t < LIBRARY OF THF. University of California. EDUC. PSYCH. LIBRARY «l GENETIC PSYCHOLOGY THE MACMILLAN COMPANY NEW YORK • BOSTON • CHICAGO ATLANTA • SAN FRANCISCO MACMILLAN & CO., Limited LONDON • BOMBAY • CALCUTTA MELBOURNE THE MACMILLAN CO. OF CANADA, Ltd. TORONTO GENETIC PSYCHOLOGY AN INTRODUCTION TO AN OBJECTIVE AND GENETIC VIEW OF INTELLIGENCE BY EDWIN A. KIRKPATRICK, B.S., M.Ph. AUTHOR OF " FUNDAMENTALS OF CHILD STUDY " THE MACMILLAN COMPANY 1910 All rights reserved 10L06 ± EDUC. PSYCH. LIBRARY Copyright, 1909, By the MACMILLAN COMPANY. Set up and elcctrotyped. Published May, 1909. Reprinted January, 1910. Nortoooli ilreaa J. S. Gushing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. PREFACE The theory of evolution has completely revolu- tionized the biological sciences and is now mak- ing similar changes in psychology, the science dealing with the highest form of life, that of con- sciousness. All life phenomena, from those of plant growth to the most complex processes of consciousness, are in certain respects similar. Therefore, not until the facts and theories of all sciences concerned with life phenomena have been studied to determine their common and their dif- ferentiating characteristics, can we have a psy- chology that is a fitting apex of these sciences. In other words, all psychology must be founded on genetic principle;^ and become genetic in character. It is with the purpose of helping to more clearly define and establish this point of view, which is being more and more taken by present-day stu- dents of life activities, that this book has been prepared. It is hoped that this tentative formu- lation of the truths supplied by various sciences may help to promote more harmony of effort on the part of workers in the several related fields. vi PREFACE In origin and plan of treatment, however, peda- gogical interest has played a large part. After nearly a score of years devoted to the study of child psychology, the impulse to formulate the broader truths of genetic psychology as a dis- tinct subject came from the experience of giving courses in both subjects to summer students at Columbia and Chicago Universities. The inter- est and comprehension shown by those students developed the belief that the facts of genetic psy- chology, incomplete as they are, could be profitably formulated for the use of educators. Subsequent experience in giving parts of this book in nearly their present form, to a class in a normal school, has confirmed this belief. It is probable also that popular interest is great enough to make the book acceptable to the more serious of those interested in animal behavior. Teachers will be most inter- ested in Chapters IX and X, treating of various types of intelligence. In working out the general principles of mental genesis it was found that the more specific problem of mental phenomena as organized in individual minds could not be satisfactorily treated till the general truths of organic activity and of mental genesis had been formulated, and that space would not admit of the treatment of both in a single volume. The author hopes to treat of mental development in individuals and some PREFACE vii of the pedagogical implications in a subsequent volume. The author is indebted to so many patient in- vestigators and writers for facts and suggestions that no enumeration other than is indicated by the references will be made. To Dr. Jennings he is also much indebted for the use of a number of cuts. For stimulus to the work the author is most indebted to students, and for literary help to his wife. Acknowledgment is also gratefully made to Dr. C. F. Hodge for suggestions con- cerning Chapters II and VI and to Dr. A. H. Pierce for criticisms, especially concerning con- sciousness, although neither is responsible for anything the book contains. E. A. K. FiTCHBURG, January, 1909. LITERATURE The books most likely to be helpful to students of this work are the psychologies of James, Angell, Thorndike, and Judd, and the following books: Morgan's " Comparative Psychology," Hobhouse's " Mind in Evolution," Washburn's " The Animal Mind," and some such zoology as Jordan and Kellogg's, References to these and considerable other literature will be found at the close of each chapter, but no attempt has been made to con- struct a complete bibliography. References likely to be most generally useful and accessible to stu- dents are starred. CONTENTS PAGE Preface . . . . • v Literature CHAPTER I Introduction Nature and Scope i General Characteristics of Organisms ..... 5 Evolution and the Genesis of Behavior and of Mind . . 8 The Psychic Factor in Behavior . . . . . .13 References . . . . . • . . . .14 CHAPTER II Structural Basis of Behavior General Principles ..... Specialization of Sensitive Structures Suggestive Stimuli .... Somatic and Kinsesthetic Sense Structures Development of Motor Structures . Somatic Motor Apparatus Specialization of Connecting and Regulating Apparatus References 16 17 26 30 31 33 33 37 CHAPTER III Types of Animal Behavior Amoeba ........... 39 Infusoria — Paramecium ........ 43 Lower Forms of Metazoa — Mydra, Medusa .... 53 Starfish ........... 58 xu CONTENTS PAGB Mollusca 60 Crustacea .......... 62 Fishes 64 Amphibia .......... 66 Frogs 66 Tortoises 67 Insects 68 Ranatra .......... 68 Ants .......... 72 Mammals and Birds 76 Guinea Pigs 76 White Rats 78 Domestic Animals and Birds 81 Raccoons and Monkeys ....... 83 Summary of Characteristics of Behavior .... 85 DiiTerentiation of Physiological Processes and Behavior . . 87 References 88 CHAPTER IV Imitation, Curiosity Complex Behavior Characteristic of Species — Instincts Nature and Differentiation of Instincts . Fundamental Forms of Instinctive Behavior Individualistic Instincts Parental Instincts . Social Instincts Adaptive Instincts, Play, Specialization of Instincts Constructive Instinct Collecting Instinct Esthetic Instinct Teasing . Jealousy . Expressive Instinct Regulative Instincts References 92 93 93 95 97 99 102 102 102 103 105 105 106 106 109 CONTENTS XUl CHAPTER V Behavior of Individuals — Acquisition of Habits AND Ideas PAGE Habit Formation . . . iii Complications of Instincts and Habits . . . . .119 Free Ideas • . . . . . . . . .126 References . . . . . . . . . '139 CHAPTER VI Structures Concerned in Complex Behavior and IN Ideation The Nervous Apparatus of Vertebrates 141 Differences between tlie Nervous System of Man and of Other Animals . . . . . . . . . .146 General View of Brain Functioning . . . . .152 Physiological Basis of Special Mental Processes . . .156 Perception . . . . . . . . .156 Mental Images . . . . . . . .158 Memory Images ........ 160 Concepts ......... 161 Physiological Mechanism of Attention and Thought . . 162 References ; . . 168 CHAPTER VII Consciousness Objective Tests of Intelligence and Criteria of Consciousness I. Structure . II. Behavior . 1. Discrimination 2. Motion 3. Purposefulness 4. Modifiability Subjective Criteria of Consciousness and its Functions Organic Unity and Continuity .... 169 169 171 171 172 174 176 179 191 XIV CONTENTS PAGE Seeming Continuity of Consciousness ..... 193 01)jective and Subjective Terms ...... 198 Probable General Characteristics of the Consciousness of Animals .......... 206 References 211 CHAPTER VIII Specific Conscious States General Character of Feeling in Animals Pain .... Intellectual States . Sensations Space Perception Perception of Objects Images and Memories Concepts and Reasoning Volitional Activity . References 214 217 222 222 227 233 238 247 250 254 CHAPTER IX Types of Adaptive Activity or Intelligence A Broader Conception of Intelligence Physiological Intelligence Sensory Motor Intelligence Representative Intelligence Conceptual Intelligence . The Four Types of Intelligence in Man References ..... 257 259 264 270 275 281 284 CHAPTER X Types of Learning Activity Nature of Learning The Physiological Type of Learning 286 288 GENETIC PSYCHOLOGY CHAPTER I INTRODUCTION NATURE AND SCOPE Psychology is usually defined as "the science of mind or consciousness." The words "Genetic Psychology" therefore at once suggest a science concerned with the beginnings and growth of mind. One naturally thinks of it as dealing with the growth of ideas or other states of consciousness in the minds of adults, of the development of children's minds and of the various grades of animal in- telligence and its development from the lowest species of animals to the highest races of men. These ideas sug- gested by the name all properly belong with the phe- nomena considered in this new science. Genetic psychology is properly concerned with changes in minds, especially with their development from simple beginnings into more complex forms, yet in order to know the facts regarding such changes and the laws of develop- ment, we cannot limit its field to a study of changes as they take place. Changes involved in the development of ideas and of minds may extend over periods of time ranging from minutes to millions of years. The same mind cannot be 2 GENETIC PSYCHOLOGY studied continuously but the changes must be observed at intervals. In many cases, instead of comparing the same individual at different ages it is necessary to compare indi- viduals of different ages and to compare species with species. In the study of the genesis of mind in the race it is utterly impossible to observe the changes as they take place, and the only mode of procedure possible is to study the difference in the minds of lower and higher animals and men, with a view to determining what changes have taken place, on the theory that simpler forms of minds have developed into more complex forms, and the simpler feelings and ideas into those of a higher type. Comparative psychology is primarily concerned with comparing and grading the intelligence of different species of animals and races of men, but genetic psychology is interested in grading the intelligence of animals only as a means of knowing what changes have taken place in the evolution of mind in the race, the order of such evolution, and the relation to each other of different types of mental activity. In attempting to compare, for the purpose of discovering changes in mind and ascertaining the laws of development, it is necessary to begin with characteristics that are com- mon to all creatures, rather than those possessed only by the higher creatures. Common characteristics in organisms may be sought (i) in structure, (2) in behavior, and (3) in conscious states. In ourselves and the higher animals these are all closely correlated, and it is reasonable to suppose that the same is true of the lower animals in so far as they possess these three characteristics. There is no doubt that all organ- INTRODUCTION 3 isms are similar in being composed of protoplasm and that they are active. Hence structure and behavior are com- mon to all. The third characteristic, that of conscious states, cannot be directly observed in animals, but can only be inferred from structure and behavior. We are justified in inferring consciousness only when their behavior has the same characteristics as behavior in ourselves that is always accompanied by consciousness. It is clear that the basis of genetic psychology should be entirely different from that of general psychology. The general psychologist finds in his own mind a great variety of mental phenomena, and by observing the actions of others and listening to their words, he can compare his mental states with those of others and thus determine the general truths regarding conscious states in adult human beings and the general laws of conscious activity. Physi- ological psychology supplements his study ,by facts of anatomy and physiology, while the experimental psy- chologist makes exact observations and measurements of mental states and objective behavior under definitely de- termined conditions. In genetic psychology the mode of procedure must be the reverse of that followed by the general psychologist. It must begin with structure and behavior instead of with mental states. The student of genetic psychology cannot observe the mental states of animals and infants, but the structure and the behavior of the simpler organisms may be studied with great exactness and a basis thus formed for inference regarding probable mental states. The comparative simplicity of such organisms and the possi- bility of removing parts without destroying life is of great 4 GENETIC PSYCHOLOGY advantage in this mode of procedure. The facts regarding structure and behavior of all creatures from the lowest to the highest, are open to investigation by this method, while the facts of consciousness may be directly studied only in one's own mind. The genetic psychologist cannot obtain a knowledge of the mental states of animals and young children by means of words as can the general psychologist learn of the mental states of adults. It would be very unwise, therefore, for the genetic psychologist who seeks to trace the development of mind in the race from the lowest animals to man, to base his science on the facts of consciousness. He must start with the facts of structure and behavior and trace their growth in complexity in the race and in the individual. In order that he may not unintentionally base his science on facts regarding conscious states that are possessed by himself but that perhaps are not found at all in animals and infants, he should describe the facts of behavior as far as possible in objective terms. When the facts and laws of behavior in animals and children have been determined without reference to consciousness, then inferences as to whether the activities described were or were not accom- panied by consciousness may be made. In doing this the behavior of adult human beings must be studied, not as does the general psychologist by giving the chief attention to the most prominent conscious states, but to the least prominent conscious states and to the activities that may be carried on successfully with little or no consciousness. Inferences regarding conscious states of animals and children may best be made from the states that are the least prominent, least highly developed, and that have been least considered INTRODUCTION 5 by the general psychologist, since the mental states dis- covered by the finer analysis of the general psychologist are likely to lead away from rather than toward the truth. The genetic psychologist, therefore, in order to ac- complish his purpose of throwing light on the genesis of mental states, must take the point of view of the objective sciences, and must determine the facts regarding activity, behavior, functioning, whether conscious or unconscious, before attempting to describe the development of conscious states. There must first be the science of the genesis of behavior before a true science of the genesis of mind and of conscious states can exist. The genetic psychologist must study the typical modes of behavior of all organisms, even giving some attention to the growth activities of plants, the laws of which conform to the fundamental laws gov- erning the behavior of animals. By thus determining the fundamental facts and laws of activity, whether conscious or unconscious, he will be able to formulate more correctly the laws of psychical development which may be looked upon as one form of activity. GENERAL CHARACTERISTICS OF ORGANISMS Since genetic psychology is concerned with all kinds of organisms, it is worth while to spend a little time in getting a conception of the essential characteristics of an organism. An organism may very well be regarded as a living machine composed of protoplasm, built in nature's factory, and fitted as are other machines for doing certain things. A machine is made in a comparatively short time and does not change its structure except in the way of wearing out, 6 GENETIC PSYCHOLOGY decaying, or breaking. An inorganism is a growth from small particles of other organisms whose ancestors have a long history of development, and it is changed by every- thing that it does into something somewhat different from what it was. An organism differs from an inorganic machine in being self-running, self-feeding, self-repairing, self-changing, self-regulating, and self-reproducing. No machine or in- organic substance is capable of doing any of these things to any considerable extent. These characteristics may all be expressed in a sentence by saying that an organism possesses and maintains unity. A crystal has unity but does not maintain it. If a crystal is injured, it does not repair the damage ; but if a plant or animal is injured, not too seriously, the damage is repaired. A molecule has unity which it maintains under certain circumstances, but with change of temperature and contact with other molecules, the unity may be broken, the atoms enter into new combinations and form a unity of an entirely different type. In an organism, on the other hand, though the molecules of which it is composed are continually chang- ing, yet the unity of the organism is maintained. Indeed, change in the molecules is the means by which an organ- ism maintains unity amidst changing influences. Death and disintegration result whenever the internal changes or activities are not of the right kind or degree to maintain unity among environing forces. The environing influences may modify the organism, but only when they kill it or cause it to cease to be an organism do they prevent it from maintaining its unity. The germ of an acorn becomes an oak, if it lives, and nothing else. Even when a part of a INTRODUCTION 7 plant or animal is grafted on another, the tendency to preserve a unity of the original type of organism is evident ; e.g. a peach bud or branch produces peaches though grow- ing on a plum tree. The unity of an inorganic thing is also static as compared with that of an organism, which is dynamic. It simply resists external forces for a greater or less time, instead of giving forth and taking in material from the environment and organizing it as a part of itself, as does the organism. The unity of an inorganic thing once formed is not changed except in a destructive way, while the unity of an organism varies as it grows and passes through different stages of development. Even after it is mature, an organism is subject to some modifications in its characteristics and modes of maintaining unity. Again, machines and molecules do not reproduce them- selves, while organisms not only maintain their own unity but produce other organisms like themselves. This is perhaps the most distinctive of all their characteristics. Between the two great types of organisms, plants and animals, there is no absolute distinction ; but in general, plants maintain their unity by taking suitable substances from the environment and building them into their own structure, while animals take in objects as wholes, disin- tegrate them, incorporate into their structure what is suitable, and excrete the rest. Animals not only use the substance taken in for forming their structure, but they also utilize the chemical energy set free by molecular changes in maintaining the heat of the organism and in keeping its various mechanisms, especially the muscular, active ; while plants use little or no energy in the movement of 8 * GENETIC PSYCHOLOGY organs and the maintenance of heat. Again, plants main- tain their unity chiefly by slow growth changes that bring them more favorable and less unfavorable stimulation and more usable substances which are simply absorbed, while animals usually preserve their unity by movements of parts or all of the body in such ways as will secure favorable stimuli and avoid unfavorable, and they find and secure food, disintegrate and distribute it to different parts of the body by the actions of organs (antennae, feet, teeth, intestines, etc.) specially adapted to those purposes. EVOLUTION AND THE GENESIS OF BEHAVIOR AND OF MIND The problem of the genesis of mind is simply one phase of the problem of evolution. It is not a question of crea- tion, but in a broad sense, one of how organisms are formed in nature's w^orkshop so that they behave in certain ways and perhaps exhibit a conscious life. Starting with protoplasm, which is simply a form of matter more highly organized than any single chemical molecule, nature, in the course of the ages, has produced an infinite number of species of organisms, each of which has its own peculiarities of structure and behavior and possibilities of being modified through elimination of some individuals and the reproductive activities of survivors. Every individual w^hich survives, attains a certain form and size and acts in such a way as to maintain life as an indi- vidual and produce descendants by which the species is perpetuated. How each species of animals came to have its charac- teristic size, structure, and mode of behavior is the problem INTRODUCTION g of evolution and of genetic psychology. The answer to this question must always be sought in the history of the species as well as in the laws of chemical and physical activity. The chief factor to be recognized in studying the history of the species is expressed by the words " natu- ral selection." The way in which this factor in evolution works may be illustrated by a concrete question, the answer to which in one case has been experimentally demonstrated. Why arc not sparrows as large as geese or as small as flies instead of being just about the size they are? After a severe storm a large number of sparrows were picked up in a helpless condition and as many as possible resuscitated. All were then weighed and measured to determine the size and proportion of parts. It was found that nearly all that varied to any considerable degree from the average were dead, while most of those near the average in all respects were alive. This of course means that a certain size and proportion of parts are most favorable for a sparrow living in this climate, and that those birds that vary the most from the normal are likely to be destroyed and produce few or no descendants. In a different environment or liv- ing a different life, the size and proportion of parts of the sparrow might be different, but in any case environment determines through natural selection the size of sparrows living in a certain way in a certain place. What is true of the size of the sparrow is true of all his other character- istics, including his behavior ; for if he attempted to do . what his structure does not fit him to do, he would be at a disadvantage and would be eliminated by natural selec- tion and along with him that mode of sparrow behavior. lO GENETIC PSYCHOLOGY What is true of sparrows is true of all creatures ; all are destroyed whose modes of behavior and structure do not correspond so as to enable them to maintain proper rela- tions with the environment. In studying the structure and behavior of various types of organisms we must inter- pret them as means of survival for the individual or for the species, and we must expect the usual behavior to be effective in proportion as the conditions under which the individual acts are the same as they have been for his ancestors for many generations. If the~ con- ditions are radically different, what was an effective mode of maintaining existence may be useless or even destructive, e.g. it is of advantage for sheep to follow their leaders on their native plains, but in the mountains they may thus be led over a precipice. So far we have indicated only how organisms having certain characteristics suitable to a certain mode of life and environment are prevented, while the species remains under those same conditions, from changing their charac- teristics in any considerable degree. Both the genetic and the complete evolutionary view, however, demand something more. Evolutionary theory demands that we shall also explain how various species of animals have changed their size and characteristic correlations under domestication, and how a number of differing specjes in a natural state may have developed from common ancestors instead of the original characteristics only of the species having been preserved by natural selection. If we suppose that each type of organism possesses potential characteristics that may either be made prominent or suppressed, then without INTRODUCTION II any assumption other than we have already made, we may explain such transformations either by changes in the mode of behavior of different groups of the common species, which necessitated corresponding changes in structure, or by different groups being subjected to different environ- ments so that characteristics that were harmonious in one were eliminated in another. Some species of sea animals, for example, have remained practically the same through many geological ages, probably because their environment and mode of life have not changed, while land animals, exposed to great variations in environment due to lati- tude and changing elevation, have dift'erentiated into a great variety of species, living and extinct. Structure, behavior, and intelligence in any species of animals are all correlated modes of insuring survival in a given environment according to certain modes of life which have remained the same for many generations. In so far as the conditions are uniform, behavior is machine- like. Each individual may be regarded as a typical ma- chine formed by natural selection to do the things in the given environment which will usually secure survival for members of his species. The mode of life and environment of the species must be known in order to understand the action of an individual organism, just as we must know the purpose of a machine and the materials upon which it works in order to understand it. Genetic psychology must not only consider these correlations in different species and determine common principles of correlation in all species from the simplest to the most complex, but it must also trace the changes in these correlations as species have developed into higher forms in the life of the race. It 12 GENETIC PSYCHOLOGY must also determine the relation existing between the stages of development of the individual and those of the race, and the interaction between racial, individual, and en- vironmental factors in the life of the individual. In the life of an individual organism, however, there are many changes from the infantile mode of maintaining exist- ence to that of the mature creature. Every change in struc- ture and mode of life must be accompanied by other changes in order that the balance upon which life depends shall be preserved; e.g. various muscles must have developed be- fore the young creature can successfully change from a life of dependence upon parents for food and protection, to that of complete independence; and the abandonment of liquid for solid food by the human infant needs to be correlated with the development of teeth. One of the chief problems of genetic investigation is to determine just what, in detail, are the normal correlated changes in struc- ture and behavior in each stage of development of the individual, in order that he may at all stages be in harmony with his environment. Natural selection has no doubt determined what these correlations are at each stage of development, in the same way as it has determined the cor- relations of the mature individual, but with slightly less definiteness, because temporary variations are less likely to result in death than permanent ones. So far we have assumed two principles upon which evolutionary theory is founded ; that of like producing like, or heredity, and that of variation, because of which descendants are not exactly like ancestors and not exactly like each other. The last gives opportunity for natural selection to work and the first helps to perpetuate what INTRODUCTION I3 natural selection has caused to survive. These factors in evolution will not here be discussed further than to say that the chief question to be answered is, "What are the causes of variation?" the chief points in dispute being as to whether environment is a factor in producing varia- tions as well as in destroying inharmonious ones, and as to whether variations acquired during the life of an in- dividual are transmitted to its descendants. THE PSYCHIC FACTOR IN BEHAVIOR Since we know nothing of the conscious states of animals except by inference, it is best to seek to explain just as much as possible of the behavior of all organisms from the lowest to the highest without presupposing the psychic factor. When we can find nothing similar to our unconscious physiological instinctive and habitual behavior by which the behavior of any creature may be explained, then we are justified in trying an explanation that involves con- scious states similar to our own. Whether consciousness is or is not an element in any particular form of behavior is to be determined by the facts rather than by presup- positions, but it is safer not to assume conscious states until all the simpler and more demonstrable factors in behavior have been given due weight. At the same time we are to retain the right to suppose consciousness an effective factor in behavior whenever necessary. It is reasonable to believe that this, like all other characteristics of organisms, is the product of natural selection, and that it has been preserved in certain kinds of behavior of certain organisms because it has proved 14 GENETIC PSYCHOLOGY useful. Of course, if one chooses to suppose that conscious- ness, like protoplasm, is an element in all organisms and in every organic activity of plant or animal, it is useless to dispute his claim, but we should still be governed by the same principle of using conscious states like our own as explanations of behavior only when the behavior can be explained in no other way. Even if we admit that con- sciousness is present in some form in all organic activity we must not allow ourselves to believe that the conscious- ness is like that we experience until such a supposition gives the most probable explanation that we can obtain. The habit of explaining our own actions and those of others in terms of consciousness is so strong that it is hard to avoid thinking of conscious states as the cause of the behavior of organisms, and when one does resist the tend- ency, it is often hard to find terms not implying conscious- ness in which to describe clearly and briefly the behavior of even the simplest creatures. A special set of terms is needed for this purpose, but in the absence of any that are well known, we shall try to make our meaning clear by using, when necessary, old psychical terms with broader meanings. REFERENCES *Angell. Psychology, Chapter I. Baldwin. Mental Development, Methods and Processes, Chapter I. Baldwin and Cattell. Consciousness and Evolution, Science (N.S.), Vol. II, pp. 219-223. *BuMPUS, H. C. Elimination of the Unfit, Biological Lectures at Wood's Hole, 1897-1898, pp. 209-226. Carus, p. The Soul of Man, pp. 54-65. *Conn, H. W. The Story of the Living Machine. INTRODUCTION 15 Davies, Ernest. Suggestions toward a Psychogenetic Theory of Mind, Jr. Phil. Psych. &= Sci. Meth., Vol. IV, pp. 342-356. *Hall, G. S. a Glance at the Philetic Background of Psychology, Am. Jr. Psych., Vol. XIX, pp. 149-212. Herrick, C. L. The Nature of the Soul and the Possibility of the Psycho-Mechanic, Psych. Rev., Vol. XIV, pp. 205-228. ■ Genetic Modes and the Meaning of the Psychic, Psych. Rev., Vol. XIV, pp. 54-59- *HoBHOUSE, L. T. Mind in Evolution, Chapters I and II. *JuDD. Psychology, Chapter I. Kjrkpatrick, E. a. a Broader Basis for Ps3'chology Necessary, /;-. Phil. Psych, b' Sci. Meth., Vol. IV, pp. 542-546. *Moore, J. H. The Universal Kinship. Mills, W. Animal Intelligence, Chapter I. ♦Morgan, L. Comparative Psychology, Chapter III. Animal Life and Intelligence, Chapter I. Comparative and Genetic Psychology, Psych. Rev., Vol. XII, pp. 78-97. Romanes, G. J. Mental Evolution in Animals, Chapter I. *Washburn. The Animal Mind, Chapter I. *Wundt. Human and Animal Psychology, Chapter XXIII. CHAPTER II STRUCTURAL BASIS OF BEHAVIOR GENERAL PRINCIPLES Just as any movement made by a machine is determined by the nature of its parts and their relation to each other, so also must the behavior of an organism be the result o^ its structure. In the lowest organisms, such as the amoeba, there is little permanency of form, and action differs somewhat according to the form the creature has at the moment. In higher animals structure is compara- tively permanent, though subject to gradual growth or decline. Such structures as bones are relatively rigid, while other parts, notably muscular and nervous tissue, are more or less easily and permanently changed in their size and re- lation to each other by repeated and sometimes by single experiences. Where the various nervous and muscular ap- paratus are grouped into only slightly connected reflex mechanisms, the modifications produced by experience are comparatively slight. If an animal's behavior is dependent upon the action of fixed structures it must, in order to survive, either come into helpful and harmful relations with a very few phases of its environment, or else it must possess a great many varieties of fixed structures with which to make the right i6 STRUCTURAL BASIS OF BEHAVIOR 17 reaction to the various situations that affect it favorably or unfavorably. As a matter of fact, most organisms, like many machines, instead of having an apparatus for each thing to be done, are capable of a variety of adjust- ments for various purposes and to meet varying situations. A creature possessing a small number of fixed structures, yet having a mechanism by means of which the different parts may be made to act in various combinations to meet a great variety of situations, is fitted to survive in an en- vironment affecting it in many ways. If, in addition to the natively possible adjustments, the creature is so made that combinations that have had favorable results are more readily made again, then the individual animal can quickly adapt itself to new phases of its environment. As we shall see, the fundamental characteristics of all organisms are similar. The higher organisms can do many things that the lower cannot, and they are often able to reach the same results in more eco- nomical ways. This is not because they are composed of substances of an entirely different character or because they possess many varieties of apparatus, but because of specialization in structure and more complete correlation and cooperation between parts. We must therefore take a very general view of the specialization in structure upon which the behavior of animals depends. SPECIALIZATION OF SENSITIVE STRUCTURES The skin of man, like the surface of the amoeba, re- sponds to electrical, chemical, mechanical, and thermal stimulation. In the amoeba all parts respond equally, 1 8 GENETIC PSYCHOLOGY while in man and the higher animals some parts are much more sensitive than others. JNIOreover, the parts most sensitive to one kind of stimulus, as heat, may be less so to another, as pressure. No organism, whether possess- ing nervous tissue or not, is insensitive to these fundamental stimuli. Nearly all possess some specialized touch apparatus for responding to mechanical stimulations, and the same apparatus is frequently quite sensitive to other kinds of fundamental stimuli. This touching surface is always correlated with the form of the animal and its habits of life in a given environment. In most creatures the whole of the surface is sensitive in some degree to mechanical stimulation, but the parts near the mouth are usually most sensitive. Movable parts are especially sensitive, particu- larly those that are likely to be stimulated in moving around in search of food. In creatures having a hard and comparatively insensitive surface, like crabs and beetles, there are usually special touch organs at the anterior end in the form of antennae. These parts are usually very sensitive, not only to contact and pressure, but also to other fundamental forms of stimu- lation. In mammals the tongue and lips are most sensi- tive of all portions of the skin to contact and pressure. These parts are also sensitive in a general way, like the rest of the skin, to other fundamental stimuli. in addition to this, certain portions of the tongue and mouth are provided with special forms of nerve endings that are sensitive in a special degree to chemical stimuli that in man give sensations of sweet, salt, sour, and bitter. Specialized organs of taste are found in all the higher STRUCTURAL BASIS OF BEHAVIOR 1 9 vertebrates, but are not easily demonstrated in fishes and frogs, though the Crustacea and worms act as though they possessed such organs. By means of these sensitive sur- faces particles unsuitable for food are discriminated and rejected more effectively than would be possible with a surface sensitive to contact only. Near the mouth is often found a specialized surface that is particularly sensitive to other kinds of chemical stimuli than those of taste. Stimulation of this surface in man gives rise to the various sensations of smell. The organs for receiving these stimuli conveyed to them in the air do not appear to be at all complex in structure, but they are won- derfully sensitive, being excited by smaller amounts of matter than any other sense organ, and giving rise to an immense variety of specifically different sensations. The olfactory apparatus is much larger in a great many animals than in man. In fishes and other aquatic animals it is sometimes very large, but as the stimulus must come to them in liquid form the sense is probably more allied to taste than to smell. With a well-developed olfactory apparatus an animal can react not only to objects that are in actual contact with it but to emanations that are in a way samples of objects at a considerable distance. He is thus greatly aided in escaping danger and in finding food. Water ani- mals provided with the proper sensitive apparatus, whether it be called a taste or smell organ, may also react to ob- jects not in contact with them, though not when they are at such great distances. Taste and smell are usually classed together as chemical senses and the biological purposes they serve are evidently 20 GENETIC PSYCHOLOGY similar. Even in man these two senses are not clearly differentiated from each other or from contact and tem- perature sensations. Coffee and ice cream are relished only when all three senses are properly stimulated, al- though we usually, perhaps, think of taste as the only sense involved. Light is primarily a chemical stimulus of slight intensity. It is responded to more or less quickly by creatures with- out any specialized surface for its reception and by some creatures, such as worms, after their visual organs have been cut out. In this condition they may respond not only to variations in light intensity, but also, as Graber showed, to rays of different vibration length, since they come to rest chiefly in one colored compartment rather than those of other colors. In such animals all the life processes are probably increased or decreased by changes in light in- tensity and the effects of waves of certain length are greater than those of others. In general, animals that seek the light, or in other words are positively phototropic, are likely to go to the ultra violet end of the spectrum, while those that avoid the light, or the negatively phototropic, move toward the red end of the spectrum when light cannot be avoided. The most primitive special organ for responding to light stimulation is only a slightly modified portion of the touch organ, skin, or tentacle that is more sensitive than the rest to variations in light intensities. The pigmented eye spots of the starfish are organs of this type. With such organs an animal can react to the shadow of an object that has not yet touched it, as does the clam, because of the variation in light intensity produced by the approaching STRUCTURAL BASIS OF BKHAVIOR 21 or the approached opaque objects. In such cases the reaction is not due so much to the immediate chemical effects of variation in light stimulation upon the whole organism as to the excitation of a sensitive apparatus that then causes a motor apparatus to move a part or all of the body. Some animals thus respond to variations in light in- tensity caused by objects, although no shadow is produced. If objects of a certain color in the environment are usually injurious or helpful, then all individuals but those most sensitive to this stimulus will be eliminated by natural selection. We may suppose therefore that sensitiveness to different kinds of light stimulation in any species of animals depends upon what kinds of light stimulation it has been most necessary for it to respond to in its usual environment. Yerkes' experiments prove that light rays do not always pro- duce the same relative effects on animals as on man. He found that two colors of the same brightness to human eyes were reacted to as if different by Japanese mice, while colors of differing brightness to human eyes were responded to by the mice as if they were the same. We know in our own case that some colors are distinguishable in a dim light more easily than others. The same is true of periph- eral compared with foveal vision. Probably it is more useful to discriminate some colors in a dim illumination than others. The visual apparatus of each creature doubtless fits it for discriminating significant stimulations under the usual conditions in which the species lives. For all species to discriminate brightness, is probably more important than to discriminate colors ; hence organs for responding to brightness develop earlier than those for responding to special colors. 