; the background of the picture was an
illusory memory, in which the dreamer seemed to have lived
over the events successively. There is undoubtedly a slip
somewhere in all such stories either an exaggeration of the
number of experiences involved or a wrong interpretation of
the experience itself.
The rate of change in perceptions and thoughts is limited
by the rate of conduction of the nerve impulse. The highest
velocity of nerve impulse so far discovered by physiological
experiment is about 400 feet per second. The resistance at
the synapses causes delay, and this lengthens the time of
passage from neuron to neuron.
308 MENTAL SUCCESSION [CH. xiv
Having found this physiological limit, the next step is to
determine in how short a time a simple mental act can be
accomplished. This has been determined by experiments in
the laboratory. A stimulus is given a sudden flash of light
or a noise; as soon as the subject perceives it he presses a key.
By means of electrical connections the stimulus starts the
hands of a chronoscope [Fig. 79], and the pressure of the keys
stops them, so that the duration of the entire stimulus-
response process is accurately measured. This duration is
called reaction time. If the subject has been trained to react
to the stimulus as quickly as possible, the reaction time repre-
sents his utmost speed for this particular kind of perception.
Reaction time is divided into three periods: (1) Sensory
conduction from the receptor to the brain center. (In this
period is included the time required for the stimulus to excite
the receptor and sensory nerve.) (2) Central processes. In
simple reactions this period is devoted to the mental process
of perceiving; but in complicated experiments certain other
central processes, such as discrimination or association, take
place before the motor impulse starts. (3) Motor conduction
of the nerve impulse from the brain to the muscle, together
with the time needed for the muscular contraction to take
place.
Although the rate of nerve conduction is approximately
known, the duration of the two conduction periods is not
completely determined, because we do not know how much
time is required for the impulse to pass through the synapses
nor the length of the reception and muscular-contraction
periods. Visual reaction, for example, is found to be consid-
erably longer than auditory or tactile reaction, probably
because the eye takes longer to receive its stimulus than the
ear or the touch corpuscles. There is also found to be con-
siderable difference in the reaction times of the same person
according as his attention is fixed on the stimulus (sensory
reaction) or upon the movement (muscular reaction). While
FIG. 79. HIPP CHRONOSCOPE
Instrument used for measuring reaction time. Each dial is divided into 100 units. Upper
dial measures thousandths of a second (0.001 second = 1 sigma); lower dial measures
tenths of a second. Clock-work (behind the dials) is started and stopped by pulling the
cords A, A' at left; hands do not move till an electric current meshes a cogwheel (back of
upper dial) into the clock-work. The wires of the circuit are joined with the Hipp at bind-
ing posts B, B'. Circuit is made when the stimulus is given, and broken when the subject
reacts by pressing a key. Weight C furnishes motor power for clockwork; the speed is gov-
erned by vibrations of a small reed D, which vibrates over a cogwheel.
310 MENTAL SUCCESSION [CH. xrv
there is considerable variation between the reaction times of
different individuals, the figures given in Table XIII repre-
sent the average perceptual reactions of trained subjects.
The unit of measurement is the thousandth part of a second,
which is called a sigma (a).
TABLE XIII. REACTION TIME OF PERCEPTION
Stimulus Sensory Attention Muscular Attention
Light 290(7 180<r
Sound 225 120
Electric on skin 210 105
[From Titchener, Text-book, p. 432.]
If the observer is directed to perform some mental act in
addition to perception before he presses the key, the experi-
ment measures complex reaction time. The experimenter may
show in turn a number of different colors in chance order, and
require the subject to recognize the color before pressing the
key. Or the subject is required to press one key for blue,
another for red, and so on. This is discrimination reaction
time. In any complex reaction the conduction time to and
from the center is the same as in perception reaction, so that
the increased duration of the reaction represents the time
required for the additional mental process.
Titchener found in his own case that recognition of a color
required 280" longer than simple visual reaction. His recog-
nition time for a letter of the alphabet was 51 o- and for a short
word 45<r. These relations hold generally, though the abso-
lute times vary for different persons; it requires less time to
recognize a word of three letters than a single letter.
Experiments have been made on the time required to
associate one thought with another. The stimulus is a
printed or spoken word. When the observer sees or hears the
word it arouses a thought in his mind; he is directed to react
just as soon as this thought suggests another idea. The
experiment may be safeguarded by having the observer react
by speaking the word aloud instead of pressing a key; the
CH. xiv] REACTION TIME 311
voice strikes a sensitive membrane, whose vibrations press a
small hammer so that it makes the electric contact. In a
series of over 6000 auditory association reactions on 22 per-
sons Wreschner found that the average association reaction
time was about 2000<r (2 seconds).
The experimental investigation of reaction time has not
fully solved the problem of the rate at which our experiences
follow one another. Slight changes in perceptions may take
place much more rapidly than the rise of new perceptions;
thoughts may be modified in some of their details more
quickly than a brand-new association can be formed. But
just as light has a limiting rate of transmission, so we are
certain that thought and perception have their speed limit.
'Quick as lightning 7 does not mean 'instantaneously';
neither does ' quick as thought.'
The Stream of Perceptions. A large portion of our expe-
riences are the direct result of stimuli outside our body.
These stimuli are changing constantly, and give rise to a
stream of perceptions. Our mental life often consists for a long
time of a series of perceptions, uninterrupted by any notable
experiences of other sorts. We may see, hear, ' palp,' and
' heft ' the things about us without being affected by any
striking emotion, and without having any definite thoughts
or memory pictures.
The succession of these experiences depends primarily upon
conditions in the environment. Stimuli which affect our
eyes, ears, skin, and nostrils are due mainly to forces out-
side our own body, which are for the most part independent
of our will. We do not control the flow of perceptions in the
same way that we control our own movements, feelings, and
ideas.
I can readily arouse a thought of my brother; but I cannot
arouse a perception of him if he happens to be a hundred miles
away. You can arouse the memory of a rose and the feeling
of pleasure at its form and odor; but you cannot get a per-
312 MENTAL SUCCESSION [CH. xiv
ception of its form or a sensation of its odor if there is no rose
present to stimulate your eyes and nostrils.
Our ability to control our perceptions is mostly by way of
prevention not production. We can reduce a perception
to the margin of consciousness by attending to something
else; we may get rid of it entirely by closing the eyes or walk-
ing away. Often we modify a perception by adding images or
thoughts, so that a tree seen in the dusk becomes a bird or
camel. But we have little power to produce any desired per-
ception at will. The ultimate source of perception lies in the
world outside us.
The succession of perceptions is determined by the follow-
ing factors :
(1) External stimuli and their changes.
(2) The manner of stimulation. We see an object differ-
ently according as we look at it with the center of the eye or
the periphery.
(3) Retention of the effect of similar stimuli that occurred
in the past. Repetition and retention improve one's ability
to pick out certain stimuli and combine them into perceptual
states.
(4) Systemic and motor stimuli which occur at the time.
Excitement, pain, distaste, pleasure, may inhibit certain
perceptions and emphasize others. Motor stimuli and the
resulting motor activity enable us to get rid of certain ex-
ternal stimuli and substitute others.
Of these four factors all but the first are conditions within
our own body. Yet the external factor is the great determin-
ing condition of perception and outweighs in importance all
the others combined..
The Stream of Thought. The mental life of civilized man
often includes a long succession of memories, images, and
thoughts uninterrupted by perceptions. The starting-point
of such a series is always a perception or some other sensory
experience; but the train of ideas, once started, may proceed
for a long time without interference.
CH. xiv] STREAM OF THOUGHTS 313
In subhuman species prolonged trains of ideas apparently
do not occur. If an animal has a memory or any other image,
it either leads directly to motor expression or is quickly fol-
lowed by some new perceptual experience. A dog gives evi-
dence of remembering his master after prolonged absence,
but instead of this memory starting a train of reminiscences,
it leads at once to barking, frisking about, and vigorous wag-
ging of the tail. Even while the memory image lasts it may
be interrupted by a word or a gesture from his master, which
starts a new sensory experience. In lower animals memory
is even more fragmentary.
In man imagery, and more especially thought, tends to
become one of the most important phases of mental life. A
perception arouses a thought, this thought excites another
thought, this in turn a third, and so on. A long series of
thoughts may arise in quick succession, each independent of
external stimulation except at the very beginning. Such a
train of thoughts is called thinking.
For example, you hear a certain humming noise and think
of an airplane. This suggests the thought of the airplane
post, then you think of crossing the Atlantic, then of a great
Atlantic liner, of the amount of coal consumed in a steamer,
of mining coal, of a miner who became a clergyman, of revival
services, of gospel hymns, of a boy choir, of the Boy Scouts,
of one of your boyhood games, of a certain school teacher, and
so on through a long series of thoughts.
The succession of mental images and thoughts is com-
monly called association of ideas. It is the same process that
we examined under Recollection (ch. viii). Recalling a
memory is merely a special case of caljing up any image or
thought; in fact, when the memory we want does not come
immediately we usually have a long succession of other ideas.
The principles which were enumerated as ' laws of recol-
lection ' are fundamental laws of the association of ideas:
(1) Law of Similarity and Contiguity. The idea aroused by
314 MENTAL SUCCESSION [CH. xiv
association is partly similar to the one preceding it, and the
remainder consists of experiences that were formerly experi-
enced near it in time and place. (2) Law of Frequency,
Original Vividness, and Recency. As between different pos-
sible associations with a given idea, that one is most likely to
follow which has occurred most frequently, or which was orig-
inally most vivid, or which has occurred most recently.
These laws of association are not arbitrary ; they depend on
the activity of the nerve impulses in the brain. In passing
from center to center the current always follows the path that
offers least resistance. The resistance is diminished by the
retention of the effect of former impulses in various centers;
similarity, contiguity, frequent repetition, original strength
of impulse, and recency of excitation, are factors which
determine the relative degree of resistance of several possible
pathways; they determine which way thought will jump.
In addition to these principal factors which determine the
course of a train of thought, there are certain secondary
influences. Our general bodily condition often plays an
important part in determining the direction of our thinking.
If our digestive organs are working well, our thoughts are
likely to dwell on pleasant subjects and the things we expect
to accomplish. If we are dyspeptic we are prone to think of
difficulties and annoyances. So, with the same thought as a
starting-point, we may proceed along two entirely different
lines of thought according to the different systemic stimuli
that we are receiving. The reproductive organs affect our
thought trains in the same way. In adolescence thoughts
tend to be directed at times rather persistently toward sexual
matters; in later life this tendency may vanish of its accord.
The influence of stimuli from the respiratory and circulatory
organs on thinking is less marked than that of the other
internal systems.
Another secondary influence on the direction of thought is
our general view of life and the special interests that appeal
CH. xiv] STREAM OF THOUGHTS 315
to us. The trend of a person's life determines his attitudes
(ch. xv), and his attitudes determine very largely the direc-
tion of his thinking. One man's thoughts run to money,
another's to athletics and sporting subjects, and so on. We
are not likely to notice this in ourselves, but if we meet one
whose interests are quite different from our own we are often
amazed to see how persistently he turns the conversation
toward his own special interests and away from the channel
of our own thoughts. Fixed ideas are an exaggerated and
usually pathological form of this tendency. Certain insane
patients persist in thinking that they are followed by ene-
mies; their thoughts always hark back to this fixed delusion.
All these secondary influences which determine the direc-
tion of thought may be summed up under a single principle,
the Law of the Personal Equation: As between different
possible associations with a given idea, that one tends to
succeed it which carries most interest to the individual or is
most in keeping with his present systemic condition,
v Control of Thought. Thoughts are not the direct result
of external stimuli. The first thought in a train may be due
to something we see, hear, or read, but those that follow
depend chiefly on processes within the brain itself. To this
extent thinking is ' free ' ; our thoughts are not driven into us
by external forces, like our perceptions. We ourselves deter-
mine their course in accordance with the principles of associa-
tion.
We may direct our thinking along certain lines by taking
a definite attitude and holding a given problem or goal before
us. You wish to recall a certain name, and this desire atti-
tude may direct the course of your thinking for a long time.
You have the notion of a half-complete invention, and pro-
ceed to work out the details in thought. You are called on to
solve a mathematical problem or arrange a concert, and you
think over various possibilities till the best solution or pro-
gram appears in thought. In all such cases the direction and
316 MENTAL SUCCESSION [CH. xiv
to some extent the material of your thought are under your
own control.
Thinking may also be controlled indirectly by motor acts.
You tie a knot in your handkerchief, or before going to bed
you hide a stocking. The sight of the knot or the absence of
an important article of apparel suggests to you the particular
thought that induced this unusual action. The association is
more direct when you place in your hatband a letter to be
mailed. A written memorandum ' draw money,' ' see
Smith,' ' return umbrella ' is still more effective.
Sometimes a thought leaves a trace in the nerve structure
which arouses another thought long afterwards. A friend
asks you to dine at his house next Wednesday. The thought
makes a vivid impression, and is gone. But Wednesday
afternoon it somehow reappears you remember the en-
gagement. (Not always, unfortunately!) These retention
traces seem to be impressed on the lower centers and to be in
some way connected with our subconscious life. This is
indicated by some of the phenomena of sleep and the hyp-
notic state. You determine to awake to-morrow morning at
6 : 30. If you are practiced in the art, you actually do awake
at almost exactly that hour. The controlling medium here is
subconscious.
All these mental and behavior operations are means by
which an individual controls his own thinking. Thinking is
at once ' free ' and ' determined.' It is not compelled by
outside forces, but it follows definite paths determined by
the make-up of our nervous system and by the attitudes
built up through our entire past experience.
A train of thought once started continues indefinitely till
something occurs to check it. An intense external stimulus,
producing vivid sensations and perceptions, may put an end
to your thinking. You are aroused from thought by hearing
some one call you, or by some striking object appearing before
your eyes. If the central nerve impulses are discharged into a
CH. xiv] CONTROL OF THOUGHT 317
motor pathway, and you start to act, the train of thought is
broken off. The sudden thought that it is time to attend a
class sets you in motion, and ends your reverie.
Several different kinds of thought trains may be distin-
guished: (1) Casual thinking, which is subject only to the
general laws of association. This is the ordinary type, which
we have been discussing. (2) Dreaming, in which the now of
thought is modified by a special condition of the brain called
sleep. (3) Hypnotic thought processes, which are modified
by a special condition of the nervous system called hypnosis.
(4) Rational thinking, in which the succession is determined
by a special mental attitude and by the meaning of the
thoughts.
Dreams. Sleep is a special condition of the nervous sys-
tem. It is an essential part of the repair process of living
creatures. The period of sleep enables the organism to restore
the nervous energy used up by the activities of waking life.
In man the period covers about one-third of the entire day.
As a physiological condition, sleep is just as normal as waking
life, but the mental activities that occur during sleep, called
dreams, present many unusual features.
The distinctive fact in dream experiences is that the central
neurons are almost wholly cut off from their sensory and
motor connections. The synapses which join the sensory
paths with the brain and the brain with the motor paths
become highly resistant. Only intense impulses penetrate
to the higher centers, or impulses which play a prominent
part in our mental life.
During sleep we are not ordinarily affected by sounds,
lights, odors, or other external stimuli. A loud sound may
penetrate to the centers and arouse us; or a sound which pos-
sesses unusual personal interest, as when the child's fretting
wakens the mother. Organic stimuli are often very effective;
the unpleasant and terrifying dreams known as nightmares
are attributable to indigestion. Temperature stimuli suggest
318 MENTAL SUCCESSION [CH. xrv
dreams of a conflagration or of walking the streets unclad.
Tactile stimuli are rarely effective. 1
On the other side of the arc, motor discharge is checked,
so that an idea which in waking life would lead to speech,
locomotion, or some other coordinated activity either remains
without any motor expression, or at most produces a very
slight effect. Occasionally a strong motor impulse breaks
down the resistance, as when we turn over in bed or talk in
our sleep. Sleep-walking occurs when specially strong motor
impulses find effective expression without wakening the
sleeper. The very beginning of such movements serves to
waken most persons, but in certain individuals and under
certain conditions somnambulism proceeds in a coordinated
manner. The same is true of sleep-talking. Where the
motor impulse does not produce actual movement, slight
twitching movements of the feet, arms, fingers, and throat
often occur. These incipient movements are probably more
common than is generally supposed.
There is usually no indication to an outside observer that
the sleeper is dreaming, and the sleeper himself may recall
nothing on waking. This is not conclusive proof that the
higher brain centers are inactive. The connection between
sleeping thoughts and waking thoughts is often very slender;
we sometimes recall a dream immediately after waking only
to lose all recollection of it soon after. When any one tells us
that he never dreams, it means only that he is unable to
recall dreams. On the other hand, the fact that many dreams
are forgotten does not justify the sweeping conclusion that
the sleeper is always dreaming. It may be that sometimes
the entire cortex is inactive.
Dream life differs from waking life principally in having
a much narrower field. Because the cortical centers are
largely cut off from sensory impulses, our experiences consist
1 During sleep the autonomic processes proceed much as in waking life.
The breathing is more regular and may take on a new rhythm.
CH. xrv] DREAMS 310
chiefly of imagery and thoughts. This seems sufficient to
explain the fantastic character of dreams and the absurdities
they exhibit. Dream images may not be actually more
intense than the imagery of waking life; but since there are no
sensations with which to compare them, they stand out
vividly and seem to be actual perceptions.
The strangeness of our dream experiences is due to this
mistaking of our thoughts for perceptions. Any one of your
dream pictures might readily have come to you as a thought
in waking life, and it would not have seemed absurd. For
example, it is entirely natural for you to think of your friends
after their death. But you do not see your dead friends in
waking life, so that their lifelike appearance in dreams is often
startling after you awake. At the time it seems quite
natural, because your brain centers are cut off from one
another, so that you do not associate the thought of the man's
being dead with his appearing before you.
At times some incongruity may be noticed during the
dream itself, and may puzzle us. I was once surprised in a
dream to see a friend who had been dead for some years. At
once I recollected that the report of his death was a mistake
that it was really another friend who died. 1 This supposed
memory recollection was merely a new thought; in waking life
it would be called an hypothesis. We would suppose the
report of the man's death was a mistake.
The incongruities and absurdities in the succession of inci-
dents in dreams are to be explained in the same way. A
dream is really a train of thought and not a succession of per-
ceptions. 2 But our dreams seem at the time to be real per-
ceptions. After we awake many of the incidents strike us as
1 This sometimes happens in waking life. Some time ago the papers
falsely reported the death of C. R. W. Two weeks later I met him. Not
having heard the report denied I was far more astounded than in the dream
incident.
2 The train of thought described on page 313 might easily have occurred as
a dream; and we would have considered it a most fantastic dream.
320 MENTAL SUCCESSION [CH. xiv
absurd because real beings and things do not act in this
fashion. The motion pictures have succeeded in reproduc-
ing in visible form many striking effects which formerly were
obtained only in dreams and vivid imaginations. A study of
cinematograph effects will help us to appreciate better the
construction of dreams.
Since dreams are thoughts, and not voluntary acts, it is not
surprising that honorable persons sometimes dream of com-
mitting dishonorable actions, such as lying, stealing, or kill-
ing. Every one thinks of these acts, though in waking life we
usually think of them as performed by some one else. In
dreams, experiences take a more personal form. When you
dream of the act of stabbing, the muscle-sense memories are
more vivid than in waking life, and the brain conditions of
volition are reproduced without the motor activity; you pic-
ture yourself as performing the act. One need not be alarmed
at such dreams. They do not imply any hidden flaw in 'a
person's character. A thought is by no means always a wish.
Subconscious life plays a more important part in dreams
than in waking experiences. Just as ideas are more vivid
through the absence of ' real ' perceptions, so subconscious
experiences are apt to rise to the surface and become con-
scious during sleep, because there are fewer intense impulses
in the brain to inhibit them. Our general attitudes also
influence the direction of our dream experiences just as they
direct our trains of thought in waking life.
To sum up, dream life differs from waking life in the fol-
lowing respects: (1) the higher brain centers are cut off from
one another and from most sensory and motor paths; (2)
as a consequence, our experiences are fragmentary and inco-
herent, and thought is mistaken for real perception; (3) our
personal control is diminished, and our subconscious tenden-
cies are more prominent. With the exception of these differ-
ences it appears that dream experiences are formed in the
same way as waking thoughts, and that dreams (that is,
CH. xiv] DREAMS 321
trains of thought in sleep) follow the same laws as ordinary
trains of thought in waking life.
Hypnosis. Another special condition of the nervous sys-
tem is hypnosis. 1 In hypnosis the sensory and motor paths
are not cut off from the brain as in sleep, but certain pathways
become more resistant, while others are unusually open to
connection with the centers.
There are various ways in which a person may be hypno-
tized: by having him fix his gaze on a bright object, or talking
to him in a droning voice, or making him move his two hands
in a rhythmic, circular way. He will then gradually pass
into the hypnotic state and lose the power of coordinating his
thoughts and controlling his actions.
The hypnotized person is peculiarly susceptible to sugges-
tion. If told that he is in a lake he immediately begins to
make swimming movements. If the hypnotizer tells him
that a sheet of blank paper is a letter from a friend he starts to
read it. His actions are not inhibited as in sleep, but they
are controlled by the mind of another person. Generally the
hypnotic subject is governed by suggestions from the one who
induced the hypnotic state and he pays no attention to any-
one else. The process of hypnotizing focuses his attention
on one individual.
In normal life our personality, molded by past experiences,
inhibits to a great extent the effect of suggestion. In the
hypnotic state these inhibitions are lacking, and suggestions
received from the hypnotizer are all-powerful. The hyp-
notic subject does what he is told to do. The ordinary sense
of fitness is lacking and he will unhesitatingly perform acts
which ordinarily would be checked by the feeling of absurdity
or fear of ridicule. Suggestions are resisted only if they con-
flict with his deepest moral sense.
Hypnotic suggestion may induce anesthesia of one or more
1 This is popularly called hypnotism. Hypnotism means the 'theory of
hypnosis'; hypnosis is the physiological condition.
MENTAL SUCCESSION [CH. xiv
of the senses. The subject will not flinch when pricked by a
needle or touched with a hot iron, if the proper command is
given. At other times the hypnotic suggestion may bring
about hyperesthesia; the subject is able to distinguish one
blank sheet from another when told that they are photo-
graphs of different people. Hypnosis is a condition in which
the thought-life is raised to the focus; perceptions and other
experiences are subordinated to them. The stream of ex-
periences in hypnosis follows the laws of thinking rather
than the laws of perception; but the succession of thoughts is
constantly guided by verbal stimuli; it is not self-guiding, as
in ordinary thinking and in dreaming.
The peculiar behavior of a hypnotized subject is under-
stood if we compare him with a dreamer. In both sleep and
hypnosis our thoughts are especially vivid and are mistaken
for perceptions. In sleep the flow of thoughts is ordinarily
not disturbed by outside impressions nor accompanied by
motor activity; in hypnosis the succession of thoughts is
determined by verbal suggestions from another person and
results in motor activity appropriate to the thought, but not
in keeping with the real surroundings.
Summing up, (1) in hypnosis there is an abnormal condi-
tion of the brain centers; (2) the hypnotic subject receives
external stimuli, but only verbal suggestions have conscious
effect; (3) he is able to make real movements instead of hav-
ing merely ideas of movement and speech as in sleep; (4)
his senses may be sharpened or blunted by suggestions;
(5) his actions are more completely controlled by suggestion,
and the effects of this suggestion may last over into waking
life. For practical purposes we may consider hypnotic expe-
rience as a dream-like mental condition, induced and con-
trolled by some one else, instead of by the dreamer's own
mental processes.
Reasoning. Rational thinking, or reasoning, is another
special kind of thinking. Dreams and hypnosis are lower and
CH. xrvl REASONING 323
less organized than casual thinking, while reasoning is a
higher, more adaptive variety. The stream of rational
thoughts is made up of concepts and judgments ; the succes-
sion is determined by their meaning instead of by mere simi-
larity and contiguity, as in casual thinking.
In our waking life the stimuli from the external world
affect us in haphazard order, so that the succession of per-
ceptions is often quite unsystematic. This haphazard con-
nection of unrelated perceptions tends to be reproduced in
our ordinary trains of thought, so that we often associate
objects or events which are not actually connected in nature.
You may readily think of gold being discovered in your own
back yard, and go on to picture how you would mine it and
what you would do with the proceeds. This train of thought
is casual thinking. Very different were the thoughts of
Captain Sutter in 1848 when gold was actually found at his
mill. His thinking was about real gold and the real conse-
quences this discovery would have on his life.
Reasoning is a special type of thinking in which the associa-
tions correspond to processes in nature. If the original thought
in the series corresponds to real things or events or facts,
then the whole train will represent something real. If we
think of fourteen dollars added to a pile of twenty-seven dol-
lars we conclude that there will be forty-one dollars in the pile.
This is rational thinking, because whenever we actually carry
it out the result tallies with our thought. Of course we may
not have the fourteen dollars to begin with; and then the
result does not happen at all. But the thinking is rational
just the same: if we lack the dollars we can try it with pen-
nies or pebbles or eggs or pages in a book or anything else.
The conclusions which we reach through reasoning are called
inferences. An inference is a new thought, based on associated
meanings or values, which we believe will tally with reality.
How has man gained the ability to reason to think
rationally? Reasoning is not a special mental power. It is
324 MENTAL SUCCESSION [CH. xiv
an outgrowth of ordinary thinking, due to two circumstances :
(1) The uniformity of nature. We learn that 14+27 = 41
because we always obtain that result with dollars and eggs
and everything else. Nature is built in this way. Every-
where and in every phase we know of, the workings of nature
are found to be the same. (2) The complex organization of
the human brain. Our language centers enable us to devise
arbitrary words, " fourteen," " twenty-seven," etc., which
are symbols instead of pictures. By means of these symbols
we can do abstract thinking we can connect fourteen and
twenty-seven in thought, even without concrete things to
work with. When we find that the abstract relation actually
holds for dollars and eggs we tend to apply it to other things;
but it is the language centers that enable us to get the ab-
stract ideas in the first place.
There are many other varieties of reasoning besides arith-
metic. Logic is one of them. Man has discovered that if A is
greater than B, and B is greater than C, then A is greater
than C. If John is older than Henry, and Henry is older
than William, then John is older than William. These and
other logical relations are used in reasoning.
Rational thinking is applied also to special situations.
When you think of Niagara casually, your flow of thought
may follow all sorts of directions. You may think of your
chum's trip to Niagara and Buffalo; that you would like to
hunt buffalo in the plains; that a carpenter's plane would
smooth a man's face quicker than a safety razor; and this
may remind you of meeting a fellow named Gillette. None
of these steps of thought is based on meaning; they depend
merely on chance similarity of sound or chance contiguity.
They lead you nowhere. But if you think of actually going
to Niagara, your train of thought tends to become rational:
you think of how to reach the place, of getting a time-table,
drawing money, packing, getting to the station, etc. The
initial thought in this case is not the word Niagara, but the
CH. xiv] REASONING 325
concept Niagara, or a judgment about going to Niagara. The
science of logic points out the proper use of reasoning. A
course in practical logic is invaluable in training us to reason
correctly.
Rational thinking sometimes fails. My adding machine
gets correct results in summing up a column of figures oftener
than I do. People have been known to miss their train even
when the trip was carefully planned out beforehand. These
failures are due to a variety of causes. The most common
cause is a faulty connection in the brain. The rational asso-
ciation 4+7 = 11 becomes very strong through repeated ex-
perience, but now and then the casual association 4+7 = 12
may creep in when we add up a column. This is called a
JPallacy. Slips in reasoning are common in every one's life,
but a careful thinker is likely to discover the error by noting
some inconsistency in the results.
Sometimes the failure is due to our expecting too great
uniformity in nature. Encke's comet did not return quite
as soon as the calculations predicted : something not foreseen
by astronomers delayed it on the way. Your trip to the
Falls may be frustrated by a new time-table or a railroad ac-
cident. In such cases there is no fallacy in your inference;
there is merely ignorance of some important factor in the
situation.
A superstition is imagining some relation in nature which
does not really exist. The ancients reasoned that a certain
plant must be a remedy for heart trouble, because its leaves
are heart-shaped. If you pronounce some mystical word, the
winds or the mountains will obey your commands, because
human beings obey you when you speak with authority.
Thirteen at the table must mean death to one of the com-
pany, because there were thirteen at the Last Supper. Once
these fanciful connections are formed in our minds they are
hard to eradicate, especially if testing their falsity might
mean death to the experimenter. Yet the only way to dis-
326 MENTAL SUCCESSION [CH. xiv
tinguish between a correct inference and a superstition is for
some one to try it out and see what happens.
There is another, more insidious misuse of reasoning.
Often we arrive at a decision by some train of casual thinking
and then try to make our decision look rational by construct-
ing a plausible explanation. You advocate opening a new
street, or laying a sidewalk, or putting in more lights, on the
ground of great public need; but you originally thought of
the improvement only as a benefit to yourself personally.
You are perfectly sure it is the scenery that decides you to
take that stroll not the girl you are likely to meet on the
way. The salesman knows a hundred reasons why his goods
are better than any others; and he honestly believes them.
This mental process of constructing artificial reasons is called
rationalization. If you analyze your real motives you will be
surprised to find how frequently the rationalizing process
occurs, and how strong is the temptation to use it. The
teacher of practical ethics might well begin his instruction
with the injunction: " Be honest with yourself."
Reasoning is the most important step in the growth of
adaptive behavior. It enables us to anticipate events and
prepare for them beforehand. Rational thinking is most
effective when it is supplemented by casual thinking. We
picture imaginary situations and consider how we would act
or how nature would act. When we work with scientific
hypotheses we combine the two types of thinking.
The General Stream of Experiences. Our conscious life
is a vast stream comprising experiences of many sorts. With
the exception of perceptions and thoughts we rarely have a
long uninterrupted succession of any one kind of experience.
A feeling usually brings about action, which transforms the
. feeling into an emotion. An emotion is apt to exhaust itself
i quickly and pass over into thought or volition or speech.
Volition results in movements which usually change our situ-
ation and bring about new perceptions. In the general vista
CH. xiv] STREAM OF EXPERIENCES 327
of experience there may be long unbroken stretches of per-
ceptions and long unbroken stretches of thought; between
these, small patches of other experiences are interspersed.
In almost every human being, whether civilized or savage,
perceptions are most frequent and form the core of mental
life. Among educated adults of civilized communities
thought and imagery occupy a good second place, while
among primitive peoples the emotional life is more impor-
tant than thought and imagery. Motor experiences voli-
tion and language generally rank ahead of the emotions
among civilized races.
Our mental life at any instant may include more than one
experience: a perception, a thought, and a volition may all be
present together, one of them being vivid, the rest marginal
or subconscious. Their relations change; the perception
may fade into the background, and the thought which was
indistinct may advance to the foreground. When you are
out walking with a friend your attention oscillates between
the perception of things about you and the thoughts and
utterances of your conversation. In reality both percep-
tion and thought are present all the time; the change is in
the focus of attention in the relative vividness of the two.
What kind of experience will occupy the focus of attention
at any given moment is determined by the relative strength of
the various nerve impulses occurring in the brain at that
moment. This depends partly on the intensity of stimula-
tion. A loud noise, a flash of light, a sharp blow, or a muscu-
lar strain may force a perception upon us and crowd all other
experiences out of the focus. But unless the new stimulus is
very intense it finds a rival in the nerve impulses that are
already active in the brain. The new sensory nerve impulse
may be wholly or partly inhibited by the existing central
impulses, or it may combine with them. The direction of our
interest and attention is important in determining what the
effect will be. If you are interested in following a trail in the
328 MENTAL SUCCESSION [CH. xiv
woods, the most trivial signs will strike your attention
a blazed tree, a broken twig, or a footprint; for the time being,
the perceptive life dominates. A geometrician like Archi-
medes, on the other hand, may be so absorbed in reasoning
out a problem that no external stimulus will move him.
An emotional man flies into a violent rage or into wild exul-
tation over some event that arouses merely perception or
thought in another.
In short, the succession of our experiences in the general
stream of mental life depends both on stimulation and on the
make-up, training, and present condition of our nervous sys-
tem. It follows in part the laws of the stream of perceptions,
and in part the laws of the stream of thought. Our present,
persistent personality, which has been built up out of all our
past experiences, is an all-important factor in determining
the course of the stream.
The Stream of Actions. Mental life includes not merely
our experiences but our actions. These also form a series.
Every act involving muscular contraction stimulates the
muscle sense and may lead to another act or to a continuation
of the same activity. We are seldom entirely quiescent.
When we are not actually contracting some muscles, we are
usually maintaining their tension. Try at the present mo-
ment to relax your facial muscles, or your legs, or your arms
completely. You will find that there is some muscular ten-
sion in these members, though you may have supposed they
were quite relaxed.
Even simple acts, like catching a ball, involve a series of
coordinated movements lasting an appreciable time. And
when the act is completed it generally brings about a new
situation which demands another response. When the
fielder has caught the ball, he has to throw it; or if his play
ends the innings he is no longer wanted in the field and is
expected to run in. When the game is over he has to dress,
go home and prepare for dinner, or study, or see a friend.
CH. xiv] STREAM OF ACTIONS 329
Rarely, except during sleep, is the response life resting.
Waking life is a flow of actions a continuous succession of
responses, one after the other, each determined by our suc-
cessive experiences.
Summary. The experiences and responses which have
been examined in the foregoing chapters are not detached
events. They form a continuous stream or succession.
The flow of experiences depends partly on what effects us
from outside, and partly on our inherited and acquired men-
tal conditions. In the case of perceptions, the external
stimuli are largely responsible for the course of experience;
in thought, the succession is determined by the mental prin-
ciples of association.
Besides the ordinary or casual trains of thought, thinking
has two somewhat abnormal varieties called dreaming and
hypnotic experiences, which occur in sleep and hypnosis,
respectively.
A higher form of thinking occurs when the association is
based on the meanings and values of our thoughts. This is
called reasoning. The materials used in reasoning are con-
cepts and judgments; the inferences which we draw from
them tend to correspond to real events or general truths of
nature.
Our receptive life is a succession of perceptions, thoughts,
reasoning, dreams, emotions, volitions, and other experiences,
which come and go, wax and wane, continually. Our active
life is a succession of responses.
PRACTICAL EXERCISES:
69. Test a person's association time with a stop-watch. Choose some
noun or verb and say it distinctly, at the same time starting the watch.
Instruct the subject to call out the 6rst word which he associates with
your stimulus word, then the 6rst word associated with this second
word, and so on till he has made (and uttered) 10 associations. Stop
the watch and note the time. Repeat several times and find his av-
erage association time for a single association.
70. Sit with pencil and paper and note the first word you see in a book
opened at random. Write down the first idea which it suggests, then
330 MENTAL SUCCESSION [CH. xiv
the first idea suggested by this latter, and so on for a series of 15 or 20
successive associations. Examine each association and determine
which of the laws of association are responsible for its formation.
71. Chain reaction. Let a group of persons, including the experimenter,
join hands in a circle. The experimenter holds a stop-watch. With-
out warning he presses the next person's hand, starting the stop-watch
with the same movement. The instant the second person feels the
pressure he presses the hand of the third; and so on, around the
circle. When the last person presses the experimenter's hand, the
experimenter stops the watch. The average reaction is found by
dividing the total time by the number of persons in the circle, since
each has reacted once.
72. Analyze the succession of experiences in one of your dreams. Report
what laws of association operate; explain if possible the incongruities.
73. Attend carefully to a conversation between two persons. Note which
associations are 'rational' and which are 'casual.'
74. Examine the succession of your experiences during the past 10 minutes
and study the relation between perceptions and thoughts in the series.
REFERENCES:
On association and reaction time: H. C. Warren, History of the Association
Psychology, ch. 8 ; C. G. Jung, Studies in Word-Association (trans.).
On dreams: M. de Manacelne, Sleep (trans.); S. Freud, Interpretation of
Dreams (trans.).
On hypnosis and suggestion: A. Moll, Hypnotism (trans.).
On reasoning: W. James, Principles of Psychology, ch. 22; W. B. Pills-
bury, Psychology of Reasoning.
CHAPTER XV
HUMAN CHARACTER
Permanent Mental Conditions. Experiences leave traces
in the structure of the nervous system. These retention
traces are revived in the form of memories or imaginations,
and they tinge our perceptions with a ' sense of familiarity.'
Besides this, retention has another and far more important
effect on mental life. When the same sort of experience is
repeated over and over again, the trace may deepen into a
more or less permanent set of the nerve substance. These
enduring traces affect our way of receiving stimuli, and lead
to stereotyped behavior. The pathfinder watches for signs
of the trail in the forest; the experienced football player finds
the gaps in the opposing line; the pessimist always sees the
dark side of things. Each one, by repetition of the same sort
of experience, has acquired a mental attitude toward certain
features of the environment. As time goes on, these atti-
tudes tend to become more stereotyped and to cover a wider
territory. Each trade has its own vocabulary and code.
One can often guess rather accurately a man's occupation by
the sort of words and phrases he applies to ordinary situa-
tions. The sailor tells you about the house on the starboard
side of the road; the chauffeur, acting as butler, parks the
dishes on the serving table.
A great quantity of attitudes are built up out of material
furnished by the external senses. These fixed ways of per-
ceiving and thinking are called cognitive attitudes. The sum-
total of our cognitive attitudes make up our intellectual char-
acter, or intellect. In the same way all the attitudes based on
a person's systemic life combine to form his affective char-
acter, or temperament; his motor attitudes, taken together,
332 HUMAN CHARACTER [CH. xv
make up his motor character or skill; a man's social attitudes
determine his moral character or morality. Character is a more
permanent and fundamental condition than the attitude.
It is made up of a vast number of attitudes.
The several phases of an individual's character are not
independent. They interact upon one another. Your
temperament may be modified by your moral character, or
by your intellect. Your mental nature is the sum-total of
all the permanent mental conditions that have developed
within you up to the present. This all-embracing result of
mental organization is called personality. Personality in-
cludes our innate tendencies, our attitudes, and our char-
acter.
Attitudes, character, and personality are not particular
experiences, but permanent mental conditions which underlie
experiences. Attitudes change very gradually. They are
molded slowly; once formed they alter only as the trend of
experience takes another direction. The city-bred man takes
a citified attitude toward the world; it is only after long
experience with country life that he can change this attitude
and see the world with the countryman's eye. The country-
man is bewildered and helpless on his first visit to the city.
Character alters far more slowly than attitudes. Person-
ality undergoes a still more gradual development and trans-
formation. The growth of a man's personality covers the
entire period of his lifetime.
ATTITUDE
Nature and Classes of Attitudes. A mental attitude is
a permanent set of our mental and nervous system which
modifies the effect of stimuli and determines how we shall
respond. Your chum lands a fine job. How do you take the
news? Are you ' tickled "to death,' or do you envy him the
good luck which has not come to you? The news is the same
in either case; your attitude and your behavior are different.
CH. xv] CLASSES OF ATTITUDES 333
Because attitudes are not particular experiences we cannot
examine them like perceptions and emotions. They may be
studied through the motor expressions which they bring
about. An alert attitude, a sullen attitude, a credulous atti-
tude, almost inevitably lead to different kinds of behavior.
The popular meaning of the word attitude emphasizes this.
It means a ' motor posture.' In psychology attitude means
this and more; it includes the mental condition which governs
the motor posture.
Every attitude is the product of repeated experiences. If
you live in a certain environment you are likely to develop
certain attitudes which belong to that environment. The
street urchin acquires a whole raft of attitudes from his sur-
roundings which the farmer's lad could never develop. City
life develops alertness; country life promotes observation
of nature. Our attitudes are sieves through which certain
experiences are strained out and others are concentrated.
Attitudes begin to develop early in life. Fear of the dark
or of thunder can usually be traced to some experience in
childhood. It may take years to eradicate certain impres-
sions made by the tales of an ignorant nurse. You were told
of the man who was tossed so high that he stayed up in the
air, floating about forever; the notion sticks by you long after
you are familiar with the principle of gravitation.
Attitudes are classed according to the sort of experience
that develops them. The attitude which grows up in connec-
tion with perceptions and ideas is called interest. Our feeling
experiences develop a type of attitude called desire, and our
simple motor experiences develop the attitude of attention. 1
These three primary attitudes dominate our mental life and
exert a powerful influence on every particular experience of
the corresponding type.
1 Notice the two different uses of the word attention; (1) it denotes the
mental process of focusing an impression and making it more vivid (ch. vi) ;
(2) it also means the motor type of attitude.
334 ATTITUDE [CH. xv
In popular language we say that feelings cause desire, that
the things which we perceive arouse interest. The truth is
that the desire attitude and the interest attitude are the
product of a life-time; they are our way of receiving incoming
stimuli. Interest is not something in the mind which is
aroused by what we see; it is a mental bias or set which causes
certain perceptions or ideas to be especially vivid and per-
sistent. Attention is not really something that we turn
toward an experience, but it is a mental tendency to adjust
our muscles this way or that according to the situation.
The attitudes that grow out of emotion, thought, and other
secondary experiences develop differently from interest,
desire, and attention. Instead of becoming uniform they
take on many different forms. The emotional attitudes are
especially rich in their shading. It is not difficult to dis-
tinguish between a friendly, an affable, a gracious, and a
devoted attitude; if you train yourself to study human nature
you will be able to distinguish between the domineering,
pompous, arrogant, overbearing, lordly, condescending, and
superior attitudes which men in authority almost inevitably
assume. Language attitudes are few in number and are not
especially significant. Attitudes of thought and moral atti-
tudes are more numerous. All these secondary attitudes give
diversity to human character. [Table XIV.]
TABLE XIV. HUMAN ATTITUDES
Attitude Mental Basis
Primary:
Interest Perception, Ideation
Desire Feeling
Attention Conation
Secondary:
Dispositions Emotion, Sentiment
Appreciation Thought
Conscience Social situation
Proclivities Volition
Language attitudes Language
Ideal attitudes Ideals
CH. xv] INTEREST, DESIRE, ATTENTION 9S5
Interest, Desire, and Attention. The three primary at-
titudes interest, desire, and attention generally work
together; their influence is observed in almost every experi-
ence. Suppose you are watching a baseball game. The
chances are that you are there on account of your interest in
the game. As you watch the significant plays you look at the
actions of the players with interest with a very different
attitude from your cursory perception of the foul-line or the
glove accidentally dropped on the turf. If you are interested
in one of the teams, you have a desire that this team shall win.
At critical points in the game this desire becomes strong and
causes violent heart-beating, deep breathing, and perhaps a
feeling of ' goneness ' in the pit of your stomach. You attend
to each play through slight motor reactions. You knit your
brows, clench your fists, fix your eyes; all these are attention
attitudes.
These three attitudes are so closely connected together that
it is not easy to distinguish them. In popular language they
are often confused. We speak of attention when we really
mean interest. This confusion may be avoided if we practice
careful observation of our own experiences. Attention is our
motor attitude, interest is our attitude toward the perception
or idea, making it more vivid and prominent.
Attention shows itself in muscular adjustment or tension,
which enables us to receive impressions better. When you
follow a moving object with the eye, the eye movement is
the expression of your attention attitude. It is not the
significant response to the stimulus, but it helps you to per-
ceive the object better, and in this way you are able to
respond more suitably when the time comes. Your interest
in the moving object is the attitude that makes this object
' stand out prominent in consciousness.' Moving objects,
flashing signs, loud noises, and other intense stimuli are likely
to arouse attention, even though they lie outside our usual
line of interest. This is called involuntary attention and it
336 ATTITUDE [CH. xv
usually carries with it involuntary interest. A prosy speaker
pounds on the desk and makes his hearers sit up and take
notice; so far as his subject-matter goes they would prefer to
relax and enjoy a nap.
In general, a person's interest follows certain definite lines;
it brings out the things he is most accustomed to observe and
the ideas he is most accustomed to think. In reading the
morning paper one man spends most time on the stock quo-
tations, another on the sporting page, a third man on mur-
ders and accidents, a fourth on the foreign news and editorials.
The line of your general interest makes some particular part
of the paper loom large in your mind and fixes your attention.
Desire differs from interest and attention in having two
opposite forms, corresponding to the two feelings of appetite
and aversion. Our attitude toward pleasant experiences is
called satisfaction. If we are experiencing something un-
pleasant and imagine some pleasant alternative, our attitude
is dissatisfaction and something more: it carries with it a
picture of removing the unpleasantness or transforming it
into pleasantness. This attitude is called want, or need.
Satisfaction is less distinctive than want. In satisfactory
situations the pleasantness of the experience itself dominates,
and the attitude usually plays an unimportant part. But in
unpleasant situations the attitude of ' want ' tends to share
the focus with the feeling of unpleasantness.
In discussing memory we found that definite systemic
memories and systemic ideas rarely occur. Instead of
remembering this feeling or that, we generally have a want,
which is an attitude due to many past feelings. You want a
motor car because of imagined pleasure. You want break-
fast not merely on account of present hunger, but because
you recall the satisfaction of eating breakfast on other occa-
sions. The desire for honors, wealth, praise, success, rests on
similar grounds. Want leads to motor activity which tends
to remove the unpleasantness or to bring about the desired
CH. xv] INTEREST, DESIRE, ATTENTION 337
pleasantness. Our actions do not always succeed in accom-
plishing this. But it is characteristic of the want attitude
that it spurs us to action. As our mental adjustment be-
comes perfected, we become better able to do the right thing,
which in this case is to f ulfill the desire. When this is accom-
plished the want gives way to satisfaction.
Interest, desire, and attention enable us to guide and con-
trol the course of our experiences and actions. In this
respect they belong among the motives of human life.
Emotional Attitudes. No phase of human life is more
worthy of study than our emotional attitudes, or dispositions.
To one who has learned to interpret them, they furnish one
of the very best indications of a man's personality. In civi-
lized society, emotional expression is usually repressed; only
critical situations call forth unbridled displays of emotion.
But the emotional attitude is rarely washed out completely.
The emotion of joy simmers down into a cheerful disposition;
repressed emotions of anger lead to a hostile disposition. In
talking with a person you can usually tell whether he is
annoyed or pleased, whether he is well-disposed toward you
or defers to you or considers himself a bit above you, by
something in his manner or tone, if not by his words and
actions. You know at once if a stranger is distrustful or
ready to accept you. You can often tell that a certain man
is worried or overburdened before he says a word.
Our most casual acts and words may be thoroughly satu-
rated with concentrated emotion. " They left me out."
" In my humble opinion ." " Won't you listen to me?"
Who cannot guess the emotional background of these phrases !
The poker player trains himself to suppress or disguise even
the simplest manifestations of feeling, and the business man
endeavors to obliterate them with more or less success.
Often it becomes a contest between concealment and detec-
tion not unlike the struggle for supremacy between defen-
sive armor and penetrative shells. If you cannot get rid of
338 ATTITUDE [CH. xv
your own emotional display, you can at least learn to detect
the slight twitchings of certain muscles and inflections of the
voice in other persons, which will reveal to you their emo-
tional dispositions.
Popular psychology distinguishes between a disposition,
which is a more or less permanent attitude, and a mood, which
is liable to frequent fluctuation. The distinction seems valid,
but it is of social rather than psychological importance.
Our emotional attitudes become established by slow degrees,
and the border line between a passing mood and a permanent
disposition is indefinite.
Sentimental attitudes are closely related to emotional atti-
tudes; this probably accounts for the popular confusion
between emotions and sentiments. Doubt gives rise to a
perplexed attitude; strong belief mingled with strong dis-
belief produces a biased or prejudiced disposition. Certain
dispositions are derived directly from instinctive tendencies,
with no emotional tinge whatever; as for instance the miserly
and orderly dispositions.
Nearly every class of emotion develops a corresponding
attitude or disposition. 1 In Table XV only the most notice-
able dispositions are given; it would be hopeless to include
the numerous finer shades. The great wealth of emotional
attitudes is in striking contrast with the one single form of
the interest attitude.
Even our judgments of fact are usually tinged with emo-
tional bias. Read any account of the American Civil War
written in the '60's or '70's or even the '80's. Notice the
adjectives applied to Lee and Davis by Northern historians,
or to Lincoln, Grant, and Sherman if the writer is a South-
erner. It fairly startles us to find our own countrymen mani-
festing these emotional attitudes in writing plain history.