22 GENETIC PSYCHOLOGY Moving objects are in general more significant to animals than motionless ones, hence we find that the more primi- tive organs of vision are especially adaj^tecl to the percep- tion of motion, a condition retained in the periphery of the human eye. In many of the lower animals reaction to the stimulus of a moving object is made possible by the possession of many simple eyes or by compound eyes. Insects possessing compound eyes appear to discriminate stationary objects of different colors, yet their own motion and the difference in the brightness of the colors may be the chief factors, and there may be no color or form per- ception of stationary objects when the creature is at rest and the object not moving. Animals that react to objects of different colors, such as fish, insects, and higher animals, have lenslike structures over the portion specialized to respond to light stimula- tions, which concentrate the rays upon this more sensitive part, thus increasing the effects of the stimulus. In the invertebrate eye the lens concentrates the rays of light, but in general the nerve fibers going to the eyes do not cross. In the vertebrate eye the pigment layers are behind the nerve fiber layer and at least a portion of the fibers cross, which probably makes possible some use of the two eyes together. In some instances the eyes are so located that both may be affected by the same object while in others they are not. When they do not have almost the same field of view they are usually nearly stationary in the head, and the head or the whole body must be moved to get a change of view and perhaps any perception of form of the stationary object. It is not likely that chickens, for example, have a clear perception of the outline of STRUCTURAL BASIS OF BEHAVIOR 23 objects. Their perceptions and those of most birds and mammals are probably no more clearly defined than is one's perception of the exact outlines of an object in a fog or in semi-darkness. The retina of the lower vertebrates is relatively undiffer- entiated, only the rodlike structure of the retina being present ; while in the higher, there arc both rods and cones and they are much more crowded together near the fovea. This differentiation of the sensitive visual surface is prob- ably necessary to clear vision of stationary objects and to the perception of specific colors, since cones seem to be the special organs for discrimination of color differences. Experiments upon man show that only when both the ob- ject and the eyes are nearly stationary can the form of the object be clearly seen, although the mere presence of objects is more readily discovered when they or the eyes are moved. In man's activities, form is of great significance and there is good reason to believe that he discriminates form far more perfectly than other animals. This is made possible by the wonderful optical instrument with which he is furnished. As a lens for bending the rays of light it is probably no better than that of many animals, but the retina presents more variations between the fovea and the periphery than are found in any other animal. This, with the power of accommodation for different light in- tensities and distances of objects, and the power of accurate fixation and movement of the two eyes so as to make the two images combine, renders it possible to perceive the form of stationary objects with wonderful accuracy. In its fundamental nature, sound stimulation is pro- duced by waves of air or liquid, instead of objects, striking 24 GENETIC PSYCHOLOGY a sensitive surface. Probably all portions of organisms that are sensitive to mechanical stimuli are sensitive to sound stimuli in some form or in some degree. Certain it is that deaf people not only feel jars but can enjoy music through the fingers resting on a piano or other vibrating surface. Helen Keller also readily distinguishes the vibrations caused by the step or voice of a child from those of an adult. Some of the lov^er organisms react to a jar just as they would to a touch on their most sensitive surface. The simplest form of specialized organ is the otocyst, which contains stonelike bodies that when set in motion stimulate the auditory nerve. Organs of this same general character, called statoliths, surrounded by liquid, serve also as a means of maintaining equilibrium, being stimulated by variations in the pressure of the liquid, as the animal moves. In some creatures that make sounds, and therefore probably hear, organs of hearing are not easily demon- strated. In the case of fishes, frogs, and higher animals, when the organs of hearing are clearly present, it is often difficult to get definite responses to sound stimulations. Yerkes could not get from frogs any response to any kind of sound stimulation given alone under laboratory condi- tions, though a sound stimulus was found to modify the reactions of the frog to other stimuli that were being given at the same time. The observations of Courtis show that frogs in the mating season respond to the call of mates. Yerkes obtained response from Japanese mice to auditory stimuli only from young animals for a few days at a certain stage of their development, and he could obtain no response from adult animals. STRUCTURAL BASIS OF BEHAVIOR 2$ Sounds that arc not very intense are in themselves neither harmful nor helpful to most animals, and since a large proportion of sounds are rarely or never followed by stimuli that are either harmful or helpful to many species of animals, it would be a useless waste of energy to react to every sound. Most animals therefore do not respond to most sounds unless they are very loud or sudden. The sounds that they do most surely rcsj)ond to are those that in the life of the species have usually meant unfavorable or favorable stimuli to follow. We find therefore that the sounds most surely reacted to are the calls and cries of companions signifying food, danger, or the presence of a mate. Sounds made by enemies, e.g. the rattlesnake, and by prey, are also frequently reacted to instinctively; but most other sounds bring no response, unless sudden, intense, or of a kind that in individual experience has been associated with unfavorable or favorable results. Sounds repeated again and again rhythmically, as in music, are reacted to by both animals and man, though they are not suggestive of any stimulus to follow. This is probably because there is summation of the slight stimuli on account of the rhythm, so that the vibrations set up in the nerves spread to the muscles, which then produce either rhythmic movements or a balanced con- traction of parts that keeps the body, as a whole, still. Even in us this is more a mechanical and physiological result than it is a psychical, for we can often keep time more perfectly in an involuntary than we can in a voluntary way. The effect of strong or rhythmical sound stimulation is a mechanical effect comparable to the chemical effect of light stimulation of strong intensity. It may also produce important physiological changes as light does. 26 GENETIC PSYCHOLOGY The anatomy of the ear of higher animals is more com- plex in its adaptation for the reception of stimulation than any other sense organ. There is an external ear for catching the sound vibrations, a middle ear for intensifying their effects, and a very complex structure in the internal ear, not yet fully understood, for receiving vibrations of different lengths and exciting nerve endings. Though suited to respond to vibratory motion, the organ as a whole is not movable as is the eye. Animals whose safety de- pends upon perceiving the direction of a sound usually have the external ear movable. In man the motion needed to determine the direction of sound stimulation is effected by means of the muscles of the neck. Since the ear cannot, like the eye, shut out stimulation and cannot of itself react in a motor way, its stimulation is naturally more closely connected with the muscles con- trolling the vocal organs than with other parts of the body. Since there is not usually a sufficient immediate motor outlet for the effects of sound stimulation, and since sum- mation effects are possible, it is not strange that more in- tense feeling may be produced by sound stimulation than by visual. SUGGESTIVE STIMULI It is worthy of note that the most highly developed sense organs are not those of most fundamental importance in the life processes, not those stimulated directly by the ob- jects themselves, not those that receive immediately useful or harmful stimuli, but those that receive chiefly what may be designated as ^^ suggestive stimuli," which are not in themselves favorable or unfavorable. It is also to be STRUCTURAL BASIS OF BEHAVIOR 27 noted that it is not simj^ly the sensitive surface itself that is highly specialized for the senses of sight and hearing, but the apparatus for conducting the stimulus to the sensitive surface and intensifying its effects. Why is this ? Prob- ably because elaboration of sense organs for receiving stimuli from objects with which the creature comes in contact is not necessary, since there is little that is useful to do except to get into closer contact with the stimulus already being received or move away from it, according as it is immediately helpful or injurious. Mechanical stimuli can vary significantly in only a few directions and the same is true of taste stimuli. Hence an organ giving a great variety of sensitiveness is not in either case neces- sary. In general, the reaction of higher animals to the visual stimulus of objects is not a direct reaction to the chemical stimulus, which in itself is only slightly different for differ- ent objects, but the visual stimulus is suggestive of some other more intense stimulus of a favorable or unfavorable character. The suggestive stimulus is therefore reacted to in much the same way as if the frequently associated and more intense stimulus were actually given, as when, for example, the head is drawn back as if struck, when a moving object suddenly appears in front. Reactions to all but the most intense sounds are also almost universally of this character. Where the life of the species has been such that a certain visual or auditory stimulus has nearly always been fol- lowed by something that was harmful or helpful, those animals that do not resj)ond to the suggestive stimuli are soon eliminated from the species by natural selection. 28 GENETIC PSYCHOLOGY The scattering and seeking of cover by chickens when an object comes quickly from above, is a good example of the characteristic reaction of all members of the species to a suggestive stimulus that, in the life of the race, has frequently been followed by the attack of an enemy. Nearly all learning in the case of higher animals and in the case of human beings, in so far as it is of a sensory motor character, is in the nature of the acquisition of a reaction to a suggestive stimulus of some kind that has usually brought with it either favorable or unfavorable results. Smell acts at a distance from the main bulk of the stimu- lating body so that time is given for a complicated and varied sei-ies of movements before the stimulating object itself can do harm or good. The olfactory organ is, therefore, wonderful in its power to respond in a specific way to a great variety of objects which are likely to be injurious or helpful to the creature if it comes in actual contact with them. No elaborate external structure is provided for this purpose, but there is such great differentiation of nerve endings in the nose and the brain that an immense number of chemical stimulations significant in the animal's life may be responded to. In the case of the suggestive senses, sight and hearing, distant objects of all kinds may give stimulations and the slightest variations in their character may be of the great- est significance in determining the favorable or unfavor- able character of the distant object. Hence elaborate and complex structures are necessary in order that these slight variations may be detected and reacted to in the proper relations. The number of significant objects in STRUCTURAL BASIS OF BEHAVIOR 29 the environment revealed to creatures possessing such sense organs is so great that it would be impossible to have a single characteristic kind of response, as in the case of smell. Hence these senses respond, not in a specific way for each class of objects as does smell, but to an infinite number of variations and combinations of a few elements. For example, in odor, a dog and a mouse are doubtless specifically different to a cat, whether they are near or distant, large or small, stationary or moving; but in the visual sensations they cause, a dog and a mouse are not specifically different, but the appearance of the two animals varies according to their nearness, position, and move- ments, and the direction and the intensity of the light. It is not any one quality by which they are distinguished but the peculiar combination of qualities presented in any given situation. The visual and auditory organs are wonderful structures for intensifying a few varieties of stimulations and co}n- bining them in many ways, while the olfactory organ is a marvelous structure for responding to a great variety of specifically different stimulations, but it can do little or nothing in the way of combining them. Speaking figura- tively, it gives samples of objects while the eye and the ear give letters which may be combined in an infinite variety of ways into words signifying objects. Man has found no mechanical means of making the organs of touch, taste, and smell more effective, and it is probably neither desirable nor possible that he should do so. On the other hand, the suggestive sense organs of sight and hearing have had their effectiveness wonderfully increased by inventions that have brought us into relation 30 GENETIC PSYCHOLOGY with an environment of the almost infinitely small and almost infinitely distant. Defects in these organs may also be corrected by artificial means, but little or nothing can be done by any mechanical de\ice to correct defects in the senses of touch, taste, or smell. SOMATIC AND KINiESTHETIC SENSE STRUCTURES Although the greatest specialization of sensitive surface is shown in the special sense organs that are portions of the surface of the body, it must not be forgotten that there are special sensitive structures within all the vital organs that are stimulated by changing conditions and activities of those parts, so that one organ may respond in an appro- priate way to changes taking place in other parts of the body and thus equilibrium and unity of life processes be maintained. These internal sensitive structures relate the organism as a whole in an indirect way to its environment by respond- ing to variations in the amount of food and air in the body, by sensations of hunger, thirst, suffocation, exhilaration, fatigue, etc. Many of these somatic sensitive responses rarely or never produce conscious sensations, though they are doubtless all the time playing an important part in the physiological processes involved in adjustments of circula- tory, respiratory, and digestive activities, and indirectly affecting conscious states. There are also certain sensitive structures located chiefly in the movable portions of the body that are concerned in the direction of movements, sometimes called kinesthetic sense organs. There is some question about the existence STRUCTURAL BASIS OF BEHAVIOR 31 of these structures in the muscles themselves, but they are readily perceived in the attachments of muscles and bones and in joint surfaces. These sensitive structures are stimulated not so much by external objects or by in- ternal conditions as by the activity of the movable parts as they react to external things. They are therefore espe- cially important in responding to external stimulations appropriately, according to the space relations of the body and its parts to each other and to surrounding objects. THE DEVELOPMENT OF MOTOR STRUCTURES No improvement in sensitiveness can be of any advantage to a creature unless it has also a motor apparatus capable of a corresponding delicacy of movement. We must expect therefore a close correspondence between sensory refine- ment and motor complexity. Some of the lower animals, such as crabs, squids, and millepeds, have many movable parts, one serving one purpose and one another. In the higher animals there are fewer prominent organs of move- ment but much more cooperation of the parts in perform- ing each of various movements. Not only do the limbs cooperate with each other in the higher birds and mammals, but the toes and lingers in which they terminate cooperate with the limbs and with each other in a way that would not be possible if they were merely finer organs of movement separately attached to the body. Man has special advantages in his motor endowment because of his upright position, that permits the effective use of the hands, because of the llexibility of the hands, and the possession of a thumb that can be opposed to the 32 GENETIC PSYCHOLOGY fingers in manipulating objects and handling tools. The motor mechanisms of his vocal organs and of his eyes are also extraordinarily versatile and delicate. Without such motor structure no degree of sensory refinement would give man his preeminence above other animals. The movements that are most frequently useful to the species are, in the higher animals and in man, provided for by the arrangement of the muscles into groups that are connected with bones which serve as levers, in such a way that when certain muscles begin to act, other mus- cles act in a correlated way, and a movement of a definite type results as surely as the pulling of one rope in a series of pulleys and cords causes the object to which they are attached to move in a certain direction. The extent to which movements are determined by the arrangement of muscle groups instead of by nervous connections has re- cently been found to be much greater than was formerly supposed. It is possible for a dog with a nerve cut, which connects a limb with the central nervous system, to use the limb fairly well in walking. Pressure resulting from the weight of the animal and the consequent movement of some muscles, apparently, in such cases serve as a stimu- lus to the moving of other muscles. Man's advantage in dealing with objects arose origi- nally from the high development of a motor apparatus capable of a variety of adjustments. He has. greatly in- creased this advantage by a great variety of tools and other mechanical devices for moving and modifying objects with force, quickness, and exactness. He not only uses tools to direct and increase his strength, speed, and effectiveness in moving and modifying things. STRUCTURAL BASIS OF BEHAVIOR 33 liut constructs machines to utilize and direct the energy of animals and of wind and water. He does not stop here, but manufactures power through the transformation of one form of energy into another, transports it and directs it by means of machines in the performance of all kinds of acts. The strength, accuracy, and rapidity of motion that he can control is therefore almost unlimited. SOMATIC MOTOR APPARATUS Not all motor organs are concerned in obtaining favor- able relations with the environment. A vast number of small and less conspicuous organs help to carry on the internal activity of the vital organs. They also transport to every portion of the body the material needed to continue its activity and take out of it waste materials. Muscular tissue is found not only in the heart, lungs, and intestines, but connected with every blood vessel and gland. This system of motor organs is in general separate from that concerned in relating the organism to its environment. SPECIALIZATION OF CONNECTING AND REGULATING APPARATUS A very small organism in direct relation with its environ- ment can act as a unit without any special connecting and regulating apparatus. A larger animal with parts well balanced may be able to do some things successfull}- without a close organic connection between parts. The abdomen of a bee can sting as effectively when properly stimulated as a whole bee, but the animal is verv much 34 GENETIC PSYCHOLOGY crippled if one wing is clipped. Connection between parts is, however, of advantage even in the lower animals. One arm of a starfish can right itself when severed from the body, but the whole animal is unable to right itself if the nerve ring connecting the arms is severed, because each arm then acts against the other arms instead of cooperating with them in the turning movement. In the case of animals that react, not by means of a special apparatus for making a particular kind of mo- tion, but by means of several organs combined in a certain way, connection of parts is absolutely necessary. Since in such animals various combinations of such apparatus must be made in accomplishing different purposes, an apparatus that not only gives communication of one part with another, but also helps to determine what particular combinations to make, is needed. Such an apparatus will be more useful if it acts differently according to the results of previous experience. In the nervous system we have an apparatus that combines these qualities in a high degree, although other tissues, especially the muscular, have the same qualities in a slight degree. A typical nervous apparatus consists of a sense organ connected by a sensory nerve with a center, which is con- nected by a motor nerve with a motor organ. When the sense organ is stimulated, the impulse passes along the nerve fibers to the sensory cell bodies, and through the dendritic processes the excitation is carried to the motor cell bodies, and an impulse passes from them to the muscle, causing it to contract. Groups of such cells constitute nerve centers. In the higher animals there arc not only many such groups corresponding to different parts of the body, STRUCTURAL BASIS OF BEHAVIOR 35 but as we shall see later there arc often several centers at different levels connected with the same parts of the body by means of which one part is adjusted to another. The nervous structure is remarkably susceptible to modification and very retentive of such modification. Hence such animals as possess a highly developed nervous system are able in a way to carry about with them the re- sults of past experience. The nervous system is a regula- tive apparatus, at least in the sense that it connects parts more effectively than other tissues, and determines what combinations shall be made, not merely by reacting more or less readily than formerly to certain stimuli being re- ceived, but by acting as if former stimuli were now pres- ent. In other words, it not only transmits impulses by means of which the proper relation of })art to part and of the whole to the environment is maintained, but it also serves as a storage house of experience which may at any time largely direct the reactions. In large animals an immense number of strands or nerve fibers are needed to go to all parts of the skin, to other organs of special sense, to the vital organs, and to the muscular apparatus. The natural place of meeting for the fibers carrying these stimulations is somewhere inside the body. In vertebrates there is a continuous line of nervous tissue near the center, known as the spinal cord, into and from which the nerve fibers run. In animals below the vertebrates the fibers end in groups of nerve cells called ganglia, sometimes largely isolated from ganglia in other parts of the body, and sometimes massed into what is called a brain. Usually they are grouped around or near the mouth. 36 GENETIC PSYCHOLOGY These central masses of nerve tissue serve as means of connecting not only sense organs with muscular mechan- isms, but each sensory apparatus with every other, and less directly, all organs and tissues with them and with each other. In the higher animals there is a very large mass of nervous matter at one end of the spinal cord which con- stitutes the brain. In fishes the brain is very small, and it may be cut away without greatly affecting their movements. Frogs live for a considerable time after its removal, and can scarcely be distinguished from normal animals, except that they make few movements when not stimulated, and that the results of stimulation can be more accurately predicted. A brainless frog will croak with almost as much certainty when stroked in a certain way as an electric bell will ring when the button is touched. A con- tinued stimulus, however, of a brainless frog may result in a change of reaction, just as we shall find is the case in some of the animals much lower in the scale of develop- ment. For example, if a continued acid stimulus is ap- plied to the tlank of a frog, there is not simply a movement of contraction, but the foot moves as if to wipe off the acid. If it cannot do so, and the stimulus continues, the other foot may be used. Similar phenomena of the spread of the effects of a stimulus to organs on the other side of the body, and sometimes to all parts of the body, have been found in experiments upon the nervous system of other animals. Pigeons with most of the brain removed react to immedi- ate stimuli in much the same way as ordinary pigeons, but they do not usually respond to suggestive stimuli in a way indicating perception. For example, they respond to contact with a mate in much the same way that they would STRUCTURAL BASIS OF BFJIAVIOR 37 to any other solid object, trying to get over it or around it. Dogs in a similar condition will eat food placed in their mouths, but are not likely to take it in response to a visual stimulus. It appears, therefore, that the spinal cord of higher animals performs much the same function as the nervous system of animals lower in the scale and without much development of the higher sense organs of sight and touch. Besides the great mass of nervous tissue in the spinal cord and brain of the higher animals, which is concerned in making all parts work together in responding to the environment and modifying it for the good of the individual and the species, there is a large amount of nervous tissue forming a system by itself, known as the sympathetic nervous system, which connects all the internal organs in such a w^ay that they can act harmoniously and effectively in maintaining life. This system plays the same part in unifying the physiological processes that is played by the brain and spinal cord, or central nervous system, in unify- ing the behavior of an organism in its relation to its en- vironment. The two systems are, however, connected, and the activities of each influence the other. REFERENCES *Angell. Psychology, Chapter II. *Ayers, E. a. Eyes and Vision from Worm to Man, Harper's Monthly, September, 1908. Baird, J. W. The Color Sensitivity of the Peripheral Retina, Publications of the Carnegie Institution. *Carus. The Soul of Man, pp. 66-106. ♦Carpenter. Mental Physiology, Chapter II. *CoLE, L. J. An Experimental Study of the Image-Forming Powers 38 GENETIC PSYCHOLOGY of Various Types of Eyes, Proc. Am. Acad, of Arts cf Sci., 1907, pp. 335-417- Hall, G. S. and Donaldson, H. H. Movement Sensations of the Skin, Mind, Vol. X, pp. 557-572. J.A\rES. Psychology, Chapters II, III, IV, and V. *JoRDAN and Kellogg. Evolution and Animal Life. *JuDD. Psychology, Chapters II and V. Keller, Helen. Sense and Sensibility, Century, February, 1809. Kakuen, G. Hudson. Speech as a Factor in the Diagnosis and Prognosis of Backwardness in Children, The Training School (Vineland, N.J.), April, 1908. KiRKPATRiCK. Fundamentals of Child Study, Chapter III. *Loeb, J. Comparative Physiology of the Brain and Comparative Psychology. ♦Morgan, C. L. Animal Life and Intelligence, Chapters II, VII. Nagel, Dr. Oskar. On Seeing in the Dark, Psych. Rev., Vol. XV, pp. 250-254. Parker, G. H. The Sense of Hearing in Fishes, Am. Nat., Vol. XXXVII, p. 185. The Skin and the Eyes as Receptive Organs in the Reactions of Frogs to Light, Am. Jr. Physiol., Vol. X, p. 28. The Function of the Lateral Line Organs in Fishes, Bull. Bureau of Fisheries , Vol. XXIV, p. 183. Hearing and Allied Senses in Fishes, Bull. U.S. Fish Commis- sion for 1902, pp. 45-62. *Washburn. The Animal Mind, Chapters V, VI, VII. Yerkes, R. M. The Instincts, Habits, and Reactions of the Frog, Associative Processes of the Green Frog, Harvard Psych. Studies, Vol. I, p. 579. * The Dancing Mouse, Chapters III, IV, V, VI, VII, VIII, IX, X, XL CHAPTER III TYPES OF ANIMAL BEHAVIOR AMCEBA The amoeba is the simplest of organisms, without organs or distinct parts, and with no permanent form. Its be- havior is similar to that of inorganic semifluid particles and yet is distin- guished by some of the fundamental characteristics of all organisms. When floating free in the water it has no means of locomo- tion, but it can change its shape Fir,. I. — Amoeba proteus suspended in the Dy Senaing out -water, showing the long pseudopodia extended in pseudopodia or all directions. After Leidy (1879). From Jen- armlike projections "'"^^' in every direction. This is likely sooner or later to bring it in contact with food particles or other solids. If one pseudopodium touches a solid, it remains against it, and the rest flow into it, and then the whole creature in its new form 39 40 GENETIC PSYCHOLOGY can move along the surface of the solid by a sort of flowing movement, by which the upper parts flow in the direction of movement over the lower. Sometimes several pseu- dopodia lead the advance, but none form in the rear. Slight obstacles modify the direction of movement by causing pseudopodia to project out to one side into which the rest of the creature flows, and thus it gets around the obstacle if it is small. If the obstacle completely bars the way, the flowing particles reverse their direction, and the creature moves backward. The direction of movement may also a t c Fig. 2. — Method by which a floating amoeba passes to a sohd. From Jennings. be modified by thermal, chemical, electrical, and light stimulations, the direction of movement in general being away from injurious stimuli. If the particle touched is small, the amoeba flows around and incloses it, and if it is a food particle, digests and ab- sorbs it into itself. If the particle touched rolls, the amoeba follows and begins the inclosure again. In a case observed by Jennings, where an amoeba, partially inclosed by another, sent out pseudopodia and escaped, the larger amoeba, which had started to move away, reversed its movement and followed and caught the smaller amoeba again, a movement that suggests the pursuit and capture of prey by larger animals. On the other hand, if we sup- TYPES OF ANIMAL BEHAVIOR 41 pose that there is a certain amount of tension in the amoeba, it is conceivable that on mechanical principles the movement would be reversed when the tension in the rear was relieved by the passing out of the smaller amoeba at that end. Although subject to simple mechanical and physical prin- ciples of movement, an amoeba Fig. 4. — Negative reaction to a me- chanical stimulus when the entire an- terior end is strongly stimulated, a and h, successive stages. The arrow x shows the original direction of motion; the arrows in a show the currents im- mediately after stimulation. In b a new tail {t') has been formed from the former anterior end, uniting with the old tail (/). From Jennings. Fig. 3. — Negative reaction to me- chanical stimulation in amoeba. An amoeba advancing in the direction shown by the arrows is stimulated with the tip of a glass rod at its an- terior edge (a). Thereupon this part is contracted, the currents are changed, and a new pseudopodium sent out {b). From Jennings. is a particle of organized matter that tends to move because of energy gener- ated within itself, though the direction of its move- ments is changed by the various stimuli that it re- ceives. Its movements are also in general of such a character that food is ob- tained and injuries avoided. In this it resembles higher animals, and also in the fact that it responds to nearly all 42 GENETIC PSYCHOLOGY the principal stimuli that they do, except the auditory. It appears also that its movements are not mechanically produced from without but from within, as influenced by previous motion and the effects of external stimuli. The migratory cells of some of the corpuscles of the blood of human beings, and many of the bacteria, behave in a manner very much the same as the amoeba. Immunity to disease of various kinds is due in many cases to increase in number of those cells in the blood that feed upon and destroy the disease germs. If such cells in our own bodies are organic mechanisms without individual consciousness, the amoeba and other lower forms of animals probably are, while, on the other hand, if we regard the amoeba as con- scious, we should think of many of the cells of our own body and the swimming spores of plants as having each a consciousness of its own. Even if it is admitted that the amoeba is conscious, its responses to mechanical, chemical, electrical, thermal, and light stimulation, do not necessarily imply definite sensa- tions of contact, heat, taste, smell, or sight. There is little or no differentiation in its reactions to these various stimuli, but merely positive or negative reaction according as the stimulus of whatever kind is favorable or unfavorable. So long as the response of any animal to a stimulus is not specifically different from the response to other stimuli, there is no more reason to suppose differentiated sensations for each stimulus than there is to suppose that a person who responds to sounds of all degrees of pitch, or light of all colors, necessarily discriminates each from all others. On the other hand, failure to respond to any stimulus does not positively prove that it produces no effect, for TYPES OF ANIMAL BEHAVIOR 43 stimuli that have no practical significance to animals may be ignored by them as they often are by man. INFUSORIA These are more completely organized than the amoeba, with more permanency of form and specializa- tion of parts. The surface or ectosarc is thicker and less flex- ible than that of the amoeba, so that pseu- dopodia cannot be sent out or food in- closed by all portions of the body. There is an opening for taking in the food, known as the oral cavity or mouth, and another for excretion. Movements are made chiefly by means of cilia, though the be- p,^ ^_ _ p.