The school histories of an earlier generation took a similar
emotional attitude toward the ' Tories ' and ' red-coats '
1 Compare Table XV with Table VIII (p. 215).
CH. XV j
EMOTIONAL DISPOSITIONS
339
TABLE XV. HUMAN DISPOSITIONS
1. Expressive
Attitude Emotion
Cheerful
Despondent
Dazed
Frivolous
Zealous
Erratic
Joy
Grief
Shock
Mirth
Ecstasy
Restiveness
Exuberance
Wonder
2. Reproductive
Attitude Emotion
Affectionate
Lascivious
Jealous
Motherly
Love
Lust
Jealousy
Tenderness
4. Aggressive
Attitude Emotion
Romantic
Devout
3. Defensive
Attitude Emotion
Cowardly Fear
Courageous
Aversion Disgust
Cautious Timidity
Reserved Shame
Servile Awe
Attitude Emotion
Devoted Affection
Friendly Cordiality
Compassionate Pity
Attachment ? f Gratitude
Loyal > | Admiration
Antagonistic Detestation
Sullen Revenge
Distrustful Suspicion
Supercilious Scorn
in the American Revolution, and those of the next generation
will emotionalize toward the several nations concerned in the
World War. The killing of the Austrian archduke has been
described both as a dastardly assassination and as a sublime
act of patriotism. The judges who sentenced King Charles
are still called ' regicides ' by sturdy British royalists a
suggestion of the word homicide, with its moral stigma.
Where the narrative itself is unimpeachable the choice of
adjectives will frequently betray to an acute observer the
writer's emotional bias.
Most of our dispositions, like our emotions, are imper-
Hostile
Anger
Vindictive
Hatred
Malicious
Envy
Ambitious
Pride
Arrogant
"
Bold
Exultation
6. Instinctive and Sentimental
Attitude
Basis
Miserly
Acquiring instinct
(Avaricious)
Orderly
Cleanliness
Nomadic
Wandering instinct
Credulous
Belief
Skeptical
Disbelief
Perplexed
Doubt
Biased
Belief and Disbelief
340 ATTITUDE [CH. xv
fectly adjusted to the conditions of civilized life. If we test
our attitudes (or better still the attitudes of others) by social
experience, we find that the emotional element generally
hampers the intercourse of man with man. The servile dis-
position is as disconcerting as the arrogant. There are some
exceptions. Loyalty, compassion, and the like are disposi-
tions which promote cooperation among men and assist the
socializing trend of human development. From the peda-
gogic standpoint the early training of emotions and dispo-
sitions seems even more important than the cultivation of
motor habits.
Appreciation and Conscience. Of the remaining attitudes
the most important are those which develop out of thought
experiences and social situations. The principal attitudes in
these two spheres of life are shown in Table XVI, together
with certain prominent attitudes of other sorts.
A special group of attitudes develop in connection with our
casual, ordinary thinking. Some persons constantly revert
to the past; they live in retrospection. Others reach out
toward the future; they tend to take the anticipatory attitude.
The highly imaginative mind assumes an imaginative atti-
tude; or this tendency may result in desultory thinking.
The attitudes which grow out of rational thinking may be
grouped together under the head of appreciation. One of the
most important of these is the problem attitude. 1 This
means that when we are given a problem or a question to
solve we tend to keep this problem before us as the basis of
our thinking. A succession of thoughts follow, but they all
relate to this particular problem. The attitude is not the
particular problem, but the tendency to keep a definite prob-
lem before us and direct our thoughts with reference to it.
In the case of Langley or the Wright brothers, the problem
thought was how to devise a flying-machine; the problem
1 Also called task or question attitude; the German equivalent Aufgabe
is frequently used in English books.
CH. xv] APPRECIATION, CONSCIENCE 341
TABLE XVI. HIGHER HUMAN ATTITUDES
1. Thought Attitudes
Attitude Basis
(a) General:
Retrospective Memory coefficient vivid
Anticipatory Purpose (volition marginal)
Desultory, Imaginative Associative thought
Naive
(b) Rational Appreciation:
Interrogative (Problem attitude) Doubt (feeling marginal)
Impartial, Dogmatic Belief ( " " )
Interpretive Meaning
Evaluative Value
Esthetic appreciation Esthetic sentiment (feeling marginal)
Logical appreciation Rational thought
Analytic
Synthetic, Constructive
Critical
2. Social and Moral Attitudes 3. Other Secondary Attitudes
(Conscience)
Conciliatory, Cooperative (a) Volitional Attitudes (Proclivities):
Contrary, Competitive Persevering, Obstinate
Inculpatory, Condemning Vacillating
Laudatory, Approving
Judicial (b) Language Attitudes:
Receptive
Self-centered, Self-satisfied Expressive
Altruistic Voluble
Penitent Reticent
Suppliant
Forgiving (c) Ideal Attitudes:
Prudish Idealistic
Irresponsible Practical
Superstitious (fetish and tabu) Sensual
Duty-bound (moral obligation) Scientific
Artistic
attitude enabled them to maintain this central thought per-
sistently year after year, or to return to it repeatedly, so that
their thinking was ever on the subject of human flight.
The interpretive and evaluative attitudes permeate our
perceptual life as well as our thoughts. We become trained
to observe differences in kind and quantitative differences
among the objects that we perceive. An interpretive atti-
342 ATTITUDE [CH. xv
tude toward thought is cultivated by modern education.
Writers learn to appreciate subtle distinctions in the mean-
ing of words. Even the average reader acquires an attitude
toward individual words. James speaks of the feeling that
attaches to such minor words as and, if, but, and by. These
are really instances of the appreciative attitude, which leads
us to interpret or evaluate the relations of words in a sentence
with as much keenness as we interpret scientific laws.
Esthetic appreciation is the attitude which approves a
musical composition or a painting as artistically correct, or
condemns it on account of faulty technique. Logical appreci-
ation is our thirst for logical accuracy and correct reasoning,
whether we agree with the premises or not.
In our relations to other men and to society at large a
number of important social attitudes have arisen. A satis-
factory classification of these is difficult, because they shade
from emotional or volitional experiences into the sphere of
conduct by gradual degrees. Thus the fault-finding attitude
contains a large element of emotion, but is tinged with a slight
sense of obligation toward society; the inculpatory attitude
of a public prosecutor, on the other hand, has scarcely any
emotional tinge. Midway between these is the accusatory
attitude so frequently noticed in modern political and com-
munity life.
The term conscience is commonly applied to moral and
social attitudes. It generally carries an emotional tinge;
and this is historically justified, because the emotions have
been a powerful factor in developing our social ideals and
conduct. But the notion of conscience may be extended to
such unemotional phenomena as the judicial attitude and the
sense of moral obligation (the duty-bound attitude).
The two attitudes of contrariness and condemnation illus-
trate the tendency of social and moral attitudes to become
fixed and generalized. The contrary-minded man raises
objections to anything his friends suggest. If you propose a
CH. xv] APPRECIATION, CONSCIENCE 343
walk he wants to stay at home. If you order coffee, he orders
tea. If you suggest going to one theater he prefers another.
Any statement you make he is ready to challenge. The
fault-finder takes a somewhat similar attitude in the moral
sphere. He is forever picking flaws in the actions of others
or in the social order of the community. " Why did n't
you ," and, " Will you never learn ," and, " Any idiot
would have known better," are typical of the condemning
attitude. This same attitude revels in denunciation of the
flaws in our social organization. When the fault-finder sees
a break in the pavement the road commission is blamed. If
he sees newspapers scattered about the public parks he
berates our lack of social breeding.
Social and moral attitudes evolve in much the same way in
all races, but the situations which evoke them vary greatly in
different communities and stages of civilization. To put it
the other way round, the same act or the same objective situ-
ation may yield very different attitudes in various races and
culture-stages. It depends upon the traditions and cus-
toms of the people whether the attitude of obligation is
assumed in a given situation or not.
For example, in many communities the child is regarded as
the slave of his parents, who do not recognize any obligation
toward then- offspring except to feed and clothe them. In
other communities there is recognized an obligation on the
part of the parents to educate then* children and fit them for
their life-work.
Among the ancient Romans it was customary to expose
deformed and weak children and let them die. A similar
custom prevails to-day among the Eskimos. In other socie-
ties, such as our own, these weaklings are especially cared for
and protected.
The prudish attitude illustrates even more strikingly how
social attitudes depend on custom. In certain countries the
sight of a woman's unveiled face shocks the moral sense.
344 ATTITUDE [CH. xv
Elsewhere the same shock is caused by a skirt revealing the
ankle or the knee.
Even the attitude toward fundamental social relations,
such as marriage, varies. From the standpoint of ethics the
question of monogamy and polygamy is of prime importance.
The science of ethics seeks to determine which of these two
conceptions of duty is higher and better. Psychology studies
duty only as a mental attitude it does not attempt to pass
judgment on its particular applications.
The attitudes which grow up in connection with volition,
language, and ideals are not especially prominent. Volition
develops the persevering attitude, with its extreme limit,
obstinacy; in the other direction it may lead to vacillation.
The use of language results in receptive and expressive atti-
tudes; the reticent man is inclined to listen, while the voluble
man insists that every one else shall listen to him.
An ideal is made up of thoughts, feelings, and volitions.
Because of this complexity our ideals are seldom definite,
concrete experiences. But they develop in the form of deep-
lying ideal attitudes, which serve as motives of action and con-
trol the course of our lives. The idealistic man, the practical
man, the scientist, and other types are distinguished on the
basis of certain underlying attitudes which govern their
behavior and conduct.
Attitudes and Consciousness. Our attitudes always con-
tribute something to our experiences. But usually the
material they contribute is so obscure that it is not observed
by the man himself at the time; it is subconscious. In an
earlier chapter l we distinguished between subliminal and
subordinate consciousness. Attitudes are generally sub-
liminal they are too faint to be noticed, though they exert
a real and usually a powerful influence on our experiences.
But the question arises, what becomes of an attitude when
it is not actually in use? Does it act subconsciously (that
1 Ch. vi, pp. 136-138.
CH. xv] RELATION TO CONSCIOUSNESS 345
is, in a subordinate consciousness) when it is not working con-
sciously? It seems probable that our attitudes do work sub-
consciously at times, but not often. An attitude is a reten-
tion trace, only it is cut far deeper than any single memory
impression. Memories are not stored away in the mind;
the traces are there ready for use, but they are inactive so
long as they are not actually used. And just so with our
attitudes. Usually they are not active; they are neither sub-
liminal nor are they constantly working in a subordinate con-
sciousness. In fact all that persists between-times is the
trace which makes the attitude possible. When the trace is
aroused, then the attitude appears as an element in our con-
scious experience.
CHARACTER
Nature of Character. Character arises from the consoli-
dation of attitudes into more permanent trends of life. Just
as the constant repetition of similar experiences leads to the
development of fixed tendencies called attitudes, so our atti-
tudes tend to combine into deep-lying general tendencies.
A man's various thought attitudes are not independent,
because man is an ' integrated ' individual, leading one single
life. If your interest centers in the study of biology, this
affects your attitude toward languages; you are interested in
the classics because biological terms are derived from Greek
and Latin roots, or in German on account of the biological
works written in that language. You may be wholly unin-
terested in Arabic or Russian, because they have only a slight
bearing on your subject. On the other hand if you are a
linguist you are interested to some degree in all languages,
while your interest in biology may be limited to its use of
Greek and Latin roots.
The interworking of countless attitudes in each sphere of
mental life results in building up a ' composite attitude ' in
that sphere. Our thought and perception attitudes unite to
346 CHARACTER [CH. xv
form a composite attitude toward this kind of mental material.
This composite attitude is called our intellectual character.
There are four principal lines of character development;
three correspond to the three great varieties of sensation
external, systemic, and motor the fourth arises from our
social relations. These phases of character are:
Intellect (or intellectuality)
Temperament
Skill (or skillf ulness)
Morality
The study of character carries us beyond the examination
of separate experiences. We begin to see the individual as a
whole, and we can compare one man with another. A man's
character is his general rating in one of the four chief phases of
mental life. It is the measure of his mental capacity and
attainment in that phase of life.
Character is a combination of many particular attitudes.
Each separate attitude may be regarded as a trait of char-
acter; and in practice our measure of a man's character con-
sists in rating each important trait. Each attitude or trait
manifests itself in concrete actions, so that practically we rate
a man's traits and his character through his responses. Col-
lege examinations are a means for rating a student's intellec-
tual character in certain definite lines. A soldier's behavior
in battle enables us to rate him for courage. Strictly speak-
ing, a man's character is not the rating which his fellows
actually give him; ] for such ratings are liable to error.
Character is really the rating which the man would receive if
one could appraise him correctly.
Intellect. Intellect is the phase of character which grows
up in connection with the information received through our
external senses. The impressions obtained through these
senses are especially apt to be retained, so that our memories
and thoughts of the external world play an important part
1 This practical rating is a man's reputation.
CH. xv ] INTELLECT 347
in our lives. In rating a man's intellect, his ability to reason,
think, and remember counts more than accurate perception
and vivid imagination.
Intellectual development proceeds in two distinct direc-
tions, which correspond in a figurative way to breadth and
height. The breadth of a man's intellect is measured by the
number of different traits that he has developed; height
means the amount of his growth in each independent attain-
ment. The breadth of your intellect depends essentially
upon the complexity of your inherited nerve structure, while
its height depends more largely upon your education.
Both breadth and height must be taken into account in
rating a man's intellect. There are instances of mathemati-
cal prodigies and memory geniuses who in other respects are
far below the average mental level. And there are men of
great mental versatility who fail to measure up to the aver-
age in any one particular; their minds are too spread-out.
A man of high-grade intellect is one whose attainments are
both broad and high.
Various attempts have been made to measure intellectual
attainment. The great difficulty has been to distinguish the
independent phases of intellect and to estimate their relative
importance. An important step in this direction is the scale
devised by Binet and Simon for measuring the mental growth
of children. This scale consists of a large number of tests
involving various mental processes, and so graded that the
child's success in performing the tests will indicate his gen-
eral intellectual level. For example, the growth of memory
is tested by his ability to repeat sentences of various lengths
and series of numbers of three, four, five, and more figures.
Rational thought is tested by giving the child a statement
which contains some absurdity, and asking him to point out
what is wrong in it. There are also tests involving simple
mathematical problems, tests of practical judgment, 1 tests to
1 E.g., "What is the thing for you to do if a playmate hits you without
348 CHARACTER [CH. xv
show the extent of the child's vocabulary, and many others.
In practice the tests are arranged in order of increasing diffi-
culty. Five tests cover each year of mental growth.
The success of the Binet Scale as a measure of intellect is
due to the fact that the intellectual development of children
is relatively simple; they have not yet developed a great
variety of complex mental traits. On examining all the
children in a large school and comparing those of the same
age, it is found that fifty per cent of the ten-year-old children
succeed in a certain number of these tests. This number is
taken as the measure of the average intellectual level at ten
years. A child of ten who succeeds in five more tests than the
average child of his age, is one year advanced. Children of
ten years who only attain the nine-year standard are said
to be one year retarded; their ' mental age ' is nine years.
The same procedure is used in determining the standard for
each age.
In applying mental tests to adults a difficulty arises owing
to the great individual differences in breadth. A man may be
highly developed along certain lines and deficient in others.
It has not yet been determined satisfactorily how to compare
these different attainments with one another so as to repre-
sent fairly the individual's mental level. The most satis-
factory adult tests at present are those used during the World
War in the United States Army. The Army Alpha Tests
were applied to about 1,500,000 recruits and officers, and are
believed to have successfully rated the intellectual standing
of these men. 1
A mental scale for adults, to be complete, should include
separate tests for each independent intellectual trait. It
meaning to do it?" This is answered correctly by the average child of
eight years.
1 The Binet, Alpha, and other tests of this sort are usually called ' intelli-
gence tests.' In point of fact most of them measure only intellectual devel-
opment not skill, morality, or temperament. An animal maze test would
measure motor intelligence, or skill.
CH. xv] INTELLECT
should distinguish also between traits that have been devel-
oped by special training or schooling, and those that grow up
under the ordinary influences of social environment. The
latter seem to deserve a higher rating. Mere scholarship
and information do not denote so high a degree of intellectual
development as the less cultivable processes which underlie
them.
Mental tests differ from school or college examinations in
just this. An examination in any subject brings out merely
the training which the student has had in that particular line;
it indicates only in a general way his degree of mental devel-
opment. A dull person will stand low no matter how much
drill he has had in the subject; but except in this crude way
examinations do not indicate a person's general mental fitness.
Entrance examinations do not show whether the student is
mentally fitted to pursue the college course. Entrance tests,
if well selected, determine just this point, which is of prime
importance in picking out suitable students.
In applying mental tests special care should be taken that
the results are truly representative. If the individual tested
has been ' coached,' his answer to a question supposed to
involve reasoning may be really a feat of memory. A phono-
graph, supplied with the proper record, might pass a very
advanced test and give results indicating a superlative degree
of intellect. Such a result would measure the intellectual
grade of the individual who prepared the record not the
intellect of the phonograph itself. Unless due care is taken
in giving a mental test (or a college examination for that
matter), the results may indicate the intellect of the ' coach '
not the mental level of the testee.
A question which interests psychologists at present is
whether there is such a thing as general intellectual training:
Does training in any special line (mathematics, classics,
science) result in all-round intellectual improvement? Or is
the improvement limited to the trait that is being trained?
350 CHARACTER [CH. xv
The answer is not yet clear. The weight of evidence at
present seems to indicate that training is ' specific,' not gen-
eral. To the extent that two mental traits have a common
factor, training in one does improve the other. But there
does not appear to be a factor of general intelligence. Gen-
eral intelligence is a combination of many distinct traits.
Temperament. Temperament is the phase of character
which develops out of our desires and emotional attitudes.
It is the permanent cast of our systemic life. In general a
man's temperament develops quite independently of his
intellect. To say that a man is phlegmatic tells us nothing at
all about his intellectual capacity.
The reason why these two phases of character are inde-
pendent is not difficult to understand. Intellect depends
on external stimuli, temperament on stimuli which arise
from the operation of our inner organs and glands. These
two sets of sensory nerves lead to different brain centers,
which are not closely related. Chronic indigestion, over-
development of one of the ductless glands, oversensitivity to
pain, or any other particular internal condition will affect our
systemic experiences; this may modify our temperamental
character more or less profoundly, but it exerts only a slight
influence upon our intellectual growth. What we see and
hear serve to develop our intellect, but these experiences of
the outer world affect our temperament only to a slight
degree. These two sides of human character develop each
in its own way. We rate a man's temperament in altogether
different terms from his intellect.
The ancients recognized four kinds of temperament, the
choleric, melancholic, sanguine, and phlegmatic. This classi-
fication was based upon a doctrine of internal secretions which,
though in the main erroneous, contained a germ of truth.
Temperament is possibly correlated with the modes of
heart action. The heart-beat may be strong or weak, and
it may be rapid or slow. Combining these pairs we get four
CH. xv] TEMPERAMENT 351
varieties of temperament, which correspond to the classic
types. But this does not take into account the distinction
between pleasant and unpleasant feeling, which is really the
most significant characteristic of systemic sensations.
A more natural classification is based on both the type of
activity and the quality of feeling. The motor side has two
phases, active and passive; the feeling element three phases,
pleasant, unpleasant, and indifferent. Combining these two
groups of characteristics we obtain six varieties of tempera-
ment. [Table XVII.]
TABLE XVII. CLASSIFICATION OF TEMPERAMENTS
Motor Phase Feeling Tone Temperament
5 Pleasant Sanguine
Unpleasant Choleric
Indifferent Mercurial
( Pleasant Jovial
Passive < Unpleasant Melancholic
( Indifferent Phlegmatic
While temperament is not so important a factor in life as
intellect or the other phases of character, it should not be
overlooked in our study of the mind, nor yet in education.
The choleric and to some extent the melancholic tempera-
ment are a practical handicap in meeting the situations which
confront us in social life. People do not relish having inti-
mate relations with a man who is hopelessly addicted to
violent emotions of the unpleasant type nor yet with one
who is perennially grim and sour. It is up to the parent and
teacher to train the child away from these unsocial trends, so
far as education is capable of molding the temperament.
Systemic stimuli come from the glands and from the
internal organs controlled by the autonomic nervous system.
The autonomic system works somewhat independently of
voluntary control; but it has connections with the central
nervous system. Our thoughts affect our digestion and
secretions. By deliberately cultivating cheerful attitudes,
352 CHARACTER [CH. xv
we can develop a cheerful temperament. A similar influence
is exerted by social example and systematic education.
These influences do not entirely solve the problem. The
real solution is to train our internal organs to work properly.
This is partly the task of the physician. Whether by drugs
or by diet or by baths and other agencies, it lies within his
power to modify the temperament to a far greater extent
than can be accomplished through the central nervous sys-
tem. The individual himself can cooperate here and in many
cases can accomplish the results alone. Regular habits of
eating, plenty of physical exercise, a proper amount of sleep,
will keep the normal body in good working order and develop
the temperament in the right direction.
Skill. Skill is the phase of character which develops out
of our motor attitudes and habits. It is the permanent mold-
ing of our ' response ' life. A man's motor character is rated
according to the effectiveness of his muscular activity; and
this rating is distinct from the measure of his intellect and
temperament. Like intellect, skill develops in two dimen-
sions : breadth and height. The breadth of skill is measured
by the number of independent motor acts that the individual
can perform. Its height is the degree of success in perform-
ance.
The remarkable breadth of motor development in civilized
man will be realized if we attempt to make a list of the com-
mon acts of modern life. The catalogue would include such
varied acts as eating, moving about, dressing, writing, draw-
ing, conversing, playing games, and a host of other perform-
ances. Besides these common activities each trade and
technical profession has its own particular motor program.
In comparing the motor character of individuals, and hi
rating the comparative development of various races, breadth
of skill is an important factor to consider.
On the other hand, height the man's degree of success in
performing any particular kind of act furnishes a more ade-
CH. xv] SKILL 353
quate index to skill. In determining height of motor attain-
ment two separate factors must usually be measured: speed
and accuracy (ch. xi). In tests of skill we seek to determine
(1) the time required to perform the act, and (2) the number
of errors made, or amount of inaccuracy.
It is often difficult to estimate the relative value that
should be assigned to these two factors. In certain kinds of
work accuracy or precision is of far greater importance than
speed; in other cases the opposite is true. A telescope lens
must be ground to the utmost limit of accuracy, regardless of
time expended. A ready-made garment on the other hand
must be finished quickly, in order to reduce the cost of pro-
duction; irregularities in the cutting are taken as a matter of
course.
Sometimes the conditions are such that speed and accuracy
are combined into a single factor. In a certain tapping test
the individual is required to insert a plug into a series of holes
in succession, and to do it as rapidly as possible. Each inser-
tion produces an electric contact and makes an audible click.
If the subject misses the hole at first he must correct the error
before proceeding to the next hole. Here the inaccuracy
factor is eliminated entirely, and speed is the only variable to
be measured.
A scale of skill, like the scale of intellect, should include a
great variety of typical acts of various sorts, if it is to indicate
breadth as well as height of attainment. Up to the present
the construction of a measuring scale for skill has not pro-
gressed so far as the scale for intellect. The importance of
intellect seems to have been somewhat overemphasized in
modern civilization. We are only beginning to recognize
that skill is an essential phase of human character.
The education of skill belongs largely to technical schools
and institutions for manual training. But some progress
can be made at home. Boys should be taught to drive nails,
saw straight, and perform the common motor activities of
354 CHARACTER [CH. xv
every-day life with accuracy. The home training of girls in
the household arts is more advanced, though it still leaves
much to be desired.
Games of skill, such as baseball, billiards, golf, and tennis,
furnish good training in the fundamentals of motor accuracy.
A general system of motor education, corresponding to the
intellectual education of our primary and secondary schools,
remains to be developed. It is one of the great tasks of the
present-day educator.
Morality. Morality is the phase of character which con-
cerns a man's relations to his fellows. It depends upon our
family and social life. There are no separate receptors or
senses for social stimuli. All our information regarding our
fellow men is received through the external senses of sight,
hearing, touch, and the rest.
Owing to the peculiar relations in which human beings
stand toward one another, our perception of other persons
arouses within us certain special kinds of emotions and senti-
ments, and leads to social responses. If you soothe a sick
child, or give a coin to a beggar, or rescue a drowning man,
the act is due to a social feeling within you. Your plunge into
the river to save a man is a different sort of act, mentally
speaking, from the plunge you take for mere pleasure, though
the muscular activity in the two cases may be similar. In a
word, our social relations develop social attitudes, and these
attitudes develop a new phase of human character, called
moral character or morality. So important is this side of our
mental life that in popular language the word character is
often equivalent to moral character.
Moral character, like intellect and skill, develops in two
dimensions: breadth and height. Our range of social rela-
tions extends gradually with the progress of civilization. It
includes two separate fields : the family, and the tribe or social
group. Family relations include several sorts: marital,
parental, fraternal, and filial, each of which involves a num-
CH. xv] MORALITY 355
ber of separate duties. Community life gives rise to many
relations with corresponding duties : friendship, business and
other economic dealings, community organization, and the
general relationship of man to man. As civilization devel-
ops and the social organization is perfected these relations are
extended, giving rise to broader relations and duties toward
our country, our race, and mankind.
More significant than the range or breadth of social rela-
tions is the degree to which an individual enters into these
relations. The height of a man's moral character is measured
by the extent to which his social ideals and acts tend to bene-
fit his fellows and avoid doing them injury.
Social behavior is called conduct. A man's moral character
is measured practically by his conduct by what he does
and what he neglects to do. The rating is not determined by
what one actually accomplishes but by what he intends to
accomplish. The psychologist and moralist measure conduct
in terms of the man's motives, not in terms of the motor
result. When you give a dollar to a beggar you may actually
start him on a debauch or help to settle him in a life of idle-
ness and uselessness; yet the motive of the gift may be thor-
oughly good. It is this that makes the true rating of moral
character particularly difficult. A scale of morality must
take into account not merely a man's explicit conduct, but
the attitude underlying his actions; and this involves a
determination of his social thoughts, emotions, and senti-
ments.
Religious conduct and character are closely related to the
social. The religious side of man's nature is a striving to
propitiate some higher being or beings, to be guided by an
all-powerful and all-wise personality, to commune with God.
Religious rites and practices belong to the same phase of
mental life as social conduct; religious attitudes develop in
much the same way as social attitudes. The code of ethics
differs from the religious code, but the mental basis of the
356 CHARACTER [CH. xv
two is the same. Man's religious character develops with
his social growth rather than with his intellect or tempera-
ment.
Moral character is quite susceptible to social training. The
child starts life with an inherited social tendency; he also
inherits very pronounced self-preservative tendencies which
often conflict with social ideals. The first duty of moral edu-
cation is to foster the child's social trend and repress his self-
seeking tendencies.
But this is not all. The child at the outset is quite ignorant
as to what acts are moral and what are immoral. Left to
himself he may work out the fundamental distinctions in
the course of time. The function of moral education is to
shorten the learning period, and to instill in the child many
social customs, some of which rest on convention rather than
on natural human relations. He is taught to speak the truth,
not to take the property of others, to say he is sorry when he
has unwittingly done wrong. The conventions of decency
and politeness are pointed out to him concretely before he is
old enough to appreciate their meaning or place in life. The
tendency of the human mind to generalize helps the learning
process immensely. A few instances are usually sufficient to
teach the child what society expects of him in any given sort
of situation.
The responsibility for moral training rests largely with the
parents; for the home life presents a vastly greater variety
of social relations and far more opportunities for moral or
immoral conduct than are found at school.
Reward and Punishment. Character training in all
phases of character is partly a matter of natural mental
growth, partly a matter of example and education. The
incentive of reward and the deterrent effect of punishment
have always been extensively used in education. Rightly
handled these two instruments are very effective in speeding
up the training. A word of praise when the child has mas-
CH. xv] REWARD AND PUNISHMENT 357
tered an intellectual problem or controlled his temper, serves
to fix the successful response; a word of disapprobation often
obviates a repetition of some wrong-doing.
The danger in the use of reward and punishment as a
method of training children lies in a wrong conception of their
psychological meaning. We must look upon them solely as
means for developing the child's character. The old notion of
punishment was that when a child makes a misstep he must
pay a penalty for his error. Psychologically this idea is all
wrong. The child has only limited experience; his mental
powers are undeveloped. It is to be expected that he will fail
more often than he will succeed, whether in intellectual prob-
lems, in temperamental demeanor, in problems of skill, or in
moral acts. To make him suffer for these failures is wretched
pedagogy. He needs assistance, not reprobation. But the
inhibitive power of pain and discomfort is strong. If the
child cannot make the proper nervous and mental adjust-
ments without a pain incentive, the use of punishment is
justified. An admonition or a whipping clinches the warn-
ing and often prevents a repetition of the same mistake.
The danger in applying this method too frequently is that the
child may come to regard the parent and teacher as an agent
for retribution instead of a guide. Punishment of any sort
should be used sparingly and only when other means of train-
ing have failed.
The use of reward has its dangers also. It may serve to
make the child careless, or he may strive for the reward itself,
instead of aiming for successful development, which is the
only psychological justification for rewards. This is true
even in later life. Not infrequently the college educator
finds his students inquiring whether their grades are high
enough to qualify them for Phi Beta Kappa. The question
shows that they are working for the symbol of success not
for the mental attainment itself. Rewards should perhaps
be used merely as a counterbalance to punishments. If a
358 CHARACTER [CH. xv
child needs no punishment he probably needs no reward
except of course the expression of friendly sympathy, in-
terest, and comradeship on the part of his parents and
teachers.
Summary. Experiences leave traces, and these traces
tend to consolidate into permanent mental conditions. The
first step in this process is the development of attitudes, due
to the frequent repetition of similar experiences. The funda-
mental attitudes are interest, desire, and attention, which grow
out of external, systemic, and motor experiences respectively.
Among the complex attitudes, the dispositions, based on our
emotional life, are most significant.
Attitudes consolidate into more general trends called
phases of character. The attitudes which grow out of external
experiences enter into our intellectual character or intellect;
systemic attitudes build up our temperament; motor attitudes
regulate our skill; social relations build up a fourth phase of
character, called morality. All these are subject to growth,
and except in the case of temperament they develop in two
dimensions: height and breadth. Mental scales serve to
measure a person's mental development in comparison with
other individuals. The intellectual phase of character has
been most successfully measured.
PRACTICAL EXERCISES:
75. Compare the direct effect of the stimulus and the influence of your
attitude in reading a novel, in watching a ball game, in discussing some
question with a friend.
76. Analyze the attitude of pique ('being peeved') in yourself and others,
including its characteristic manifestations; also the jealous and cau-
tious attitudes.
77. Examine the report of some important congressional or legislative
debate; determine to what extent the attitude of the participants was
conciliatory, accusatory, and judicial.
78. Test children from four to twelve years old for the number of figures
and words (syllables) which they can repeat successively after one
hearing. Report the progress according to age.
79. Analyze your temperament, and compare it with that of some intimate
friend.
CH. xv] SUMMARY 359
80. Examine what has been the effect of punishment and reward on your
mental and moral development.
REFERENCES:
On attention and interest: W. B. Pillsbury, Attention; F. Arnold, Attention
and Interest.
On temperament: J. Jastrow, Temperament and Character.
On mental tests: L. M. Terman, Measurement of Intelligence; R. M.
Yerkes (ed.), 'Psychological Examination in the U.S. Army' (Trans.
Nat. Acad. of Sci., vol. 15); G. M. Whipple, Manual of Mental and
Physical Tests (2 vols.) ; Pintner and Patterson, A Scale of Performance
Tests.
CHAPTER XVI
PERSONALITY AND CONTROL
Nature of Personality. Personality is the entire mental
organization of a human being at any stage of his develop-
ment. It embraces all four phases of human character:
intellect, temperament, skill, and morality, and every atti-
tude that has been built up in the course of one's life.
Stimuli are constantly pouring in upon you; in a broader
way, situations are constantly affecting you. How do you
' take ' them? Your behavior is the joint product of (1) the
nerve impulses that penetrate to your centers and (2) your
entire mental organization. This second factor is your per-
sonality.
Personality is not inborn and unchangeable. It is a
gradual growth. We are very different persons at five, at
fifteen, and at twenty-five. The difference is due to the fact
that we are all the time gathering in new experiences and
assimilating them. The ground-work of personality is inher-
ited. Every creature inherits a nervous system of a certain
type, with certain possibilities and certain limitations. The
brain and nervous system of the lower species are too simple
to permit the development of language or thought. The
normal human being is born with a complex and plastic
brain, so that he is capable of learning to speak and think.
Given the right sort of nervous system to start with, the
power of speech and thought is developed through repeated
experiences. Our personality is broadened or heightened as
each new sort of experience is acquired; it continues to grow
and expand throughout our lifetime.
It is more difficult to rate a man's personality correctly
than to measure any single trait or any phase of his char-
CH. xvi] NATURE OF PERSONALITY 361
acter. You think you have sized up a certain friend of yours
pretty accurately. A crisis brings to light some unsuspected
strength or weakness. The retiring, timid fellow shows a
grit, a perseverance, a boldness perhaps, with which you
never credited him. The steady, masterful man suddenly
goes off the handle. Why? Because of some streak in his
personality which has not hitherto been connected up with
his ' general self.'
If personality were merely intellect or any other special
character it would not be difficult to determine a man's
future development at the age of twenty. But our contest
with the environment often takes unexpected turns, which
call into play every side of character. Our temperament
influences our intellectual growth and our moral develop-
ment. They may work together or at cross-purposes. .^A,
critical situation may find the ^ej|l|^spof4n our armor ;\>r a
combination of /orkmate circumstances may develop strength
in every part of our equipment and make'ua conquerors. A
well-rounded personality's one that enables us to cope with
all the usual situations in life. Overdevelojmient in*, wne
direction may be as disastrous ab underdevelopment. '
Attempts to measure human personality scientifigaily have
met with little success. Most of the essays aid books on
personality are written by amateur psychologists, who have
no appreciation of the real problems involved. They em-
phasize certain striking individual features, or deal merely
with a few distinctive traits of character. The trained psy-
chologist is apt to shirk the problem altogether. There is an
excellent reason for this. Before we can measure person-
ality we must determine the relative importance of the dis-
tinct phases of character that make up personality. This is a
difficult task. In a general measure of human mentality
what proportion should be assigned to intellect? How much
should temperament, skill, and morality count? The only
satisfactory solution, apparently, is to value each factor
362 PERSONALITY AND CONTROL [CH. xvi
according as it assists in adapting our behavior and mental
organization to the external conditions of life.
Personal Identity and Multiple Personality. In normal
human beings, the whole mental life is organized into one
continuous chain of complex experiences. The greater part
of your past experiences may be brought into relation with
the present if the proper nerve connections are made. Your
conscious life stretches back as far as you can rememoer, and
every event that you recall is felt to belong to one and the
same self. Your present thoughts and feelings and activi-
ties are tinged with a scarcely describable element which may
be called a " sense of ownership "; they belong to you.
This sense of the me and mine is your experience of personal
identity. The feeling of personal identity arises from the fact
that ordinarily the whole mass of an individual's experiences
belong to one continuous series ; his mental life, though com-
plex and intricate, is a unity.
In certain cases this unity of self is broken. Groups of
experiences may be dissociated from the general mass and
organized into a more or less definite personality of their own.
This happens most noticeably in disorders of the central
nervous system, such as hysteria. But there are also cases
in normal life. Many of our subconscious mental processes
are ' split-off ' experiences.
When you carry on two acts at once, such as eating dinner
and making plans for the next day, or knitting and talking,
the two activities are probably controlled by two separate
systems of mental organization. Individuals susceptible to
trance or hypnosis may be absorbed in conversation and at
the same time may write automatically on some entirely
different topic without knowing it. When we have planned
out beforehand the itinerary of a walk and carry out our pro-
gram without thought, the succession of actions is probably
controlled by a subconscious organization. These are typi-
cal cases of subordinate consciousness or secondary personality.
CH. xvi] PERSONAL IDENTITY 363
There are occasionally pathological instances where the
secondary personality becomes so completely organized as to
form a separate self. This is called co-consciousness or duch
personality. The secondary self has developed into a coordi-
nate primary self. The patient leads two distinct lives, one
alternating with the other. Sometimes in one state he has
no memory of his experiences and doings in the other state;
or state A may be remembered in state B, but not the reverse.
The temperament and moral character of the two personali-
ties may be quite different. Pierre Janet and Morton Prince
have studied cases in which three or more alternating per-
sonalities all strikingly different appear in the same
person.
There is something fascinating to most of us in the study of
these unusual phenomena. The casual observer regards them
as weird and uncanny perhaps as demon-possession or
manifestations of a mysterious spirit-world. To the student
of psychology all these instances, whether of secondary per-
sonality or of dual personality, serve to emphasize the general
unity of the self. Multiple personality is the exception. In
most persons experiences are woven together and organized
into one single personality.
The Notion of Self. Our self-notion arises in connection
with this unity of personality. It grows out of sensations
especially connected with our body. The child perceives his
own body through the external senses, and he has a mass of
organized systemic and motor sensations from within the
body. All the sensations and ideas which refer to his own
body and its activities combine into a general self-perception
or self-feeling. This is not a ' notion ' but a sensory experi-
ence.
As thought and language develop in the child, a name is
attached to this self-feeling. At first the child calls himseM
' Baby,' or uses his own name: " Jack is hungry "; " Show it
to Baby." His own personality stands on the same footing
364 PERSONALITY AND CONTROL [CH. xvi
as that of other human beings. This first step toward the
self-notion may be called the objective stage.
When the child learns to use pronouns (you, I, he) the
notion of self becomes sharply distinguished from the general
notion of ' human beings.' This second step is the subjective
stage; the child has begun to recognize the special relation of
his own body and its activities to his own conscious experi-
ences. The true self-notion dates from this stage. It devel-
ops constantly throughout life, especially among civilized and
reflective beings.
Finally, the child discovers a personality, with experiences
like his own, in other human beings; he even reads it into
lower animals and inanimate objects. The child punishes
the naughty chair that tipped him out; older people treat a
dog as if he could reason. This ejection of our self-experiences
into others is a third stage in the growth of the self-notion.
The notion of self is not a special, higher stage of mental
development, as is commonly imagined. Self-consciousness l
runs through all stages of mental growth, but it only begins to
acquire distinctness when language and thought appear, and
the difference between 7 and you comes to be recognized.
General Problems of Personality. In studying any
science we necessarily proceed in a piecemeal way. Each
element and factor must be examined separately before we
can attempt to study their mutual relations or their bearing
on the whole subject. This is especially true of psychology.
First we study the nervous system, then the various senses
which furnish the material out of which our experiences are
formed. Then we examine one by one the various kinds of
experiences and types of behavior. The real study of mental
life begins when we examine the succession of experiences and
the principles of their connection. Finally we investigate
1 Self -consciousness in psychology means consciousness of our own person-
ality; this meaning should not be confused with the popular use of the term,
to denote embarrassment.
CH. xvi] PROBLEMS OF PERSONALITY 365
the permanent mental conditions which mold our mental
life into an enduring self. Our attitudes grow up out of single
experiences, constantly repeated; the consolidation of similar
attitudes results in the organization of our several character-
phases; and the final outcome is our personality or self,
which includes our entire mental organization.
In the course of this study several general problems have
no doubt occurred to the reader which are of more than
theoretical interest. Every one of us asks himself at one
time or another to what extent his personality is fixed by
heredity, and how far it is molded by his special environment.
We often wonder at the great differences that appear between
different individuals. The most practical question of all is
how far we can mold our own lives and control our environ-
ment. These three great problems of personality may be
stated as follows:
What are the factors in mental organization?
What different types of mind are found in man?
To what extent do we personally control our environment
and the course of our own lives?
Mental Organization. The term organization is applied
to any complicated structure whose several parts perform
different operations but all work together to accomplish some
definite result. A locomotive is an organization; its various
parts do different things, but all parts cooperate to make the
machine go and to regulate its movements. Living crea-
tures are organizations J whose organs perform different vital
processes, but all work together to maintain the life of the
creature and perpetuate the species. The social organiza-
tion of man has the same general characteristics; a govern-
ment or an industrial concern includes many human beings
who perform different duties, but they all cooperate to accom-
plish certain general results.
Our mind, or mental organization, is the joint product of
1 This particular kind of organization is called an organism.
366 PERSONALITY AND CONTROL [CH. xvi
two distinct sets of factors: (1) An inherited physical struc-
ture consisting of the nervous system with its receptors and
effectors. (2) Acquired experiences and modifications of this
structure due to stimuli and other forces which act upon it.
Examining more closely, we can break these up into six sepa-
rate factors:
Inherited structure
Terminal organs and conducting nerves
Central nervous system
Effects of external and internal forces
Disorganizing influences
Stimuli and general surrounding conditions
Social influences
Educational influences
a. TERMINAL ORGANS AND CONDUCTING NERVES: The
receptors and effectors are the two terminals of the nervous
system. These terminal organs, joined together by chains of
connecting neurons and intermediate centers, are responsible
for the great diversity in our experiences.
The wealth of different sensations which we get in sight
and hearing is due to the complexity of the eye and ear. No
matter how many kinds of stimuli existed in the environment
they would all give us the same kind of sensation if the recep-
tors were not constructed in such a way as to receive them
differently. The number of different sensations we are cap-
able of having depends on the degree of development of our
sense organs. Color blindness shows how the number of
color sensations is lessened when the eye is imperfectly
developed.
In the same way the variety of different motor responses
that we are capable of making depends on the multiplicity
of muscles and glands. A game knee or a stiff finger-joint
will interfere with a surprisingly large number of coordinated
movements. Notice how a glove on the hand hampers many
simple manual tasks. Notice what a number of muscles all
CH. xvi ] MENTAL ORGANIZATION 367
over the body are concerned in the movements of rising to
your feet and in keeping your equilibrium. Clear pronun-
ciation and the varied intonations of the human voice require
the cooperation of numerous muscles of the jaw, tongue, lips,
cheeks, throat, and thorax.
The motor organs are more substitutive than the receptors.
If certain muscles are wanting we can often develop some
other combination that will serve the same purpose. A man
born without arms may be trained to use his feet for hands
and his toes for fingers. But this motor substitution has
definite limits. No group of human muscles has succeeded in
accomplishing aerial flight. Nothing in the lower animals
quite takes the place of the human thumb.
The conducting nerves may be regarded as part of the
receiving and reacting machinery. The sensory nerves con-
vey the impulses from receptors to centers. If there is a
break anywhere in the chain, the information is not received.
In the same way the motor nerves convey motor impulses
from the centers to the effectors. They are part of the
' motor mechanism.' In short, the inherited terminal organs
and conducting nerves determine the number of different
sensations that a man can have, and the number of different
responses that he can make.
b. CENTRAL NERVOUS SYSTEM: The central nervous sys-
tem is the most important part of our mental endowment.
It is the means by which we put together the mosaic of infor-
mation and use it effectively in our actions. Even though
our receptors are defective, or if some are entirely lacking, we
can often get equivalent information from other senses, so
that we can meet the ordinary situations of life effectively.
The blind and the deaf can think and reason as well as the
normal person if their central system is unimpaired.
The same is true on the motor side. It goes without say-
ing that there can be no movement without muscles; but the
coordination and fine adjustment of muscular movements is
368
PERSONALITY AND CONTROL [CH. xvi
brought about by the central nervous system. A study of
handwriting will demonstrate this. First write a phrase in
the ordinary way; then write it in very small letters, using
only finger-movements; finally write the same phrase in
large letters on the blackboard, keeping your wrist and fingers
rigid and using only the elbow and shoulder. In the two
last cases entirely different muscles are used; yet there is a
marked similarity between all three results. [Fig. 80.] This
shows that the individu-
a man's handwrit-
A
ing is due to characteris-
^4* tics of the nerve impulses
/ / from his brain centers,
not to the constitution of
his muscles. The reedu-
cation of crippled soldiers
demonstrates the same
thing in another way.
The brain, and in a lesser
way the lower reflex cen-
ters, are the organs of ad-
justment. This central
system enables us to
' grasp ' the environment
and respond suitably to
the situations presented
to us. Man's mental su-
premacy is due almost
wholly to his inheritance
of a highly complex cor-
tex, furnished with a vast number of interconnecting neurons.
Integration of stimuli, coordination of responses, and adjust-
ment of response to stimulation all depend upon the central
nervous system and especially upon the cortical tracts.
These are all inherited structures.
FIG. 80. HANDWRITING WITH DIFFER-
ENT MUSCLES
The upper writing was made with wrist and fin-
gers. (Slightly reduced in the cut.) In the middle
specimen only the fingers were used. The speci-
men below was made with sweeping movements of
elbow and shoulder on a large blackboard; wrist
and fingers rigid. (Much reduced in the cut.)
Although entirely different muscles were used in
the second and third, the writings are similar,
showing that individuality in handwriting is due to
the coordinated motor impulse sent from the writ-
ing center in the brain.
CH. xvi] MENTAL ORGANIZATION 369
c. DISORGANIZING INFLUENCES: The inherited structure
which governs mental processes is liable to be impaired in
various ways by the destructive action of agencies that lie
outside our body. Our eyesight may be injured by over-
exposure to light or by some sharp body mutilating the
eyeball. The loss of a foot or hand cripples our motor ex-
pression. Injury to the brain by a fall or other acci-
dent often leads to serious disturbance of the adjustive func-
tions.
There are also disorganizing influences within the body
itself. A tumor in the brain affects the structure of certain
centers or their operation, and this may give rise to patho-
logical mental manifestations, such as aphasia. Malnutri-
tion, disorders of digestion or other vital functions, persistent
use of narcotics, stimulants, and other drugs, may alter
the course of mental activity to such an extent as to affect
a man's character and personality profoundly. Thomas
Carlyle's pessimistic attitude is attributed to his chronic
dyspepsia. Diseases which destroy the tissues may affect
the nerve substance or some of the receptors or effectors.
Deafness may be brought on by measles; infantile paralysis
impairs the power of locomotion.
All such effects represent the destructive action of the
environment on our inherited mental organization, since even
the destructive agencies within the body may generally be
traced to something harmful in the environment.
We can look at the matter this way : Nature, through our
heredity, has furnished us with a splendid apparatus for using
our environment to promote our life interests. This appara-
tus is admirably fitted to cope with all ordinary situations.
But it does not provide against every contingency. It is
liable to injury and destruction. Yet we can often cope suc-
cessfully with these disorganizing factors in an indirect way.
We can avoid destructive weapons, shun infection, keep our
body in good condition by regular living. Even when unfore-
370 PERSONALITY AND CONTROL [on. xvi
seen or unavoidable circumstances injure the apparatus, our
mental and social organization often provides a means of
repairing the injury. Medicine, surgery, therapeutics, and
education may cure the disorder or train some other organ to
take the place of the one that is impaired.
d. STIMULI AND GENERAL SURROUNDING CONDITIONS:
Mental organization becomes effective by use. What we
inherit is merely the capacity for certain reflexes and instinc-
tive actions and the possibility of acquiring intelligent
responses. These possibilities become actual modes of
behavior only when stimulation occurs. Even the simplest
reflex path has to be joined up before it can be used. Unless
the proper stimuli occur at a certain period of life the connec-
tion may never be made, as we find in the case of the ear-
twitching reflex.
Intelligent actions are even more dependent on stimulation.
Their nerve paths are not ready for use at the start. The
connections are established slowly, by repetition of the same
stimuli. We do not inherit language, or thought, or such
special activities as house building and automobile steering,
in the same way that we inherit walking and eye-movement.
Our inherited nerve structure merely makes intelligent action
possible. The ability to perform the act is acquired and
perfected gradually through the working of stimuli upon the
nervous system.
There is one striking difference between the nervous mech-
anism and man-made machines. A machine may limber up
and do better work after the first few trials, but after that it
does not improve, and it does not develop totally new uses.
One can scarcely imagine a harvesting-machine being con-
verted into a printing-press. Our nervous organization, on
the contrary, improves continually by use, and admits of
most astonishing adaptations. The human hand, with the
nervous system to guide it, is used for tilling the soil, for
feeding, and for writing.