^amedum, viewed from the oral ginningS of contract- surface. Z., left side; i?, right side; o?«., anus; ile or muscular tissue "'' "''°'^|'"= '"" ^"dosarc; /.v., food vacu- oles; g, gullet; w, mouth; wa., macronucleus; can be detected in mi., micron ucleus; o.g., oral groove; p., pel- these creatures. '''^'^' ''"' trychocyst layer. The arrows show ,_, . the direction of movement of the food vacuoles. The Paramecium, From Jennings. 44 GENETIC PSYCHOLOGY often visible to the naked eye in fresh water among de- caying vegetation, is typical in its behavior. It is cigar- shaped, with the mouth nearer the pointed end, which enables us to use the term "anterior" for that end and "posterior" for the other end. The surface opposite the mouth may be called the aboral surface (back) of the ani- mal. Viewed in this way the animal has not two similar sides but is slightly spiral in form. The path of the animal /. ^- FiG. 6. — Diagram of the avoiding reaction of Paramecium. A is a solid object or other source of stimulation. i-6, successive positions occupied by the animal. (The rotation on the long a.xis is not shown.) From Jennings. in swimming is spiral because the cilia strike in a slightly oblique direction and because the oral ones strike more vigorously than the others. In backward movement the cilia simply reverse, and the path is still spiral, the direction changing as the oral or mouth portion is up or down. Since there is continual rotation, the general direction of the spiral may be maintained. Its characteristic avoiding movement when it strikes a solid is to reverse cilia, move backward, turn to one side, and move forward again. This movement, repeated if TYPES OF ANIMAL BEHAVIOR necessary, usually gets it away from or around an obstacle. The more rapid movement of the cilia next the mouth causes a current down the mouth that brings food and also gives the animal samples of the liquid from various directions, thus offering a chance for reaction to chemical or other stimulation before the creature has actually entered the medium containing it. If it approaches water that is hot, the cilia reverse, causing the animal to move backward ; then they act directly again, and the animal is turned partly over and moves for- ward in a new direction. If the unfavorable medium is not thus avoided, the action is repeated again and again, till, if possible, a favor- able direction of movement is found. In the presence of chemical and thermal stimuli the front sometimes swings around until the unfavorable stimulus is not received, then the forward movement takes place. Fig. 7. — Spi- ral path of Par- amecium. The figures I, 2, 3, 4, etc., show the successive posi- This movement is quite analogous tions occupied. . .1 , r • 1 The dotted areas to that 01 a person or animal ... „ i with small ar- when he looks around before mov- rows show the ing in what seems to be the most ^""^"^^ ^"^ ^^^^^ ^™ from in front. From Jen- favorable direction, except that the nings. 46 GENETIC PSYCHOLOGY injurious stimulus is actually present instead of being suggested by another stimulus. If it is dropped into water slightly hotter than it is used to, it makes the avoiding reaction once or twice, then a ;' ^ > ; '/' '_ : '-.'■/'w'-' ,'/',--/:■/: ;.- --; ;-I 19- 19' l L|ir-£-.-I%5£->i :-: = .-■-; '.-'.'■' 26- ""■ 38- c IH 10' 25- Fig. 8. — Reactions of paramecia to heat and cold, after Mendelssohn (1902). At a the infusoria are placed in a trough, both ends of which have a temperature of 19 degrees C. They are equally scattered. At h the tem- perature of one end is raised to 38 degrees, while the other is only 26 degrees. The infusoria collect at the end having the lower temperature. At c one end has a temperature of 25 degrees, while the other is lowered to 10 degrees. The animals now collect at the end having the higher temperature. From Jennings. ceases, the change, not the absolute temperature, evi- dently being reacted to. If the water is very hot, it con- tinues the alternate reversal and forward movements until it dies. The turning is always toward the aboral side, and this helps to avoid injurious media, when, as usual, they affect TYPES OF ANIMAL BEHAVIOR 47 the mouth first; but if experimentally the stimulus is given on the aboral side, the turning is toward instead of away from the stimulus, and the injurious medium is entered instead of being avoided. Thus the movements that under the ordinary conditions of its life are helpful are, under unusual conditions, harmful. Seemingly positive reactions are often really negative, as when animals in a half per cent salt solution gather in a drop of one tenth per cent solution. This is because they accidentally get in the weaker solu- tion as they move in various directions and react by rever- sal whenever they touch the stronger and less favorable solution. In a simi- lar way they gather where light and temperature are least unfavorable, the avoiding reaction occurring only when they pass away from the optimum. If a weak acid instead of a salt solution is placed in the water, the para- mecia collect in it for the same reason. The animals themselves give off carbonic acid, which is favorable, hence they are likely to gather in groups because movement into pure water produces the avoiding reaction. Experiment shows that the avoiding reaction is not pro- portional to the osmatic pressure or to the strength of injurious substances, some solutions producing avoiding reactions only at the killing strength and others at a small fraction of the killing strength. Paramecia pass into all Fig. g. — Collection of paramecia in a drop of bV per cent acetic acid. From Jennings. 48 GENETIC PSYCHOLOGY acid solutions without the avoiding reaction, but give it upon starting out, hence they remain, although in some cases death is the result. This is another illustration of behavior determined in a certain environment by natural selection; for the substances not reacted to until of killing strength are not usually found in the medium in which the Paramecium lives. When the paramecium is moving slowly and strikes lightly against a solid, it may move backward a short dis- tance, then forward again, and come to rest against the solid. In this case the cilia against the solid become still and those of the posterior end may either move or become quiet ; but those next the mouth continue to move, which often results in food being drawn into the mouth from decaying vegetation, against which the animal is in such cases likely to be resting. In swimming, paramecia are likely to move in a direc- tion opposed to gravity until they are near the surface. When resting against a solid, the anterior end may point in any direction, but is rather more likely to point upward, perhaps because of the different specific gravity of the substance of which the animal is composed. Slight local contractions of the ectosarc occur in response to various stimuli, though no muscular substance has been discovered in it. Experiment shows that the animal responds more readily to mechanical stimuli on the anterior end than on the posterior, hence there is some differentiation of the surface into more and less sensitive portions. This may be looked upon as the beginning of surface dift'erentiation upon which proper space reactions and space perceptions OF TYPES OF ANIMAL BEHAVIOR 49 depend. A jar is reacted to by an avoiding movement just as if the more sensitive anterior end had been stimu- lated, hence local signs or differentiation of surface are evidently the determining factor in space reaction. When two stimuli are acting at once, paramecia show more variability in reacting, thus one receiving the contact stimulus does not respond so readily to heat, mechanical, or chemical stimulation as one that is swimming ; while on the other hand, strong thermal stimulation modifies the contact reactions. Again, electrical stimulation modi- fies reaction to heat and chemicals. A paramecium that is feeding does not respond so readily to stimula- tions. This is analogous to the behavior of higher organ- isms that are said to be ignoring one stimulus because they are attending to another. Internal conditions, due to previous stimulations or movements or to nutritive conditions, greatly modify behavior. A paramecium that has recently fed and is in a favorable medium, usually remains quiet if not disturbed, and if stimulated, does not respond c^uite so readily as usual, while one that has not fed for some time is likely to move around a great deal. Unfavorable stimulation also causes great activity. This illustrates the general truth that all organisms, including man, do more and de- velop more when the conditions of life are not all favorable. From a study of paramecia it appears that seemingly positive movements in search of favorable stimuli are often due to hunger or unfavorable conditions produced by an injurious medium, that these movements are as likely to be away from as toward favorable conditions, and that favorable conditions are obtained chiefly through negative 50 GENETIC PSYCHOLOGY reactions to all unfavorable stimuli that arc received, and continued positive movements, until the creature is again in harmony with its environment. Positive reactions to favorable stimuli, therefore, first appear chiefly in the form of a slowing of movement or its cessation when a favorable stimulus is received. There is no reaction, either negative oi positive, to a stimulus not touching the animal, though there is reaction in some cases before any part but the mouth has been stimulated. The paramecium differs from the amoeba chiefly in having a better developed and more permanent apparatus for making preservative move- ments. It is indeed a wonderful illustration of how many and how varied movements, that are generally useful, can be made by means of the same simple apparatus. In taking food, the method of trial and varied action is used by the paramecium, everything being taken that can be, the larger and harder particles being rejected by an avoiding movement, while digestible substances are ab- sorbed and smaller useless particles are passed on and eliminated. No discrimination is shown in taking food, but different objects produce different movements after they are taken. That movement depends on internal conditions as affected by previous stimulations, is shown very clearly by the behavior of stenlor, another variety of infusoria with greater possibilities of varied movement than the Paramecium. These creatures are usually attached to some surface by a tube into which they can contract. If stimulated by a jet of water that is not harmful, they contract, then after they have resumed a normal position, a similar jet of water is not responded to, the animal ap- TYPES OF ANIMAL BEHAVIOR 51 parently having become used to this new form of harmless stimulation, just as higher animals become used to a sound that is repeated several times in succession. If the stimu- FiG. 10. — Stentor roeselii, showing the currents caused bj' the cilia of the peristome. From Jennings. lus is given more strongly , there maybe several contractions, or the body may bend to one side as if to avoid the stimulus in that way. When an injurious stimulus is given, the first avoiding 52 GENETIC PSYCHOLOGY reaction is usually that of bending first to one side and then to the other, which, if not successful, is followed by contracting into the tube. If the stimulus still continues, it contracts violently in its tube till it breaks its attachment, when it swims away from the irritating stimulus. It then moves around as if searching for a suitable place, and after finding it, oscilates over it in a way that hastens the forma- tion of mucus, by which it soon becomes attached. Such behavior is, on the one hand, suggestive of consciousness, while on the other it is very analogous to phenomena found by physiologists in studying the effects of repeated stimu- lation of a nerve and muscle that have been dissected out for experimental pur- poses, also similar to the movements of a headless frog. Summation of stimuli Fig. II. — ■ Stentor ,-,.„. . roeseiii contracted into ^nd diffusion to Other parts, causmg new its tube. From Jen- and Varied movements as in the stentor, ^^^^' are common in all animal mechanisms. The resulting movements are like the trial and success move- ments of the Paramecium, only in a greater variety made possible by more complex motor apparatus. The changes in behavior must be due to changes within the creature, since the stimulus and other external conditions remain the same. The action seems to be self-preservative or regulatory, like learning by experience in higher animals ; but the m^odification is temporary, perhaps lasting no longer than the condition immediately produced by the stimulus. However crude and wasteful these methods of maintain- ing life may be, they are not to be confused with the chance TYPES OF ANIMAL BEHAVIOR 53 movements of an inorganic body affected by wind, wave, or other force, for the organism is not moved by the stimulus but moves itself in response to it. The move- ments are also regulatory, since if they are not at once successful, they continue and vary until relief is obtained. Fig. 12. — Spontaneous changes of positions in an undisturbed hj-dra. Side view. The extended animal (i), contracts (2), bends to a new position (5), and then extends (4). From Jennings. LOWER FORMS OF METAZOA — HYDRA, MEDUSA Types of the lower forms of the mctazoa are the hydra and medusa. The hydra has nerve cells with branching processes scattered through the body, evidently performing the usual function of nervous structure, that of connecting parts with each other. 54 GENETIC PSYCHOLOGY Under the same conditions a hydra that has been without food for some time is more active than one that has had Fig. 13. — Hydra looping along like a leech. After Wagner (1905). 1-6, successive positions. From Jennings. enough. Any movement is hkely to bring it sooner or later into contact with food, hence is advantageous. The more usual position of the hydra is with foot at- tached and head free. Gravity does not seem to determine the position, for if there is a solid above to which the foot TYPES OF ANIMAL BEHAVIOR 55 may be attached, the animal hangs with head down and of course free. Some relatives of the hydra seem very responsive to gravity. Under the stimulus of hunger or unfavorable stimulus the head of the hydra bends over and becomes attached and the foot straightens up, thus producing inversion. Fig. 14. — A chemical {ch) is brought against a certain spot on one side of a Hydra {a). Thereupon this spot contracts, bending the Hydra toward the side stimulated (6). From Jennings. This is followed by bending to attach the foot, the raising of the head, and the righting movement. By such motions the animal continues to change his position till relief is obtained. As a rule, movements in response to unfavorable stimu- lation are sooner or later such as result in relief, yet if the whole animal is thrown into hot water, they continue, though nothing is gained. The mechanical character of the movements is still further indicated by the fact that if the foot instead of the head is stimulated, the movement of contraction is the same and thus the stimulus is ap- 56 GENETIC PSYCHOLOGY preached instead of receded from. This is of course only another illustration of natural selection fixing a movement that is under usual conditions beneficial, so that it will be made, whether in the particular case it is beneficial or harmful. Local stimuli sometimes produce local reactions only. Thus if a hydra is stimulated lightly on the side, the por- tion affected contracts, and as a result the animal bends over. Hydrae gather on the moderately lighted side of a vessel rather than on the dark side. Food is more often found on that side, so the gathering on that side may be partly due to the greater activity when hungry and less activity when there is plenty of food. Hydrae gather where there is oxygen, which is usually at the surface, probably because of negative reactions when they start to leave the region of oxygen. Unless very hungry the food-taking reaction is not called forth by mechanical stimuli alone as in paramecia, and not usually by chemical stimuli only, meat juice alone not producing it unless the animal is very hungry. Both kinds of stimuli are usually necessary, hence we have what amounts to a partial selection of food, everything not being swallowed as it is by the paramecium, but only such particles as give both contact and chemical stimulation. In the medusa the nervous and contractile tissue is better developed than in the hydra, with the nervous tissue arranged in two rings and connected with the contractile tissue. This improved structure makes possible a more effective form of reaction than that of trial movements. In the medusa the first contraction often helps to move TYPES OF ANIMAL BEHAVIOR 57 the part stimulated and the whole animal away from the stimulus. Such movements are the forerunners of reflexes and instincts that become more definite with elaboration of mechanisms for producing them so that they are im- mediately protective and not merely advantageous by varied action and final success. The hydra, as we have seen, changes its position when intensely stimulated, but is as likely to move toward the stimulus as away from it. The medusa is said to "fish" with its tentacles, and it is more active when food is near if it has not just fed, but the food is found by trial and error rather than by direct approach. After the food has been touched, the whole body works together to secure and swallow it. Mild food-securing reactions may be called forth by experimental use of mechanical and chemical stimuli that have no food value, but they soon cease when the usual series of food- securing stimuli are not received. Contact with a moving and struggling object causes the food reaction to be made and completed, while contact with a motionless object does not produce the reaction at all. This is a further basis of food selection, since living, moving objects are the usual food. The mechanical nature of the food-taking reaction of the medusa is strongly suggested by experiments in which one tentacle with its base is separated from the others, and when stimulated with food, bends in the same direction it would have bent had it been still a part of the whole animal. When such a mechanism is a part of the whole body, it may be made active by the movement of an adja- cent part in response to a stimulus and its own activity may be either greater or less because of what is taking 58 GENETIC PSYCHOLOGY place in adjacent mechanisms. This is typical of what takes place in reactions of higher animals, except in them the relation of part to part is, as we shall see, much closer. Thus not simply the part stimulated, but the whole body is modified by, and reacts in response to, a local stimulus. The connection of parts is closer because of a more com- plete and developed nervous system that greatly facilitates transmission of stimuli as well as contractile effects. STARFISH The echinoderm family is best represented by the star- fish. The general form of the starfish is suggested by its name. Attention, however, should be called to the fact that besides the five movable arms with secondary motor organs in the form of tube feet, there are a vast number of little organs known as pedicellariae all over the surface of the body that serve the purpose of protecting the many little openings that serve as gills and also for capturing prey. These little organs rise up above the spines and open their jaws whenever the gills are stimulated by a small moving object and close upon whatever is then in contact with them. The delicate gills are thus protected and various animals captured for food. The stimulus that causes one or more pedicellarise to rise, spreads without nervous connection and causes others to rise. Those that have recently been stimulated are most sensitive, as is shown in a striking way by the fact that pedicellariae that have been recently stimulated may rise when others at some distance do so, although the intervening pedicel- larise do not. These facts indicate that although nervous TYPES OF ANIMAL BEHAVIOR 59 tissue is especially suited to the transmission of excitation, yet other tissue can perform that function. In general the starfish moves away from light, but it seems to have some sort of rudimentary sense of sight that causes it to move toward objects when not in their shadow even when it must pass through a slightly brighter space to do so. It reacts as a whole to tactual and other stimuli in such a way as to get away from unfavorable stimuli and secure favorable ones. The stimulus given by a moving object may result in its seizure, but unless a chemical stimulus is also given the movement of bringing the object to the mouth is not produced. As a result, it rarely swallows any but living objects. The behavior of starfish in righting themselves when turned over has been most studied. All the arms are likely to begin to be more or less active, but as soon as one or two have become attached to some object the others join in a unified impulse by folding under and turning the whole body over. A particular specimen, studied by Jennings, used certain arms for righting itself more than others, while one arm was not used at all. The attempt was made to induce the animal to use this arm by preventing it from turning over unless it did. The attempt was successful, and further practice was given in the use of that arm until it was readily used. The creature was then placed on its back and al- lowed to right itself without interference and was found to use the formerly unused arm much of the time even after an interval of two days. Here we evidently have an instance of behavior in an individual organism, modified by the results of previous 6o GENETIC PSYCHOLOGY activity, in a manner very analogous to what in higher creatures we call memory. In the organisms previously studied we have noted changes in behavior due to the per- sisting effect of recent stimulation and movement, but here we have something more. It is not simply the immediate after effects that remain, but a more persisting modification of the organism. The change in habit in the case of the starfish disappears rather rapidly if it is allowed to right itself under various conditions, because the direction of righting is influenced by the direction of the light, the position of the body, the kind of surface with which the several arms first come in contact and also by previous movements and various other external and internal factors. The repetition of any factor that proves to be dominant may therefore start a new habit that will soon be as strong as the one given the animal by special training. MOLLUSCA In these creatures, of which the clam is the most gener- ally known, sense organs are not highly developed, but some portions of the body are more sensitive to light than other portions. Their reactions to light are not due chiefly to the immediately harmful or favorable effects of light stimulation, but to the usual significance of the variations in the light stimulus. For example, clams close their shells in response to the shadow of a moving object, not because the shadow is injurious, but because it is the pre- cursor of a possible enemy. Nearly all the reactions of these and higher animals to light are due not to the immedi- ate physiological effects of the light stimulation but to the TYPES OF ANIMAL BEHAVIOR 6l relation of light variations to helpful or harmful objects in the surroundings. Bohn has shown that the movements of littorinas nidis, a species of periwinkle, may be directed at will by means of light and dark screens of various sizes placed in appropriate positions, the direction of movement of the animal being the result of the positive and negative effects of light upon it. The shadows of rocks and other objects in its natural environment probably serve as directors of its movements in searching for food. In this, as in other cases, there is no permanent and un- changing mode of reaction to light stimulation, but the reaction is influenced by various causes internal and ex- ternal, connected with the usual conditions of life. This is well illustrated by the reactions of different varieties of the littorina living at different elevations among the rocks washed by the tide. When the tide is out they move over the rocks in search of food, those at a higher level moving toward the water and those at a lower level away from it toward the rocks, the movement in one case being aw^ay from the shadow of the rock, and in the other case toward it. Those at the middle level show more marked varia- tions in their positive and negative reactions correspond- ing to the position of the sun and the coming in and going out of the tide. These movements are not, however, de- termined wholly by the immediate stimulus of variations in light and in moisture, but are to some extent the result of rhythmic changes in the organisms which render them at one time positively j)hototactic and at another time nega- tively phototactic. This was demonstrated upon specimens of these animals in an aquarium by means of experiments with light and dark screens at different times of the day. 62 GENETIC PSYCHOLOGY Bohn proved that other sea creatures have a rhythm estab- lished in their organism by the tides. A sea anemone that Uves attached to stones in pools closes when the tide is low and oxygen becomes scarce and opens when the waves of the high tide strike it. Artificially produced waves in an aquarium call forth the reaction at the time of high tide but not at other times. Individuals that have lived in deep water so that they were not exposed at low tide, do not react in this way. CRUSTACEA In Crustacea, of which crabs and lobsters are the most familiar examples, there are clearly developed organs of sight and the reactions of these creatures to light are de- termined, not by its effect upon the body as a whole, but upon the amount and portion of the eye surface that is illuminatedo Their reactions to light stimulations, as determined by surrounding objects, are much more com- plex than in the case of mollusca. Since they react to numerous objects, favorable and unfavorable, in various ways, it follows that the explanation of their reactions cannot be found in .the mere physical fact of variation in light stimulation but in the habits and necessities of existence of the creature in its usual surroundings. Spaulding found that hermit crabs, when undisturbed, sought the lighter portions of the aquarium, though when threatened by an enemy they sometimes hid in dark corners. He found that if food was placed behind a screen where it was dark they moved toward it as the chemical stimulus from it came to them. Food was placed there day after day, immediately after inserting the screen TYPES OF ANIMAL BEHAVIOR 63 and after a while they would go behind the screen when it was put in place though there was no food there. This seems to be a case of learning by experience to respond to a light stimulation in a way slightly opposed to the in- stinctive mode of reacting to such stimulations. This habit persisted for a number of days. To other forms of stimulation the crab does not readily change his mode of reaction. Bethe found that crabs that took refuge in a dark corner continued to do so, although they were mal- treated every time they went into that corner. It has also been found by Ransom that the antennae of a crab may be clipped off by shears again and again without his learning to react to the suggestive visual stimulus of the shears, although he draws back every time the antennae are cut. Yerkes found that crabs, after from forty to two hundred and fifty trials, aUvays took the right path to the aquarium. These experiments indicate that the crab's reactions to visual stimuli may be modified, after a number of trials, by faA^orable results, but that unfavorable results do not readily change reaction so as to inhibit an instinctive tend- ency. Reactions to stimulations other than those of light are well illustrated by Bell's experiments upon the reactions of crawfish to chemical stimuli. He found that chemical stimuli, such as meat juice, acid, salt, etc., were responded to more or less definitely when applied to any portion of the body, but that in general the responses were more vigor- ous and definite in the anterior portions, especially those around the mouth. The reactions to meat juice were in general positive ; that is, such as tended to give the animal more of the stimulus, the movements made often being 64 GENETIC PSYCHOLOGY such as would bring a solid particle of food into the mouth if the chemical stimulus had come from such a particle. The reactions to lavender water, to acids, and to salt were clearly of the opposite character, often being so definite that the exact spot affected was rubbed. The reactions to the other fundamental taste stimuli, sweet and bitter, were very slight. When food is placed in the water, crawfish do not go to it in response to the visual stimulation, but after a little time they move in rather an uncertain or trial manner toward it, evidently being directed by the chemical rather than by the visual stimulation. When they come in con- tact with food, it is seized by a very definite movement ; but the same is true when they are touched by stones and other inedible food particles. When out of the water they will not move toward meat though it is quite near them. This may be because they are not sensitive to a chemical stimulus in gaseous form or it may be because of their instinctive tendency to feed only when in the water. Crustacea are affected to a slight extent, if at all, by sound stimulations. The otocysts with which they are provided are probably stimulated by vibrations of the water and by changes in position in maintaining equilibrium, but reac- tions to sounds do not seem to play any part in their usual behavior. FISHES In fish we have a still further complication of reaction to light. It is no longer a response to the mere chemical effects of light, as in the lower forms of animal life, nor to shadows, as in mollusks, nor to objects varying in size and TYPES OF ANIMAL BEHAVIOR 65 brightness as in Crustacea, but a response varying accord- ing to the color of objects. This has been proved by experi- ments of Washburn and Bentley upon a creek chub. The fish was fed with forceps upon which were red and green strips of wood, but he was allowed to have the food only when it was on the red forceps. The instinctive tendency to snap at the food was so strong that the failure to get it from the green forceps did not, after many repetitions, inhibit the movement. When, however, both forceps were disclosed to view at once, the red with food and the green without, the fish learned, after about twenty-five trials, to go to the red forceps, showing that he was differently affected by the two colors. This was true after the dark red was changed to light red and after the green was re- placed by blue. The fish would also go to the red forceps when both were empty and this was sometimes true even when the food was in sight near him. The attempt was made to reverse this reaction to color that had been developed by training, by putting the food on the green forceps and leaving the red empty. The fish snapped at the red fourteen times, then at the green, but failed to get the food. It then returned and snapped at the red again thirteen times. After long practice, however, it learned to go to the green first. In the process of learn- ing, it would do this immediately after having had a number of trials, with considerable certainty, but the next day it would be more likely to go to the red the first time. Finally, however, a positive reaction to green was established. The fish has a more completely developed auditory apparatus than the Crustacea, and experiments have shown that it is affected not only by vibrations produced in the 66 GENETIC PSYCHOLOGY water, but by sounds made outside of the water, although its behavior does not seem to be determined to any con- siderable extent by auditory stimuli. The lateral-line canals extending along the sides of the fish probably in- crease the sensitiveness to vibrations of the water. AMPHIBIA In animals of this class, of which frogs and turtles are common types, a much greater variety of behavior is necessary than in the case of fishes which live in the water all of the time. Some of the amphibia live in the water most of the time, while others live almost entirely on land. Their behavior is considerably more complex than that of even the higher Crustacea, which can exist for a considerable time out of the water but spend most of their lives in it. In the frog sight seems to be the dominant sense, par- ticularly when stimulated by a moving object. Although it does not react directly to all moving objects, it is very sensitive to such stimulation. Experiments of Yerkes show that its reactions to stimulations of the skin are modified very definitely by the stimulus of a moving object. If the moving object is seen about one tenth of a second before the stimulus is given, the reaction is reenforced, while if it is given less than a twentieth of a second before the stimulus the reaction is inhibited. This reenforcing and inhibiting effect of stimulation given at nearly the same time that reaction to another stimulus is being tested, is of the same nature as has been found in many experiments, notably those upon the tendon reflex in man. Frogs rarely react directly to sound stimuli, although TYPES OF ANIMAL BEHAVIOR 67 they have a pretty well developed auditory apparatus and will themselves make sounds. The chief sound to which they respond at almost any time is that made by another frog jumping into the water. At the breeding season the females respond very definitely to the call of the male. Under laboratory conditions it appears to be impossible to get any direct response to sound stimuli of any kind. It is found, however, that sound as well as light exerts an inhibiting or enforcing effect when given at the time or just before a reflex movement is being made. In this way Yerkes showed that they were thus affected by sounds varying in vibration rate from fifty to ten thousand. Tortoises seem to be higher in the scale of intelligence than frogs. They react quite definitely to objects of vari- ous kinds and to sounds of certain kinds. To what extent they discriminate color has not yet been determined. Yerkes found that a tortoise could learn a complicated path in five trials as perfectly as crabs could learn a simpler path in forty. Their behavior is therefore much more subject to modification than that of the Crustacea and also than that of most fishes. One of the marked differences between land and water tortoises, as shown by Yerkes' experiments, is in their space and gravity perceptions, or, in other words, their reactions when there is no stimulus giving them the sense of support. Water tortoises that are used to getting out on the land and on logs or rocks and jumping off into the water when danger threatens, crawled oft' boards elevated from the floor without hesitation, while land tor- toises, like most other land animals, reacted in a negative way whenever stimuli giving a sense of support were lack- ing. Vision seemed to play a large part in such sense of 68 GENETIC PSYCHOLOGY support and the hesitation was greater with increased height of the board from the floor. When blindfolded, the land tortoises became cautious about moving, and in some instances drew back soon enough, after a foot had passed beyond the board, to prevent falling. INSECTS The characteristics of insect behavior are perhaps best shown in Holmes' experiments upon the common water scorpion or needle bug, ranatra fiisca. These creatures are capable of living on land, though they spend most of their time in the water and they are able to walk, swim, or fly. This implies considerable complexity of organization, and yet careful experiment shows that they, more than almost any other creature, are composed of parts capable of acting reflexly, to a considerable extent independently of other parts, and that the reactions of the whole animal are determined largely by