CH. xvi] MENTAL ORGANIZATION 371
In addition to particular stimuli, mental life depends upon
certain general and relatively permanent conditions of the
environment. Climate and temperature, abundance or
scarcity of food, the presence of material for protection and
defense, assist in determining what our life shall be.
In short, the course of our mental life and the progress of
its organization depend not merely upon our inheriting a
certain nervous structure, but upon our using that structure.
The direction of mental development is determined by the
action of forces outside and inside the body, working upon
the inherited nervous system.
e. SOCIAL INFLUENCES : Social situations are perceived by
the very same senses that inform us of things in general.
There is no distinct ' social sense.' But social forces differ
in many important ways from other external forces, and the
situations which they represent play a peculiar part in mental
organization. Because our fellow men have a nervous sys-
tem similar to our own, and because their aims and interests
in life are of a piece with ours, social stimuli have a different
effect from other stimuli.
Language and the whole process of communication depend
upon the presence of a social environment. The develop-
ment of thought is assisted by the fact that one man's mental
processes are much like another's. Our ability to speak
readily and think clearly is apt to be impaired by constant
seclusion from the world, though alternation of solitary and
social conditions often stimulates rational thinking.
The extent to which the development of mental life
depends on social influences is shown by certain instances of
children brought up apart from human surroundings. In
the case of Kasper Hauser, whose early years were apparently
devoid of social intercourse, intellectual development was
irremediably stunted. He could never be raised above the
condition of an imbecile. 1 Helen Keller, cut off from social
1 This may have been due to hereditary deficiencies.
372 PERSONALITY AND CONTROL [CH. xvi
stimuli through blindness and deafness, made no progress in
mental growth till taken in hand by an expert teacher.
Much of our mental growth in childhood is due to sub-
conscious absorption of ideas and imitation of customs from
those about us. Our mental organization is molded after
the pattern of the community in which we live. An indi-
vidual with a certain heredity may become a notorious crimi-
nal or a power for good, according as he is placed in an unfa-
vorable or favorable social environment. The example set
by others excites a molding influence on mental development,
even apart from education.
/. EDUCATIONAL INFLUENCES: Education in the sense of
organized teaching is a separate factor in mental life. It is
the systematic effort of society to develop the mental organiza-
tion of its members.
Teaching occurs in a rudimentary form in primitive races,
but its real significance is seen in the higher stages of civiliza-
tion, where it exerts a tremendous influence in developing
the mind. Beginning with home and church training it
extends through the schools to the university and to technical
institutions of every sort. By means of systematic training
mental growth is ' forced ' mental organization develops
at a rate far exceeding that attained through the mere influ-
ence of social example.
Human personality and mental organization depend upon
every one of these six factors. They are all needed in a
systematic explanation of what we are and why we think and
act as we do. The student of human nature realizes how
dependent a man is upon his parentage and surroundings,
and is more inclined to sympathize with the dullard, the
social misfit, and the criminal than to condemn them. This
sympathy should not take the form of mawkish sentiment,
but should aim to remedy their disabilities as far as possible.
Education, not punishment, is the means to use. If the
CH. xvi ] MENTAL ORGANIZATION 373
defect is without remedy we can at least find an environment
suited to the individual's limitations. The ' lunatic asylum '
has given place to the ' hospital for the insane.' There are
training schools for the mentally defective, and special
classes for dull students. The prison system should empha-
size the educational side especially moral education
instead of the penal side. Applied psychology has an im-
portant task before it in picking out suitable occupations for
social misfits. A feeble-minded boy who had set fire to
several houses was committed to the Vineland institution.
They assigned him the duty of tending the furnace. From
a dangerous criminal he was transformed into a useful work-
man.
Mental Types. When we compare human beings we find
striking differences in both the degree and the type of their
mental development. The variations in degree of develop-
ment or mental level are measured by mental tests (ch. xv).
Varieties in mental type are qualitative differences between
the minds of various men. Each type of mind represents
a predominance of some phase of mental life. The most
significant differences are found in sensory types and types of
character.
The differences of sensory type have been examined ex-
perimentally. One person is found to be preeminently a
visualist. He is eye-minded. In his case the visual sensa-
tions and images are especially vivid and form the most
prominent part of his mental experiences. He must see a
thing before he can understand it. He learns by reading
better than by listening. In science his interest is in the
microscope or in maps. If he is an author, his books abound
in color terms and visual pictures.
Another person is of the auditory type. He is ear-minded.
He thinks in terms of the sound of words. He understands
oral instructions readily, so that he learns more easily from
listening to lectures than from poring over text-books; he is
374 PERSONALITY AND CONTROL [CH. xvi
quick at ' mental ' arithmetic. His auditory imagery and in
most cases his appreciation of music are developed above the
average.
A third belongs to the motor type. He is muscle-minded.
With him language is primarily a motor phenomenon; he
thinks in terms of sensations from the vocal muscles, and his
imagery is largely of muscular movements. He is quick at
memorizing speeches; his interest is in motor activity. A
deaf-blind person is probably of the tactile type.
It is a mistake to assume that every one belongs distinc-
tively to one of these types. In some cases the mental
organization is rather evenly balanced. In many persons
certain activities are preeminently of the visual type while
other activities are based upon motor or auditory data. A
man may be an ' auditory linguist ' in one tongue and a
' visual linguist ' in another. He may be a visualist in
geometry and of the motor type in physics. The growth of
types depends partly on inherited brain structure and partly
on circumstances of training. In the earlier stages of educa-
tion it is important to train the type of imagery and thought
along the lines best suited to each particular topic. Later,
when we find out the type to which the child naturally be-
longs, it is wiser to fit the educational method so far as
possible to the individual : teach the visualist through books,
the audile person by oral instruction.
The growth of character brings out another set of types.
In certain persons the intellectual side is dominant, in others
temperament, in others skill. When we speak of a tempera-
mental personality, we mean that the person referred to is
subject to frequent sweeping changes of temperament; this
is usually accompanied by deep emotional displays. An
intellectual man looks at the world from an unemotional,
logical point of view; and so on.
There are individuals in whom the various phases of
character are mingled, but with a decided bent of mind in
CH. xvi] MENTAL TYPES 375
some definite direction. You have no difficulty in distin-
guishing a timid mind, a nasty mind, a schemer, an aggres-
sive personality, a snobbish nature. Some persons develop
traits of manner, voice, and thought such that they are
known to every one as having an ' attractive ' personality;
others seem to be inherently * uninteresting.' Various other
types might be added to the list: the ' slobbery ' man, the
1 belly acher,' the dreamer.
The development of these types depends largely on in-
herited nervous structure; certain brain centers may be more
highly developed, or some of the connective nerve tracts.
But use and systematic training can foster certain phases of
character and check the growth of others. John Stuart Mill
seems to have been by nature of the esthetic type. Under
his father's rigid intellectual schooling he grew into a pro-
nounced intellectualist. His case is somewhat exceptional
in that the drastic training was successful. Usually the
attempt to divert a person's mental life into entirely new
channels is disastrous. In the interests of the man's happi-
ness it is wiser to mold his character, from childhood onward,
along the lines of his natural propensities, taking care only
to eliminate any overdevelopment of one side which might
hamper his social or moral welfare.
Control. A question of great practical importance in life
is how and to what extent a person can control his own
actions and cope with the situations with which he is con-
fronted. The subject has unfortunately been coupled in
the popular mind with speculative theories concerning
human ' freedom ' to think and act. Our study of mental
processes has shown that men do not think and act in an
arbitrary manner. The succession of thoughts depends
on definite principles of association and proceeds in an or-
derly way new thoughts are not spontaneously generated.
Psychology assumes that voluntary decisions are definitely
determined by principles of mental activity, and not by
376 PERSONALITY AND CONTROL [CH. xvi
chance. We never pull ourselves completely away from our
own character and personality by sheer will, any more than
we can pull ourselves off the earth by tugging at our own
boots.
The psychological problem of control has no relation to
these philosophical gymnastics. It is concerned with the
efficiency of man's mental organization. There are two
questions involved: (1) What are the processes by means of
which a human being controls, directs, guides his own life?
(2) What does this control accomplish?
(1) MEANS OF CONTROL: Every response is an exercise of
control. Reflex actions show this control in its most rudi-
mentary form. The reflex wink protects the eye; swallowing
carries food to the digestive organs. Many reflexes which
taken by themselves have no special significance, are essen-
tial parts of organized actions. The autonomic processes of
digestion, circulation, etc., are splendid instances of control
and regulation, but they are mainly concerned with the
maintenance of the body substance and not with our re-
sponses to external situations.
The three most important means of control are instinctive
actions, intelligent actions, and the special type of intelli-
gence called rational actions.
Instinctive behavior is especially effective in controlling the
permanent, stable features of the environment. The bee's
honey-gathering actions are useful because there are honey-
giving flowers in every bee's environment at certain seasons
of the year. The nest-building instinct of birds is effective
because there are trees and materials for constructing nests
in the bird's environment. The preying activities of some
animals and the grazing activities of others are due to certain
permanent features of the world in which these animals live.
Intelligent behavior is effective in controlling more change-
able situations. Voluntary actions usually deal with situa-
tions that are at least partly new. When you catch a ball,
CH. xvi] MEANS OF CONTROL 377
your movements depend on the speed and angle of the ball,
both of which factors are open to all sorts of variation.
Speaking and writing bring about useful results because we
utter or write different words according to circumstances.
Inventions and social customs spring up from time to time
and change continually; we learn to operate machines and to
follow social customs by intelligent responses.
Rational behavior is based on the fact that nature is uni-
form that physical, chemical, biological, and mental
events take place according to permanent, enduring princi-
ples; but it depends quite as much on the fact that the
situation varies from time to time. The airplane inventor
and the pilot who runs the plane must take into considera-
tion both the general principles of aeronautics and the
varying conditions which a plane will encounter.
(2) OBJECTS OF CONTROL: What is it that we control?
The simplest sort of control is control of our own responses.
In the case of reflex and instinctive behavior this control is
practically complete. Inherited nerve paths enable the
creature to make the proper movements from the start. In
the case of intelligent and rational actions we learn to control
our movements by slow degrees. At first the motor outcome
is generally wrong. Step by step we acquire control of our
muscles and do what we have planned to do. The process is
one of central adjustment. We learn to improve our motor
coordinations by means of our higher brain centers. There
is apparently no limit to the improvement.
Another variety, slightly different from this, is control of
ourselves. Self-control is confined almost wholly to man and
is due to the development of higher brain centers. Man
learns to inhibit or modify his own systemic and motor
processes. This is illustrated in the repression of emotion
and less obviously in the regulation of our daily work. The
special significance of this kind of control lies in the fact that
it enables us to govern the course of our own life. This
378 PERSONALITY AND CONTROL [CH. xvi
means a distinct advance in efficiency. To master the
tongue and the fist is a mark of high mental develop-
ment. The man who can control himself can usually con-
trol others.
A more significant type of control, so far as outward results
are concerned, is the ability to modify the environment itself
by our actions in such a way as to assist our life processes.
When primitive man prepared skins of animals and used
them to clothe and protect himself, he advanced a step to-
ward control of his environment. The making of forest trails,
building of huts, sowing of fields, and domestication of
animals are other early instances of man's active influence
upon the physical world. Ships, railroads, harvesters,
lighting plants, and all the products of modern industry may
be regarded as instruments for the control of nature by man.
Along the same line is the improvement of our receptors
and effectors by artificial devices. Man has succeeded in
overcoming to a large extent the natural limitations of his
senses and motor organs. He has devised spectacles, the
microscope, and the telescope to supplement his eyes. The
telephone extends the range of the human ear. Weighing
scales take the place of hefting with our hands; the ther-
mometer adds precision to our temperature senses. Our
motor organs are supplemented in the same way. The
hammer takes the place of the human fist; the bicycle and
railroad train increase man's locomotor ability; the plow,
crane, and countless other tools supplement his arms and
hands. These measuring instruments and tools may be
treated as artificial receptors and effectors, developed by
human intellect and skill instead of through biological
evolution. They are added means for controlling our en-
vironment.
Still another type is social control. By means of language
a human being is able to guide the actions of his fellows and
is guided in turn by them. Your control of other men may
CH. xvi] OBJECTS OF CONTROL 379
be regarded as part of your control of your environment.
But when you yourself are governed by social influences a
new phase of control arises. Your own mind is no longer the
supreme director of your behavior. The center of control is
shifted to some other mind or to the collective influence of
the community. The soldier and the hired servant are con-
trolled by other human minds. The office holder in a demo-
cratic nation is subject to control by the group. The actions
of individuals in any community are determined largely by
custom and tradition; to this extent we are all subject to
group control.
The growth of our mental organization may be either pro-
moted or impeded by social control. The training of chil-
dren and systematic education of every sort illustrate the
useful side. One is often inspired to better things by the
example of others. Psychotherapy is the improvement of
bodily and mental conditions by suggestion. The discipline
of the workshop and the army are useful on the economic
side, though they tend to diminish a man's independence and
self-reliance.
Social control is distinctly bad when one individual comes
so fully under the domination of another that his mental
growth is seriously thwarted. The slave and the profes-
sional hypnotic subject illustrate the harmful working of
social control. The result here is mental deterioration
instead of mental development.
Control is the most significant feature of behavior. Our
motor activities are effective just so far as they serve to
control our environment or our bodily organization. Civi-
lized man, through the enormous development of his brain,
by means of his acquired information and motor habits, and
with the aid of measuring instruments and tools of his own
devising, is able to guide his own destiny. He learns to
govern himself and others. He directs his motor acts and is
able to alter his environment to a large extent to change
380 PERSONALITY AND CONTROL [CH. xvi
the face of nature. He is at once " master of his fate " and
" captain of his soul."
Conclusion: Practical Bearings of Psychology. In this
book we have been attempting to study in a systematic way
the characteristics of human nature. Man is a being who
experiences and acts. His experiences, we have found, are
built up out of sensations obtained through the receptors and
nervous system, which inform him concerning his environ-
ment. These separate sensations are organized into percep-
tions, memories, emotions, thoughts, volitions, language, and
other definite sorts of experience. The repetition of similar
experiences builds up special and general attitudes, and these
mold the different sides of his character. The final summa-
tion of our entire experience life is personality.
On the active side, mental life starts with isolated responses
to isolated stimuli. These separate reflexes are organized
into instinctive acts, and by the learning process they develop
into intelligent acts, of which rational action is a specialized
form. By means of these various forms of behavior we come
more and more to control our movements, our bodily organs,
our fellow men, and the world about us. The final outcome
of this progressive organization of behavior is our personal
control of the whole situation.
There is a special glamour surrounding the mysterious.
The conjurer who extracts eggs from your mouth and
rabbits from your pocket attracts your interest. The spell
is gone when you discover how the trick is performed. The
mysterious workings of the human mind arouse our wonder
in much the same way. Will this feeling be dispelled alto-
gether when we discover the orderly way in which mental life
proceeds? Let us hope not. The study of psychology gives
us a clue to the workings of the most wonderful contrivance
in existence a mechanism which has enabled man to col-
lect a tremendous mass of information about the world in
which he lives, to use this information for furthering his aims
CH. xvi ] APPLICATIONS OF PSYCHOLOGY 381
in life, and to transform the face of nature itself. Should we
not feel greater admiration and awe when we realize that
ail this is accomplished by means of the same orderly processes
that operate throughout nature?
Our present study has necessarily been limited to funda-
mental facts and principles. When these are mastered, we
are in a position to branch out into more practical fields. If
we understand how the grown-up human mind works, we
can compare its processes with those of the child mind and
with the mental processes of animals.
A knowledge of psychological principles will assist us in
our own mental training in our efforts to form new habits
or break bad ones, to govern our passions, to become socially
fit, to judge men, to understand their failings.
Psychology has many practical applications. One of its
fields is to assist in selecting the most suitable man for any
given position industrial, scholastic, or political. If we
know our own type of mind it will help us in choosing our
career. The judge and the physician must appreciate the
significance of mental deficiency in order to treat their ' cases '
correctly. The lawyer and the preacher must understand
the workings of the human mind in order to make their
pleas effective. In these and other directions a knowledge
of scientific psychology is of the utmost value.
Every one has some inkling of how the mind works, just
as every one has a smattering of chemical and physical facts.
But amateur knowledge is a long way behind accurate
knowledge. Which of us would undertake, without training,
to run a locomotive? Yet the human mind is far more
complex than any man-made contrivance. It is true that
the mind is to a large extent self-acting. We are capable
of meeting situations by our own native power of mental
adjustment. But if we wish to use our mind effectively, and
if we would cope successfully with the minds of others, our
untutored insight and judgment are not sufficient. We must
CONCLUSION [CH. xvi
understand the fundamental principles of mental life as
formulated by psychology.
PRACTICAL EXERCISES:
81. Analyze how far your personality appears to be due to heredity and
how far to your social environment.
82. Determine so far as possible to what sensory type or types you belong.
83. Describe instances you have observed of the growth of control in
various directions emotional expression, sketching, systematic study,
moral conduct; if possible take your own case as one instance.
84. What is your present idea of mind?
85. Give instances from your own observation of notably good and bad
effects arising from social control of one person by another.
REFERENCES:
On the self -notion: J. M. Baldwin, Social and Ethical Interpretations, ch. 1.
On multiple personality: M. Prince, Dissociation of a Personality.
On applications of psychology: H. Miinsterberg, Psychology, General and
Applied, bk. iii.
REVIEW QUESTIONS 883
i
REVIEW QUESTIONS
CHAPTER I
What is meant by mental life? What is the distinction between mental
and biological life?
In what way does interplay occur between the creature and his environment?
What kinds of questions do we consider in human psychology?
What is meant by (1) self-study, (2) behavior study, and (3) nerve study?
Distinguish between observation and experiment. How may observation
and experiment be used in behavior study?
Describe the various branches of psychology.
What branches of psychology might undertake a study of play? (Give
reasons why each should be included.)
Define human psychology, and describe the method of study used in this
book.
CHAPTER n
Mention six different kinds of cells in the human body.
How does a neuron differ from a muscle cell?
Describe the axon.
How are neurons connected together?
Name the parts of the cerebrospinal system.
Distinguish between sensory and motor peripheral nerves.
Distinguish between spinal and cranial nerves.
How do sensory nerves enter the cord? How do motor nerves go out of the
cord? Where do sensory and motor nerves join?
What is the gray matter in the spinal cord? How do you account for the
H shape of the gray matter?
How does a nerve impulse pass from the left side of the body to the right
side of the brain?
Describe the medulla oblongata; the cerebellum; the pons Varolii; the basal
ganglia; the cortex.
Where are the centers for moving various parts of the body located in the
cortex?
Describe the position of the several lobes of the brain in relation to one
another and to the fissures.
Distinguish between projection centers and association areas.
Describe the autonomic system. How is the autonomic system related to
the cerebrospinal system?
CHAPTER in
Describe a simple nervous arc.
What are the five successive steps in every case of nervous activity?
384 REVIEW QUESTIONS
Describe the course of the nerve impulse in the nervous arc when an insect
lights upon your hand and you turn your eyes to look at it.
How is a nerve impulse started, and what determines its intensity and
quality? (Illustrate in the case of a sound.)
What is meant by excitation?
What is the peculiarity of conduction along a nerve fiber?
Point out the difference between retention and fatigue in the nervous system.
giving an example of each.
What are the properties of collection and distribution?
Why are our actions called responses?
Distinguish between muscular and glandular responses, and describe just
what occurs in each.
What is meant by (1) integration, (2) coordination, and (3) adjustment?
Describe the adjustment process at any moment in the case of some one
reading music and playing it on the piano or violin.
CHAPTER IV
Give a classification of the senses.
Describe the structure of the eye.
Describe the various motor functions concerned in sight.
Describe the process of focusing light on the retina. How do near-sight and
far-sight affect this process?
Explain the relations between changes in hue, shade, and tint.
How are color relations shown on the color spindle?
What are the primal colors and how do we determine this fact?
What is meant by complementary colors?
Distinguish between positive and negative after-sensations.
What is color blindness? Describe its most common form and how it may
be tested.
How does the Ladd-Franklin theory of sight reconcile the three fundamental
colors with the four primal colors?
CHAPTER V
Describe the arrangement of the middle ear and cochlea.
What differences in the stimuli for hearing produce (1) deep tones, (2) shrill
tones, (3) loud tones, (4) faint tones, (5) noises?
Distinguish between absolute pitch and relative pitch.
How are overtones produced? What is timbre?
Explain how beats and difference tones are produced.
Describe the receptor and stimuli for smell.
Describe the relation of the various sorts of odors.
Describe the receptor and stimuli for taste.
How do you account for differences in the flavor of foods, if there are only
four qualities of taste?
REVIEW QUESTIONS 385
Describe the receptors for cutaneous sensations. Name some of the quali-
ties of touch sensation.
What evidence have we that touch, warmth, cold, and pain are distinct
senses?
Mention some of the principal organic sensations and discuss the sensation of
hunger.
What is the stimulus for pain, and what is the pain receptor?
What information is furnished by the muscle sense?
Describe the receptor for the static sense.
What evidence have we that the semicircular canals are receptors for static
sensations?
Distinguish between the external, systemic, and motor senses.
Discuss the relative importance of tie different senses.
CHAPTER VI
If consciousness is not a concrete thing, how can it be studied?
What is meant by impression and suggestion?
Show the relation between retention and revival.
What is meant by attention?
What is meant by fusion and colligation?
What is meant by discrimination?
Distinguish between a sensation and an experience.
What kinds of experiences are composed of a single class of sensations?
What three faults are found in the writings of psychoanalysts?
Give an example of subliminal consciousness.
Describe an experience occurring in the subordinate field of consciousness.
Describe conditions of anesthesia and hypcresthesia.
CHAPTER VII
What is the relation of perception to sensation?
Why do perceptions sometimes fail to indicate the real relations of external
objects?
Why is the difference between 64 Ibs. and 62 Ibs. less noticeable than the
difference between 4 Ibs. and 2 Ibs.?
Explain Weber's Law.
What factors are involved in the perception of surfaces?
Describe the chief factors in the visual perception of depth with one eye.
How does the difference between the two eyes assist in our perception of
depth?
Why does the stereoscope give the illusion of depth?
What is meant by projection?
How does the space perception of the blind differ from that of normal per-
sons?
Describe Stratton's experiment on reversing the field of vision. What light
does it throw on space perception?
386 REVIEW QUESTIONS
Explain how we perceive motion and actions.
Why do we overlook misprints and misread printed words?
How do you account for the Bering (or the Miiller-Lyer) illusion?
What activities of the central nervous system are involved in perception?
What sort of training is useful to improve perception?
CHAPTER VIII
Why do we seldom have images of systemic and motor sensations?
Distinguish between memory and imagination.
What nervous conditions and processes are essential to memory?
What is meant by projection of memory images, and what does this projec-
tion accomplish?
What is meant by the feeling of familiarity?
Explain the laws of association, with examples of each.
How does the rate of forgetting change with the length of time elapsed?
Give three reasons why you forget.
Why does the strength of memory depend on the training of perception?
Why do children confuse their fancies with their recollections?
Distinguish between fancies and anticipation images.
How do general images differ from memory images?
How do we distinguish mental images from perceptions?
CHAPTER IX
Distinguish between intellectual and affective experiences.
How is the special quality of a systemic sensation related to its feeling tone?
Under what conditions can we experience two conflicting feelings at once?
If feelings are experiences in which the systemic sensations are the main
elements, how do our perceptions of external things come to have a feeling
tone?
Distinguish between appetite and aversion.
How does the intensity of feeling vary with increased intensity of stimula-
tion?
Distinguish between feeling and emotion.
Explain the James-Lange theory of emotion, and mention some of the evi-
dence for and against it.
How far can observations of emotions in animals be used in the study of
human emotions?
Describe the most primitive emotions.
Discuss the classification of emotions given in this chapter. Why is it diffi-
cult to classify emotions?
To what extent are the emotions unsuited to civilized conditions?
Are beauty and power in the objects or in the mind?
Describe the sentiments of belief, disbelief, and doubt.
Why are sentiments generally unimportant in mental life?
REVIEW QUESTIONS 387
CHAPTER X
What is the relation between a motor experience and a response?
Demonstrate the fact that every stimulus tends in the end to bring about
some response.
Distinguish between diffused movements and reflexes.
In what respects do the autonomic functions belong to psychology?
Distinguish between lower and higher reflexes, giving an example of each.
Describe the various relations that may occur between different muscles
concerned in compound reflexes.
Explain the scientific notion of instinct, and compare it with the popular
notion.
How do instincts originate in any species, according to the theory of natural
selection?
Discuss the classification of instincts given in this chapter.
Why has man very few pure instincts and many modified instincts?
Distinguish between the clothing instinct and the modesty instinct.
Discuss imitation.
To what extent are instincts present at birth?
To what extent does your present behavior rest on an instinctive basis?
CHAPTER XI
Distinguish between the effects of fatigue and adaptation.
Describe the way in which a conditioned reflex is acquired.
Describe the transition from instinctive to intelligent behavior.
How is acquisition related to fixation?
Explain the nervous processes involved in acquisition.
Discuss the effect of repetition, intensity, recency, and conflict on the fixa-
tion process, with examples of each.
How may the laws of speed and accuracy in habit-formation be demon-
strated experimentally?
Criticize the theory that habits are lapses of intelligence.
Describe an instance of trial-and-error learning, (a) in the case of an animal;
(6) in man.
Describe the method of learning through associative memory.
Show by two examples how complex habits are made up of simpler habits.
How may habits detrimental to our welfare be broken?
CHAPTER XII
In what important respect do motor experiences differ from other sorts of
experiences?
Describe the sensations found in conations.
Describe reflex conations, instinctive conations, and habit conations.
Distinguish between sensorimotor and ideomotor actions.
Distinguish between conations and volitions.
Discuss the theory that all ideomotor actions are the result of learning.
388 REVIEW QUESTIONS
Explain what is meant by deliberation and choice.
What is the significance of a delayed response?
Explain the statement that when we will to do a certain thing, we have a
thought of the action, together with certain muscle sensations of effort
or memories of such sensations.
In what respect does a purpose differ from other thoughts?
Show how volition assists us to control ourselves and our environment.
Discuss the nature of ideals.
CHAPTER XIII
Show how a word may tend to replace an image.
What are the special characteristics of language and thought?
Why are language and thought called symbolic experiences?
Explain why language is especially adapted for communication.
Why is speech superior to gesture as a means of communication?
Why is mirror-script difficult to read and write?
Point out how the social environment is a factor in the acts of reading and
speaking.
Discuss the special brain centers for language and thought.
Describe the prominent disorders of language.
Show the relation of meaning to rational thought.
Distinguish between meaning and value, with examples of each.
What is the relation of judgment to thought?
Why is rational behavior superior to trial and error behavior?
Contrast the evolution of emotion and thought.
What is the educational significance of the training of thought and language?
Discuss the various levels of the nervous arc and their relation to experience
and behavior.
CHAPTER XIV
In what ways are our present experiences influenced by our past?
To what extent is the simile of the stream of consciousness correct?
How is the speed of perception measured?
Describe the method of determining the reaction time of an association.
What factors determine the flow of perceptions?
What are the principal factors that determine the flow of thought?
What secondary influences determine the flow of thought?
In what ways is the flow of thought subject to personal control?
Describe the chief characteristics of dreams and dreaming.
Why are dreams incongruous and absurd?
Describe the characteristics of hypnotic experiences.
How does reasoning differ from ordinary thinking?
Why do our inferences tend to agree with real events and general truths?
Why do we commit logical fallacies?
Why are our inferences sometimes wrong when we reason correctly?
REVIEW QUESTIONS 389
Explain what is meant by rationalization.
Describe how the various sorts of experiences enter into the general stream
of mental life.
CHAPTER XV
What is meant by a permanent mental condition?
How are mental attitudes built up?
Discuss the relation between interest, desire, and attention.
What classes of experiences arouse interest?
Distinguish between want and satisfaction.
How are emotional dispositions related to emotion?
Describe the problem attitude.
How far does a moral attitude depend on mental development, and how far
on social tradition?
Point out the relation of character to attitudes and to experiences.
How are the phases of human character related to the several classes of sen-
sations?
Distinguish between height and breadth of intellect.
Describe the principle of the Binet-Simon tests.
How is temperament related to feeling and activity?
Why is it desirable to have ratings of skill?
Distinguish between motives and the actual results of moral conduct.
Discuss the psychological theory of reward and punishment.
CHAPTER XVI
Why is it difficult to measure personality?
Describe the experience of personal identity.
What are the characteristics of multiple personality?
Trace the growth of the notion of self.
What is included in mental organization?
Why is the central nervous system more important in mental life than the
receptors and muscles?
Mention some of the disorganizing influences that hinder mental growth.
To what extent are stimuli helpful in building up mental organization?
Distinguish between social and educational influences on mental growth.
Distinguish between the visual and auditory types of mind.
What is meant by a temperamental personality?
How does intelligent behavior assist us in exercising control?
Distinguish between control of our own responses and control of the environ-
ment.
Point out the benefits and dangers of social control.
How does psychology help the lawyer and the judge? the physician? the
employer? the educator?
SUGGESTIONS IN USING THE BOOK
THIS text is intended for use in a full-year introductory
course; it may be used in a half-year course with certain
omissions.
The chapters generally cover about the same amount of
material, the longer ones being somewhat easier, and the
shorter ones more difficult. For a briefer course the sections
on the structure of the eye and ear (chs. iv, v) may be
omitted. To equalize assignments the latter part of chapter
vii (illusions, etc.) might be postponed and taken up in con-
nection with chapter xii; it would not be advisable to omit
or curtail the discussion of the structure and operation of
the nervous system (chs. ii, iii).
The REFERENCES at the end of the chapters are limited to
special topics of general interest, about which the student
might wish to seek further information on his own initiative.
They should not be assigned for required reading.
The PRACTICAL EXERCISES are intended to train the
student in first-hand observation of mental phenomena.
The author has found them to be the most useful part of his
own courses. One exercise is required of the student every
week. The class is given an option between two or three
exercises; one of the alternative exercises is within the ex-
perience of every student (e.g., Exercises 1, 2), another may
deal with some special topic and be available to certain
students only (e.g., Exercises 4, 21).
The exercises should be handed in regularly and promptly.
Their usefulness is greatly diminished if they are performed
weeks after the topic has been under discussion. Aside from
a deduction of credit for tardiness or obvious carelessness, it
is not advisable to grade the exercises. If an exercise is per-
392 SUGGESTIONS
formed seriously and handed in on time, it should be ac-
cepted and given full credit, however amateurish the result.
The length of the report need not be prescribed. Often a
brief report of two hundred words is more satisfactory than a
long essay. The point to insist upon constantly is that the
student shall make each observation for himself, and not
rely on his general information or on popular tradition, or
repeat the descriptions contained in the book. The form of
the report should embody this idea. It should be in the
first person: " I saw so-and-so "; " The movements in my
face and head were ." The instructor should discounte-
nance such expressions as, " When one says the word man
aloud, he ." The short-story style, with its artistic em-
bellishments, is tempting to most students, but it is rarely as
satisfactory as a plain description. If the exercises are
handed back within a week, with a few suggestive comments,
it will be found that after two or three attempts most stu-
dents get the right idea.
It is well to caution the class at the outset against the
following sources of error in the exercises: (1) Careless read-
ing of the problem, so that its real meaning is not understood.
(2) Careless observation especially of familiar experiences.
(3) Attempting to explain the experiences, instead of report-
ing them; or mingling an account of what (probably) occurs
in the nervous system with the account of what the individual
himself actually observes. (4) Casual observation in place of
measurements where the exercise is in the nature of an experi-
ment or test. (5) Describing the action of children or others
in terms of the observer's own personal experience, instead of
observing and reporting their actual behavior. (6) Substi-
tuting traditional and popular notions of mental phenomena
for the student's own personal observation.
The REVIEW QUESTIONS following chapter xvi are in-
tended to assist the student in mastering the contents of the
text. They prevent casual reading, by challenging the stu-
SUGGESTIONS 393
dent to explain the meaning of what he has read. The
student who has read the assignment but cannot answer the
questions is still unprepared. The set of questions given
here do not include classifications or definitions. It is doubt-
ful on psychological grounds whether a student should
memorize a mere list of terms, such as the table of Emotions.
This feat of memory will not advance his knowledge of
psychology materially. Definitions are distinctly useful,
though a word-for-word reproduction ought not to be in-
sisted on. This type of question is omitted here because
abundant material can be readily drawn from the glossary
at the end of the book, or from the text itself.
An excellent way of treating definitions in a written exami-
nation is by the completion method : Print the definition word
for word in the examination paper, omitting certain signifi-
cant terms with a blank in their place. The student has
merely to fill in each blank with the proper word a great
saving of time.
The GLOSSARY includes definitions of the principal terms
used in this book. The wording is in many cases more precise
than that of the text; it aims to bring out the distinction be-
tween cognate words. Carrying out this idea, the popular
use of certain terms is contrasted with their special meaning
adopted in this book. A few useful technical terms not found
in the text are included.
It is suggested that the student consult the glossary for
terms which come up constantly in class discussions, if the
meaning is not entirely clear. The page references include
only the principal treatment of a term. Where the reference
covers several pages, the number is followed by *f ' or (where a
large section is involved) *ff'; *n' after a number refers to a
footnote. Those interested in the finer meanings of terms are
advised to consult Baldwin's Dictionary of Philosophy and
Psychology.
The principles of psychology have many practical and per-
394 SUGGESTIONS
sonal APPLICATIONS. Both in examinations and in the oral
quizzes the instructor will find it useful to ask questions
which bring home to the student the intimate relation of
psychology to every-day life: "Describe the emotions you
experience at a ball game "; " How does the nerve impulse
travel in your body when you hear a sound and turn your
head toward it? "
Interest in the course will be greatly increased if frequent
CLASS-BOOM DEMONSTRATIONS are introduced. Models of
the eye and ear are almost essential to an understanding of
the structure of these complex organs. A human brain or a
model (as in Fig. 1) should be exhibited if possible; also
microscope slides showing sections of the brain and spinal
cord, and of different types of neurons.
A simple experiment in habit formation or memorizing can
readily be made in class. The chain reaction (Exercise 71)
can be performed in groups of ten to twenty persons even
without a stop-watch. Association experiments can be
made with two or three volunteers and then- results com-
pared. Many other demonstrations, such as optical illusions,
stereoscopic vision, color-mixing, overtones, etc., can be
arranged without an elaborate outfit.
Where funds are available for special APPARATUS, and the
schedule allows time for experimental work in connection
with the course, one of the standard laboratory manuals
should be consulted. For experiments requiring practically
no apparatus, see Seashore's Elementary Experiments in
Psychology. Excellent experiments with a few special
apparatus are found in Langfeld and Allport's Elementary
Laboratory Course in Psychology. A great variety of experi-
ments and demonstrations are collected in Sanford's Course
in Experimental Psychology. The most complete laboratory
manual in English is Titchener's Experimental Psychology
(4 Volumes).
GLOSSARY AND INDEX
[For suggestions as to use, see page 89S]
Aboulia = a phase of mental disorder
characterized by inability to make
decisions, 280
Accommodation, neural = the for-
mation of new synaptic connec-
tions, opening up a new path in
the nervous system, 255
visual = change in shape of the
lens as we focus for a different dis-
tance, 59, 65
Accommodation muscle (or Ciliary
muscle) = a muscle which regu-
lates the curvature of the eye-lens,
59,63
sensations = sensations stimulat-
ed by tension of the accommoda-
tion muscle, 153 f
Accuracy, see Elimination
Acquisition = the formation of a
new nervous arc, resulting in a new
response to a given stimulus, 253 f
relation to fixation, 253, 261
Action = in psychology: movement
of a living creature, produced by
motor nerve impulses affecting the
muscles, 2 f
stream of = the succession of re-
sponses which constitute the motor
or expressive life of an individual,
328
Active (or Activity) experience = an
experience derived mainly from
the motor senses, 120; cf. Cona-
tion
Adaptation (or Adaptive response)
= any response, whether inherited
or acquired, which is appropriate
to the situation presented by the
stimuli; i.e. which promotes the
creature's life processes, 228, 247
instinctive = the evolution of in-
stincts in the animal series, result-
ing in more suitable forms of re-
sponse, 236
intelligent = improvement of be-
havior due to acquisition of a bet-
ter neural adjustment by the in-
dividual, 250, 262
visual = the changes which occur
in the visual receptors when we
pass from bright to dim illumina-
tion or vice versa, 76
Adjustment = the systematic collec-
tion and distribution of nerve im-
pulses in the brain, whereby the
response becomes adapted (appro-
priate) to the stimulus ; a combina-
tion of integration and coordina-
tion, 52 f
Affective (or Hedonic) = pertaining
to the systemic senses or to feeling,
120
experience = an experience de-
rived mainly from the systemic
senses, 120, 203; cf. Feeling
Afferent (or Centripetal) = sensory,
leading from a receptor toward the
center
After-sensation (or After-image) =
a sensation which continues or ap-
pears after the stimulus has ceased,
77
negative = an after-sensation
which is the complement of the
original sensation, 77
positive = an after-sensation sim-
ilar to the original sensation, 77
Ageusia = loss of the sense of taste
Agraphia = a phase of mental dis-
order characterized by inability
to express thought in writing, 294
Alexia = a phase of mental disorder
characterized by inability to read,
294
Algesthesia, see Pain sense
Alpha tests = a scale for measuring
intellectual ability, used in the
United States Army, 348
396
GLOSSARY AND INDEX
Ampulla = an enlargement at the
base of the semicircular canals, 118
Anabolism = chemical changes
which build up the bodily tissues,
112
Analgesia = loss of the pain sense
Anesthesia = (a) a condition of the re-
ceptors or sensory nerves in which
stimuli fail to arouse sensation, 139 ;
(b) loss of the sense of touch
in hypnosis, 321
Anger emotion, 213
Anosmia = loss of the sense of smell
Antagonists (or Antagonistic mus-
cles) = a pair of muscles which
move the same member in oppo-
site directions, 51, 232
Aphasia, motor = a phase of mental
disorder characterized by inability
to speak, 293
sensory = a phase of mental dis-
order characterized by inability to
understand spoken words, 293 n
Apopathetic instincts = instinctive
behavior determined by the pres-
ence of others in the individual's
environment, 240
Appetite = feeling characterized by
pleasantness, 206
Appreciation = (a) an attitude em-
bodying the permanent effects of
thought and memory, 340 f; (b)
commonly: the evaluative atti-
tude, 341
Arborization = the ramification of
fibrils at the end of a neuron, 21
Arc, see Nervous arc
Aristotle's experiment, of the crossed
fingers, 164
Association = the succession of one
thought or image after another, or
of an idea after a perception, 313
laws = a formulation of the man-
ner in which successive ideas arise,
185, 313
verbal = (a) the association of a
name (verbal symbol) with some-
thing perceived or imagined, 182,
192, 289; (b) association of one
word with another through mere
similarity in sound, 324
Association area = a region of the
cortex composed of nerve tissue
connecting projection centers in
the same hemisphere, 33
Association time = the duration of
that portion of a nervous process
which is concerned in association
of one idea with another, 311
Associative memory, see Learning
Astigmatism = a condition of the
eye-lens in which the vertical and
horizontal curvatures differ, 65 n
Attention = (a) the mental process
of focusing certain parts of an ex-
perience so that they become more
vivid, 128, 333 n; (b) an attitude
embodying the permanent effects
of motor experiences, 335 f
span = the number of objects dis-
tinctly perceived at a single mo-
ment, 163
Attitude = the manner in which an
individual receives experiences, so
far as this is determined by the
deep, lasting traces left in the ner-
vous structure by frequent repeti-
tion of experiences of the same
fundamental type, 331, 332 ff
emotional, see Disposition
ideal, 344
sentimental = an attitude which
embodies the permanent effects of
sentimental experiences, e.g. cre-
dulity, arising from belief, 338
social, see Conscience
classification, 334
evolution, 343
subconscious factors, 344
Audition, see Hearing
Aufgabe, see Problem attitude
Automatic response, see Response
Autonomic function = a coordinated
chain or group of reflexes in the
autonomic nervous system, which
actuate the bodily processes of di-
gestion, circulation, etc., 226
system, see Nervous system
Aversion = feeling characterized by
unpleasantness, 206
Awareness, see Consciousness
Axon (or Axone) = the long project-
ing fiber of the neuron or nerve
cell, 21
GLOSSARY AND INDEX
397
Basal ganglia (or Basal masses) =
masses of nerve tissue in the cere-
brum beneath the cortex; they in-
clude the optic thalami, corpora
striata, corpora quadrigemina,
crura cerebri, etc., 30
Beat = a quaver effect which arises
when two nearly similar tones are
sounded together, 96; cf. Dif-
ference tone
Beauty sentiment, 219
Behavior = action or activity of any
sort which results from the opera-
tion of the nervous arc in an or-
ganism, 225 ff
instinctive = a coordinated chain
or group of diverse reflexes which
work together systematically, ow-
ing to inherited neural conditions,
227, 233 ff
intelligent = a coordinated set of
responses whose cooperation is due
in part to alteration and improve-
ment of the inherited neural con-
nections by individual acquisition,
228, 250 ff
rational = the motor result of ra-
tional thought; a specialized type
of intelligent behavior, 298
reflex, see Reflex
classification, 225
levels, 302 f
Behavior study = the study of the
manner in which organisms re-
spond to stimulation, 8
Belief = the sentiment or conviction
that certain ideas represent real
facts or relations, 220, 222
Binet-Simon scale = a graded series
of mental tests for measuring
intellectual growth in children,
347
Binocular (or Stereoscopic) vision
= perception with the two eyes,
presenting a single visual field in
which objects stand out in relief,
156 f
Black = a visual sensation which
arises without the usual light-wave
stimulation, 69, 82
Blind spot = a break in the retina to
the nasal side of the fovea, where
the optic nerve enters the eyeball,
60
Brain = that part of the nervous
system which lies within the head,
i.e. above the spinal cord, 3, 29 f
relation to consciousness, 124
Brain-stem = all the brain except
the cerebellum and cortex" with
connecting tracts, 29 n
Brightness (or Value) = intensity of
visual sensations, 71; cf. Shade
Broca convolution (or area) the
posterior (dorsal) part of the in-
ferior frontal convolution; the
word-speaking center
Callosum (or Corpus callosum) => a
mass of nerve tissue beneath the
cortex, which connects the right
and left hemispheres, 31, 33
Canals, semicircular = an organ in
the inner ear which serves as re-
ceptor for the static sense, 87, 117
Catabolism = destructive chemical
changes in the bodily tissues, 112
Cell = an organized mass of proto-
plasm in the living body ; the unit
of organic structure, 19 f
Cell-body = the compact body of a
neuron, exclusive of the branches,
21
Censor = a term of doubtful pro-
priety applied to the organized
subconscious life, 134
Centers = regions in the nervous
system where sensory impulses
pass over into motor impulses, 31,
122
cortical (or control, projection) =
regions in the cortex where im-
pulses from or to the primary cen-
ters are collected or distributed, 32,
33
language (or speech) and thought
= special regions in the cortex
(usually confined to the left hemi-
sphere), where thought and lan-
guage activities occur and where
motor impulses for communicative
expression originate ; they form the
adjustment center of the highest
nervous arc, 32, 34, 292 f
398
GLOSSARY AND INDEX
primary = the terminal of sensory
or motor paths in the lower part
of the brain, 31, 33
spinal = a connecting-point be-
tween sensory and motor nerves
in the spinal cord, 37
Cerebellum = a large mass of nerve
tissue back of the medulla and
above it, forming part of the brain,
30
Cerebrospinal system, see Nervous
system
Cerebrum = the upper part of the
brain, including all portions above
the medulla and cerebellum; di-
vided into two hemispheres, 30 f;
(accent on first syllable)
Character = (a) the organized effect
of all attitudes derived from the
same fundamental type of expe-
rience, 331, 345 ff ; (b) any charac-
teristic
phase of = any one of the four
great divisions of personality, 346;
cf. Intellect, Temperament, Skill,
Morality
training, 356
Chiasm, optic = the point of junc-
ture of right and left optic nerves,
34, 65
Choice, voluntary = discharge of the
motor impulse into the least re-
sistant path in voluntary action,
277
Choroid coat = the intermediate
coating of the eyeball, between the
sclerotic and retina, 60 n
Chroma, see Saturation
Chronoscope, Hipp = a clockwork
with dials and hands for measuring
short intervals of time, 11, 308 f
Clang, compound = the total audi-
tory effect of two or more tones
sounded together, 96
simple = the auditory effect of a
tone with its overtones, 95; cf.
Overtone
Cochlea = a spiral structure in the
inner ear containing the receptors
for hearing, 87
Co-consciousness, see Personality,
dual
Coenesthesia, see Organic senses
Cognitive experience (or Cognition,
Knowledge) = an experience de-
rived mainly from the external
senses, 120; cf. Perception, Mem-
ory, Imagination
Cold sense, 106 f
Collateral = an offshoot of the nerve
fiber or axon, 21
Collection (or Summation) = the
gathering together of separate
nerve impulses into a single neuron
or path, 46
Colligation = a species of mental
composition in which the elemen-
tary sensations maintain their
identity, 129
Color = a visual sensation in which
some hue predominates, 69 f
complementary, see Complemen-
taries
fundamental = three hues so cho-
sen that every other hue can be
produced by combining them, 74
primal = four specific hues, which
are believed to be the original
colors seen by man's ancestors, 75
pure = a sensation due to stimu-
lation of the eye by light of uni-
form wave-length, 69
wave-lengths, 75
zone = the region of the retina
in which any given hue is dis-
tinguishable, 80, 81
Color blindness = a congenital de-
fect of color vision in which cer-
tain hues appear gray or are in-
distinguishable from certain other
widely distant hues, 78 f
Color mixer = an apparatus for
combining two or more different
visual stimuli on the same points
of the retina, 69
Color-shades = the series of changes
in a single hue produced by com-
bining it successively with each
gray-shade, 72
Color spindle (or Color pyramid) =
a schematic representation of all
the colors and grays in their ob-
served relations, 70 f
Color-tone, see Hue
GLOSSARY AND INDEX
399
Commissure fibers = nerve fibers
which connect corresponding cen-
ters in the two sides of the brain or
cord, 33
Communication = any act of social
intercourse, 284
Communicative tendency = an in-
nate tendency to social intercourse,
243
Complementaries (or Complements)
= two hues which when combined
produce gray, 76 f ; black and white
are considered complementaries,
77
Complex = (a) a composite expe-
rience; (b) in psychoanalysis: a sub-
conscious (or repressed) emotional
attitude, pathological in nature,
which influences one's thoughts
and actions
Composition = the mental process of
uniting sensations into larger ex-
periences, 129
Comprehension = (a) understanding
spoken words, 291 n; (b) under-
standing
Conation (or Expressive state) = an
experience made up largely of
motor sensations, 224, 272
Concept = a special type of thought
which tends to represent truly the
characteristics and relations of
things, 297
Concha = the outer shell of the ear,
85
Conduct = behavior which is di-
rected toward other human beings;
social behavior, 355
Conduction = the capacity of a neu-
ron to propagate a nerve impulse
from the receiving end through its
entire length and collateral branch-
es, 44
line = the path traversed by any
nerve impulse in the nervous sys-
tem, 22
rate, 307
Cones, retinal = small bodies in the
retina of the eye, sensitive to both
light and color, 60
Conflict, in learning = two or more
responses involving partly similar
neural connections, which thereby
interfere with the fixation of a hab-
it, 257
Conflicting associations, law, 188
Conscience = an attitude arising out
of social relations and social ex-
periences, 341 f
Conscious : when a living being is re-
ceiving sensations and having ex-
periences, he ' is conscious,' 5, 123
operation, see Mental process
phenomena, see Experience, con-
scious
Consciousness (or Awareness) = a
characteristic of mental life; the
fact that a being has experiences,
122, 141; cf. Conscious
field of = an individual's total
experiences at a given moment, 138
lapsed = the passage of con-
sciousness into subconsciousness
which takes place with the fixa-
tion of habits, 262
marginal, subliminal, see Expe-
rience
stream of = the general succes-
sion of experiences, 306, 327
Contiguity, law, 185, 186
Contrast = a complementary color
effect seen on a white surface close
beside a given color and induced
by the latter, 78
Control = the effect of nervous and.
mental adjustment whereby a man
or other creature is able to make
responses suitable to the situation
in which he is placed, 275, 315,
372 ff
center, see Center
Convergence = fixating the foveas of
the two eyes upon a single point,
156
Convolution (or Gyre) = an irregu-
lar rounded ridge in the surface of
the cerebrum, Figs. 10-13
Coordination = the systematic dis-
tribution of nerve impulses through
various motor paths, resulting in
an orderly response, 53 f
Cord, see Spinal cord
Cornea = the transparent coat on
the front surface of the eye, 59
400
GLOSSARY AND INDEX
Corpus callosum, see Callosum
Corpuscles = small bodies embed-
ded in the skin, which serve as re-
ceptors for touch, warmth, and
cold stimuli, 106
Corresponding points, retinal = any
pair of points in the two retinas
which yield a single sensation, 159
Cortex = the thin layer of gray mat-
ter which forms the outer surface
of the cerebrum, 31
Corti, organ of = a system of cells
within the cochlear duct in the
cochlea of the ear, believed to be
the receptor for hearing, 87, 89
Cranial = pertaining to the head;
cf. Nerve
Curiosity = (a) an innate tendency
to seek information, 242 ; (b) a gen-
eral term, applied to many specific
motor tendencies, such as reaching,
grasping, biting, visual explora-
tion, manipulation of objects, etc.