the results of these separate reflexes. Few if any creatures react with such definiteness to light and contact stimuli. It follows accurately with its head all movements of a light when in a dark room. If the light is above or behind, it raises its head up ; if it is in front or below, its head is bent down. If the light is moved from side to side in front, the head follows it with more and more accuracy as the act is repeated. If the light is brought further around to one side the body tips toward that side. The longer it is stimulated by light the more perfectly does it come under its influence. When very much excited it may use its wings in following the light. TYPES OF ANIMAL BKILW'IOR 69 At such times it is not easily afTected by any other stimulus and cannot readily be thrown into the death feint. If it is placed on its back at this time, it will move toward the light without taking time to turn over. The creature is not, however, always positively photo- tactic. If it has been in the dark for a long time, it reacts to light with less vigor and usually in a negative way. This is true of the leg movements, which are exactly the reverse of what they are in the usual condition, although head movements are not. A negativ-e condition may also be produced by picking up a ranatra by its breathing tube and dropping it into the water. This is probably because in nature a mode of reaction to light, the opposite to the usual one, is of advantage in the presence of danger. The negative condition is produced more readily by dipping or dropping into the water than by handling either in or out of the water. If the water is warm, the negative state is more quickly replaced by the positive. Reactions to light, under experimental conditions, are not always favorable to self-preservation. It will continue to move toward a light when in the positive condition, al- though the heat becomes so great as to injure and destroy it. This is not because the movement cannot be checked in time to stop the injurious stimulus before it has become fatal, for the creature moves very slowly and its very last feeble effort at moving is toward the light that is destroying its life. This may be interpreted as a purely mechanical reaction that is ordinarily advantageous, but under these unusual circumstances is fatal. It has also been inter- preted as an instance of voluntary persistence in action that is subjectively pleasurable in spite of the fact that it is 70 GENETIC PSYCHOLOGY objectively destructive to the organism. As we shall see later, this interpretation may be true of man's acts but it is not likely that it ever is of those of any other animal. In general, the creature does not react to more than one stimulus at a time. If it is rubbing its wings or feeding or is in close contact with its mate, it is not likely to react to light, unless it be to a slight extent with its head. Symmetrical balance of parts is probably an important factor in determining the movements of the creature as a whole. If the brain is divided in the middle there is some twitching, indicating sensitiveness to light stimulation, but none of the characteristic movements of the body either positive or negative in response to the light. When the brain is intact and one eye blackened over or destroyed, the creature moves in a circle. If one eye is partly blackened over, there is a tendency to circular movement which is usually more or less perfectly corrected. Experience seems to modify the reaction in this respect, for after a number of trials an individual with one eye blackened was found to take a more and more direct course toward the light. The effect of experience was still further shown in the fact that after the animal had turned in one direc- tion a number of times in order to move toward a light in a certain position, it would continue to turn in that direc- tion, even when it was faced in such a way that it would be more direct and more natural for it to turn in the other direction and move toward the light. The results of blackening portions of the compound eye seem to indicate that different parts of each eye are connected with the movement of special parts of the body. Although capable of learning by experience, its move- TYPES OF ANIMAL BEHAVIOR 7I ments seem to be determined largely by reflex mechanisms, very few of them being of a trial character. In the unusual condition, however, when, with one eye blackened the animal's mechanism is being modified so that the creature can move more directly toward the light, its movements are to some extent of an mdefinite and trial character. A study of the death feint shows that it is affected by heat, light, and by the number of times the feint has just been produced. If the head is removed, the body reacts in the usual form of death feint, though the feint does not last so long. When the body is cut in two, the anterior portion shows the death feint, and other reflexes much as in the normal animal. The same is true of the rear portion but in a less degree. Ganglia located in the different parts doubtless make this possible. What has been found of the reaction of the ranatra seems to be in general true to a greater or less extent of all insects. Most of their reactions are of a definite reflex character, each part of the creature reacting separately in its characteristic way, and yet the animal as a whole may have its actions modified to some extent by experience. The perfectness with which the inherited structure of insects fits them for the life they are to lead, in cases where there is no possibility of learning by experience, is illus- trated by the changed activities of insects, such as the blister beetle, in the different forms that it assumes in different stages of its development. This creature, in its first stage, moves actively on six legs and finds a home on a bee, where it remains till the bee lays its eggs, when it feeds on them. It then changes into a grub, with minute feet and rudimentary masticating organs, and feeds on 72 GENETIC PSYCHOLOGY honey. It winters in a pupa-like state and emerges as an adult beetle with mouth, legs, and wings, ready to feed upon leaves and to lay its eggs under the nest of a burrow- ing bee, which is to be the host of its young. With no chance whatever for learning what to do it does just the one, of an infinite number of things, in each stage, that will preserve the species. This beetle also illustrates another prominent charac- teristic of insects. Their behavior, more than that of any other species of animals, is governed by the necessity of preserving the life of the species rather than of carrying on their own individual life. A large proportion of this beetle's activities are concerned, not with securing food and protection for itself, but with securing food and protec- tion for the next generation. Much time has been spent in studying the behavior of insects, especially ants, bees, and wasps. Nowhere has there been greater difference of opinion in interpreting the behavior of animals than in the case of these creatures. Some look upon them as nothing more than a combination of reflex mechanisms which result in their performing the usual acts of their species with little or no modification by experience or individual variation , while others ascribe to them intellectual and moral qualities rivaling in number and degree those of man. A careful study of their be- havior leaves no doubt that most of their actions are largely of a reflex or instinctive character. Yet there are consider- able variations from the typical mode of reaction in individ- ual insects and some ability to learn by experience. The ability to find the way to their nests and to food is, by native endowment, considerable in most insects, and in order to TYPES OF ANIMAL BKIIAVIOR 73 be of p^ractical use there must be some possibility of modifi- cation of reaction to surroundings in order that an individ- ual may be able to return to places thai it has previously visited. Experiments show that changes in the surround- ings of a nest may cause a wasj) to fail to recognize her nest when she comes to it. Changes in large colored cards that had been near the nest for some time were found by the Peckhams to cause confusion and failure. ]\Iany of the acts of ants that seem to be directed by intelligence similar to that of man are doubtless to be explained as slight variations in habitual reactions. For example, some ants that were cut off from food supply by birdlime or tobacco-soaked cloth, built a bridge of pellets of earth and thus were able to reach the food. In another case a watch glass was filled with water and some pupae were placed on the small island in the center of it. After apparently trying to reach the pupa?, one ant began throwing debris, others joined, and soon there was a bridge on which they crossed and carried away the pupie. These acts, which at first thought seem to indicate conscious foresight and intelligence, may take on quite a different form when considered in relation to their usual behavior. It is the custom of ants to cover sticky or wet objects near their nests with debris and this is probably the explanation of both cases of apparently intentional bridge-building. In the course of this process the animals got near the food particles in one case, and in the other near the pupic, and according to their usual mode of behavior immediately seized them. The fact that ants cover objectionable places with debris excites little comment. Neither is much notice taken of the fact that they carry food or pupte away 74 GENETIC PSYCHOLOGY when they find them. The chance occurrence of these two modes of behavior in immediate succession is what excites wonder and leads some to the probably erroneous interpretation of the ants' behavior as an instance of fore- thought and planning of means to ends. Many other seemingly remarkable actions of ants are subject to correspondingly simple interpretations. It has been claimed that they imitate each other, but it is found that ants which have no chance to learn by imitation per- form the usual actions of their species with the same skill and exactness. The so-called slave ants perform the same acts in their new home that were characteristic of them in the home nest. In the wars of ants, behavior supposed to correspond with the act of making peace be- tween armies has been observed. This phenomenon, like that of the seemingly remarkable memory of ants for their companions, may readily be explained on the basis of their usual behavior. Ants from a foreign nest are treated as enemies because of their odor, while those of the same nest have the odor associated with friendly behavior. In a battle, where the opponents mingle, they become used to the scent of the enemy, which is mixed to a greater or less extent with that of friends, and this decrease in the usual sensory stimulus to fighting would naturally result in the so-called actions of making peace. The behavior of ants of the same species is practically the same in whatever portion of the world they are found. All are capable, however, of varying slightly their mode of reaction to suit some of the common variations in environ- ment, and there are also individual differences in vigor and persistency of action and in sensitiveness to different varieties of stimuli. TYPES OF ANIMAL BEHAVIOR 75 In no case are the changes in behavior of individual ants such as involve any marked variation from instinctive modes of reaction, although they may result in two ants acting quite differently under the same circumstances. For example, two ants observed by Turner acted in quite different ways as a result of their experience in carrying pupae from an elevated stage. One had learned the route down an inclined plane, the other had not been able to learn this route but had tumbled off the edge with the pupae. After being lifted to the stage several times with a pair of pincers, it learned to go to a certain place to get on the pincers to be lifted, while the ant that had learned to find its way up and down the inclined plane, dodged the pincers whenever they were brought near him. Turner's experiments indicate that ants are not directed by odor in finding their way to such an extent as has been supposed. He finds them sensitive to the visual stimula- tion of objects, to differences in tactile stimulation from a rough or smooth surface, to differences in direction of surface, as inclining up or down, to differences in direction of light, and to differences in sounds. All of these stimu- lations, except the latter, help to guide the animal in finding his way to his nest. Variations in any of them may cause hesitation or mistakes^ and the same is true of variations in odor ; but the ant seems to react to the general direction and the general situation rather than to depend upon just one form of sensory stimulus. In going to his nest, he does not always take exactly the same course and after taking several courses he often learns to take habitually the short- est one. This indicates that he is affected by differences in distance. 76 GENETIC PSYCHOLOGY Turner docs not find cooperation in tasks as prominent in ants as has been supposed. He observes no instance of their showing evidence of communication by means of their antennae. They do not thus induce another ant to follow, but if an ant is lost, it may be carried to the nest by its companions wlio find it. Ants often carry food or pupae some distance ; then, because they get lost or for some other reason, drop their load. Any other ant finding it carries it to the nest. By coincidence this sometimes results in ants seeming to cooperate by carrying food part way to the nest and leaving it, while others carry it the rest of the way. An interesting instance of this kind is reported by Gredlcr. Some ants had learned a round- about route to a bottle of sugar which they were carrying grain by grain to their nest. Later it was observed that some of the ants were carrying the sugar out of the bottle, which was suspended by a string, and dropping it to the window sill, while others were carrying it to the nest. This is undoubtedly an instance of cooperation, but one due in all probability to chance rather than to intention. MAMMALS — GUINEA PIGS In the case of all animals previously noticed there is little difference between the structure and behavior of the young and the adults of the same species, except, of course, in the case of animals that have different forms at different stages of development, such as insects and frogs. In the guinea pig we have an example of a mammal that is at birth practically the same, in both external and internal structure and in behavior, that it is at maturity, except TYPES OF ANIMAL BEHAVIOR 77 that at birth it is smaller and not sufficiently strong to make many or vigorous movements. Observation and experiments by Allen show that any- thing which the guinea pig is capable of learning can be learned when two or three days old as readily as at any other age. It is capable of learning only a few things, but whatever it can learn is acquired without very many trials and the effects of such modification in behavior persist after many weeks. In finding its way tlirough a simple maze to food or companions, the superfluous move- ments, such as biting at a wire and going into blind alleys and other extra movements of play and curiosity, are not numerous (as they often are in higher animals), and, if success is attained at all, do not continue long. A habit once formed is not readily changed, and a path that has led to success continues to be followed though there may be much shorter ones. The guinea pig is provided with all the sense organs of higher animals but seems to be guided in its movements chiefly by vision and by the sensations of movement, though it is quite responsive to sounds made by its companions. In vision it is especially sensitive to moving objects, but it probably has little if any clear perception of form and color, since its eyes arc so situated that they cannot act together, and since there is little difference between the central and peripheral portions of the retina. Although probably night animals in their natural habitat, they find their way more quickly and with fewer random movements in the light than in the dark. Colored lights or objects do not seem to be of any significance in directing their movements along a certain path or into a compartment. 78 GENETIC PSYCHOLOGY Neither does contact with the sides serve as a guide. Differences in the appearance of food boxes or of food seem to have no influence upon their actions. They simply react to their general surroundings by movements along a certain course. Guinea pigs care for their young to some extent, but for a short time only. They react in characteristic ways to the actions of their mates, especially to danger signals. They also have sexual calls, and frequently make a chuc- kling sound, which, when started by one, is taken up by others. In these responses to social stimuli, the guinea pig shows a considerable advance over the lower verte- brates; but in this and other reactions there is no great superiority to insects. WHITE RATS The white rat at maturity is a much more active animal than the guinea pig and capable of doing a great many things with teeth and claws that are physically impossible to the guinea pig and which are entirely too complex for him to learn. While a white rat may learn to pull a string or turn a button and push against a door in order to get food, the guinea pig does not of himself even learn to push open a swinging door at which he is gnawing, though by so doing he could readily obtain food and com- panionship. In the mere matter of learning a maze there is less difference, although the rat is very much superior in the quickness with which he moves and the complexity of maze problems which he can solve. The sense organs of the white rat are very similar in development and in relative prominence to those of the guinea pig, except that TYPES OF ANIMAL BEHAVIOR 79 his vision is considerably better. In finding his way through a maze, however, vision is of only incidental assistance. The rat is probably more completely a night animal than the guinea pig, and he finds his way in the dark and when blinded with almost, if not quite, as great rapidity and accuracy as when he has full use of his eyes in the light. Watson's experiments show that when all the senses except those connected with movement are eliminated, by means of operations upon the sense organs and nerves and by etherizing the feet to destroy tactile sensations, rats learn their way though a maze with little difficulty. Rats are much more active than guinea pigs, moving about quickly, clawing and biting at various objects. For this reason they are likely to find their way out of a cage or into a box where food is to be obtained even when, to do so, very definite acts of pulling at a string or gnawing at a fastening or digging and pushing at a certain place, are required. After the act has once been performed, random movements rapidly decrease, the animal usually going directly toward that part of the apparatus where he was when he made the movement that released him. After a few trials he attacks the particular part of the mechanism necessary and soon learns to make just the right movements to effect his release. Having once learned the way to get out or in he is able to perform the act perfectly after long intervals without practice; yet if changes are made in the position of the fastening or the mode of manipulating it, it does not take him long to modify his movements. The period during which there occurs continual shortening of the path or elimination of 8o GENETIC PSYCHOLOGY useless movements is longer than in the case of the guinea pig, in about the same proportion as the number of move- ments and complexity of the acts which he can learn to perform, is greater. When two rats are together, trying to solve a problem, each is affected somewhat by the actions of the other. If one pauses and scratches or gnaws at a certain place, the attention of the other is likely to be attracted to that place, just as it is to food, when another rat finds and begins eating it. The movements of a companion serve therefore to suggest and call forth similar movements providing they are such as the rat has some instinctive tendency to make in the same situation when by himself. If one of the rats succeeds in getting out, the other follows him. After this has occurred several times, the one that does not know how to get out ceases to try to find its way out but follows the other rat around and as soon as the door is released, passes out. If one rat is placed in a separate compartment where he can see another rat get out again and again, his own actions when placed in that compartment are no different from those of a rat that has seen no other rat escape from it. When in the same compartment with a trained rat he may follow the other rat and gnaw and scratch at parts of the cage attacked by his trained companion, yet there is no evidence that he perceives the exact character of the movements made by the other rat and thus learns to per- form the act. If he learns to perform it at all it is through having made the necessary movement in a chance or trial way. The movements of the other animal appear to do nothing more, even under the most favorable circum- TYPES OF ANIMAL BEHAVIOR 8l stances, than direct his attention to the portion of the ap- paratus to be attacked. In Berry's experiments a knot on a string must be pulled by the claws in order to release the door, the string being too high to be reached with the teeth. No rat was able to learn this trick without teach- ing, and no rat was able to learn the trick from one that had been trained to perform it. It appears therefore that either their vision is not perfect enough to enable them to perceive the character of the movement made by a companion or they do not and perhaps cannot single out from the whole situation such a movement made by another and then execute it themselves. So far as the results of experiments that have been tried thus far are concerned it seems that a rat can learn how to make a given move- ment only by the experience of making it himself and not by observing another make it. One of the most striking differences between the guinea pig and the rat is the difference between the behavior of the young and of the adult. While the guinea pig when two or three days old can learn and remember whatever it is capable of learning, as perfectly as the adult, the rat at that age is blind and helpless. Not until the rat is be- tween three and four weeks old is he as mature in his behavior and ability to learn as the guinea pig is when the same number of days old. The complexity of acts that he can i)crform, however, is then many times greater than is possible for the guinea pig. DOMESTIC ANIMALS AND BIRDS Dogs, cats, pigeons, chickens, and other well-known animals have recently been made the subjects of careful 82 GENETIC PSYCHOLOGY experiments. While differing greatly in the relative prominence of the different senses and in their motor facility, as well as in their instinctive behavior, they yet show certain common characteristics, especially in ex- periments of the maze type. They all depend upon sight more than does the guinea pig or the rat, responding not only to objects of different size but to specific differences in form and color. They all learn by the same general method, that of trial and success, and they gradually learn to eliminate useless movements after they have once achieved success. Some are more affected than others by the actions of their companions, but in no case, under experimental conditions, has there been an unquestioned instance of learning how to do a thing by observing any other person or animal do it. One exception to this statement regarding imitation must be made. Parrots, crows, and a number of singing birds are known to learn new sounds from hearing them. If separated from their own species they make the usual cries and danger calls but do not generally sing the songs characteristic of the species. They learn whatever songs they hear that they are capable of singing. In the case of parrots and crows, as is well known, words and sentences are sometimes learned. It appears therefore that the vocal apparatus is to some extent indeterminate and plastic as it is in man, so that the stimulus of sounds heard cause it to function in ways that reproduce those sounds. It may not be asserted that none of the animals so far mentioned ever learn a new movement, other than those made by the vocal apparatus, by imitation ; but the fact remains, that, as yet, under experimental conditions, no observer TYPES OF ANIMAL BEHAVIOR 83 has found a single unquestioned example of such learning by imitation. As in the case of the rat, movements that they have an instinctive tendency to perform are sometimes suggested by perceiving one of their companions perform the move- ment, and their attention to certain objects that may help them in getting out, may be attracted by the movements of companions or of persons. They learn less rapidly w^hen success comes after an accidental movement on their part than when it comes in connection with an effort to get out. Thorndike thought that they could not be taught by being put through the movements, but other experimenters have succeeded in teaching movements in this way more quickly than when such help was not given. In degree of helplessness at birth and in the length of time elapsing before maturity there are great differences among the birds and higher mammals, but probably none are more completely mature at birth than the guinea pig, while some are more helpless and have a longer period of immaturity than the rat. All show considerable individual variations and are capable of great individual modification by experience. RACCOONS AND MONKEYS These animals are probably superior to most other animals in definiteness of vision, and they have a motor apparatus better adapted to manipulating objects in a variety of ways than any others. The monkey is superior to the raccoon in this respect, but the raccoon is less easily diverted from what he is doing, and hence frequently solves his problem with more rapidity and sureness than the 84 GENETIC PSYCHOLOGY monkey. Both animals show great facility in manipulat- ing apparatus in order to obtain food or freedom. The mere act of manipulating some object is, for both, often a sufficient incentive to induce them to learn rather com- plicated tricks, when there is no food or other reward to be obtained. They can learn not only to open a door fastened in various ways, but to open a door which is held in place by three or four devices which have previously been learned alone. The fact that the fastenings must be loosed in a certain order did not, in Davis' experiments, increase the difficulty for the raccoon. The records of learning such combina- tions, and of their memory after an interval, show that the order is more readily learned and less likely to be forgotten than the direction and force of movement required to undo each fastening. In Cole's experiments the raccoons varied the order in which they attacked the several fastenings. The monkey is affected more by the actions of his com- panions than the raccoon. This serves sometimes to divert him from the problem upon which he is working, while it may also sometimes help him in learning what a companion already knows how to do by directing his attention to the proper place and object. In no instance has the raccoon been known to learn a new movement from seeing a person or one of its mates perform it. Cole thought his own movements in raising cards may have helped raccoons to learn them, but impatience to have the card meaning food appear may have led to scratch- ing at the place from which it had previously appeared. He could teach raccoons by putting them through the act, but they learned much less quickly than when they TYPES OF ANIMAL BEHAVIOR 85 themselves had some part in the performance of the act. They learned to go in the top of a box Ijy being lifted in by the neck, although their legs hung limp, which shows there was no innervation on their part. Monkeys, contrary to the usual opinion, arc not found by experimenters to imitate any definite movement made by persons, although the actions of a j)erson may serve as an effective stimulus to monkeys to make them examine and manipulate objects. Kinnamen, in his studies of the monkey, observed two instances of what seemed to him clear and definite imitations of the movement of a companion. One instance was that of pulling out a plug, the other that of pressing down a lever. In both cases the monkey, after repeated attempts, had failed to make the right movement, although he had worked at the ob- jects with considerable persistence. The monkey who knew the trick pulled out the plug and the other monkey immediately afterwards did so without any hesitation or trial movement. The same was true in the case of the pressing down of the lever. Since only two cases of un- questioned imitation in the most highly developed and most imitative of all animals have as yet been found under experimental conditions, it seems absolutely certain that the tendency to imitate the actions of persons and of mates cannot be very strong in any animal except man, in whose behavior and learning we know it plays a very prominent part. SUMMARY OF CHARACTERISTICS OF BEHAVIOR We find that all organisms, from the lowest to the highest, are engaged in the business of preserving themselves as 86 GENETIC PSYCHOLOGY individuals and as species. They do this, not as passively moved by outside forces, but in response to stimuli that set free energy stored up within them which is expended for the good of the creature as determined by its structure. All are self-feeding, self-repairing, and self-reproducing. The behavior of all is affected by objects that touch them, by gravity, light, heat, electricity, and chemicals. All have characteristic modes of responding to these stimuli of different intensities but none respond in exactly the same way to the same stimuli every time. Their responses to any stimulus vary with their internal states, especially that of hunger, and with variations in the external conditions accompanying the stimulus, and because of per- sisting effects of previous stimuli and previous movements. The activity of all organisms is usually greater when unfavorably stimulated or when hungry, than when in a more favorable condition as to internal states and in rela- tion to the environment. Some of the activity of all animals is of a trial character and all react in at least two ways, positively to favorable stimuli, and negatively to unfavorable stimuli. Most animals have modes of reaction that are not en- tirely of a trial character, but are likely to secure at once either favorable stimuli or freedom from unfavorable. Continuous or repeated stimulation leads in all creatures sooner or later either to temporary or permanent modifica- tion in behavior. We see, therefore, that there is no essential difference except in degree and complexity in the fundamental charac- teristics of behavior in all animals from the lowest of the protozoa to the highest vertebrate, man. The higher TYPES OF ANIMAL BEHAVIOR 87 animals simply specialize and add to the characteristics of the lower. DIFFERENTIATION OF PHYSIOLOGICAL PROCESSES AND BEHAVIOR As we have already seen, the essential nature of an organ- ism implies that activities are constantly taking place within it by means of which its existence is preserved. In the case of very small animals in a liquid medium this internal activity is directly affected by the environment. In larger animals the environment cannot directly affect any but the outer portion of the body and that is often protected to a considerable extent. The processes taking place within the body are therefore only indirectly related to the environment. In the smaller animal it is difhcult to draw any sharp line of distinction between vegetative, somatic, or physiological processes, and the reactions by which the creature comes into relation with his environ- ment. In other words, behavior is not clearly differenti- ated from physiological processes. In the larger and higher animals the bodily processes taking place within the animal are usually very easily distinguished from behavior or movements in response to environmental stimuli. In even the highest animals the physiological processes are, however, readily affected by external stimulation and by movements; while, on the other hand, the behavior varies with the physiological condition. The relation, however, is an indirect one, while in the simpler organisms the relation between light, air, heat, etc., and the physio- logical processes, is so direct that physiological activity can scarcely be distinguished from behavior. 88 GENETIC PSYCHOLOGY As we go upward in the scale of animal life we find not only that physiological processes and behavior are differen- tiated, but that there are many other specializations and complications. The process of nutrition becomes special- ized into processes of respiration, digestion, and circula- tion, and each of these is, in the higher animals, still further specialized so that one part of the process takes place in one organ and another part in another. Behavior is also specialized into (i) that which has be- come a fixed characteristic of the species, and (2) more temporary modes of activity produced by the experience of the individual. In the lower animals there is little difference between the behavior of the species and of the individual, but in the higher animals the individual acquires many new modes of behavior. These are sometimes simply modifications of the instinctive behavior of the species and involve noth- ing more than specialization in instinctive modes of reac- tion. In other cases modes of reaction quite different from those characteristic of the species are acquired. In such cases we may distinguish a further basis of behavior in the form of capacities, which are more passive and more individual in their character than the instinctive tenden- cies, and therefore subject to greater modification by the activities of the individual. REFERENCES ♦Allen, Jessie. The Associative Processes of the Guinea Pig, Jr. Comp. Neu. b' Psych., Vol. XIV, pp. 293-299. Bell, J. C. The Reactions of the Crayfish, ifari/arJ Psych. Studies, Vol. II, p. 615. TYPES OF ANIMAL BEHAVIOR 89 Bell, J. C. The Reactions of Crayfish to Chemical Stimuli, Jr. Comp. Neu. &" Psych., Vol. XVI, pp. 299-326. Berry, Charles S. The Imitative Tendency of White Rats, Jr. Comp. Neu. &= Psych., Vol. XVI, pp. 333-361. BiNET, A. The Psychic Life of Micro-Organisms. Cole, L. J. Influence of Direction vs. Intensity of Light in Deter- mining the Phototropic Responses of Organisms. Abstract in Jr. Comp. Neu. d^ Psych., Vol. XVII, p. 193. Cole, L. W. Concerning the Intelligence of Raccoons, Jr. Comp. Neu. &° Psych., Vol. XVII, pp. 211-261. ♦Davis, H. B. The Raccoon: A Study in Animal Intelligence, Am. Jr. Psych., Vol. XXIII, pp. 447-489. Davenport, C. B., and Cannon, W. B. On the Determination of the Direction and Rate of Movement of Organisms by Light, Jr. Physiol., Vol. XXI, p. 22. Fielde, a. M., 1901. Further Study of an Ant, Proc. Philadelphia Acad. Nat. Sci., Vol. LIII, pp. 521-544. Fielde, A. M., and Parker, G. H., 1904. The Reactions of Ants to Material Vibrations, Proc. Phila. Acad. Nat. Sci., Vol. LVI. Hamilton, G. Van T., M.D. An Experimental Study of an Un- usual Type of Reaction in a Dog, Jr. Comp. Neu. 6^ Psych., Vol. XVII, pp. 329-341- Hodge, C. F., and Aikins, H. A., 1895. The Daily Life of a Proto- zoan, Am. Jr. Psych., Vol. VI, pp. 524-533. ♦Holmes, S. J. The Instinct of Feigning Death, Pop. Sci. Mo., LXXII, pp. 179-185. The Reactions of Ranatra to Liglit, Jr. Comp. Neu. 6^ Psych., Vol. XV, pp. 305-349- The Selection of Random Movements as a Factor in Phototaxis, Jr. Comp. Neu. df Psych., Vol. XV, pp. 98-112. ♦Jennings, H. S. Contributions to the Study of the Behavior of Lower Organisms, Carnegie Inst, of Wash. Pub. N'o. 16, pp. 1-256. Behavior of the Starfish, University of Cal. Pub. m Zoo., Vol. 4, No. 2, pp. 53-185. ♦Jordan, KLellogg, and Heath. Animals — A Text-Book of Zoology. 90 ■ GENETIC PSYCHOLOGY ♦KiNNAMAN, A. J. Mental Life of Two Macacus Rhesus Monkeys in Captivity, Am. Jr. Psych., Vol. XIII, pp. 98-173. Lubbock, Sir John, 188 i. Ants, Bees, and Wasps. Mast, S. O. Light Reactions in Lower Organisms, /r. Comp. Neu. S^ Psych., Vol. XVII, pp. 99-180. Mills, T. W., 1899. The Nature of Animal Intelligence and the INIethods of Investigating It, Psych. Rev., Vol. VI, p. 262. *PoRTER, J. P., 1904. A Preliminary Study of the Psychology of the English Sparrow, Am. Jr. Psych., Vol. XV, pp. 313- 346. 