Cutaneous senses, 107; cf. Touch,
Warmth, Cold
Deliberation = the delay, accompa-
nied by thinking, which occurs in
voluntary activity, 277
Delusion = a pathological condi-
tion in which imaginations are mis-
taken for reality, 200, 315
Demonstrations, in class exercises,
394
Depth, see Perception
Desire = an attitude embodying the
permanent effects of feelings, 335 f
Development, mental = changes and
improvements in mental opera-
tions and organization which oc-
cur during the individual's lifetime,
360 f, 370 f; cf. Evolution
Dextrality = an innate tendency to
prefer one hand, etc., over the other
in performing actions; e.g. right-
handedness, 242
Difference, least observable, see
Least observable difference
Difference tone = a third tone which
arises when two tones are sounded
together, due to their different vi-
bration rates, 95
Diffused expression = imperfectly
coordinated instinctive behavior
stimulated by general systemic
conditions, 239
Diffused response (or movements),
see Response, diffused
Diffusion = an indefinite distribu-
tion or spreading of the nerve im-
pulse, 256
Digestive sensations, 110
Direction = (a) the angle of a line
or contour perceived by sight or
touch, as indicated by muscle sen-
sations or otherwise, 152; (b) the
position of a visual or other distant-
sense stimulus with reference to
the observer, as indicated by mus-
cle sensations in turning the eye
or otherwise
Discrimination = the mental process
of separating or distinguishing the
parts of an experience, 129
perceptual, see Perception of dif-
ference
subconscious, 146
Discrimination time = the duration
of that portion of a neural process
which is concerned in discrimina-
tion, 310
Disorganization, mental = a rever-
sal of the process of systematic
mental organization, 369
Disposition = an attitude which em-
bodies the permanent effects of
emotional experiences, 337 f
classification, 339
Dissociation (or Dissociated expe-
rience), see Experience, subcon-
scious
Distance apart (or Linear distance)
= apparent distance of objects
from one another in the plane be-
fore us, 150; contrasted with
Depth, or distance away from the
observer
Distribution = the splitting up of a
single nerve impulse, so that it
passes into two or more different
paths simultaneously, 47
Dizziness sensation, 119
Dorsal (or Posterior) = toward the
back of the body, 27
GLOSSARY AND INDEX
401
Double interpretation illusion, 168 f
Dream = a special type of expe-
rience which occurs in sleep, 317 ff
Dual personality, see Personality
Duty, sense of (or Duty attitude),
342, 355
Dynamic sentiment = an experience
which combines a feeling with an
idea of power, 221
Ear, 85 ff
Education, relation to mental growth,
372
Effectors (or Motor organs) = the
organs at the end of the nervous
arc into which the nerve impulse
is finally discharged; muscles and
glands, 3, 5 n, 50
relation to mental organization,
367
Efferent (or Centrifugal) = motor,
leading from the center toward an
effector
Effort experience, 272
sensation, 116
Electrolytic stimulus, in taste, 43
Element, mental = a simple or un-
analyzed component of expe-
rience; e.g. elementary sensation
(57, 126), elementary mental op-
eration (127 f, 130)
Elimination, law, 258
Emotion = an experience made up
chiefly of systemic and motor sen-
sations, 209 ff
classification, 214 f
feeling tone of, 216
relation to glands, 211
training, 216 f
Emotional attitude, see Disposition
bias = a tendency to assume an
emotional attitude in narrating,
discussing, or thinking about ob-
jective facts, 339
End-brush = the fine branching of
fibrils at the end of the axon, 21
Endolymph = a liquid which fills
the semicircular canals and sacs,
117
End-organs (or Terminal organs) =
(a) the receptors and effectors at
the terminals of the nervous arc,
5, 9; cf. Receptors, Effectors; (b)
commonly limited to the sense or-
gans or receptors
Environment = everything that acts
from outside upon an organism, 2
control, see Control.
Equilibrium sense, see Static sense
Esthetic expression = an innate or
acquired tendency to esthetic be-
havior, i.e. to produce some work
of art which arouses esthetic sen-
timent in others, 243
sentiment = an experience which
combines a feeling with an idea of
beauty or ugliness, 221
Ethics, relation to psychology, 296,
344
Euphoria = a feeling of well-being,
204
Eustachian tube = the passage ex-
tending from the back of the mouth
to the middle ear behind the ear-
drum, 86
Evolution, mental = changes in men-
tal operations, etc., which take
place in organic species from gen-
eration to generation
Excitation = the capacity of neu-
rons to receive nerve impulses, 44
Excitement = a feeling whose tone
is neither preeminently pleasant
nor unpleasant, 207
Exercises, directions in using, 391
Experience (or Mental state, State of
mind) = any definite impression,
due to present stimulation or to re-
vival of former impressions or to
both; any moment of mental life
as it appears to the individual
himself; an organized subjective
occurrence; e.g. a perception, mem-
ory, emotion, 2, 130
conscious = an experience which
forms part of one's personal men-
tal life, 5, 122, 126
fundamental (or primary) = an
experience composed largely of one
single class of sensations (external,
systemic, or motor), or of ideas,
130 f
general stream of = the succession
of various sorts of experiencea
402
GLOSSARY AND INDEX
which make up the mental life of
an individual, 326 f
marginal = a faint or scarcely ob-
served conscious experience, 128,
137, 140, 326 f
secondary = an experience com-
posed of two or more classes of
sensations or ideas, 131
subconscious (or subordinate,
dissociated) = any detached ex-
perience which does not enter into
the individual's mental life, 132,
138
subliminal = the mental effect
produced by a slight stimulus (or
difference of stimuli) which is too
faint to be consciously observed,
136, 344
classification, 131, 304
relation to response, 224
Experiment = an observation of na-
ture in which certain significant
conditions are arranged before-
hand, 10 f
Expression = (a) the sending out of
a motor impulse, 275; (b) bodily
changes produced by motor im-
pulses; see Response, Facial, etc.
Expressive experience, see Conation
External senses, see Sense
Exteroceptor = an external-sense re-
ceptor
Eye, 58 f
muscles, 63
Facial expression, 258
Facilitation, law 248
Faintness, law, 188
Familiarity feeling = a quality at-
taching to memories and to certain
perceptions, which indicates that
the observer has had a similar ex-
perience before, 183, 195
Fancy, see Imagination
Far-sight (or Presbyopia) = a fo-
cusing defect of the eye due to
flattening or rigidity of the lens,
etc., whereby one can see distant
objects clearly, while near-by ob-
jects are blurred, 64 n
Fatigue = impairment of nerve,
muscle, or receptor due to over-
work or toxic conditions, 46, 116,
247
Fear emotion, 212
Feeling = (a) an experience in which
systemic sensations predominate;
120, 203 ff ; (b) often used to de-
note any sensation, 203 n; (c) feel-
ing tone; (d) popularly: ' to feel'
is used for ' to touch,' ' to believe,'
etc., 203 n
curve and law, 207 f
influence on thought, 206
intensity, 207
Feeling tone = a systemic sensa-
tion which accompanies other sen-
sations, probably due to metabolic
changes in the bodily tissues, 111,
112, 204, 216
Fiber, see Nerve fiber
Field, see Consciousness, Visual
Fissure = a depth, long furrow or
cleft in the cortical surface of the
brain, 31
central (or Rolandic) = a furrow
on the right and left sides of the
brain, which starts near the ear, and
runs to the top of the head, 31
medial = a deep cleft which di-
vides the cerebrum into right and
left hemispheres, 31
Sylvian = a horizontal furrow on
the right an d left sides of the brain,
about the level of the ear, 31
Fixation, binocular, see Convergence
of habit = the process of strength-
ening an acquired connection in
the nervous system, 253, 256 ff
visual = turning the eyeball so
that a given object lies directly
in front of the center of the pupil
and fovea, 67
Flavor = a mingled experience of
odor, taste, etc.
Focus of attention = the clearest
portion of a perceptionor idea, 161,
327
Focusing the eye = changing the
shape of the lens by the accommo-
dation muscle, so as to make a
clear picture on the retina, 65
binocular, see Convergence
Forgetting 187 f
GLOSSARY AND INDEX
403
Form-board = a board with depres-
sions of various shapes into which
solid blocks of the same shapes
are to be inserted; used to test
perception of shape or form, 174 f
Fovea centralis (or Fovea) = a de-
pression in the retina near the rear
midpoint of the eyeball, where
sight is clearest, 62
Free nerve-endings = sensory neu-
rons terminating in the skin and
unattached to any receptor; they
serve for the reception of pain
stimuli, 113
Frequency, law, 186
Freudian psychology, see Psycho-
analysis
Fringe of consciousness, see Expe-
rience, marginal
Function (or Operation, Process) =
the 'working' of anything; the
way in which something is accom-
plished, 39 ff; contrasted with
Structure
biological = a general type of
bodily process which serves some
biological purpose, 237 f
mental, see Mental process
Fusion = a species of mental com-
position in which the elementary
sensations merge together, 129
binocular (binaural) = the single
set of impressions which results
from stimulation of the two eyes
(ears), 159
tonal = the modified effect of
two or more tones when sounded
together, 96
Ganglion = a small collection of
nerve cell-bodies; see Basal, Spinal,
Sympathetic
Generative (or Sex) sensations =
organic sensations whose receptors
are in the generative organs, 111
Gesture = communication by move-
ments of the hands, etc., 288
Gland = a cell, tissue, or organ
which separates materials from
the blood or lymph and therewith
produces certain ohemical com-
pounds in solution, called secre-
tions, these secretions being either
discharged directly on the surface
of the body, or through ducts to
the outside, or (in case of endo-
crine or ductless glands) into the
blood or lymph, 51
Glandular response, see Response
Graphic language = communication
by means of durable impressions in
some material substance, 289 f ; cf.
Language
Gray = a sensation resulting from
mixed light stimuli in which no
single wave-length predominates,
69, 71 ;cf. Shade
Gray matter = grayish-looking mass-
es of nerve tissue, consisting largely
of cell-bodies, 31
Gustation, see Taste
Gustatory nerve = the sensory nerve
for taste
Gyre (or Gyrus), see Convolution
Habit = an individually acquired
and stereotyped series of responses
or thoughts, 253
mental = an acquired and defi-
nitely fixed train of thoughts or
manner of thinking, 253
motor = an acquired and defi-
nitely fixed complex motor re-
sponse, 254
relation to intelligence, 262 f
training, 267
Habit conation = a sensory expe-
rience which accompanies the per-
formance of an habitual act, 273
Habit formation, see Learning
Hallucination = confusion of images
or thoughts with perceptions, 199
Hearing sense (or Audition) , 85 ff
Heat sensation = a mingled im-
pression of warmth and cold, 107
Hedonic = pertaining to feeling
Heft = to receive a muscle sensa-
tion from lifting, 162, 311
Hemispheres, cerebral, see Cere-
brum
Heredity (or Inheritance, Heritage)
= (a) any effect of the parental
germ cell upon the nature of the
new creature, 366 f ; (b) the char-
404
GLOSSARY AND INDEX
acteristics of an organism so far as
determined by characteristics oJ
the germ cell from which it start-
ed; contrasted with Environment
Hering illusion, 170
Hue (or Color-tone) = a color sensa-
tion so far as determined by the
rate of light vibration, 69 f
Hunger sensation, 110
Hyperesthesia = a condition of
heightened sensitivity of certain
receptors or sensory paths, 138
in hypnosis, 322
Hypesthesia (or Undersensitivity) =
a condition of diminished sensitiv-
ity of certain receptors or sensory
paths, 139
Hypnosis = a special condition of
the nervous system in which the
individual is peculiarly susceptible
to verbal stimuli, 321 f
Hypnotic suggestion = an effective
verbal stimulus given to a hyp-
notized individual by another per-
son, 321
Idea (or Ideation) = an experience
or element of experience due to
traces left in the brain by former
nerve impulses; an imagination or
thought, 131, 178; contrasted with
Sensation
Ideal = a composite experience
which includes ideas, feelings, and
motor sensations, 281 f
Ideational = pertaining to ideas or
to ideation
Ideograph = a graphic symbol which
denotes a word or idea; e.g. &, 2;
contrasted with Letter, which de-
notes a sound and forms part of a
spoken word, 289 n
Ideomotor activity (or behavior) =
a response generated not merely by
sensory stimuli but by their idea-
tional effects in the brain, 274, 277
Illusion = the misinterpretation of
certain factors or elements in an
experience, 144, 199
of memory = the misinterpreta-
tion of some factor in a memory
experience, 198
of perception = a perception
which in some respects does not
correspond to the actual situation
in the environment, 144 f, 154, 167 f
Image (or Imagery) = a group of
elementary ideas which are com-
bined into a single experience,
178 ff
anticipation = an imagination
which has a lively reference to
one's future actions or experiences,
196
composite (or free) = an image
resulting from the revival and fu-
sion of several past experiences due
to the same object or person, 196
general = an image resulting
from the revival and fusion of past
experiences of many similar things,
187
imagination, see Imagination
memory, see Memory
retinal (or Retinal picture) = the
effects of retinal stimulation by
any single object, 155
systemic, motor, 179
classification, 178
relation to perception, 179, 199 f
training, 200
Imagination (or Fancy) = (a) an im-
age made up of elements from two
or more different past experiences,
194 f; (b) popularly: a thought
which does not correspond to
reality
relation to perception, 200
training, 200
Imitation = behavior which repro-
duces the responses of another
creature or whose results resemble
a given pattern or model, 241
Impression = (a) the mental process
of arousing a sensation or idea or
complex experience, 127; (b) a
sensation or idea, 121
Impulse = (a) a special sort of ac-
tivity propagated along a neuron
(sensory, central, or motor) as a
result of stimulation, 3, 39, 44 f;
(b) popularly: a tendency to act,
which originates in the brain it-
self
GLOSSARY AND INDEX
405
Individuality = the characteristics in
which one living being (' individ-
ual') differs from another, 361
Inference = a thought which is
reached by reasoning, 323
Inhibition = the blocking of a neu-
ral pathway so that the progress of
the nerve impulse is checked, 255
law, 189
Innate = inherited ; see Heredity
Instinct, see Behavior
modified = a mode of behavior in
which the inherited nervous ba-
sis has been altered by the forma-
tion of new conduction paths dur-
ing the individual's life-time, 237
classification, 236, 238
development, 243
racial origin, 236
variability, 244
Instinctive conation = the sensory
experience which accompanies an
instinctive response, 273
tendency = a tendency to act so
as to produce a certain type of re-
sult, the tendency being due to in-
nate conditions while the behavior
itself may be acquired, 241 f
Integration = the systematic as-
sembling of sensory nerve impulses
in the brain centers, 52 f
Intellect = that phase of character
which develops as a result of an
individual's perceptions and ideas
of the outer world, 346 ff
scale = any graded series of men-
tal tests designed to measure an
individual's intellectual develop-
ment, 347 f , 348 n
Intelligence = (a) the degree to
which intelligent behavior is de-
veloped in an individual or species ;
see Behavior; (b) popularly: a syn-
onym for Intellect, 348 n
animal, 251
lapsed, see Consciousness, lapsed
development, 266
relation to volition, 278
Intelligence quotient (orl.Q.) = ra-
tio of an individual's 'mental age'
to his chronological age; used as a
measure of mentality, especially on
the intellectual side; cf. Mental
age
Intelligence scale = (a) a measure
of mental development; (b) a
measure or scale of intellect, 347
Intelligence test = a mental test,
348 n
Intensity, of nerve impulse, 43
of sensation, 80, 96, 101, 104, 108
Interest = (a) the attitude which
embodies the permanent effects of
perceptions and ideas, 335 f; (b)
the feeling tone which accompa-
nies the interest attitude
Interoceptor = a systemic-sense re-
ceptor
Interval, musical = any pitch in-
terval used in music, 92, 93
pitch = the relation of two tones,
as measured by the relation of their
vibration-rates, 94
Introspection, see Self-observation
Iris = a flat, ring-shaped muscle in
front of the lens, which regulates
the amount of light admitted to the
eye; the colored ring which sur-
rounds the pupil, 60, 63
Itching sensation, 107
James-Lange theory of emotion, 210
Jastrow cylinders = an apparatus
for investigating pressure and
muscle sensations, 136 f, 146
Judgment = a thought in which two
concepts are combined, 297
Katabolism, see Catabolism
Kinesthetic sense (or Kinesthesia,
Kinesthesis), see Muscle sense
Knee-jerk reflex, 37, 248
conditioned, 248
Labyrinth = the inner ear, 86
Ladd-Franklin theory of sight, 83
Language = an experience com-
posed of ideas and motor sensa-
tions, whose motor expression re-
sults in communication, 285, 287 ff
center, see Center
development, 299 f
types, 287
Learning (or Habit formation) =
406
GLOSSARY AND INDEX
the process of forming new con-
nections in the nervous arc and
perfecting them through repeti-
tion, 253 ff
by associative memory = a meth-
od of learning characterized by a
flow of ideas ending with the idea
of the appropriate response, 265
by trial and error = a method of
learning characterized by persis-
tent, varied responses ending acci-
dentally with a successful or ap-
propriate response, 263 f
in long and short periods, 261
measurement of, 259, 260
Least observable difference, 147 f;
cf. Threshold of discrimination
sensation, 81, 96, 101, 105, 108,
116, 119; cf. Threshold of sensa-
tion
Lens of eye, 59
Lies, children's, 195, 296
Light waves = very minute trans-
verse vibrations in the ether,
which give rise to sensations of
sight, 67
Lobe = a large division of the cor-
tex; each hemisphere includes a
frontal, parietal, temporal, and
occipital lobe, with an inner con-
cealed cortical region, the island
of Reil, 31
Local sign = a slight modification
of sensation which serves to indi-'
cate what particular point in the
retina or skin is stimulated; local
signs are due not to the stimulus
but to the receptor, and are simi-
lar for all sensations from a given
receptor, 150
Location of memories, 181
Loudness = intensity of sound, 96
Love emotion, 213
Macula lutea (or Yellow spot) = the
central region of the retina, which
has a yellowish tinge, 62
Marginal (or Margin of) conscious-
ness, see Experience, marginal
Maze (or Labyrinth) = a construc-
tion consisting of an intricate set of
branching (walled) paths, includ-
ing blind alleys, with only one
route leading to the goal; used to
measure the learning ability of
animals or human beings, 251 f
Meaning = a group of marginal
elements in a cognitive experience,
which have reference to the corre-
sponding external situation, 295 f;
cf. Value
attitude, 341
in perception = ideas of the use
of an object, or of any other inti-
mate relation, which accompany
perception, 173
in reasoning, 323
in thought = the faint images of
objects which accompany verbal
thinking, 295 f
Meatus, external = the passageway
into the ear, which conveys sound
waves to the drum, 85
Medulla oblongata (or Bulb) = the
lowest part of the brain, just above
the spinal cord, 29, 30
Memory = (a) a synonym for re-
vival, 127; cf. Revival; (b) a mem-
ory image; the renewal of a former
experience, 180 ff
training, 191
Memory system = an artificial de-
vice to assist recollection, 193
Mental = (a) pertaining to mind or
any of its factors; (b) more broadly,
used to characterize the organized
activities of the nervous system or
the resulting conscious experiences
age = degree of mental develop-
ment expressed in terms of the age
at which the average of mankind
attain that degree, 348
condition (underlying or perma-
nent) = any arrangement of nerve
structure or connections, either
inherited or acquired, which molds
or modifies one's experiences and
responses, 331
development, see Development
life = the stream of experiences
and nervous activity in any or-
ganism, 35, 55, 327
organization, see Organization
process (or operation) = (a) any
GLOSSARY AND INDEX
407
change in the elementary sensa-
tions when they reach the higher
centers, resulting in the formation
of definite experiences, 127 f, 130;
(b) often used to denote the suc-
cession of experiences
scale = a graded series of mental
tests, 347
state, see Experience
succession, see Succession
test = a practical device for meas-
uring an individual's mental de-
velopment by his success in an-
swering questions, solving prob-
lems, or performing prescribed
acts, 15, 347 f
Mentality = the degree of an in-
dividual's mental development, 361
Metabolism = chemical changes in
the body, 110 n, 112; cf. Anabol-
ism, Catabolism
Mind = the total organization of ex-
periences and personality in an
individual, 17, 124 n, 365, 380
Mirror- writing (or Mirror-script),
163, 290
Mnemonic = pertaining to memory
Modification = the capacity of a
nerve impulse to change its form,
48 f
Monocular, see Uniocular
Mood, see Disposition
Moral attitude, see Conscience
character, see Morality
sentiment = an experience which
combines a feeling with the idea of
right-and-wrong, 222
Morality = that phase of character
which concerns man's relations to
his fellows and is developed by
social experiences, 354 f
Moron = a slightly retarded human
being, 16 n
Motive = a conscious or subcon-
scious condition which plays a part
in determining one's behavior or
conduct, 283, 337, 349, 355
Motor experience (or Motor con-
sciousness) = organized informa-
tion concerning one's own move-
ments, 120, 224, 271 ; cf. Conation
organs, see Effectors
senses, see Sense
Movement = motion of an organ-
ism or its parts, produced by nerve
impulses acting upon the muscles;
cf. Behavior, Response
Miiller-Lyer illusion, 170
Muscle = a contractile tissue op-
erated by the motor nerves, 50 f
antagonistic, see Antagonists
Muscle (or Kinesthetic) sense = a
sense whose receptors lie in the
muscles and other organs of move-
ment, 115 f, 151
Myopia, see Near-sight
Nausea sensation, 111, 112, 119
Near-sight (or Myopia) = a focusing
defect of the eye, due to too much
curvature of the lens, whereby dis-
tant objects are blurred, 64 n
Nerve = a bundle of neurons lying
side by side, and serving to con-
duct nerve impulses, 3, 26
cranial = a nerve connecting with
some receptor or effector in the
head, 26, 29
motor = a nerve leading from the
cord or brain to some effector, 26
peripheral = a nerve connecting
the spinal cord or brain with a re-
ceptor or effector, 26
sensory = a nerve leading from
some receptor to the cord or brain,
26
spinal = a nerve which passes
from the body (below the head)
into the spinal cord, 26, 29
Nerve fiber = the main stem of a
neuron, 21
Nerve impulse, see Impulse
Nerve-study = in psychology: the
study of the nervous system and
its activities as bearing on mental
life, 9
Nervous arc (or circuit) = the com-
plete path traversed by any nerve
impulse from receptor to effector,
23,39
levels, 302 f
Nervous system = the sum-total of
neurons (nerve cells) in the body,
3, 6, 19 ff, 39 ff
408
GLOSSARY AND INDEX
autonomic (or sympathetic) =
a semi-dependent system of nerves
and ganglia distributed through
the body, which controls the bod-
ily functions, 34 f, 351
central = the brain and cord
cerebrospinal = the main part
of the nervous system, excluding
the autonomic nerves, 26 n
peripheral = the spinal and
cranial nerves
operation, 39 ff
relation to mental organiza-
tion, 367
structure, 19 ff
Neural = pertaining to the nervous
system or to neurons
Neuron (or Neurone) = a single
nerve cell, including the cell-body,
axon, and all branches, 21 f
secondary = a neuron which does
not connect directly with a recep-
tor or effector, but only through
another neuron, 28
properties, 44 f
Noise = an auditory sensation due
to a general mixture of different
sound waves, 90, 96
Nucleus = (a) a small spherical mass
of organized protoplasm within
each cell, essential to its life, 19;
(b) in neurology: a small group of
nerve cells in the cord or brain
Object = in psychology: a physical
mass which stimulates a bunch of
receptors, yielding a more or less
complicated but unified percep-
tion, 162
perception, see Perception