1906. Further Study of the English Sparrow and Other Birds, Am. Jr. Psych., Vol. XVII, p. 248. The Habits, Instincts, and Mental Powers of Spiders, Am. Jr. Psych., Vol. XVII, pp. 306-357. Rouse, J. E., 1906. The Mental Life of the Domestic Pigeon, Harvard Psych. Studies, Vol. II, p. 580. Santord, E. C. The Psychic Life of Fishes, Inter. Quart., Vol. VII, pp. 316-333- Shufeldt, R. W., 1900. Notes on the Psychology of Fishes, Am. Nat., Vol. XXXIV, p. 275. *Small. Mental Processes of the Rat, Am. Jr. Psych., Vol. XI, p. 162. Notes of The Psychic Development of the Young White Rat, Am. Jr. Psych., Vol. XI, pp. 80-100. Spaulding, E. G. An Establishment of Association in Hermit Crabs, Jr. Comp. Neu. &= Psych., Vol. XIV, pp. 49-61. *Thorndike, E. L., 1899. The Instinctive Reactions of Young Chicks, Psych. Rev., Vol. VI, p. 282. A Reply to "The Nature of Animal Intelligence and the Methods of Investigating It," Psych. Rev., Vol. VI, p. 412. * Animal Intelligence, Psych. Rev., Monograph Supp., Vol. II, No. 4, pp. 62; 1898. The Mental Life of the Monkeys, Psych. Rev., Monograph Supp., Vol. Ill, No. 5, pp. 42; 1901. *TuRNER, C. H. The Homing of Ants : An Experimental Study of Ant Behavior, Jr. Comp. Neu. 6^ Psych., Vol. XVII, pp. 367-434- TYPES OF ANIMAL BEHAVIOR 9I Washburn, M. F., and Bentley, I. M. The Establishment of an Association Involving Color Discrimination in the Creek Chub, Jr. Comp. Neu. 6" Psych., Vol. XVI, p. 113. * The Animal Mind, Chapters III to IX. ♦Watson, J. B., 1903. Animal Education, Univ. of Chicago Contri- butions to Philosophy, Vol. IV, No. 2. KiniESthetic and Organic Sensations: their Role in the Reac- tions of the White Rat to the Maze, Monog. Sup pi., Vol. 8, No. 2. Yerkes, R. M. Inhibition and Reenforcement of Reaction in the Frog Rana Clamitans, Jr. Comp. Neu. &= Psych., Vol. XIV, pp. 124-137. Space Perception of Tortoises, Jr. Comp. Neu. 6^ Psych., Vol. XIV, pp. 17-26. 1903. The Instincts, Habits, and Reactions of the Frog, Har- vard Psych. Studies, Vol. I, pp. 579-638; Psych. Rev., Mono- graph Supp., Vol. IV. The Sense of Hearing in Frogs, Jr. Comp. Neu. 6r* Psych., Vol. XV, pp. 279-304. * Behavior of Roger, Century, February, 1908. The Dancing Mouse. Bohn's Studies in Animal Behavior, Jr. Comp. Neu. £r» Psych., Vol. XVI, p. 231. CHAPTER IV COMPLEX BEHAVIOR CHARACTERISTIC OF SPECIES — INSTINCTS NATURE AND DIFFERENTIATION OF INSTINCTS Animals belonging to the same species have certain characteristic modes of behavior, just as every plant and every chemical element has characteristics distinguishing it from all others. These modes of behavior are closely, related to bodily structure and physiological processes.' They are the modes of behavior that have usually brought favorable results to the species living its life in a certain kind of environment. In the lower organisms which live in a fairly constant environment, have few highly special- ized sensory motor organs, and perpetuate their species by division or budding, instinctive behavior has not been clearly differentiated from physiological processes. In creatures, however, that react in response to suggestive stimuli there is generally a clear distinction between physio- logical processes going on within the organism and behavior in relation to the stimulating environment. All behavior that is favorable to the survival of the individual or its species, and is called forth by a stimulus that does not of itself materially modify the physiological processes, may be considered as belonging to the instinctive rather than to the physiological type of activity. Where the reaction is of a part of the organism only, it is more properly called a reflex ; 92 COMPLEX BEHAVIOR CHARACTERISTIC OF SPECIES 93 while more complex reactions of many parts for the good of the whole organism are designated as instincts. In the lower organisms reactions are largely reflex, while in higher animals instincts become more and more prominent. In so far as all animals have common ends to be gained, the modes of behavior by which those ends are reached may be regarded as belonging to the same type of instinct, whether found in an amaba or in man. In instinctive development, as in other lines of development, there are in the higher animals specializations and additions to the simpler instinctive actions shown by the lower. FUNDAMENTAL FORMS OF INSTINCTIVE BEHAVIOR I. Where the immediate result favors the preservation of the individual reacting, and only indirectly the preserva- tion of the species, the instinctive action is Individualistic or Self-Preservative. This form of behavior is specialized in the higher animals chiefly into three kinds of activities : those connected first, with securing food; second, avoiding danger; and third, fighting enemies and rivals. The acts accomplishing these ends are different for each species and of all degrees of complexity. The individualistic instinct of securing food is always closely correlated with structure and surroundings. To an expert naturalist a single organ, bone, or tooth of an animal may give an unmistakable indication of the general charac- ter of its feeding instinct. He knows whether it be a vege- table or flesh-eater and can form some idea of the action by means of which it secures its food. The same close relation of instinct and structure is 94 GENETIC PSYCHOLOGY shown in the actions of avoiding and combating enemies. The instinct to remain motionless in the presence of a pos- sible enemy could have been established only in those par- tridges whose feathers resemble their surroundings, for all others would be likely to be destroyed if they remained still in the presence of an enemy that can see. To escape an enemy depending on other senses than sight, the partridge must, however, also have strong wings and the instinct to use them effectively. The hedgehog and porcupine have structures that make fear an almost useless instinct to them, and so they are as a rule very bold. Creatures that have no means of defense or flight, by which enemies may be escaped, are sometimes enabled to survive because of their resemblance in form, color, or sound-producing qualities, to some fierce creature, while beasts of prey, with efficient fighting apparatus, have sufficient means of survival with- out hiding or fleeing, though concealment may be helpful in capturing prey ; hence most of them have coloring corresponding to their usual surroundings. At first thought, the fighting of rivals, which are of course of the same species, does not seem to favor the survival of the species even indirectly, but a little reflection shows that such action eliminates weaker individuals and favors propagation by the stronger. This instinct is most promi- nent in animals living in groups, under conditions in which the weaker members of the species are protected from de- struction by being associated with the others. In such animals it is necessary that there should be fighting among themselves and that the stronger should dominate, in order that the species may not be weakened in its struggle for existence with other species. COMPLEX BEHAVIOR CHARACTERISTIC OF SPECIES 95 Instincts change with temporary changes in structure and physiological states at different ages, at different times of the year, and because of hunger, sickness, or wounds. Hence there is great variability in the reactions of feeding, fighting, and escaping danger at different seasons and on account of special physiological conditions of the individual animal. II. A mode of behavior that is of no advantage to the individual but favors the production of other individuals and the preservation of the species, is known as the Parental or Racial Instinct. In all animals reproducing sexually, this instinct is differentiated from purely physiological processes. In some animals, however, especially insects, the production of eggs and the provision made for their development are sometimes, as in the case of plants, only a slightly differentiated phase of the physiological processes. The nest and egg productions of insects differ from the formation of fruit cases and seed by plants, chiefly in the fact that the results are attained by move- ments that are rapid enough to be seen, instead of by slow growth processes. The care of the young, while they are developing into adults, is a higher form of the parental instinct, which is necessarily more prominent in proportion as the number of young produced is small. The salmon producing a million eggs does not as a species need the caretaking instinct of the robin, which lays only a half dozen or so eggs in a season. In the lower vertebrates the sex instinct is part of the time absent, while at other times it completely dominates behavior. In birds and mammals the instinct is stronji 96 GENETIC PSYCHOLOGY at certain times of the year but usually not to the entire exclusion of the individualistic instinct. In higher animals and in man this instinct is manifested in a great variety of forms. When it is dominant, many varieties of sensitiveness and movement are shown in connection with securing mates, preparing for the young, and feeding and defending them. Acts of adornment, singing, courage, and cunning are all specializations of behavior correlated with and more or less closely dependent upon the sex instinct and the physiological specialization in structure of the two sexes. For all species of animals the care-taking form of this instinct is very accurately adjusted, not only to the structure of the species and to the conditions of life, but also to the structure and behavior of the young at birth and at differ- ent stages of development. Any failure of adjustment would be disastrous ; for example, a hen could not rear young robins because, no matter how much food she might find, they would starve if it were not placed in their mouths; while on the other hand, if chickens were kept in a nest and fed by robins they would fail to develop properly because of lack of exercise. In the torrid zone the eggs and young are sometimes not brooded at all, while in the antarctic region the penguin, living on snow and ice, holds its one egg between the thighs so that it cannot touch the ice; and although six weeks are required for the egg to hatch and a long period of care of the young chick follows, yet natural selection in that environment has made the instinct of brooding so strong, that all the birds compete for the chance, and as soon as one drops the egg or chick another takes it. COMPLEX BEHAVIOR CHARACTERISTIC OF SPECIES 97 III. One effective means of survival for a species is that of living together in groups that cooperate to a greater or less extent in the struggle for existence. Modes of behavior concerned with such group life constitute the Social Instinct. In social insects, such as bees and ants, this instinct dominates all their behavior so that most of their actions are adapted to the preservation of the group to which they belong, regardless of what may happen to other groups or to themselves as individuals. They cooperate in producing and caring for the young of their colony and in fighting enemies, whether of their own or of another species. In order that they may do this there is often considerable specialization in structure, fitting the different members of the group to perform their part in the life of the colony. The cooperation is not so much that of individuals with each other as it is of the different classes; e.g. warriors and Workers among ants. Individuals are apparently recognized as friends or enemies, not so much by their individual peculiarity as by their colony odor. Any individual from another colony, or even from the same colony, if it has been with those of another colony long enough to get their odor, is likely to be treated as an enemy. In the case of higher animals that go in groups, such as geese, wolves, wild cattle, and horses, there is not such marked differentiation of structure and coo])eration in be- havior of different classes, though the two sexes act differ- ently and the stronger individuals take the part of leaders and fighters. In such animals there is often a wonderful sensitiveness to the action of companions and response to such actions by correlated mo\-emcnt. This is most evi- dent in following leaders, and in responding by appropriate H 98 GENETIC PSYCHOLOGY movements to special cries of companions, indicative of food, danger, fighting, or pursuing. Social action is also sho\^•n in the arrangement of a group in the presence of danger so that the helpless will be pro- tected, and in the movements of a pack by means of which prey is surrounded and captured. Wolves often cooperate in a wonderful way till their prey is captured, when the individualistic instinct resumes full sway and they fight for possession of the prey that they have cooperated with each other in securing. Other instances of social behavior of animals, such as when different members of a group act successively as sentinels while others feed or sleep, depend upon conditions and suggestions that are imperceptible to man. All animals that live successfully in groups must be sensi- tive to what companions are doing and have instinctive modes of responding to the usual behavior of other mem- bers of the group. This characteristic is shown in a marked degree in the dog as compared with the individual- istic cat. The cat is perhaps no less intelligent, learning as readily as the dog when rewarded or punished in a way that appeals to touch or taste, but it is not so much affected by the tone of voice or expression of face of the master. The dog, on the other hand, is wonderfully responsive, not only to the actions of other dogs, but to those of persons and to the tones and facial expressions of his master. His original social in- stinct, that rendered him sensitive to the actions of com- panions in the chase, has been specialized during his long domestication by artificial selection and breeding, into sensitiveness to the voice and movements of human beings. In individual dogs and horses this sensitiveness may be COMPLEX BEHAVIOR CHARACTERISTIC OF SPECIES 99 developed so as to become equal in some lines to that of human beings. In children not only is there great sensitiveness to the tones of voice and movements of other persons but also a strong tendency to act so as to attract notice and get ap- proval. Dogs show this also, but in the human species it has an extraordinary development, appearing in various forms, such as sympathy and ambition. These three most fundamental specializations in the behavior of all but the lowest animals. Individualistic, Parental, and Social, are not found simultaneously and equally prominent in any one species, except in a few that approach man in complexity of organization. Usually in the lower forms of animals one of these instincts only is dominant part or all of their lives. In higher animals, however, they may all be prominent at the same time and either support or oppose each other. This is one reason why their behavior is often so difficult to predict or even explain. The instinct that has been dominant may at any moment gi\'e way to another, and the individual thus seems to be transformed into a creature with a different nature ; e.g. in the mating season the ordinarily timid deer may savagely attack man. The other reason is that individual experience and habit have modified the behavior of indi- viduals in such a way tliat a knowledge of the history of the individual as well as familiarity with the characteristics of the species is necessary in order to interpret the behavior. Besides the most distinctly marked forms of instinctive behavior already described there are, in the higher animals and in man, many others specialized from and correlated with these three. One group of these may be designated as lOO GENETIC PSYCHOLOGY Adaptive instincts, because their functions seem to be to adapt the individual while young and plastic to modes of life that will secure survival in maturity. They are also of help to adult individuals in making quick adjustments of behavior to new conditions. Play, the first of these, is useful as a mere outlet of sur- plus energy, because it results in many and varied move- ments, which not only increase the strength of the organism but give opportunity for many movements that have fa^•or- able results to be selected for repetition and development into useful habits. This holds true even if we suppose the character of the movement made in play to be entirely a matter of chance. There is, however, good reason for saying that the playful movements of young animals are not wholly a matter of chance, as are some of the undiffer- entiated m.ovements of the spontaneous type. The movements made in play are, in general, charac- teristic of the species, and at different ages are specialized in certain directions in accordance with growth and devel- opment. Being under the protection of their parents the young animals have no need or opportunity to stalk prey, flee from danger, or fight enemies; but as the organs for performing these actions develop, energy flows out in play- ful movements of these types. The young animal thus develops powers and forms habits that will be useful in adult life, much more rapidly than he would if his move- ments were of an entirely random character. The higher forms of playful activity, as we shall see later, may be developed and specialized in many directions and to a greater extent than is demanded by the necessities of phys- ical survival. COMPLKX Hi:iI.\\l()R CHARACTICRISTIC OF SPICC'IES lor The instinct of 'nuilnlioii is another form of the a(hi];ti\e instinct which hcli)s in ac(|uiring useful modes of beliavior and saves much time that would otherwise be spent in useless trial movements. Imitation may be regarded as a specialization of the social instinct that renders an indi- vidual sensitive to what companions do to such an extent that their movements serve as a stimulus to make similar movements. An animal thus sensitive does not need to wait until he receives clearly and strongly the stimulus suggestive of food or danger, but may do at once what his companions who have received the stimulus are already doing. All the higher animals that live in groups are aided in escaping danger and securing food in this way. Young animals therefore learn to do what they will need to do as adults more readily when surrounded by companions than when alone. Men having the same instincts are strongly affected by the movements and sounds of com- panions, especially those of emotional expression. Imitation in man, however, is not confined to emotional reactions and the performance of instinctive acts under the stimulus of their performance by companions, but new movements are also imitated and thus learned. Whether animals thus imitate movements made in their presence is as yet a subject of experiment and debate ; but it is per- fectly clear that even the highest animals, other than man, do not perceive and imitate to any considerable extent movements other than of the instincti\e type. In children, on the other hand, the instinct is so strong as to form a marked feature of their playful activities and to be one of the most important means of learning how to reach de- sired ends. 102 GENETIC PSYCHOLOGY Curiosity, the third form of the adaptive instinct, is the result of special sensitiveness to new things, and is shown primarily in a tendency to approach and examine anything new in the environment. It is social only in that it is often concerned with what companions are doing as well as with changes in the material environment. In origin it is probably most closely associated with the individualistic instinct of fear, since fear reactions are most frequently called forth by what is strange and unfamiliar. An animal governed wholly by the fear impulse would avoid all new things and could not become adapted to new conditions. Curiosity, like an antagonistic muscle, impels the animal to examine the new thing that fear prompts him to run away from. The two tendencies are clearly shown in the behavior of a young puppy who alternately jumps at and runs away from a new object. An animal with curiosity soon learns not to run away from harmless things and often finds ways of utilizing them. Even as low an animal as the starfish explores new surroundings in a way suggestive of the curious survey of new surround- ings by man. Clearly, then, curiosity is of great advantage in adapting an animal to changes in environment. In man this instinct has similar and more extensive uses, and it also develops in a marked degree in playful forms that are of great significance to his mental life. SPECIALIZATION OF INSTINCTS The constructive and collecting instincts are specializa- tions of the nest-building and food-providing form of the parental instinct. In the case of insects and birds the COMPLEX BEHAVIOR CIIARiVCTERISTIC OF SPECIES 103 constructions arc made with wonderful skill and are as useful and as characteristic of each species as is their bodily structure. Some mammals show a good deal of skill, notably the beaver, which also seems to cooperate with others in its constructions. Some animals, especially foxes and crows, collect material of all kinds. This be- havior is apparently an extension in the form of play of the food-gathering and nest-constructing instinct, and is closely associated with ownership and with rivalry. In man, with motor organs capable of an infinite variety of combinations, the constructive instinct has had a wonder- ful development, but not, as in the case of animals, toward any particular kind of structure characteristic of the spe- cies. The constructions of the spider, the bee, the robin, and the beaver are closely related to, and the natural outcome of, their structure and physiological processes, Man's motor mechanism, working in no fixed way but by varying combinations in a variety of ways, naturally fails to produce any one kind of structure rather than another, except perhaps that what he constructs is, like himself, usually bilaterally symmetrical. Each individual man has the general instinct, but must learn what to con- struct and how, while individual animals instinctively construct as those of their species have always done, with little or no learning from the example of their companions. In man, both the constructive and the collecting instinct take more or less playful forms and develop in many ways not demanded by the necessity for physical survival. The toilet-making instinct and the (Esthetic instinct are probably in part extensions of the constructive and col- lecting instincts, and also correlated with certain forms of I04 GENETIC PSYCHOLOGY the individualistic, sexual, and social instincts. The toilet- making instinct is very prominent in many animals, espe- cially birds and the individualistic cat, and in its funda- mental form it is undoubtedly useful in preserving the health of the individual, while incidentally it favors a harmonious group life. The (Esthetic instinct may or may not be present in any animal below man, but in him it has an extraordinary power. A human lover of bird songs can scarcely resist the impression that a song bird is exercising his aesthetic sense in making his melodies and that other birds must be affected aesthetically by them, while the artist has much the same feelings regarding the beauty of form and move- ment in bird and butterfly. Experiments, however, show that the selection of mates is not affected by changing the color of the wings of butterflies ; hence it is not likely that the aesthetic sense is very prominent in these creatures and it is practically certain that it plays no part in the selection of mates and the development of certain types of coloring, as Darwin supposed it did. The same is prob- ably true in the main of birds and mammals. The bril- liant coloring that has been supposed to play an important part in the mating of animals is perhaps better explained as being due to the overflow of energy not used in reproduc- tion, which modifies certain physiological processes and sensory-motor activities so as to produce bright colors with beauty of form and grace of movement. In man the esthetic instinct has played an important part in mental development and in history. It is one of the most striking examples of an instinct developed beyond the necessities of physical survival and to an extent that COMPLEX BEHAVIOR CHARACTERISTIC OF SPECHIS 105 makes it, in many instances, stronger than the desire for food or the fear of danger. There are many tendencies to action, sometimes called instincts, whose origin is not easily traced to any one form of useful behavior, among which are teasing and jealousy. Leadership, teasing, and jealousy are all closely related to each other and have perhaps originated in connection with fighting and with certain forms of the social instinct. In social animals the individual whose actions impress others of his group most effectively is, to a greater or less extent, a director of group behavior and has what may be called the instinct of leadership. An individual who is sensitive to the behavior of others, especially to that of a leader, is by instinct a follower. Where a leader acts so as to direct the behavior of another without purpose other than to direct his actions, the act is a playful manifestation of the instinct of leadership, which may take the form of teasing or bullying. Teasing may be looked upon as a mild and playful form of fighting. Any creature that is sensitive to what his companions do and shows that sensitiveness in his reac- tions, is subject to teasing. Practical jokes and humor in all its forms may be looked upon as still more refined, intellectual, and human forms of the teasing instinct, which in its essential nature impels one creature to make another do useless things. Jealousy is closely related to the susceptibility to teasing, for an individual who is jealous must be sensitive to the behavior of other individuals. Any change in the behavior of a companion, especially a leader, so that the action is directed toward some other in(li\i(lual, arouses jealousy. Io6 GENETIC PSYCHOLOGY This is manifested in the form of avoidance of the formerly attractive companion or perhaps in an attack upon him or his new follower. In human beings, jealousy may appear in the form of ideas and feelings without objective action. The expressive instinct is a special form of the social instinct which leads animals to make sounds indicating their own bodily or mental states and the general character of the stimuli they are receiving, in such a way that other animals may respond by appropriate movement. Al- though the expressive instinct is generally used to influence the action of companions it may also be used to frighten enemies belonging to another species. In animals, the expressive instinct is not a means of conveying ideas but only of suggesting situations. In man, whose mental life is of greater importance than the physical, appropriate reaction to the mental states of others is continually neces- sary, and the expressive instinct is very highly developed. The instinctive sounds and gestures which he is able to make are not sufficient to meet his psychical needs, hence he has evolved a language consisting of arbitrary oral and written symbols. Man not only expresses himself in this way but also by artistic creations of all kinds. In art and literature the expressive, constructive, and aesthetic instincts blend, and the varieties of activity resulting have no possible explana- tion in the necessities of the physical organism but only in the psychical needs of man. The regulative instinct manifested in moral and reli- gious behavior is complex in its origin and perhaps takes distinct form only in human individuals after certain kinds of personal experience. Regulation of behavior for the COMPLEX BEHAVIOR CHARACTERISTIC OF SPECIES 107 present good of the organism is, as we have seen, charac- teristic of all organisms, but regulation of present behavior, so that it will harmonize favorably with the behavior of the individual at other times, is a more complex matter. A bird whose instincts, including the acts of mating, nest- building, sitting on the eggs, and caring for the young, are dominant in normal order, has the acts of one day har- monized with those of another. A disturbance of the re- sults of one day's action, by the destruction of the nest or otherwise, may cause the cycle to begin again or may send it into the next stage, as of gathering food, which may be given to a mate or to other young. It is not likely that a bird foresees the end, and the relation of each action to its attainment, but it reacts to the situation in a sensory-motor way according to the dominant instinct. It cannot regu- late activity outside of lines of behavior characteristic of its species. In man, however, actions are regulated partly by ideas of the end to be gained instead of exclusively by sensory-motor stimulation and blind instinct; hence the regulative instinct plays a prominent part in his life. The impulse and the idea giving rise to religious action are closely related to the instinct of fear. Fear is espe- cially aroused by the unknown and the strange, and is greatest when the stimulus is not perceived but only sug- gested, particularly when companions are acting as if there were a cause of fear. No panic of fear among animals or men is so great as that due to an unknown cause and vio- lently reacted to by some individuals of the group. This reaction to the unknown is the fundamental basis of the religious impulse. Natural phenomena suggesting un- seen beings may arouse the tendency to react to what is Io8 GENETIC PSYCHOLOGY not present, but the impulse is much stronger when other people react with reference to such a being or force, whether or not there is any natural phenomenon suggest- ing its presence. The memory of beings to whom one has reacted but who are not now present may also arouse the religious impulses, as is clearly shown in ancestor wor- ship. In all its various forms religious behavior is directed by stimuli suggesting the unknown and the intangible. Those who are sensitive to such stimuli and have their actions directed by them are religious, whatever the form of their actions and beliefs, while those not thus sensitive are lacking in the religious instinct. Moral behavior is more completely social in its character, and the social animals perhaps show the rudiments of moral behavior. The dog that responds to the movements and cries of others of the pack so as to cooperate in capturing the prey, is practicing canine morality. His action is regulated, not by the stimulation of things, but by the actions of companions. This is the essence of morality in animal and man, — that his actions shall be directed by the same principle of action as those of his companions. A dog that gives a false call on a chase, or fails to respond to the signal "close in," is not a favorite with his fellows any more than the man who tells untruths and does not act according to the "rules of the game." Desire for approbation and fear of punishment enforce the tendency to moral actions, while the imitative tendency helps to direct it in accordance with example and custom. In the absence of companions action may be directed along moral lines, either by memory of how other people act or by habit. A human being who had never had companions COMPLEX BEHAVIOR CHARACTERISTIC OF SPECIES 109 could not be moral, though he might be religious to some extent. In moral behavior there is no necessary sugges- tion of a Being with reference to whom customs have been formed, while in religious behavior there is always such suggestion. REFERENCES Angell. Psychology, Chapter XV. Baldwin, J. M. Social and Ethical Interpretations, Chapters IV, IX, X, XI. *BuRKE, F. S. Teasing and Bullying, Ped. Sent., Vol. IV, pp. 336- 371- *Chadbourne, p. a. Instinct. Courtis, S. Response of Toads to Sound Stimuli, Am. Natur., 1907, Vol. XLI, pp. 677-682. Delbceuf. Affections and Jealousies of Lizards, Pop. Sci. Mo., Vol. L, pp. 395-399- Forrel. Ants and Some of their Instincts, Monisl, Vol. XIV, PP- 33-36 and 177-194- Ants and Some Other Insects. ♦French, F. C. Group Self-Consciousness, Psych. Rev., Vol. XV, pp. 197-200. *Gesell, Arnold L. Jealousy, Am. Jr. Psych., Vol. XVII, pp. 437-496. *Groos, K. The Play of Animals. The Play of Man. *Hall and Smith. Showing off and Bashfulness as Phases of Self- Consciousness, Ped. Sem., Vol. X, pp. 159-199. Reactions to Light and Darkness, Am. Jr. Psych., Vol. XIV, pp. 21-83. *Hall, G. S. a Study of Fear, Ayn. Jr. Psych., Vol. VIII, pp. 147-249. Adolescence, Chapter XV. *Herrick, C. L. The Beginnings of Social Reaction in Man and Lower Animals, Jr. Com p. Neti. &-=■ Psych., Vol. XIV, pp. 118-123. no GENETIC PSYCHOLOGY *Herrick, C. L. The Relation of Instinct to Intelligence in Birds, Science, Vol. XXVII, 1908, pp. 847-850. *H0BH0USE, L. T. Mind in Evolution, Chapter IV. ♦James. Psychology, Chapter XXV. Jones, J. W. L. Sociality and Sympathy, Psych. Rev., Monograph Supp., Vol. V, No. I, whole No. 18. KiRKPATRiCK. Fundamentals of Child Study, Chapters IV, VI, VII, VIII, IX, X, XI, XII. Kline, L. W. The Migratory Instinct vs. Love of Home, Am. Jr. Psych., Vol. X, pp. 1-8 1. LoEB. Physiology of the Brain, Chapter XIII. Lubbock. Ants, Bees, and Wasps. Marshall, H. R. Instinct and Reason. Mills, W. Animal Intelligence, Part II. ♦Morgan, C. L. Animal Life and Intelligence, Chapter XI. * Comparative Psychology, Chapter XII. Peckham, G. W., and E. G. Wasps, Social and Solitary. ♦Robinson, Louis. Wild Traits in Tame Animals. Romanes. Mental Evolution in Animals, Chapters XI, XII, XIII, XIV, XV, XVI, XVII. Animal Intelligence. Terman, L. W. a Preliminary Study in the Psychology and Peda- gogy of Leadership, Fed. Sent., Vol. XI, pp. 413-451. ♦Thorndike. Elements of Psychology, Chapter XII. ♦Wasman. Psychology of Ants and Higher Animals. ♦Wheeler, W. M. The Origin of Slavery Among Ants, Pop. Sci. Mo., Vol. LXXI, pp. 55c^559- Vestigial Instincts in Insects and Other Animals, Am. Jr. Psych., Vol. XIX, pp. 1-13. ♦Wundt. Human and Animal Intelligence, Chapters XXVII, XXVIII. CHAPTER V BEHAVIOR OF INDIVIDUALS— ACQUISITIONS OF HABITS AND IDEAS HABIT FORMATION Although animals of the same species have common characteristics of behavior, yet the individuals differ greatly. These differences are due in part to variations in structure and in part to differences in surrounding conditions at the moment, as well as to the continuing effects of recent stimulation which, as shown in the chapter on types of behavior, may modify reactions to subsequent stimuli. The larger portion of individual difference in behavior is, however, to be accounted for by more or less permanent modification of individuals by the reactions they have previously made to their environment. The lines of distinction between changes in behavior produced by present conditions, the continuing effects of recent stimulation, and the more permanent changes known as "habits" are not easily drawn. The experiments of Hodge upon vorticella furnish a typical instance of per- sisting effects that have been interpreted as habit forma- tion or learning. He found that vorticella that had been made sick by yeast refused to take any more for several hours. In this case the effect of the stimulus was rather prolonged, but there is no evidence that the creatures be- haved differently toward yeast after the immediate efifects 112 GENETIC PSYCHOLOGY of the Stimulus had disappeared. In other words, it was probably not really a case of permanent modification of physiological activity or habit formation. All the lower organisms, under long-continued exposure to unusual light or temperature stimulation, are modified for a greater or less time by the experience. When trans- ferred back to the former medium they react to it in a nega- tive way. In some instances the change that may thus be produced is so great that the animal can live in a medium which would have been destructive if it had not been grad- ually accustorhed to it, and a sudden transference to the medium in which it formerly lived may cause death. Such instances as this of passive accommodation to continued stimulation are on the border line between the temporary effects of stimulation and passive habit formation. In higher animals there is often what seems to be passive habit formation in the form of decreased response to sounds and other suggestive stimuli that are not in themselves either helpful or harmful and also accommoda- tion to harmful stimuli so that they are better endured. In the case of the starfish experimented upon by Jen- nings, where the animal learned to use a hitherto unused arm, we have an example of more active habit formation. The strength of the hitherto unused arm was probably increased by the exercise so that it took the lead in the righting movement in place of the previously stronger and more active arms. All cases of habit formation probably involve a decrease in some kinds of activity and an increase in others. The parts concerned in effect- ing the right movement consequently grow in strength and determine the direction of future activity. In passive BEHAVIOR OF INDIVIDUALS II3 accommodation to continuous or repeated stimulation the modifications produced are mostly in the direction of minimizing certain activities; while in positi\"e reactions having favorable results the effect is due more to increase in acti\-ity and strengthening of the parts determining action. Behavior that appears like learning has recently been rej)orted by vStevenson Smith in an animal as low as the Paramecium. He found that, when confined in a capillary tube so that it could turn upon reaching the surface film only by doubling on itself, after a number of experiences, it reacted in this way at once when the film was touched, without the usual trial movements of backing and starting forward again. Evidence of persisting modification in the behavior of a sea anemone has been found in the fact that after repeated experience of taking, swallowing, and ejecting filter paper soaked in meat juice, it not only ceased to take it at the time but after several days. This would seem to be a real case of learning or habit formation. In the case already mentioned of crabs that learned to go to a certain part of the aquarium for food whenever the screen was inserted, we have a still clearer example of habit formation. The screen was in itself neither a favorable nor an unfavorable stimulation but became suggestive of a favorable stimulus to be received. This is typical of the kind of habit forma- tion found in higher animals. It should be noted that habits are not formed merely because of performing and repeating an act in a certain way. Whether the tendency to repeat the act shall be greater or less is determined by the results of the act. If 114 GENETIC PSYCHOLOGY the results are favorable, the tendency to repeat the act is increased ; but if the results are unfavorable, the act is either performed with less vigor or is replaced by some other act. When a cat jumps on a table and gets some food, the tendency to repeat that act is increased because of the favorable result ; but if she performs the same movement of jumping on the table and gets a blow on the head, the tendency to jump on the table is decreased. Evidently the activities of the parts concerned in behavior are modi- fied by what happens after a movement has been made. It seems probable, therefore, that favorable results follow- ing any movement tend to increase the strength of the apparatus concerned in directing the movement and the tendency of impulses to take the same course, while un- favorable results produce opposite effects. Since most animals are capable of variety of movement and are all the time being stimulated in several ways, and since the activity of one part, especially in the higher animals, affects and is affected by the activity of other parts, habit formation, in the sense of learning to do a specific thing, involves, to a considerable extent, learning to do it under certain conditions. These conditions in- volve some similarity in the number, kind, and intensity of stimuli being received and their relation to the condition that is calling forth the action which is being developed into a habit. These conditions are internal and physio- logical as well as external. In order that a habit may be quickly formed the external conditions of stimulation, and such internal conditions as hunger, and presence or ab- sence of fatigue, etc., must be the same. If under these circumstances the results are each time favorable, the BEHAVIOR OF INDIVIDUALS II5 reaction that brought these results under these conditions is quickly established as a habit. In most instances of active habit formation in the higher animals, which are affected by a great variety of stimula- tions and whose activities are all closely related, the ex- ternal and internal conditions are rarely entirely uniform. This may in part account for the fact that in habit forma- tion in the higher animals the reaction to a situation does not immediately become uniform, though it is likely to do so if the first reaction is not too complex and has im- mediately favorable results. As we have already seen, the movements first made in a given situation, as for instance in trying to get into a box where there is food, are of a varied or trial character. If success is attained, the next time the situation is presented the trial movements are fewer in number, but rarely is the successful movement immediately performed. As the situation is presented again and again the useless movements disappear, success is attained in a shorter time, and usually the movements then become uniform; but uniformity may be disturbed either by changes in the external conditions or by unusual internal conditions such as hunger or fear. Where the result of a series of movements is unfavorable, we have similarly the dropping out of useless movements ; only in this case it is the movements nearest the unfavorable result that are dropped out first instead of, as in the other case, the movements farthest removed from the favorable result. This is well illustrated by Morgan's experiments with chickens. When a furry and disagreeable caterpillar was thrown into the pen a chicken ran to it, picked it up, dropped it, wiped its bill, then turned away. When Il6 GENETIC PSYCHOLOGY another caterpillar was thrown in the chicken ran to it but did not pick it up, wiped its bill, and turned away. Later the wiping of the bill was omitted, and finally the chicken did not go to the caterpillars when they were thrown in. So far as observed, this elimination of useless movements in learning is very rare in the lower animals. As previ- ously described, the stentor goes through its series of varied reactions in response to a continued unfavorable stimulus again and again, but apparently without learning to eliminate any of the ineffective movements. Preyer thought he observed some shortening in the time required by a starfish; after repeated experience, to remove a cover- ing that he placed on one of its arms, also in the time required to get away when the animal was pinned down ; but Jennings finds no evidence that starfish eliminate useless movements and select for repetition the ones that bring success. The varied but often ununified movements possible to the starfish may be one reason for this. One of the lowest animals that has thus far been observed to learn to take a more direct course to an end is the crab in simple maze tests. In man the formation of habits conforms to the same general principles as in animals. In learning, useless movements are sometimes slowly eliminated and some- times rapidly. This applies not only to movements but also to thinking, as when one is trying to solve a puzzle or a proposition in geometry. In some instances, so far as external behavior is concerned, there are no useless movements to be eliminated, the act being at once per- formed in the shortest way. In such cases, however, if the situation is a new one, there is probably a formation BEHAVIOR OF INDIVIDUALS it; of trial ideas, and wlien llic right one has been found it is selected and the movement executed. This is often the case when a person attempts to undo a fastening or to solve a puzzle. Children, like animals in such circum- stances, are likely to make trial movements, while adults with experience in doing such things, refrain from move- ment until they have solved the puzzle either by means of trial images or by some process of reasoning. It is not to be understood that the most economical mode of reaching favorable results is necessarily acquired before the reaction becomes established as a habit. If a series of movements has favorable results more quickly than any other series of movements that has been tried, it may become established as a habit, although it is far from the shortest and most economical mode of securing the result. It is not true therefore that practice neces- sarily makes perfect. Practice may just as readily es- tablish an imperfect and uneconomical mode of reaching an end. This is an important principle to be recognized by teachers, who should be satisfied as long as a pupil is changing for the better in anything he is doing, but should take care that he does not form a fixed habit before a reasonable degree of perfection has been attained. In animals such as the turtle and the guinea jjig, which are not inclined to make many or varied movements, any reaction that is successful may quickly become established as a habit without any shortening or elimination of useless movements. Although variety of movement may not always be favorable to rapid learning of a particular thing, yet it may prevent too early formation of habits of doing things in imperfect and uneconomical ways. .•\ young Il8 GENETIC PSYCHOLOGY cat or rat does not usually drop useless movements as quickly after his first success as older ones do, but if there are several ways of succeeding he may find one more economical than that first learned. Too early fixing of habits in human beings is unfavorable to progress and to originality. After any form of reaction has been established as a habit it is likely to persist, even if the creature is in some way induced to make a reaction that more quickly brings more favorable results. If, however, the results of a habitual reaction are artificially made unfavorable and especially if at the same time conditions are changed so as to call forth varied reaction, an old habit may be broken up and a new and better one formed. It is reasonable to suppose that every habit has a cause, but only in the case of habits recently formed will removal of the cause quickly eliminate the habit. As we have already seen, the instincts of animals are determined by natural selection acting during the life and development of the species. We shall now see that there is a principle of selection concerned in the development of habits in the individual. Natural selection is effective because of the death of individuals having uneconomical modes of behavior and the consequent elimination of such behavior from the species. In the development of the individual, modes of behavior are selected because of their favorable results, while those having unfavorable or less favorable results are eliminated. Neither the creature as a whole nor any part of it is destroyed ; but the apparatus concerned in bringing favorable results is strengthened for that mode of activity, while that bringing BEHAVIOR OF INDIVIDUALS II9 unfavorable results is relatively weakened. In this way, in the individual, modes of behavior that have most favor- able results are selected for survival and developed into habits. COMPLICATIONS OF INSTINCTS AND HABITS A creature with no instinctive tendency toward any particular form of movement, but with only the general tendency to react under certain conditions by varied trial movements, would have its behavior determined wholly by environment. If it were capable of retaining the effects of past experience its habits would depend entirely upon its own individual history. As a matter of fact, however, all creatures that retain in any considerable degree the effects of past experience are also endowed with some useful types of reaction, and hence their move- ments are not of an entirely trial character. Their first reactions, and consequently many of their habits, are there- fore in part the result of instinctive modes of behavior dependent upon native structure. The first reaction of an individual in a new situation is usually neither wholly of a trial character nor specifically determined by the instincts of the species, though the general character of its behavior is determined by an instinctive tendency to a certain type of reaction. Subse- quently, individual experiences in which results are favorable or unfavorable serve to increase certain instinctive reactions, to check the development of others, and, still more fre- quently, to refine and specialize them and to associate them with suggestive stimuli. Experimenters note great differences in the readiness I20 GENETIC PSYCHOLOGY with which any particular kind of modification of behavior may be produced, depending upon whether it (i) calls only for a specialization in a mode of action instinctive to the animal, (2) involves the inhibition of instinctive re- action, or (3) requires the development of a mode of be- havior new to the species. The instinctive snapping of a fish at almost any small object appearing in his neigh- borhood is not readily inhibited by want of success or even by injurious pricks. Even though there is temporary inhibition the reaction is likely to be made again after an interval, as is well illustrated by the experiments of Mobius upon a pike, Triplett upon a perch, and Washburn and Bentley upon a chub. In every case the fish was a long time learning not to react to a useless or even injurious stimulus, and when some time had elapsed after an interval of practice, it would again dart at the object, especially when it appeared suddenly. When two stimuli, as red and green objects, were pre- sented at once to the chub, one of which meant food and the other not, the learning was much more rapid because the instinct of darting at an object need not be inhibited but only specialized into darting at the red instead of the green object. The more definite and reflexlike an instinct, the more difficult it is to produce permanent modification, and es- pecially to produce inhibition of the act. On the other hand, a less definite and permanent instinct, such as that of following moving objects, shown by chickens and sheep, may readily be inhibited by painful results. It is more difficult to teach a cat to retrieve objects thrown into the water than it is a dog, because a cat in- BEHAVIOR OF 1NI)I\IDUALS 121 slincti\"c'ly draws away from the water, while most clogs do not. It is a very difficult task to teach a pig to walk on a very narrow path, such as the edge of a board, be- cause its instinct is to avoid such paths. It is less diffi- cult to teach this trick to a dog, while cats and monkeys learn it without teaching. A new movement, like that of walking on the front feet, is difficult to teach to either dogs or monkeys, not so much because there is an instinct opposing this movement as be- cause there is no instinct favoring it. For a similar reason Berry found it hard to teach rats to pull a string with the paw rather than with the teeth, although cats readily learn this movement. Most of the training of animals by showmen and much of that given by scientific experi- menters with higher animals, involve at the same time special increase in response to one stimulus and decrease to others. When Thorndike fed monkeys when he put bread in his left hand and did not feed them when he put it in his right, they had to learn both to respond to one stimulus and to inhibit the tendency to respond to the other. The same is true when any specific signal, such as a form or color, is given as a preliminary to feeding, in such a way that the specific stimulus and not the total situation means food. Such experiments also in\-olve specialized discrimination which may, by careful training, be refined almost to the j^hysiological limit. The development of specific reactions into habits is influenced by the nature and order of the external stimu- lation, by the favorable or unfavorable results of reaction, and by the general instinctive tendencies of the creature. If these were the only influences determining the develop- 122 GENETIC PSYCHOLOGY mcnt of a habit, practice in performing the act could only be obtained when the external conditions were repeated wholly or in part, and the development of any particular reaction into a habit would be very slow. There is, how- ever, a general neural tendency to continue or repeat any activity, and for nervous impulses to readily pass out along channels that have just been taken by other nervous impulses. Because of this, reactions are fre- quently repeated after the external stimulus has ceased. This is illustrated by the fact that infants when in the "da-da and bla-bla" stage often repeat several times any sound or movement that they have made. It is espe- cially likely to occur when the movements produce a stimu- lus similar to the one starting the reaction, as is the case in imitating a sound that has been heard. The name "circular reaction" has been given by Baldwin to this phenomenon, and it is properly regarded as an important factor in hastening the development of habits and as a basis of imitative acts. The phenomenon is found in all animals, from the lowest to the highest, and in the highest type of mental activity. A child is likely to work a problem in the same way in which he has just worked another problem, even though it may be of a different kind, and a scientist is likely to apply the same theory to a great variety of facts. When an animal is becoming adapted to many phases of a complex and frequently changing environment, the method of trial movements, even though facilitated somewhat by the fact that chance is partially eliminated by native structure and instinctive tendencies, would not be sufficiently effective even though habit formation is hastened by spontaneous repetition. He needs something BEHAVIOR OF INDIVIDUALS 123 that will cause him to develop the power to make effective reactions to situations before those situations occur at a time when they in\olve immediate and serious conse- quences. This is especially needed by all of the higher animals and man. They arc aided in preparing to meet future situations by the play instinct, which causes any surplus energy to flow out, not only in random movements, but in kinds of movements often made in the instinctive reactions of the species. In this way the organs for such movements are strengthened by abundant exercise and there is much greater likelihood of the right reaction being made when the situations are first seriously met. Even this, however, is not sufi'icicnt to always insure proper reactions to the en^•ironment if reactions could be learned only by the individual's own exj^erience. It is of great ad\-antage to a creature if he can jjrofit by the individual experiences of others of his species. This is pro- vided for to some extent in the higher animals, and in a very marked degree in man, by the imitative tendency. A creature that imitates must not only be responsive to the objects in his environment but must be especially sensitive to what his companions are doing. j\Iany animals are thus sensitive, so that they respond to the mo\ements and cries of their companions that have percci\ed an enemy or food without waiting until they themselves perceive it. In this form of the imitative tendency the animal makes no movements new to his species, or, in other words, no movement that is not to some extent instinctive ; but he begins such mo\'ements in response to his perception of them as made by companions, instead of in response to the stimulus that has excited them. 124 GENETIC PSYCHOLOGY In man wc have an imitative tendency of a somewhat different kind. He is so sensitive to what companions do that he not only docs what they do when the actions are of the usual type, but he is so affected by movements which he perceives, that he reproduces them, although they are entirely new. This kind of imitation is possible in man, (i) because of the greater development of the social instinct which makes him more sensitive than other animals to what companions are doing, (2) because of the character of his motor apparatus which may be ad- justed in an infinite variety of ways, and (3) because he possesses nerve centers that can readily acquire the power to make these adjustments. A child is often able, without any preliminary practice, to imitate simple sounds and gestures with considerable accuracy. In other cases a movement or sound crudely like that which has been per- ceived is produced and repeated with variations until it is made with accuracy. When a child yawns, coughs, cries, smiles, frowns, or performs any other reflex, expres- sive, or instinctive movement when he perceives some one else perform it, his imitation is not different from that of the higher animals, but when he makes a movement that is not instinctive in character, such as waving his hand or playing pat-a-cake or uttering a word when he perceives some one else do it, he is engaged in a kind of imitation that is exceedingly rare, if not utterly impossible, in nearly all species of animals. The exceedingly varied character of imitati\'e acts that can be performed by children makes it difficult to explain them as due wholly to inherited structure and even more difficult to explain them as originating wholly in the BEHAVIOR OF INDIVIDUALS 125 previous experience of tlie indi\idual. The extraordinary facility with which children sometimes reproduce sounds which they hear, often, without practice, rivaling the accuracy of the j)honograi)h, indicates that there must be a close relation between the centers for sound percep- tions and the centers controlling the movement of the vocal organs. The facility with which gestures are imi- tated indicates that the visual centers are related to the centers controlling arm movements. If it were en- tirely a matter of chance as to what movement should be made in response to the sound of the letter "a," it would take a lifetime of experience in which this sound was continually being heard and some kind of res[)onse given, before the sound would be uttered. On the other hand, we cannot suppose that the apparatus concerned in the perception of the letter "a" and the apparatus concerned in its utterance are definitely connected at birth in such a way that the sound must produce the correct movement. It must be however that imj)ulses which are at first wirlely diffused, spread more readily from the auditory centers to the centers for vocal utterance than to any other part of the brain, and that the spreading of impulses in response to the sound "a" is slightly differ- ent from that in response to the sound "b." The imita- tive movement is therefore at first partly determined and partly of a trial character and it becomes accurate in the same way as do other reactions. The pleasure of imitat- ing what has been perceived hastens the process. The possession of the imitative instinct greatly facili- tates the learning of individual cats, dogs, birds, and horses in the lines of their instinctive behavior, as is shown 126 GENETIC PSYCHOLOGY by the fact that they learn much more rapidly when as- sociated with companions. In the case of children, who have so much to learn and who are able to learn not only in the line of instinctive movements but also to learn all kinds of new movements, the imitative tendency plays a still more important part. A human being without opportunity to imitate companions would scarcely be recognized as a human being. It is largely because of his great power of imitation that man is able to acquire an almost infinitely greater variety of motor skill than any other animal. Imitation is especially helpful in acquiring complex movements, the elements of which are already familiar, and in such acquisitions by man, nerve centers concerned in the formation of free ideas are developed and play an important part in connecting the series of movements. FREE IDEAS We have already found that modifications in behavior may be produced in all organisms. In the lower organisms they are usually either temporary or else become permanent only by a sort of slow growth process. In the higher organisms the modifications are much more rapid and more permanent. Such modifications are more properly de- scribed as learning, especially when the activity varies in the direction of eliminating useless movements and securing ends in a more economical way. In the higher animals this elimination of useless movements may proceed very rapidly. If all but the essential movements are omitted at once we have a type of learning common in men but rare in animals. BEHAVIOR OF INDIVIDUALS 127 Such learning seems to invoh'c an analysis of the situation as a whole and a reaction to the essential stimulus only. It is claimed that such a mode of learning is possible only to a creature capable of forming free ideas of the elements of the situation and reacting to them, regardless of the other elements with which they are associated. It will be admitted that most of the behavior of most animals may be explained without supposing them to possess such free ideas. The instances in which such ideas seem needed to explain animal behavior are few and may have occurred by chance, or it may be that individual animals, either because of special training or because they are the geniuses of their species, are able to form some free images. In objective terms the question involved is really this. Is there an apparatus that can respond to the essential elements of a situation after a single experience and that can be aroused to activity by the recurrence of the essentials of the situation in connection with another set of elements? It will be much more convenient however in discussing this question to use subjective terms and to speak of the func- tioning of such a specialized apparatus as a free idea. We shall therefore anticipate later discussion of con- sciousness and not only use subjective terms but consider the matter from the standpoint of our own conscious experience. The results of a single experience that seem to exist in such a form as to direct subsequent l)ehavior may take the form of a memory image, a free image or idea, or of an anticipatory or perceptual image. IMost persons would probably think of the memory image as first in the order of mental genesis and the anticipatory image as the last. 128 GENETIC PSYCHOLOGY If by memory is meant simply the persistence of the efTects of a former stimulus there would be good ground for this view, but if memory means, as it usually means in psychol- ogy, not simply the reproduction of the former state, but a consciousness that this mental state was experienced in another situation than the one now present, this view is probably exactly the reverse of the true one. It is a well-known fact that associations are more effective in the same direction in which they were formed than they are in the reverse direction. When we cannot recall the next element in a series, whether it be a movement, a word, or an idea, we are likely to begin again the series, hoping that the desired and anticipated element will be brought into consciousness by the repetition of those that preceded it. In the case of partly learned quotations, series of movements, or steps in reasoning, we are often able to pro- ceed when given a portion of a series, before we are able to give the series independently as a whole or any one element of it separately. We may know just what to do, say, or think when started on the series, although we could not of ourselves begin the series. In cases where we cannot immediately take the next step and hence cannot definitely image it, we may still know its general character and may be able to recognize at once whether any element suggested is or is not the one desired. This ability to continue a series indicates some kind of an anticipatory idea which makes us know when the right thing is presented, but it does not mean that we have any such idea independent of the series calling it up, and still less does it mean that we have a genuine reminiscent memory of the element in some other situation not now presented to us. BEHAVIOR OF INDIVIDUALS 129 In other words, the order of development in consciousness is first, indefinite antici])atory images of the general char- acter of what is to come; second, more definite images when the series or situation which formerly preceded or accompanied it is reproduced ; third, partially free images of an element in a series or situation, aroused by another scries or situation, most of the elements of which are different; fourth, a free image which may be aroused with- out any direct sensory stimulation ; and fifth, a reminiscent or memory image of the element as having occurred in another situation or series. Not only does a study of our own mental processes lead to this view of the case, but biological principles point in the same direction. It is relatively of little importance to a creature to be able to form images of a situation formerly present. The essential thing is to be able to act in such a way as to secure favorable results now and in the future. This means that the action is to be guided by what will happen as a result of any series of reactions. If the situa- tion and the series of movements begun in response to it suggest an unfavorable result to follow the continuation of the series, we may suppose that such an anticipatory idea would have the same effect in the way of decreasing and inhibiting action as was formerly produced by the unfavor- able results themselves. An anticipatory idea of the results to follow a given series of movements would therefore serve the very useful purpose of inhil^iling movements that would bring unfavorable results, and of insuring and increasing . the vigor of movements that would bring fa\-orable results. Such an anticipatory image would be useful even if the exact nature of the results were not represented. 130 GENETIC PSYCHOLOGY Definite memories are also less necessary than definite anticipatory images. The choice of the right mode of ac- tion in a new situation may often be made without definite memories of what formerly occurred in connection with the elements determining the reaction. If these elements were greatly emphasized in the original experience they may, so far as consciousness is concerned, constitute about all there is of the new situation and may suggest at once the idea of the result without any consciousness of the result as having been experienced in another situation; e.g. an object that has caused pain may be shunned in an entirely new environment without a definite memory of the former experience and surroundings. As we have already seen in the case of the starfish righting itself, the different parts may at first act independently, but when the impulse to turn itself over appears, the action of each part is modified in such a way as to bring about the turning by some one method. In a similar way the actions of all creatures are unified and correlated by the end to be ob- tained. It is natural therefore to suppose that when consciousness begins to play a part in the direction of be- havior it takes the form of an anticipatory idea of results to be secured, which helps to unify and direct behavior in accordance with results of past experience. Conscious- ness of elements to be combined in a new way to secure desirable ends, and reminiscent images of past experi- ences, would naturally be much later in development and useful not so much in determining the general character of the reaction as in choosing the most effective means of reaching the end. All the higher animals act as if they had some idea of BEHAVIOR OF INDIVIDUALS 131 results, and nearly all students of animal life will admit that they do ha\e such ideas. They can also learn to recognize, with great accuracy, specific elements in a situation, to which they react. Many persons do this without forming images, and it is probable that animals do. When they do form images they are usually aroused by a sensory-motor series that has previously led to the corresponding ex- perience. Animals do not readily learn the elements in any situa- tion unless reacted to by themselves. Thorndikc thought that they could not learn in any other way than by their own movements, but Cole found that raccoons were helped to learn how to get food by being put in the box where it was to be obtained, and he thought that they got the idea of how to get the food by this experience. He also found, as some other experimenters have, that putting an animal through the movements helps him to learn a series, although he does not learn as quickly as when he can in some way be induced to go through the series himself. In order that free ideas may be formed, elements of the whole situation and the corresponding reaction must be selected, and then these elements must be freed from their connection with any one series or situation. The fact noted by Davis that a raccoon was almost as much dis- concerted by approaching a familiar fastening from a new direction as by a new fastening, indicates that an animal's reaction is to the whole situation as it confronts him. He also reports a striking instance in which one of the raccoons studied by him showed little evidence of analyzing the situation, and learned by trial instead of by perception of elements and relations. After the raccoon had learned to 132 GENETIC PSYCHOLOGY open a door fastened with a bolt on the left side of the door, the bolt was removed and a bear-down lever placed on the right side. The raccoon worked for a long time where the bolt had been, trying to push what was not there. After assuming all sorts of positions he accidentally pushed the lever down with his hind foot, which slipped off the corner of the box, where he was standing with his head down. He opened it four times in this way, then his foot failing to open it when it slipped, he turned and opened it with his fore paws. The next day he assumed the upside down position, then turned and used the fore paws. Later he did not assume that position but still put his hind foot against the lever before pushing with the fore paws. With further practice he doubtless could have learned to push it with one front paw only. Evidently the analysis of the whole situation, so far as there was any, corresponds closely with the dropping out of useless movements as the more favorable mode of reaction is acquired. It is probable that the process of analysis of situations is, as in this case, always closely correlated with the elimination of useless movements. The importance of having success follow the right move- ment in learning how to do anything, is well illustrated by the fact that after a raccoon had succeeded a few times in getting a door open by pressing down a lever, in one case after pressing it down he reversed the movement and thus brought it in place again so the door did not open. The lever was fixed by the experimenter so this could not happen again, but not until after about fifty trials did the raccoon open the door with as few errors as before his failure to get the door open by the right movement. The negative re- BEHAVIOR OF INDIVIDUALS 133 suits of some experimenters may perhaps be accounted for in this way as well as the lack of success of unappreci- ative teachers of children. The process of forming free ideas by both men and animals involves attention to the elements of the situation, and reaction to those elements not simply as a part of one situation leading to an end of a certain kind, but as elements in a variety of situations leading to various ends. A free idea of a lever and its characteristics, whatever the situation and the end to be gained, is easily acquired by man, who has used it under many cir- cumstances and for different ends ; but by an animal that has used it only as a means of getting food under certain conditions such an idea cannot possibly be formed. A monkey observed by Hobhouse, which had learned to throw a cloth over an object that it could not reach, and draw it nearer, was given a stick to use for the same pur- pose. By drawing the attention of the animal to the stick by moving it, the animal was induced to take it and to begin scratching around with it, and largely by accident the object was thus brought within reach. After a time the monkey frequently used the stick to get things that it could not reach. Previous action in drawing things toward it evidently helped m learning to use the stick, but trial move- ments rather than the image of the motion to be made seemed to be the chief factor in learning. The stick had a hook on the end, which made it much more effective if rightly used ; but the animal did not seem to notice this characteristic of the tool, and there was little or no evidence of his possessing an idea of the movement to be made in order to use the stick effectively. 