Objective = pertaining to the exter-
nal world
Observation = attentive study of
events as they occur, 7
Odor = a sensation of smell, 99
prism, 101
Olfaction, see Smell
Olfactometer = an apparatus for
testing the sense of smell, 101
Olfactory nerve = the sensory nerve
for smell, 99
Operation, see Function
Optic nerve = the sensory nerve for
sight, 65 f
chiasm, see Chiasm
thalamus, see Thalami
Organ = an associated mass of cells
in the body which performs some
definite process or function
Organic sense = the sense or senses
whose receptors lie in the diges-
tive, reproductive, respiratory, and
other bodily organs, 110 f
Organism = a living plant or ani-
mal, including man, 365 n
Organization = any group or system
of interworking parts, 365
mental = the entire central ner-
vous structure, which (in connec-
tion with stimuli) determines the
individual's experiences and re-
sponses, 365 ff
Otoliths = small solid particles
within the utricle and saccule, 118
Overtone (or Harmonic) = a faint
tone accompanying the tone which
is sounded, due to subsidiary vi-
brations of the instrument in some
multiple rate of the main or funda-
mental tone, 94
Pain sense, 113 f
stimuli, 42
Palp = to receive a touch sensation,
162, 164, 204 n, 311
Path (or Pathway) = the line along
which a nerve impulse proceeds
through the chain of neurons in a
nervous arc, 39, 55, 226 f , 235, 247 f ,
253 ff
Pawlow's experiment, for measuring
the strength of a conditioned re-
sponse by the flow of saliva, 249
Perception = an experience (usu-
ally complex) due chiefly to direct
impressions from the external
senses, 143 ff
binocular, see Binocular Vision
errors of, see Illusion
of depth (or Projection) = per-
ception of the distance of objects
from the observer's body, 153 ff ;
contrasted with Perception of sur-
face
GLOSSARY AND INDEX
409
of difference, 146
of direction, 152
of objects, 161 f, 165
of rhythm = the grouping of a
succession of tones, etc., into a
pattern, emphasizing one tone in
each group of three, four, etc., 166
of space = perception of depth
or of surface, 149, 164
of surface = perception of the
shape, direction, and apartness of
objects in a flat field before us,
taking no account of their distance
away from the observer's body,
149 ff ; contrasted with Perception
of depth
of time and events, 165
stream of = a succession of per-
ceptions uninterrupted by other
experiences, 311 f
affected by habit, 163
agreement with the external sit-
uation, 143, 167
by the blind, 161
classification, 146
relation to brain, 171
training, 173
Perception time, 310
Perimeter = an apparatus for in-
vestigating sensations received
from the periphery of the retina, 74
Periphery of retina = the region far-
thest from the fovea, 63, 80, 83
Personal equation, law, 315
Personal identity = (a) the continu-
ity of one's entire mental life, 362;
(b) the feeling that all one's past
experiences belong to the same in-
dividual, 362
Personality (or Self) = the total out-
come of an individual's mental or-
ganization, comprising all his per-
manent mental conditions and or-
ganized experiences at any period
of life, 134, 332, 360 ff
dual, multiple (or Co-conscious-
ness) = a mental disorder in
which two or more distinct per-
sonalities occur in the same indi-
vidual, now one, now another be-
ing dominant, 363; cf. Personal-
ity, secondary
secondary = an organized group
of split-off experiences, capable of
becoming dominant; 362; cf. Per-
sonality, dual
problems, 364
rating, 360
Perspective, spatial = perception of
the relative distance of objects
(or their parts) from the observer,
155, 161
temporal = memory of the rela-
tive distance in time of various
past experiences from the present
moment, 183
Pitch = quality of tone as deter-
mined by the rate of sound-wave
vibration, 91
absolute = ability to recognize
or identify any given tone, 91
relative = ability to recognize or
reproduce pitch intervals, as in
humming a tune, 92
standards, 91
Plateau = a temporary halt in the
progress of learning, 261
Play = an innate tendency to per-
form acts not directly concerned
with bodily or mental welfare, as
an outlet for nervous energy, 242
Pleasantness = a feeling tone prob-
ably due to anabolism, 111
Poggendorff illusion, 171 f
Pons Varolii = a broad band of neu-
rons which extends laterally across
the medulla, 29
Present, perceptual = a short period
of time during which a succession
of experiences seem to be before us
all together, 165
Pressure sensation, 107
Problem attitude (or Aufgabe) =
the attitude which enables one to
keep a given question or problem
in the foreground, 265, 340
Process, see Function
Proclivity = an attitude embodying
the permanent effects of volitions,
341, 344
Projection, perceptual = the per-
ception of objects as situated at a
distance from the observer's body/
see Perception of depth
410
GLOSSARY AND INDEX
in touch, 160
of sounds, odors, temperatures,
159 f
visual, 158 f
Projection center (or area), see Cen-
ter, cortical
Proof-reader's illusion, 168
Property = a characteristic of any-
thing, either as regards its make-
up (structure) or in its capacity to
act in certain ways (function),
44 f; cf. Structure, Function
Proposition = the language equiva-
lent of a judgment, 298
Proprioceptor = a motor-sense re-
ceptor
Protoplasm = a name given to the
chemical substances which com-
pose an organism
Psychiatry = the study of mental
disorders (' psychoses ')
Psychoanalysis = a method em-
ployed by Freud and others to
bring subconscious impressions
into the foreground, 134
Psychology = the systematic study
of events arising out of the inter-
action between an organism and
its environment by means of re-
ceptors, nervous system, and ef-
fectors, 1, 5
abnormal = the study of disor-
dered or undeveloped minds, 13
animal = the study of the mental
life of animals, exclusive of man, 13
applied = the practical applica-
tion of psychological principles to
the affairs of life, 15, 380 f, 394
child = the study of mental de-
velopment in the human young, 13
comparative = the comparative
study of mental life in various ani-
mal species, 13
experimental = the experimental
study of human mental life in the
laboratory, 14
general = psychology of the nor-
mal adult human being, 12
human = the science which deals
with the interaction between man
and his environment by means of
the nervous system and its termi-
nal organs, together with the ac-
companying mental events, 5, 12
physiological (or neurological) =
the study of the nervous system in
its relations to mental life, 14
social = the study of mental life
as influenced by the interaction
of individuals upon one another, 15
branches, 12 f
methods of research, 8 f
practical bearings, 380 f, 394
problems, 5, 365
Psychophysics = the experimental
study of the relation between
stimuli and sensations, 15
Punishment, educative effects, 356 f
Pupil = a circular opening in the iris
through which light is admitted to
the eye, 60
Purkinje phenomenon = a variation
in the relative brightness of differ-
ent hues in brilliant and dim il-
lumination, 76
Purple hues = a series of colors not
found in the spectrum, produced by
combining red and violet light-
waves, 70, 73
Purpose, biological = the prolonga-
tion t of life or perpetuation of the
species so far as this depends upon
the creature's bodily processes, 237
Purpose idea = an anticipation im-
age or thought of what one is go-
ing to accomplish by his own motor
initiative, 275, 280
Quality = any characteristic of stim-
uli, sensations, and experiences
which is not quantitative nor di-
rectly expressible in numbers;
sort; kind
of sensation, 68 f, 90, 99, 104,
107, 110, 113, 116, 119
of stimulus, 43
Rational behavior, control, thought;
see Behavior, Control, Thought
Rationalization = the mental proc-
ess of constructing artificial rea-
sons to justify an inference which
is actually based on other grounds,
326
GLOSSARY AND INDEX
411
Reaction, see Response
Reaction time = the time interval
between stimulation and response,
307 f
Reading = seeing and understand-
ing written words or any graphic
expression, 291
Reading aloud = the translation of
graphic symbols into speech, 292
Reality feeling = the sentiment or
conviction that the perceived ex-
ternal objects are real, 220
Reason = the ability to think or act
rationally, 298; cf. Thought, Be-
havior
Reasoning = a succession of rational
thoughts in which all the connec-
tions correspond to actual relations
or processes of nature, 322 ff
error = an unobserved substitu-
tion of a casual association for a
rational inference in a train of rea-
soning, 324
Recency, law, 187
Receptor (or Sense organ) = a spe-
cial organ at the beginning of the
nervous arc, which receives stimuli
and excites a sensory neuron, lead-
ing to sensation, 3, 57, 68 f, 85,
99, 103, 107, 117
in muscles, 51
relation to mental growth, 366
Recognition = the identification of
the present memory or perception
with a previous experience, 184
Recollection = the arousing of a
memory image, 184 f
Reflex = a definite response to a
definite stimulus, due to an inher-
ited arrangement of nerve paths,
40, 226, 229 ff
antagonistic = a pair of reflexes
which involve antagonistic muscles,
232
compound = a reflex which in-
volves two or more related muscles,
231
conditioned = a reflex in which
the inherited nervous connections
have been altered by use, 248 ff
cranial = a reflex whose center
lies within the head, 40, 231
higher = a reflex which involves
some higher center, so that the re-
sponse is delayed, 230
spinal = a reflex which involves
nothing above the spinal cord, 37,
40
classification, 233 f
Reflex conation = an experience
which accompanies a reflex, 273
Relief = perception of the relative
distance of different parts of an
object or scene from the observer,
155; cf. Perspective
Religious character and conduct, 15,
355
Resistance experience, 272
Respiratory sensations, 111
Response (or Reaction) = any activ-
ity of muscles or glands due to
motor nerve impulses, with the re-
sulting bodily movements and
changes; the end-result of stimu-
lation, 9, 49 f ; cf. Behavior
adaptive, see Adaptation
automatic = any response which
takes place without delay or de-
liberation, 279
diffused = an uncodrdinated re-
sponse, in which the motor impulse
spreads to several muscles and the
action bears no significant relation
to the stimulating situation, 225 f,
239
glandular = a response which
involves activity of the glands
(secretion), 51
implicit = adjustment of the vocal
muscles without actual utterance,
295 n
muscular = a response which in-
volves muscular contraction, 50
social = a response which di-
rectly concerns other beings of the
species and tends to bring about a
social relation, 354
classification, 214, 225
Retardation, mental = stunted men-
tal growth, 14
Retention = the capacity of neurons
to preserve traces of the impres-
sions produced by excitation, 45
in memory, 180
412
GLOSSARY AND INDEX
Retina = a thin coat which covers
the inner surface of the eyeball
except in front and contains mi-
nute rods and cones sensitive to
light, 60
Reversible perspective illusion, 168
Review questions, directions, 392
Revival = the mental operation of
renewing or repeating a former ex-
perience, 127, 180
Reward, educative effects, 356 f
Right-handedness, see Dextrality
Rods, retinal = minute bodies in
the retina of the eye, sensitive to
light but not to color, 60
Rolando, fissure of, see Fissure
Saccule = a spherical hollow or sac
near the semicircular canals, part
of the static-sense receptor, 118
Sacs, see Utricle, Saccule
Salivary reflex, 249
Satisfaction = a type of desire atti-
tude which embodies the perma-
nent effects of pleasant experiences
(appetites), 336
Saturation (or Chroma) = the rela-
tive amount of pure hue to gray in
a given color sensation, 72, 73; cf.
Tints
Scala tympani, Scala vestibuli = two
tubes running side by side within
the cochlea, 87
Scale, auditory = the series of audi-
ble tones from deepest to shrillest,
91
mental, see Mental scale
musical = a group of tones com-
prising certain definite pitch inter-
vals, used in musical composition,
93
Sclerotic (or Sclera) = the outer
coating of the eyeball, covering all
but the front surface; the ' white of
the eye,' 59
Self, see Personality
Self-consciousness = (a) conscious-
ness or experience of our own per-
sonality, 364 ; (b) popular use : em-
barrassment, 364 n
Self-control = (a) ability to modify
or direct one's own behavior, 377; |
(b) inhibition of one's emotional
expression
Self-notion (or Notion of self) = the
total experience of one's own per-
sonality, 363
Self-observation (or Introspection)
= the systematic study and re-
porting of one's own individual ex-
periences, 8, 125
Self-perception, 364
Self-preservation instinct = a gener-
al term used to denote the useful-
ness of instinctive behavior to pre-
serve the creature's life, 243
Self-study, see Self-observation
Semicircular canals, see Canals
Sensation = an impression due to
stimulation of the receptors, 57,
68, 90, 99, 103, 143 n; cf. Sense
secondary motor = any sensation
of sight, touch, etc. which assists
one in the perception of his own
movements, 116, 272
Sense = a mechanism for receiving
information through stimulation,
57 ff ; cf. Sight, Hearing, etc.
to = to receive impressions
through the senses, 203 n
contiguous = a sense which is
stimulated by objects in immediate
contact with the body, 57, 102
distant = a sense whose stimuli
originate in objects at a distance
from the body, 57, 102
external = any sense which is
stimulated by objects outside the
body, 57, 119
motor = any sense which is stim-
ulated by movement or position of
the body or its members, 57, 114,
120
systemic = any sense which is
stimulated by conditions and
changes within the body, 57, 109,
120
classification, 58, 119 f
Sense organ, see Receptor
Sensibility, general = a general feel-
ing tone pervading the whole body,
112
Sensitivity (or Irritability) = capa-
city of the receptors to receive
GLOSSARY AND INDEX
413
stimulation or of the sensory nerves
to transmit nerve impulses, 139 f ;
cf. Excitation
Sensorimotor activity = a response
due chiefly to sensory stimuli and
not to ideational effects in the
brain, 274
Sentiment = an experience made up
chiefly of ideas and systemic sensa-
tions, 218 ff
classification, 220
Set, neural, see Trace
Sex sensations, see Generative sen-
sations
Shade = the relative brightness or
.darkness of a gray sensation or of a
color sensation, 71
Shades (or Gray-shades) = the se-
ries of grays from white to black,
71; cf. Color-shades
Sight sense (or Vision), 58 ff
Similarity and contiguity, law, 185,
186
Situation = the entire aggregate of
stimuli at a given moment, 171,
263, 360, 380
Skill = that phase of character
which develops out of the individ-
ual's motor attitudes and habits,
352 f
scale = any graded series of tests
designed to measure the develop-
ment of skill in an individual, 353
Sleep = a special condition of the
nervous system, in which the syn-
apses are highly resistant to the
passage of nerve impulses, 317; cf.
Dreams
Smell sense (or Olf action), 98 f
Social factors, 371; cf. Control
Somesthetic sense, see Touch
Somnambulism = sleep-walking, not
controlled by the higher brain
centers, 318
Sound waves = longitudinal vibra-
tions of the air or of solid bodies or
their particles, which give rise to
sensations of hearing, 88
Space perception, sec Perception
Span, see Attention
Spectral lines = certain bright lines
observed in sun-light, etc. when
the different waves are separated
by passing through a prism, 75
Spectrum = the entire series of vis-
ible light waves, 68
Speech (or Vocal language) = com-
munication by production of
sounds with the mouth, etc., 288;
cf. Language
Speed, see Facilitation
Spinal = pertaining to the spinal
cord
cord (or Cord) = a mass of neurons
within the back-bone, forming
paths of conduction, 26 f
ganglion = an enlargement of the
sensory nerve just outside the
cord, containing cell-bodies of
sensory neurons, 27
nerve, see Nerve
Split-off experience = an experience
which is not connected with the
main stream of the individual's ex-
periences, 362; cf. Subconscious;
Personality, secondary
Staircase illusion, 169
State, mental, see Experience
Static sense = a sense whose recep-
tors lie in the semicircular canals
and sacs of the inner ear, and
which furnishes information of one's
position and changes of position in
space, 117 f
Stereoscope = an apparatus by
means of which two slightly dis-
similar pictures, seen by the two
eyes, are perceived as one and
stand out in relief, 157 f
Stereoscopic vision, see Binocular
vision
Stilling test = an apparatus for in-
vestigating color blindness, 80
Stimulation = (a) an effect produced
in a receptor and the adjacent neu-
ron by some object or force out-
side the nervous system, 41 f ; (b)
often used for Excitation
Stimulus = anything which causes
stimulation and starts a nerve im-
pulse, 9, 39, 42, 99, 103, 107; cf.
Sight, Hearing, etc.
relation to mental organization, 370
Strain sensation, 116
414
GLOSSARY AND INDEX
Stratton's experiment, of the re-
versed visual field, 165
Stream of consciousness, thought,
etc.; see Consciousness, Thought,
etc.
Structure = the shape or composi-
tion or arrangement of parts of
anything, 19 ff ; contrasted with
Function
Subconscious : when an impression is
received but does not enter into
the individual's conscious experi-
ence, the effect is called 'subcon-
scious,' 123; cf. Experience, Atti-
tude, Dreams
Subconsciousness = the fact of hav-
ing subconscious impressions or
experiences, 133
Subjective = (a) experienced or
sensed by an individual; (b) con-
scious or subconscious
Sublimation = a term used by some
psychologists to denote the purifi-
cation or elevation of motives from
primitive instinctive tendencies
Sublime = a sentiment which com-
bines a feeling with the idea of both
beauty and power, 221
Subliminal, see Experience
Succession, mental = the sequence
of experiences or responses, 306 ff ;
cf. Association
Suggestion = (a) the mental process
by which one idea passes over into
another, 127; (b) popular use:
words or actions of another person
which serve to guide one's thinking
or behavior, 281
Suggestions, in using this book, 391 ff
Summaries, 16, 36, 55, 121, 141, 176,
201, 222, 245, 269, 282, 304, 329,
358
Superstition = belief in a concept or
judgment which has been shown
not to correspond to nature, 325
Sylvius, fissure of = see Fissure
Symbolic experience = an experi-
ence which does not resemble or
correspond to the situation which
it represents, 286
Sympathetic system, see Nervous
system, autonomic
ganglia = distributing centers in
the autonomic system, 34
Sympathy emotion, 213
Synapse = the place of connection
between two neurons, where their
end-fibrils intermesh, 23 f, 254 f
Synesthesia = persistent association
of a certain color with a certain
sound, or any other arbitrary
grouping of sensations
Systemic senses, see Sense
Tachistoscope = an instrument for
exposing a word, picture, etc., to
view for a fraction of a second ; used
in investigating visual perception
Taste sense (or Gustation), 103 f
Telepathy = a direct means of com-
munication supposed by some psy-
chologists to exist between human
beings, in which the receptors are
not concerned, 284
Temperament = that phase of char-
acter which develops out of the in-
dividual's desires and emotional
attitudes, 350 f
classification, 351
Temperature senses, see Warmth,
Cold
Tendency = the effect of inherited
or acquired conditions in the nerv-
ous system, favoring certain par-
ticular modes of behavior; cf. In-
stinctive tendency
Term = the language equivalent of a
concept, 298
Terminal organs, see End-organs
Test, see Mental test
Thalami, optic = an important pair
of nerve tracts (basal ganglia) be-
neath the cortex, which contain
the primary sensory centers, 30
Thinking = a train or succession of
thoughts, 312 ff
abstract, 324
rational, see Reasoning
Thirst sensation, 111
Thought = a type of experience akin
to language, composed of symbolic
ideas and motor sensations, which
tends to supplant pure imagery in
the human species, 285, 294 ff
GLOSSARY AND INDEX
415
Control = the directing of a suc-
cession of thoughts along a given
line, 313 f
attitude, see Appreciation
center, see Center
rational = a thought in wlych the
meaning or value is prominent,
297 f
stream of = a succession of
thoughts and images uninterrupted
by other experiences, 312; cf.
Thinking
classification, 294
development, 300
rapidity, 307
training, 300
^hreshold (or Limen) of sensation =
the point at which, with increasing
intensity of stimulation, a sensa-
tion just begins to be observed,
136 f; cf. Least observable sensa-
tion
of discrimination = the point at
which, with increasing difference
of intensity between two stimuli,
their difference just begins to be
observed; cf. Least observable dif-
ference
Tickle sensation, 108
Timbre, 95
Time perception, see Perception
perspective, see Perspective
Tingling sensation, 107
Tints = the series of changes in any
given hue produced by combining
it in various proportions with a
gray, 72
Tone, auditory = a sensation due to
stimulation of the ear by sound
vibrations of uniform wave-length,
90
Tongues = the various human lan-
guages, 288
Tonus (or Tone) of muscles = a
condition of tension or stretch in
the muscles which exists apart
from specific stimulation
Touch (or Tactile) sense, 106
Trace (or Set) = a more or less per-
manent mark of former nerve im-
pulses preserved in the nerve sub-
stance, 45, 331; cf. Retention
Tract = a bundle of nerve fibers in
the spinal cord or brain, 66
Trait = a rather generalized atti-
tude; the sum-total of traits in any
one phase of experience make up
the corresponding phase of charac-
ter, 346
Transformation (or Mental chemis-
try) = the mental operation by
which the nature or quality of an
experience becomes altered, 130 n
Trial and error, see Learning
Tropism = a response resembling a
reflex which occurs in lower organ-
isms, especially those which have
no nervous system
Tympanum = the ear-drum, 85
Types, mental = differences among
individuals in the prominence of
one sense or one phase of character
over others; e.g. auditory, motor
type; intellectual, temperamental
type, 373 ff
Unconsciousness = a condition of
the living organism in which (to
all appearances) no impressions
are taking place; e.g. dreamless
sleep; often used for Subconscious-
ness
Undersensitivity, see Hypesthesia
Understanding = the arousal in one
individual of an experience cor-
responding to some experience of
another individual through the lat-
ter's speech or writing, 291
Uniocular (or Monocular) perception
= visual perception in which only
one eye is concerned, 153 f
Unpleasantness = a feeling tone prob-
ably due to catabolism, 111, 114
relation to pain, 114
Utricle = a spherical hollow or sac
near the semicircular canals, part
of the static-sense receptor, 118
Value (or Idea of value) = the idea of
the actual intensity or quantita-
tive properties of objects, events,
situations, etc., which accompanies
verbal thinking, 219, 295; cf.
Meaning
416
GLOSSARY AND INDEX
attitude, 341
Vascular sensations, 111
Ventral (or Anterior) = toward the
front of the body, 27
Vestibule = the midportion of the
inner ear, 87
Visceral sense, see Organic senses
Vision, see Sight
Visual field = the entire range of vis-
ual sensations at any moment, 158
theory = an attempt to explain
how the eye furnishes color sensa-
tions and to account for visual phe-
nomena generally, 82 f
Vividness (or Attention, Mental fo-
cusing) = (a) the mental operation
by which sensations or experiences
become distinct or noticeable irre-
spective of the intensity of stimu-
lation, 128; (b) the prominence of
some part of an experience, wheth-
er due to intensity of stimulation
or to a central process, 162
in perception, 162
law, 186
Vocal language, see Speech
Volition = a complex experience
made up chiefly of motor sensations
and ideas, 120, 275 f
its automatic expression, 279
training, 279
Voluntary activity, see Ideomotor
activity
Walking = a modified instinct, 244
Want = a type of desire attitude
which embodies the permanent
effects of unpleasant experiences
(aversions), 336
Warmth sense, 106
Weber's law = a statement of the
quantitative relations between
stimuli and sensations, 148, 149
Whirl experience, 272
Will, 275 n, see Volition
Windows, oval (Fenestra ovalis) and
round (F. rotunda) = two win-
dows in the wall between the mid-
dle ear and inner ear, 86
Wink reflex, 40
Word, a unit of thought or language,
285
World, external (or outer); see En-
vironment
Writing, see Graphic language
7<511ner illusion, 171
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