134 GENETIC PSYCHOLOGY Attempts to teach a monkey such tricks as this do not usually succeed, seemingly because the animal's attention cannot be directed to the exact movements made by his teacher. He may, in performing the act, succeed more quickly by having his attention directed to the object to be moved ; but he is not likely to notice specific facts regarding it, such as in just what direction and how far a fastening must be moved to open a door. He gets such knowledge not by observing another animal or person undo the fastening but as the accidental result of trial move- ments, Watson, after a long series of attempts, found it impossible to teach a monkey how to use a rake or perform any other movement simply by seeing him or a companion perform the act. This lack of interest and attention to the exact character of the movements made by persons and companions is doubtless the reason why animals learn little that is new by imitation. It is doubtful if they even observe the exact character of their own successful movements. The chief help that they get from seeing acts performed is in having their attention directed to the right place or object, and the object rather than the movement is apparently the center of interest. Haggerty has recently made the interesting observation that monkeys imitate strange monkeys more readily than companions. This is probably because they watch a stranger more closely. Any means by which essential elements are made im- pressive so that they determine action will be helpful in the first stage of the process of learning. The reaction once acquired may be specialized to almost any extent by slight variations in the situation, and in this way a certain element may come to be reacted to without regard to its BEHAVIOR OF INDIVIDUALS 135 surroundings; e.g. a signal given in a certain situation and accompanied by various gestures and followed by im- mediate reward may be reacted to when given without such accompaniments and in a form scarcely perceptible to a human observer. It is not however freed in this way from the movement made nor from the end gained by the movement. After the essential elements in the situation have been learned so that they are accurately recognized, they are not necessarily known as separate elements but as the significant portion of the whole situation or series. The pigeon may learn to discriminate a square as a means of food when it is placed on one of several vessels in a cage and always has food under it. In other surroundings it might not look under a square for food. The location of the square is the significant element in the whole situa- tion and there is not necessarily any idea of the square apart from the situation in which it serves as a food signal. If a monkey learned to use a rake, but only for getting food outside of the cage, it would not have a free idea of a rake but would know it only as a part of a certain situation. Hobhouse quotes a remarkable instance of an animal which either by coincidence or because of unusual intelli- gence used a reaction learned in one situation to meet quite a different situation. A dog had learned, when given meat, to go to the door and wait for it to be opened that he might go out and eat the meat. One time, hearing some dogs outside that he evidently wanted to be with, he picked up a piece of bread (which he would never eat), went to the door, and waited for it to be opened. The immediate object, to get out of 136 GENETIC PSYCHOLOGY doors, was the same, but in one case it was to get out of doors to eat the meat, and in the other, in order to join some other dogs. Also the article used, a piece of bread, was different from the one customarily used in this act. We seem therefore to have a case of the essential element, the standing before the door with something in the mouth, selected and used as a means for obtaining re- sults that were only partially the same as had previously been secured by this reaction. This is probably as strong evidence of the possession of a free idea as has been authentically reported. If such actions were usual instead of the rare thing among animals, there would be little ground for denying that they do possess some free ideas. If they are not explained as the result of chance they still serve to emphasize the fact that free ideas must very rarely be possessed by animals, otherwise they would not be considered worth describing. An infant of two years who would do such a thing might be regarded as "bright" and the incident related to friends ; but actions of this character are so common in older children and adults as not to be considered worthy of notice. Such incidents as that of the dog which had chased a rabbit into a drain a number of times and which finally took a direct course to the mouth of the drain (instead of following the roundabout course of the rabbit) and thus succeeded in catching the animal, can be explained much more easily on simpler principles than the functioning of free ideas. As we have already seen, in the learning stage of habit formation, the movements are not the same each time but vary in the direction of eliminating useless move- ments and reaching the end by more direct means. There BEHAVIOR OF INDIVIDUALS 137 is especially likely to be change of movements when those that have been made have not had favorable results. The taking of the more direct course to the drain where the rabbit had frequently been smelled was therefore of the same general character as the behavior of animals in finding their way through a maze. There is no reason to suppose that free ideas play a part in such instances except when the change takes place very quickly. As we have already indicated, man is endowed with motor apparatus capable of being adjusted in an infinite variety of ways, hence he can manipulate objects freely for various purposes. The monkey, which is the most facile of animals in the use of his hands, is still far inferior to man, partly because he cannot use his thumb in opposition to the fingers. In general, animals that are capable of the greatest variety of motor adjustments are regarded as most intelligent. This is probably not alone because the ability to make a variety of movements makes it possible for them to more fully express their mental states, but because the making of this variety of movements develops the mental states indicated by them. In other words, mental control in the form of free ideas is developed during the process of gaining varied motor control. We have also found that man possesses a greater variety of instincts than any other animal. This means that he has a greater variety of ends to be obtained, or, in other words, has a variety of interests. The use of a certain object or movement, not only in new situations but for entirely different ends, is the most effective means of free- ing that element from any particular series or situation in which it has occurred. Very rarely does an animal use an 138 GENETIC PSYCHOLOGY object or a movement as a means to more than one end. To a child an object of a certain shape may be of interest to him as an indication of food, as a sign of the direction to be taken in going home, as an object to be used in play, etc. With such experiences as these it cannot be to him simply an element in some one situation, but it comes to have a significance of its own, and he can form an idea of it to be used in new situations and for a different purpose. If animals could react in a sufficiently varied way and for a sufficient variety of ends, it is not improbable that they could form free ideas just as man does by such reactions. Perhaps such animals as the monkey and the elephant may form some ideas of objects distinct from any particular sur- roundings or movements. The fact, however, that they are limited in their ability to manipulate objects and hence in their power to use or construct tools, that they have no language by which to designate objects in their absence, and the fact that each species of animals has only a limited number of interests that dominate his activity, make it im- possible for them to form many free ideas and utterly impossible to form any that are so completely free as are those formed by man. The possibility of forming free ideas and of combining movements without previous experience in their combina- tion, which is involved in imitative acts, opens to man modes of learning utterly impossible to animals. He can learn not only by his own experiences but by the experiences of others. He can acquire this knowledge not only by imi- tating combinations of movement, which he would other- wise hit upon only by accident, but he can also profit by the experience of others, because, through the association BEHAVIOR OF INDIVIDUALS 139 of free ideas with words, he can have those ideas aroused in his mind and combined in a way corresponding to the ex- periences of other persons. This latter mode of learning is utterly unattainable by animals. They may have famil- iar experiences recalled by words, but they cannot possibly learn new things by means of words. The possession of free ideas also makes it possible to form trial ideas instead of making actual trial movements ; hence the much greater possibilities of rapid learning by man. REFERENCES *Allen, a. Some Experimental Conclusions on Practice and Habit, Jr. Ped., Vol. XIX, pp. 237-254. Andrews, B. B. Habit, Am. Jr. Psych., Vol. XIV, pp. 121-149. ♦Angell. Psychology, Chapter III. ♦Arnold, Felix. The Initial Tendency in Ideal Revival, Am. Jr. Psych., Vol. XVIII, pp. 239-252. Bair, J. H. The Acquirement of Voluntary Control, Psych. Rev., Vol. VIII, pp. 474-510. Bentley, I. M. The Memory Image and Its Qualitative Fidelity, Am. Jr. Psych., Vol. XI, pp. 1-48. *Cole, L. W. Concerning the Intelligence of Raccoons, Jr. Comp. Neu. &= Psych., Vol. XVII, pp. 211-261. *Dexter. Survival of the Fittest in Motor Training, Ed. Rev., Vol. XXIII, pp. 81-91. * James. Psychology, Chapter X. Jennings, H. S. Progress in the Study of the Behavior of the Lower Organisms during the Past Year, Psych. Bui., June, 1908, pp. 179-190. JuDD. Studies in Genetic Psychology, Jr. Ped., Vol. XIII, pp. 295- 304- * Psychology, Chapter VIII. *KiRKPATRiCK. Development of Voluntary Movement, Psych. Rev., Vol. XIII, pp. 275-281. I40 GENETIC PSYCHOLOGY LiNDLEY. Psychology of Puzzles, Am. Jr. Psych., Vol. VIII, pp. 431-493- Mills, \V. Nature and Development of Animal Intelligence. ♦Morgan. Habit and Instinct. Comparative Psychology, Chapter XVI. Scott. Se.x and Art, Am. Jr. Psych., Vol. VII, pp. 153-226. Spence. Development of Voluntary Motion, Pop. Sci. Mo., Vol. XIII, p. 444. Swift and Schl^yler. The Learning Process, Psych. Bui., Oct. 15, 1907. *SwiFT, E. J. Studies in the Psychology and Physiology of Learning, Am. Jr. Psych., Vol. XIV, pp. 201-251. *Thorndike, E. L. Animal Intelligence. * Elements of Psychology, Chapter XIII. Function of Visual Images, Jr. Phil. Psych. S^.Sd. Meth., Vol. IV, pp. 324-327- Mental Antecedents of Voluntary Movements, Jr. Phil. Psych, df Sci. Meth., Vol. IV, pp. 40-42. *Triplett, N. The Educability of the Perch, Am. Jr. Pysch., Vol. XII, p. 354- *W.ASHBURN. The Animal Mind, Chapter X, XL Washburx, M. F., and Bentley, I. M. The Establishment of an Association involving Color Discrimination in the Creek Chub, Jr. Comp. Neu. &= Psych., Vol. XVI, p. 113. *Watson, John. Imitation in Monkeys, Psych. Bui., June, 1908, pp. 169-178. *Yerkes. The Dancing Mouse, Chapters XII, XIII, XIV, XV, XVL The Formation of Habits in the Turtle, Pop. Sci. Mo., Vol. LVIII, p. 519. Habit Formation in the Crayfish, Harvard Studies, Vol. I. CHAPTER VI STRUCTURES CONCERNED IN COMPLEX BEHAVIOR AND IN IDEATION THE NERVOUS APPARATUS OF VERTEBRATES The following abstract of the results of Loeser's experi- ments upon frogs, which correspond closely with what has been found by other investigators, will serve as an indica- tion of the portions of the nervous apparatus concerned in the various forms of behavior in vertebrates. If the cerebrum is removed on one side, there is muscular weakness on the other side of the body that lasts for several days, while removal of both sides of the cerebrum produces weakness on both sides that is also only temporary. No other marked change is observed from the removal of the cortex of the cerebrum only. When the optic thalami (which are comparatively large in the frog and perhaps correspond in function as much to the cerebral cortex of man as to the thalami, which in man are located inside the cerebrum) are removed, there is considerable loss of sight and of the sense of touch. If only one of the thalami is removed, the decreased sen- sitiveness is on the opposite side only and is not so great as when both are removed. The animal no longer re- sponds to suggestive stimuli in the form of flies, as does a normal frog, and he shows little improvement in sen- sitiveness though allowed to live for a long while after the operation. 141 142 GENETIC PSYCHOLOGY If, in addition to the thalami, the optic lobes are removed, what is known as " forced movements" are common. The limbs assume unusual positions and the animal when stimu- lated may respond with such vigorous, uncontrolled jumps as to injure himself. The removal of both lobes produces more marked results than the removal of one, but with no special difference in character, and in either case there is little or no recovery. If only the posterior portions of the optic lobes are removed, other parts being uninjured, there is no loss of sight, and there is recovery after several weeks from the condition in which forced movements are promi- nent. The removal of the cerebellum results chiefly in weakness of movement. In higher animals injury to one side of the cerebellum may produce circular movements. The removal of all of the brain above the medulla leaves the animal, after recovering from the operation, with the power to croak, to turn over, and to swallow in response to direct stimulation, and also to move into a more favorable position when the object upon which the animal is resting is tipped. The physiological processes of circulation and respiration are carried on as in the normal frog. He does not respond to suggestive stimuli, and makes few or no movements except when externally stimulated, and then his movements are very definite, so that one who is familiar with an animal in this condition can predict with almost absolute certainty just what he will do. When the whole brain of a frog was removed, including the medulla, leaving nothing but the spinal cord and the sense and motor apparatus connected with it, the physio- logical process of respiration and heart beat ceased, though STRUCTURES COx\CERNED IN COMPLEX BEHAVIOR 143 life was maintained for five hours. In this condition the animal showed no evidence of sight, did not turn over when placed on its back, did not move when the surface upon which it was resting was tipped, and the croaking and swallowing reflexes could not be called forth. Tactile stimuli, on the other hand, were responded to by move- ments of the limbs more quickly and accurately than in the case of a normal animal. When a portion of the cord next the brain was removed so as to affect the centers concerned in the movements of the fore limbs, incoordination of movement appeared and the animal could no longer move its body as a whole success- fully. Considerably more of the cord could be removed, however, without interfering seriously with the movements of the hind legs when the animal was suspended in such a position that movements could be freely made. These results correspond in a general way with the re- sults of experiments on higher animals. In the case of higher animals, the results of removal of portions of the nervous system are likely to be more profound and perma- nent, and the animal is more likely to die from the injuries. Goltz, however, who succeeded in removing practically the whole of the cerebrum of a dog without destroying its life, found that the animal reacted like normal animals to direct sense stimuli but showed no evidence of memory, intelli- gence, pleasure, or envy, and that its responses to stim- uli were immediate rather than deliberate. From these experiments we may conclude that the physiological processes are chiefly under the control of the medulla in connection with the sympathetic nervous sys- tem. The reflex movement of swallowing, so closely con- 144 GENETIC PSYCHOLOGY nccted with the physiological processes, and some other complex reflexes, arc also under the control of the medulla. The simpler reflex movements in response to direct tactile stimulation are chiefly under the control of the spinal cord, while the ganglia between the medulla and the cortex, the optic thalami, the corpora striata, and the corpora quad- rigemina (sometimes called collectively the "basal ganglia") are concerned in the more complex reflex and instinctive movements of the whole body in response to direct sensory stimulation. The nervous energy concerned in stimulating the motor centers to action seems to be stored up in part in the cere- bellum and probably also in the cortex of the cerebrum. These organs therefore make it possible for movements to be executed with vigor, and they doubtless are concerned in the coordination of movements, since they determine the amount of energy sent to various centers of move- ment. An injury to one side of the cerebellum therefore naturally interferes with balance and coordination of movement. The more conscious processes involved in responding to suggestive stimuli and in carrying on the higher mental processes are made possible by means of the wonderful complex structure of the cerebral cortex, whose most marked characteristic is its capacity for being modified by experience. It thus becomes a great storehouse of past experiences and an organ for bringing present and past stimuli into relation with each other so as to direct activity toward definite ends. The frontal lobes of this organ seem to be especially concerned in the coordinating activity of attention by means of which mental and motor processes STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 145 are unified and directed toward a definite end. In the low- est vertebrates, which have scarcely anything that can be called a cerebrum, there is very little reaction to suggestive stimuli and very little capacity for learning by experience. The functioning of the frontal lobes in learning is clearly indicated by the experiments of Franz. He trained mon- keys to perform tricks, then removed the frontal lobes. There was no indication of paralysis or of loss of sensa- tion, but the animals did not seem to perceive the mean- ing of objects and signals involved in the tricks recently learned and for that reason apparently could not perform them. Instincts and well-established habits on the con- trary were unaffected. This indicated that the frontal lobes, which are concerned in the unifying act of attention, are necessary to the learning of complex acts and to the successful execution of them until the apparatus more immediately concerned in their execution is so well devel- oped that it may function successfully without the direct- ing activity of the frontal lobes. Similar conclusions may be drawn from the noted case of a workman who had a large portion of the front of one half of the brain destroyed by a crowbar which passed through the side of his head. It has sometimes been stated that he showed little evidence of the loss of function after the wound had healed. As a matter of fact, a careful study of the description of his actions and his subsequent life shows that his dis[)osition and intellectual ability were changed in a marked way, although his habitual acts were performed about as well as ever. He was more moody, impulsive, and less controlled in his actions, and he was unable to concentrate his mind in the planning of new 146 GENETIC PSYCHOLOGY work. In consequence of these deficiencies he was obliged to give up his position as a foreman. rttFFERENCES BETWEEN THE NERVOUS SYSTEM OF MAN AND OF OTHER ANIMALS In order to explain the wonderfully complex activities possible to human beings we must notice some of the promi- nent differences between the brain of man and of the lower animals. The spinal cord of man is very much the same as in other of the higher vertebrates, though it is perhaps more highly specialized in man into an organ for connect- ing the surface of the body with certain portions of the brain, while in animals the cord is not concerned so much in making connections with the brain as it is in responding itself to tactile stimulations. The total size of the cord is small in man as compared with other vertebrates, espe- cially the lower ones, and his brain is relatively very large. The brain of man is absolutely larger than the brain of any but the largest vertebrate, and relatively larger, in proportion to the size of the body, than in any but the smallest vertebrate, while in comparison to the rest of the nervous system it is relatively larger than that of any other animal. As we have previously seen, man is endowed with highly specialized sense organs and with a motor apparatus that admits of great variety and accuracy of movement, this variety and accuracy of movement being made possible by the possession of a few motor organs whose movements can be combined in an infinite variety of ways. A motor apparatus of this type would not be effective if it were not STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 147 connected with a nervous apparatus of sufTicicnt size to effect the proper connections and adjustments involved in the various combinations that are required, just as many telephones in a system demand a large switchboard. This is one reason why the brain of man needs to be much larger than that of any other animal. Man is still further distinguished by the size of his cerebrum in proportion to the rest of the brain, and still further by the large size of the frontal and parietal lobes. These facts are doubtless correlated with the fact that man has many instincts not possessed by animals and is cap- able of many forms of mental activity impossible to them. In comparing the surface of the cerebrum of man with that of the dog or the monkey there is a general corre- spondence, though the frontal and parietal regions are in man much larger and contain an immensely greater number of connecting nerve elements. In a young child only a comparatively small portion of the surface of the cerebrum is connected with other parts of the nervous system by meduUated nerve fibers. The sense centers having medullated nerve connections are connected not with each other but with the basal ganglia and the spinal cord. Medullation of nerve fibers probably corresponds in a general way to the insulating cover on electric wires, preventing impulses from spreading to other nerve elements. It probably indicates not merely that impulses may pass to and from centers connected by such fibers, but that impulses passing over these fibers must pursue a definite course. The medullation of fibers is therefore probably correlated in part at least with learn- ing and habit formation. 148 GENETIC PSYCHOLOGY As the infant grows older and has experiences by means of which he learns to make all sorts of combinations of motor apparatus under various circumstances of stimu- lation, the nerve fibers having medullary sheaths increase in number. Those connecting the various sense centers in the cortex with each other soon acquire their medullary sheaths. In a child the spaces between the sense centers, sometimes called "association" centers, are much greater than in animals. This probably corresponds to the fact that young animals are capable of many instinctive move- ments, while the child is capable of very few, but has a much greater capacity for acquiring new combinations of movement. The fact that large portions of the cortex in the child are unmedullated, and that the number of medullated fibers continues to increase in the cortex of man long after he is physically mature and has practically ceased to learn new combinations of movement, indicates that there are other functions performed by the 'cortex of man than those of combining movements. Some of these portions of the cortex that at birth are unmedullated doubtless constitute the apparatus by means of which man is able to store up the results of past experience in the form of free images and ideas. It has long been known that sensation and movement may be lost through injury to the spinal cord without the higher intellectual powers being affected. It is also not unusual when the brain is injured or diseased for the mental powers to be seriously affected without any disturbance of sensation and movement. More definite localization of mental functions was first STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 149 clearly established in the case of portions of the brain concerned in the use of symbols. It was found that in- juries to the left hemisphere in the temporal region usually resulted in language disturbance of some kind, designated by the general term " aphasia." The particular portion of the brain concerned in the use of symbols, especially words, was discovered doubtless, not because the functions in- volved in language are more defmitely localized than are other functions, but because any deficiency in language could more easily be detected and its exact nature more accurately determined than a deficiency in any other men- tal power. It is for this same reason that further facts as to the exact portion of the cortex concerned in different forms of language functioning have been determined with a good deal of accuracy. Injuries to other portions of the brain may not produce changes in mental characteristics that a stranger would detect, while friends would be able only to say that the indix'idual is "queer," without discern- ing the exact deficiency. The deficiency in language may consist in inability to understand spoken words, although there is no deafness to sounds; or inability to understand the meaning of visual words, although sight is not affected ; or inability to speak words, although there is no paralysis and words may be understood ; or inability to write, although the arm is not paralyzed and words are recognized and understood when seen. These various deficiencies, which have received technical names, may be combined in all sorts of ways, but one may appear almost wholly alone, and perhaps exist only for certain classes of words, in persons who show no sensory or motor deficiency and who can form images of 150 GENETIC PSYCHOLOGY things and reason as well as they ever could. It seems quite certain, therefore, that there is a certain portion of the brain especially concerned in the use of symbols, al- though it is complex in character and closely associated with apparatus concerned in other mental functions. Detailed evidence as to the existence of specific apparatus concerned in the various other forms of mental activity is not so easily obtained and not so clearly established as in the case of the language apparatus. There is sufficient, evidence, however, to justify the claim that the apparatus concerned in imaging things is not wholly the same as that concerned in sensing them. Experiment shows that, when coming under the influence of chloroform, the power to image and to think remains after all sensation is lost. This indicates that the centers concerned in these pro- cesses are not the same as those concerned in sensations. The phenomena of dreaming supports this view. A most striking illustration of the fact that the apparatus concerned in imaging is distinct from that concerned in sensation and in thought, is furnished by the instance of a man who was an exceptionally good visualizer, so good that he could image a business letter as a whole and read it just as if it were before his eyes. After a period of mental strain he found himself utterly unable to form visual images. He could no longer use such images in memory as formerly, and buildings and persons that he had long known also seemed strange to him. His reason was un- affected and he continued to carry on his business suc- cessfully. In order to do so he practiced using auditory images, remembering in this way what he had formerly remembered in the form of visual images. This is only STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 151 one of the most striking of many cases, indicating that the image centers are, at least in part, distinct from the sen- sory centers and the conceptual centers. Pathological cases and hypnotic experiments furnish other instances which, as we shall see, are supported by psychological analysis. The nervous system of man can best be conceived as being very much like that of dogs, monkeys, and other animals, but with considerable portions specialized for the performance of more complex operations. Those centers which are slightly if at all represented in the brains of the lower animals are first, centers concerned in forming images of things; second, those concerned in the produc- tion of word or symbol images; and third, those concerned in the formation of concepts and in the processes of abstract thought. The imaging centers are excited to action primarily by external stimulations that pass through the centers concerned in sensation. These image centers, when developed by experience, may send impulses to each other without the centers concerned in sensation and movement being concerned in the activity to any consider- able extent. They may also be excited to activity by im- pulses coming from the centers concerned in the produc- tion of word images and also by images coming from the conceptual centers. The symbol or word-imaging centers are excited pri- marily by external stimulation passing through the sen- sory centers, just as are the centers for imaging things ; but when fully developed may be excited from other word centers and by impulses coming from the conceptual centers. 152 GENETIC PSYCHOLOGY The conceptual centers are excited primarily by impulses from the image centers and from the word centers. The same centers are concerned to a considerable extent in attention. When developed, one conceptual center may arouse another to actix'ity either with or without the exci- tation of the image centers. What is practically the same external reaction, for example, the drawing away of the hand, may be directed wholly by the sensory motor apparatus excited by an ex- ternal stimulus, or may be produced without an external stimulation by an impulse coming from either of the three centers already named. It is because of this fact that a creature with such centers is to a considerable extent inde- pendent of his environment, being able to act in accordance with images of past experience instead of in response to present stimulations only. Some specialization in the brain structure of the higher animals may exist, corresponding to one or more of those centers named above as existing in the brain of man, but the specialization has not proceeded far enough to admit of very much independent activity of those centers. It is not possible therefore for animals to carry on to any con- siderable extent the function of imaging independently of external stimulation and of external movement, because the apparatus for independent action of such centers is not sufficiently developed. GENERAL VIEW OF BRAIN FUNCTIONING In man the various mechanisms concerned in mental processes can function to a considerable extent inde- STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 153 pendenlly, bul one may readily start another into action and these higher centers in the brain inllucnce and are in- lluenced by the basal ganglia, the spinal cord, and the sym- pathetic nervous system. The relations between the vari- ous parts of the nervous sys- tem and the possibilities of separate and combined action may be conceived as being similar to the rela- tion between boiler, engine, lathes, drills, etc., of a large machine shop, only infinitely more complex and delicately adjusted. The accompanying dia- gram may help to give a general idea of the various apparatus concerned in the mental and motor opera- tions of man and the rela- tion of one part to another. To simplify matters each Fig. 15. -Diagram showing in a general type of apparatus is repre- way the relation between the conceptual, ,11 • 1 . , representative, and svTnbol centers of the sented by a smgle circle or , , ,, ■ , , , ., -' rt upper level, the perceptual centers of the center. As a matter of fact, midflle level, and the instinctite, reflex, all of these centers are com-^"^P^^'''"'°^"''""*'^''°^"^'^^°^^"^'='""'' plex, and their parts, instead of being located together, are found in different parts of the brain. For example, the sensory motor center includes all the special senses, although the auditory center is near the middle of the cerebrum and the visual center in the back portion. On 154 GENETIC PSYCHOLOGY the Hughlings Jackson" three level theory" the conceptual, symbolic, and representative centers vi'ould constitute the upper level, the perceptual centers the second, and the instinctive, physiological, and reflex the third. In considering the function of the nervous system two important principles have until recently been largely ig- nored or not given sufficient weight by physiologists and psychologists. These are (i) what has been designated in mechanics as the "factor of safety" in construction and only recently recognized as applicable to the body, and (2) the principle of the "common path" made so much of in Sherrington's great work on the physiology of the nerv- ous system. Mechanics always recognize the factor of safety in their constructions by making a bridge or other structure from six to ten times as strong as is needed to bear the strain to which it is likely to be subjected. In many machines the same principle is recognized by having several sets of apparatus to do the same work, so that the machine will be effective when subjected to unusual strain or when some portion of it is broken or out of order. In the construc- tion of the body, nature has recognized this principle to as great if not a greater extent than have machinists. Men have lived for years and done their ordinary work with only a part of one lung, a portion of the liver, or a part of one kidney ; and it has recently been demonstrated that even so important an organ as the stomach may be removed and yet the process of digestion be carried on successfully. There is no doubt that the nervous system is constructed in such a way that considerable portions of it may be de- stroyed without permanently interfering with the functions STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 155 that they have previously i)erformed wholly or in part. If the visual center is lost, auditory images may take the place of the visual, or the same work may, under certain circumstances, be performed by a conceptual center or by the sensory motor apparatus. The principle of the " common path" is correlated and to some extent contrasted with that of the "factor of safety." If the path concerned in the execution of movements is in- jured, certain functions, e.g. writing, which might otherwise have been directed either by sensory, representative, or con- ceptual centers, may be interfered with. Again, injury to a sensory tract leading from the lower to the higher centers may interfere with the activity of sensory, conceptual, and representative centers in the performance of certain kinds of tasks; e.g. injury to the optic nerve prevents reading. Again, the development of a certain kind of motor ability may increase in a marked way the power of conceptual, rep- resentative, and sensory centers. A striking instance of this is that of a man who could not talk and was supposed to be an imbecile, unable to master the simplest subjects. After an operation on the tongue and some training of the vocal organs, he developed mentally and later became a success- ful business man. Skill in drawing always increases the fineness of sense discrimination, clearness of representation, and variety and defmiteness of conception. In the other direction the development of a clear concept may increase the representative and perceptive power and sensitiveness in the same line, as is shown by the fact that one who is familiar with an object sees it more readily. Many machines are capable of doing a great variety of things by means of special attachments; e.g. the sewing 156 GENETIC PSYCHOLOGY machine, although the machine as a whole works in much the same way with one attachment as with another. In a similar way we may suppose that higher animals and man, with the same general type of nervous system, are enabled to do an increasing variety of things because of some spe- cialization in motor, sensory, or representative apparatus. The nervous system of some of the lower animals may be compared to the old hand printing press and that of the higher to the modern Hoe press. The general character of the result is the same, but with the modern machine the process is infinitely more com}jlex and rapid. PHYSIOLOGICAL BASIS OF SPECIAL MENTAL PROCESSES The various mental processes described in psychology, when considered from the physiological point of view, must be conceived as the functioning of neural elements organized so as to react in certain relations. In the case of reflex and instinctive processes these organizations of elements are largely structural and independent of experience. In the case of conscious processes described in psychology the organization has been produced, in part at least, by experi- ence, the relations of neural elements to each other being modified by every experience of combined activity. In perception, the physiological apparatus involved is much more complex than that concerned in simple sensory motor reactions and is to a much greater extent the result of experience. The variety of specialized elements concerned in perceptions is as much greater than of those concerned in reflex movement as is the nervous apparatus of a frog more complex than that of the hydra. The perception of any STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 157 object, as for example an apple, may involve correlated activity of nervous elements located in visual, auditory, tactile, olfactory, and motor centers of the brain. Re- peated and various experiences with such an object cause elements in all these centers to become related and or- ganized into a perceptual apparatus all of which is active to some extent whenever one of the sensory centers con- cerned is stimulated. The functioning of such an appara- tus is the physiological side of the process indicated in psychology by the name perception. A definite object, usually located spatially, is perceived whenever this appa- ratus is excited to activity, whatever the sense by which the activity may be initiated. Our perception of a book is much the same whether we see it, hear it fall, or touch it. The perception differs greatly, however, according to the kind of interest we have in the book at the moment and what movements we are going to make in connection with it. This means that the functioning of the perceptual apparatus is influenced by other apparatus dominating and determining the general character of the activity of the perceptual apparatus. The percept of a flower as an object of beauty is entirely different from the percept of the same flower as an article of merchandise, as a scien- tific specimen, or as a cure for a certain disease. It is probably not too much to say that the perceptual reaction of a man to a single object may in a few minutes involve as much variety in physiological and mental activity as is shown in the reactions of a frog to all phases of his envi- ronment during his whole life. A percept is to be thought of, not as a mere comljination of sensations, but as the result of the functioning of a 158 GENETIC PSYCHOLOGY highly organized perceptual apparatus usually dominated by higher centers and discharging into definite motor channels. Sensations involve the activity of a simple apparatus long used by the species, while perception in- volves the activity of a much more complex apparatus organized by repeated experiences of the individual. It probably always involves the activity of at least one sen- sory center other than that directly stimulated, along with the activity of centers determining attention, and motor centers, and in man, imaging and conceptual centers as well. If the perceptual apparatus is excited by a stimulus affecting a sensory center, one may seem to have a percept of an object that is not present. Hallucinations are not produced, as is sometimes thought, merely by excessive activity of the imaging centers, although the activity of such centers may help to determine the particular character of the hallucination. A real object seems to be perceived instead of being merely imaged because in some w^ay, either because of irritation of nerves leading to sensory centers, or because of an external stimulus of a general character, the perceptual apparatus is excited from the periphery. Only when thus excited does one have the feeling of the reality of the perception and fail to distin- guish it from an image. Mental images are the result of impulses that do not come directly from the periphery as in perceptions. They in- volve the functioning of apparatus that is at least partially different from that involved in perception. In so far as the centers concerned are the same, they are made active in perception by impulses coming from a sensory center, STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 159 while in imaging they may be made active by impulses coming from some other direction. The power to image may remain after the power to make the corresponding perception has been lost, and there may be power to per- ceive or recognize objects that cannot be imaged when they are not present. This does not necessarily mean, however, that the apparatus concerned in the two processes is wholly different, but only that it is partially different and excited to activity in a different way. A percept, being produced by an object, is necessarily perceived in space and in relation to what surrounds it. A free image, on the other hand, is not necessarily connected in any way with surrounding objects, but may be associated in any desired way with other images which are also not connected with any object at the moment stimulating the senses. Free images are under subjective control, and the apparatus concerned is usually excited internally, while percepts are objectively initiated and the apparatus concerned is made active by some object in the immediate surroundings. In purposeful perception, however, the activity of the sense centers concerned is doubtless increased and modified by impulses from within. In perception, impulses usually discharge to some extent into motor centers, while in imaging, the discharge is directly into other imaging centers or into conceptual centers, and if there is any discharge at all into motor centers, it is indirect rather than direct. The imaging apparatus is first developed by impulses from sensory centers, but free images are not formed till the imaging apparatus can be excited from several direc- tions and can have its connection with other apparatus l6o GENETIC PSYCHOLOGY readily shifted so as to effect a variety of combinations. This is a marked characteristic of the imaging apparatus, that its units may be united or disconnected in almost any desired way with great facility, just as we may sep- arate and combine letters. While the perceptive apparatus is comparatively stable in its organization, always present- ing the same combination of qualities, yet one may be emphasized more than another according to the kind and intensity of the external stimuli and the kind of stimulus coming from the higher centers determining the purpose of the activity. Where other sense centers than the one stimulated are excited, as is the case in nearly all perception, the resulting mental states are more like sensations than genuine free images ; e.g. we seem to actually feel the smoothness, weight, and coldness of a piece of ice perceived visually. The term "mediated" or "secondary" sensations might well be applied to them. They certainly are not free images, for they are the result of co-functioning of sense centers, one of which is directly stimulated, while free images are the result of separate functioning of centers either partially or wholly different from those concerned in sensations. Memory images differ from free images in that not only does an image unit occur again but it occurs in the same combination with other units as at some previous time. If under a given set of circumstances a combination of image units is incomplete or different in arrangement from what it was originally, the memory is defective. In im- agination, on the other hand, change in the way in which image units are combined is an essential characteristic. On the physiological side memory involves the making STRUCTURES CONCERNED IN COMPLEX BEHAVIOR i6i of the adjustments or series of adjustments that have been made one or more times before, and on the psychical side, the consciousness that the adjustment has been made previously. Concepts are the result of the functionina; of apparatus further removed from direct stimulation of objects than are the imaging centers. Conceptual centers arc aroused to activity by impulses from the image centers which, as we have seen, are primarily made active by impulses from the sensory centers. When fully developed, the conceptual centers are capable of being excited by imj)ulses from the symbol centers and by impulses from other conceptual centers. Conceptual centers are so specialized that im- pulses from the perceptual apparatus are more completely analyzed than in the image centers, and it is possible to have ideas of the qualities of objects totally unrelated to the objects themselves. This is quite beyond the powers of the perceptual and imaging centers, which are concerned to a greater or less extent with objects as wholes or with qualities of objects instead of qualities unrelated to objects. This greater specialization of activity is correlated w^ith an increased capacity for making all sorts of combinations of these qualities. On the physiological side this doubt- less means much greater specialization of fine neural elements, and at the same time much more complex and extensive combinations of neural elements, that may be made and changed with the greatest facility. Combinations and changes of adjustment of neural elements are involved in acts of attention, association, and thinking, and such acts determine the general direction of the activity of the imaging and perceptual apparatus. l62 GENETIC PSYCHOLOGY Injury to the attentive-conceptual centers may affect the action of the lower centers because the adjusting and organizing power is affected. Simple sensory motor processes are usually less affected, and the same is true of the perception of familiar objects, while new percep- tions and all combinations of image and conceptual units are impossible except in the case of some that are very well established by habitual activities. Conceptual activity doubtless involves the activity of an apparatus as complex and highly differentiated in com- parison with the perceptual apparatus as the perceptual is, compared with the sensory apparatus. In connection with its own complex and delicately adjusted activity, it calls into action either slightly or extensively the imaging and perceptual apparatus. The excitation of the symbol apparatus is almost as necessary to conceptual activity as is the excitation of sense and motor centers to perceptual activity. In proportion as the symbol apparatus is active in connection with the conceptual it is unnecessary that the imaging apparatus shall be active in the process of thinking. PHYSIOLOGICAL MECHANISM OF ATTENTION AND THOUGHT Attention in animals and in men may be regarded as a process by which the direction of activity is determined. The direction of activity is determined in part by stimuli in a way analogous to that by which the movements of bodies acted upon by several forces are directed according to the law of the resultant of forces. In physiological activity, however, the guidance applies not only to the move- STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 163 mcnt made at the time but to the way in which combined and successive movements are unified so as to accomplish the definite end. In this respect attention may be com- pared to the movements of a sailboat under the influences of wind and water. The analogy is not complete, how- ever, without supposing that the boat moves toward some definite point in response to adjustments of a rudder. The behavior of the starfish in turning itself over will serve to illustrate the fundamental character of attention in its simplest form, considered physiologically. Each arm may work independently for a while, but when a cer- tain mode of righting begins, all the arms modify their activity in such a way as to help in effecting the turning in this way, rather than in some other way such as might be used at another time. Not only does the mode of per- forming an act involve a unification of several activities, but the end to be gained unifies action in one direction rather than in another. When an animal is seeking food, the direction of activity is determined by the end, that of securing food. If he is fleeing from danger, much of the same apparatus may be used, but unified in a different way. Under certain cir- cumstances it may be uncertain for a time whether an ani- mal will eat the food that is before him, flee from an enemy that is approaching, or attack the enemy; but in either case, the direction of activity having been determined, the activity of all parts is unified and directed by the end to be gained. Stimuli which in the attainment of one end would seem to dominate the action would, in attaining another end, have little or no influence. Attention as a mental process is the conscious correlate l64 GENETIC PSYCHOLOGY of such acts of unified behavior. It is clear that such a process must involve on the physiological side enforcement of certain activities and inhibition of others. In creatures with a highly developed nervous system the influence of the activity of one part upon the activity of other parts is greater and more general than it is in the lower animals. The closeness of relation of parts in man is well illus- trated by experiments upon the tendon reflex. When the leg is crossed and the tendon just below the knee cap is struck, the foot kicks in an entirely involuntary way. It is found, however, that the extent of the kick is influenced by other stimuli given at the same time, by any movement that may be made by the subject, such as clenching the hand, and by mental processes, such as addition. Ex- periments also show that the amount of the influence, and whether it shall be positive or negative, varies accord- ing to the time elapsing between the receiving of another stimulus, or the execution of a movement, and the stroke upon the tendon. If this simple movement is influenced by the activity that is taking place in the sensory, motor, imaging, and conceptual centers, it would seem reasonable to suppose that the activity of every nerve center influences to some extent the activity of every other nerve center. It is not to be supposed, however, that the activities in all parts of the nervous system are affected to the same extent. The native structure of the nervous system is such that some parts are more closely related than other parts. The nervous system is also modified by its activities so that parts which were not naturally closely related come to exercise a strong influence upon each other, while those naturally related may have their influence upon each STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 165 other's activity decreased. In general, those that have acted together recently and repeatedly with favorable results are likely to inlluence each other most. This is the basis of the general laws of habit and association and of development of attention. We may conceive of activity in one part of the nervous system affecting activity in every other part, but in some parts earlier and to a greater extent than in others. When a number of parts are made acti\'c by several diverse stim- uli and by the activity of motor centers, the direction of activity will, in a general way, be the resultant of the various influences. When the activity once takes a cer- tain direction, the activity of one part is increased while that of others is decreased in such a way that the tendency is toward a definite end to which each part contributes. In experiments upon the ner\-ous systems of animals it is found that nervous impulses spread most readily to corresponding nerve centers on the other side of the body. In a frog, for example, if one hind leg is stimulated and the stimulus continued, the other hind leg will be moved also. In the case of a dog, which uses a hind leg alter- nately with a front leg, the stimulus applied to the hind leg affects the fore leg on the other side of the body be- fore it does the other hind leg. In experiments upon attention in which an object that may be seen in two ways is presented, it is first seen in one way,thenin another. This moreor less rhythmicchange of attention is i)robably due, in j)art at least, to changes in the blood supply and to fatigue. The rhythm of attention can, however, be greatly modified by changes in sensations or in ideas. Where a figure is seen alternately as concave l66 GENETIC PSYCHOLOGY and convex its perception as a convex figure may be pro- longed by emphasizing certain lines by moving them slightly, or by forming images or thinking of the properties of convex figures, and by the utterance of the word "con- vex." In a similar way the time during which the figure is seen as concave may be prolonged. The difference between the attention of men and of animals is chiefly in the fact that the attention of animals is determined by sensory stimulations either from without or within the body, and by movements; while the attention of man is determined only in part by sensory stimuli, the activity of imaging and conceptual centers having a greater influence than the activity of the sensory and motor centers. In trained adults these centers exercise much more influence than in children and uneducated adults. The analysis of a situation into elements always involves attention and is usually initiated and accompanied by some kind of instinctive or acquired interest. Most concepts are formed by bringing a number of these analyzed elements into relation with each other in the satisfaction of some kind of a need. It follows therefore that concepts and at- tention are necessarily closely related to each other. No grouping, analyzing, or connected thinking is possible with- out acts of attention and feelings of interest, by means of which the elements are related to each other and unified in their relation to an end. We should expect, therefore, to find the apparatus concerned in the formation of con- cepts and in the direction of attention closely connected, if not to a considerable extent the same, and that increase or decrease in either the power of generalizing or attending would be accompanied by a corresponding increase or STRUCTURES CONCERNED IN COMPLEX BEHAVIOR 167 decrease in the other power. Observation of faih'nf^ mentality in a human being supports this view. Injuries to the frontal lobes in both animals and men are found to interfere seriously with the power of attention and the unified activity of the other parts of the brain, especially in the performance of non-habitual processes. The most extreme ideas have been held regarding the specialization and localization of function in the cortex. Some experimenters find evidence of very definite and specific localization of function in the cortex of men and animals. Others produce equally strong evidence that the cortex always functions as a whole. It would seem, from the preceding discussion, that both may be right in the main. Although each portion of the cortex may have a very definite and highly specialized function to perform, yet even the simplest processes involve the associated activity of so many parts of the brain, and the activity of one part is so greatly influenced by the activity of other parts, and all are so modified and unified in the directing of activity in a certain way by the process known as attention, that there is also truth in the statement that the brain functions as a whole rather than as separate parts. This is the usual normal condition of the brain. In pathological cases this correlated activity in all parts of the brain is disturbed. In that form of insanity due to fixed ideas, certain centers exert an undue influence and deter- mine the direction of mental activity whatever may be the external conditions and in spite of all attempts to arouse to vigorous action other conceptual centers that ordinarily play an important part in directing mental activity. In cases of double personality there seems to be a disassocia- l68 GENETIC PSYCHOLOGY tion of one system of connections from the others, so that each system is, in the main, independent of the others, and the states of consciousness corresponding to the activity of each system have little or nothing in common. In such a case the sensory motor mechanism may function equally well with either system, or more perfectly with one than with the other. REFERENCES *Angell. Psychology, Chapter II. Barker. The Nervous System. Bastian. Aphasia and other Speech Defects. *Carus, p. The Soul of Man, pp. 107-218. Collins, Joseph. The Faculty of Speech. Donaldson, H. Growth of the Brain. Ferrier. Functions of the Brain. Franz, S. I. On the Functions of the Cerebrum: The Frontal Lobes, Archives of Psych., No. 2. James. Psychology, Chapters VII, VIII, IX. *JuDD. Psychology, Chapter III. LoEB. Physiology of the Brain, Chapters XV, XVI, XVII, XVIII. LoESER, Wilhelm, M.D. a Study of the Functions of Different Parts of the Frog's Brain, Jr. Comp. Neti. df Psych., Vol. XV, PP- 355-373- *Meyer, M. Nervous Correlate of Pleasantness and Unpleasantness, Psych. Rev., Vol. XV, pp. 207-216, 292-322. *PiLLSBURY. Psychology of Attention, Chapters XVI and XV. Sherington, Chas. S. The Integrative Action of the Nervous System. *SlDis, B. The Doctrine of Primary and Secondary Sensory Ele- ments. Psych. Rev., Vol. XV, pp. 44-68, 106-121. Are there Hypnotic Hallucinations? Psych. Rev., Vol. XIII, pp. 239-257. An Inquiry into the Nature of Hallucinations, Psych. Rev., Vol. XI, pp. 15-29, 104-137- *Thorndike. Elements of Psychology, Chapters IX, X, XL CHAPTER VII CONSCIOUSNESS OBJECTIVE TESTS OF INTELLIGENCE AND CRITERIA OF CONSCIOUSNESS Up to this point we have described behavior and mental processes as far as possible in objective terms. From this point on we are to give more attention to the conscious states themselves. After a preliminary consideration of the tests and objective indications of consciousness we shall reverse our point of view, and starting with the facts obtained by introspection attempt to infer from our own mental states what the mental states of less highly developed minds may be. The standards for judging intelligence are similar to the criteria of consciousness ; hence the two may be considered under one heading. We have direct knowledge of our own consciousness only. We infer that other beings are conscious. The basis for our inference is that they are similar (i) in struc- ture, and (2) in behavior. I. As to structure, importance is usually attached not so much to form of body as to the possession of a certain kind of structure, i.e. nervous tissue, with which conscious- ness is usually supposed to be associated. Injuries to the nervous structure in man produce more disturbance in consciousness than injuries to any other portion of his body. It is often thought that where there are no nerves 169 lyo GENETIC PSYCHOLOGY there can be no consciousness, and hence that animals without any nervous structure must be without conscious- ness. This view may be correct, but the possibility of consciousness existing where there is no nervous structure must be admitted. There is digestion without any special- ized organs of digestion in the lower forms of animal life, and for aught we know there may be consciousness in creatures possessing no nervous system. This does not mean, however, that they have a conscious- ness like our own. It is utterly improbable that creatures possessing a nervous system of a very simple kind, without any specialized sense organs and without a complex mo- tor apparatus, have mental states with any more than a slight similarity to our own. Definite specialized states of consciousness are probably found only in animals having a highly specialized sensory and muscular structure, with a nervous system closely relating each part with every other part. The habit of thinking of other beings as conscious tends to make us ascribe consciousness to the behavior of crea- tures much lower than ourselves; but the whole physical structure of a fly, a clam, and an amoeba is so different from our own that w^e have no reason, on the basis of struc- ture only, to suppose that they have a consciousness like ours. Similarity in the structure of the nervous system would give us reason to think there is much in common in the consciousness of man, monkeys, dogs, and birds; and yet, because of the larger brain of man and the larger amount of modifiable nervous material in his cortex, it is probable that he has many states of consciousness entirely impossible to them. coNsciouSiSrEss 171 II. The basis of inference regarding consciousness of other creatures most depended upon by scientists and others, is that of behavior. Similar behavior is usually supposed to be accompanied by similar states of conscious- ness, especially when the creatures comjjared are similar in their general form and structure. From the purely objective point of view, behavior is supposed to indicate consciousness and intelligence according as it involves certain essential characteristics. The characteristics that have been named as indications of consciousness are; (i) discrimination, (2) motion, (3) purpose, (4) modi- fiability. (i) It is not safe to say that any creature has conscious- ness simply because it is able to discriminate differences, since this is a characteristic of inorganic as well as organic bodies. A magnet may be said to discrim- inate steel ; and every chemical atom has its special affinities which, in an objective way, involve discrimina- tion to as great an extent as does the reflex and instinctive behavior of animals. There is no organism, either plant or animal, that does not discriminate in the sense of reacting to different stimuli in different ways. It is true, however, that fineness and accuracy of discrimination in animals and men are usually taken as one evidence of intelligence. This however is not to be looked upon wholly as a charac- teristic of consciousness, but as dependent upon the delicacy of the mechanism with which the individual is provided. The number of different discriminations possible is often considered a better measure of intelligence than fineness of discrimination. The lower animals with fewer special- ized sense organs make fewer discriminations than do the 172 GENETIC PSYCHOLOGY higher, and the broadly cultured man makes many dis- criminations unnoticed by the uncultured. A more significant fact regarding discrimination is found in the characteristic of discriminating between what is favorable and what is unfavorable to the organism. All animals have something of this regulative discrimination, by means of which they act so as to get away from or avoid unfavorable conditions and so as to maintain or secure favorable ones. This phase of discrimination cannot be readily explained on the basis of structure only, neither is it certain that the laws of physiological equilibrium will fully explain this phenomenon. Consciousness, if not absolutely necessary, is doubtless of great help in deter- mining the favorable or unfavorable character of any particular stimulation. Certain it is that we are more inclined to ascribe intelligence to creatures that quickly and easily discriminate between w^hat is injuring them and what is for their good, and still more do we ascribe intelligence to those that discriminate suggestive stimuli that are neither harmful nor helpful in themselves but are the forerunners of favorable or unfavorable stimuli to follow. (2) Motion is always suggestive of consciousness, prob- ably because the motions which we notice most are those of persons to whom we are in the habit of ascribing con- sciousness similar to our own. When, therefore, we see movement in animals we infer that there is consciousness accompanying the motion and directing it. This is prob- ably the reason why, in the common mind, all animals that move are conscious, while plants which do not as a rule move are unconscious, notwithstanding the fact that CONSCIOUSNESS 173 some plants are more highly organized than some animals. The recent experiments of Bose, however, have sliown that movement which is supposed to be exceptional in plants is really common. The movement in plants, however, is very slow, the response to stimulation occupy- ing minutes where that of an animal would occupy only a fraction of a second. Accuracy of movement is often considered an evidence of intelligence, perhaps because it is intimately associated with discrimination. Like fineness of discrimination, accuracy of motion is to be explained by the structure of the apparatus rather than by consciousness. It is true only in a general way and for certain forms and grades of in- telligence that accuracy of movement is associated with greater general intellectual power either in animals or men. The results of sensory and motor tests have been found to correspond to the judgment of teachers as to the intelligence of small children, but not in the case of college students. Variety of movements is sometimes considered as a better standard of intelligence, and it is generally true that the higher animals are capable of a much greater variety of movement than the lower, and man of a greater variety than any other creature. As we have already seen, this is due in part at least to the peculiar type of motor organiza- tion with which he is so highly endowed. Whether such a type of motor mechanism could be successfully perfected and operated without conscious intelligence, may well be questioned. A still more trustworthy standard of consciousness and intelligence is \.\\q fitness of the movement to m.cet the situ- 174 GENETIC PSYCHOLOGY ation. However complex and varied, or however well it might be suited to some other situation, a movement is not regarded as evidence of intelligence unless it meets the particular situation in such a way as to bring favorable results to the creature. This standard of consciousness is one very difficult to apply, for all creatures are able to make fitting movements characteristic of their species under the usual situations, while in unusual situations their move- ments are often injurious instead of helpful. Similarly, men of different training and habits, each successful in his own field, may fail completely when attempting to do some- thing in another line of work and be regarded as exceedingly stupid by the specialist in that line. The higher animals, and especially man, are regarded as more intelligent because they are able to meet and react properly to many changing situations. This is generally considered as one of the strongest evidences of intelligence, providing some definite end is secured by the varied reac- tions to the new situations. (3) One very common standard for judging conscious intelligence is that of the purposefulness of the movements made. Objectively, purpose means simply action toward the attainment of some end, and many suppose that where such adaptation is shown there must be a consciousness of the purpose to be achieved. This view however cannot be logically adhered to unless plants are supposed to be conscious also, for their growth processes are very perfectly adapted to the ends of producing seed and providing for its protection, dissemination, and future growth. In the case of animals, purpose is objectively indicated in their reflex and instinctive movements, but the fact that certain results CONSCIOUSNESS 1 75 come through these movements docs not prove that they are conscious of acting to secure those results. Judging from our own reflex movements there is no consciousness of what is to be done, but merely of the results as they occur. The same is usually true of instinctive movements. Variety of ends toward which action is directed is gener- ally considered indicative of conscious intelligence. The higher animals are endowed with a much greater variety of instinctive behavior than the lower, and man with a still greater variety. The cultured man also seeks many more ends than the uncultured. Where the action of human beings is for remote rather than immediate ends we are more apt to ascribe intelligence. The savage provides for the wants of to-day and perhaps to-morrow, while civilized man makes preparations for desirable ends years hence. In the animal world there is no very close correspondence between the immediate- ness or remoteness of ends toward which instinctive action is directed and the degree of intelligence of the creature. The suitability of the end toward which the actions are directed is always a basis of judging of intelligence. Any creature that acts to secure that which would be of no value to him is regarded as lacking in conscious intelligence; while those that most successfully choose that which is for their own good are regarded as the most intelligent. Where the good to be secured corresponds closely to ends that are commonly secured by instinctive action, intelli- gence is not usually supposed to be so great as where the advantage is peculiar to the individual and perhaps op- posed to what, under ordinary circumstances, is good for 176 GENETIC PSYCHOLOGY the species. This would seem a very good basis for infer- ring conscious intelligence, but it is not always easy to tell whether the suitable action is characteristic of the species, native to the individual, or one based on individual experi- ence. The behavior of ants previously described seems less intelligent when we realize how nearly it conforms to the usual instinctive behavior of the species. (4) Modifiahility, or the capacity to be changed by ex- perience, is perhaps used more than any other standard tor determining the presence and degree of consciousness possessed by any creature. It cannot, however, be taken as the absolute standard of the presence or absence of con- sciousness unless we suppose that all organisms are con- scious, for all are subject to modification by experience and surroundings. Plants transplanted from one latitude to another are different in their growth from those grown in the same locality, which shows that they have been modified by the different conditions to which they have been sub- jected. As we have already shown, even the lowest animals are very soon modified by variations in light, heat, and chemical condition of their surroundings. In higher ani- mals such modifications in behavior are much more permanent and more quickly made. The pigeon can learn to pass through a maze and obtain food by the shortest route in ten repetitions, while a crab, to acquire equal success in a simpler maze, needs several hundred. The readiness with which the behavior of animals is thus modified is a very good standard of the degree of in- telligence that they possess, providing the behavior modi- fied in each case is equally characteristic of the species compared, and the conditions are equally suitable to their CONSCIOUSNESS 177 mode of life. The rat readily learns to find its way through a maze either lighted or unlighted, while the pigeon does not learn so readily in a lighted maze and still less readily in a darkened one. This is not a clear j^roof of the greater intelligence of the rat, because threading mazes constitutes a large part of the instinctive activity of his species and usually this is done in darkness, while threading mazes is an exceptional form of activity to the pigeon species and movement in the dark very unusual. Where a creature not only readily learns to do one thing, but can also easily learn to do a great variety of things, we have still more ground for ascribing to him intelligence. This is one of the marked distinctions between higher and lower animals, and especially between man and other animals. Every animal is a specialist in his instinctive mode of life, while man rivals animals in most lines of be- havior, besides engaging in many imj)ossible to them. Again, if a creature learns something and a few hours or a few days later shows no evidence of having learned it, he is not regarded as so intelligent as one who retains the modi- fication through a long period of time. Whether quickness of learning and permanence of retention arc more likely to be found associated than in reverse relationship cannot be stated with certainty from what is known of these characteristics in animals and in man ; but recent evidence indicates that permanency of retention is more characteris- tic of species and individuals that are easily modified. The kinds of modifications that take place with refer- ence to present and future needs are also regarded as indi- cations of intelligence. IVIodification of behavior that at no time brings any advantage is not regarded as evidence N 178 GENETIC PSYCHOLOGY of intelligence, however easily, rapidly, and permanently it may be made. Although none of the criteria named above, when taken alone, is positive evidence of consciousness or measures of intelligence, yet several of them combined give a good basis for inferring consciousness and estimating the degree of intelligence. The finer, more varied, and advantageous the discriminations, the more accurate, varied, complex and useful the movements; the more behavior is suited to securing many and distant ends, and the more all these have been the result of modifications produced in the life of the individual by his own experience, the better the ground for affirming conscious intelligence of a high degree. The essential characteristic of all intelligent action is, from the objective point of view, that it shall be adapted to the securing of useful ends. In this sense an animal in his usual environment appears to be intelligent by instinct. The word has, however, generally been used in a sense some- what contrasting with instinct, to designate actions that effectively and economically meet situations that cannot be met so effectively or perhaps at all by the usual instinc- tive behavior of the species. In the preceding discussion, however, the common characteristic in instinctive and acquired actions of being suited to the attainment of favorable ends has been strongly emphasized as important in comparisons of species and individuals. This broader use of the term intelligence is more favorable to the forma- tion of genetic conceptions of behavior than that which narrows the meaning of the word to make it contrast with instinct. In later discussions we shall show the useful- ness of this broader meaning. CONSCIOUSNESS 1 79 SUBJECTIVE CRITERIA OF CONSCIOUSNESS AND ITS FUNC- TIONS Since all our knowledge of consciousness is based on our knowledge of our own consciousness, we must introspec- tively observe our own behavior to determine when con- sciousness is most intense and in what circumstances it is most helpful, and from such observations we may in- fer the presence of consciousness when similar behavior is shown by other creatures. By noticing what can and what cannot be done without consciousness and what can be done better with and without it, we may also form a better idea of the real functions of consciousness. We note first that consciousness is most prominent when there are changes in situation and behavior, the degree of consciousness appearing to vary with the rapidity of the change. A very gradual decrease in the tempera- ture of an object touching the skin, or of the air or water surrounding the whole body, is scarcely felt, while a much smaller change, occurring suddenly, gives a very distinct sensation. The gradual dawning or fading of the light of the sun is imperceptible except by comparison with the memory of how it looked a few moments before; but the sudden flashing or going out of the tiny flame of a match gives a very distinct sensation. The same truth holds re- garding all sensations and movements and also regarding perceptions, images, and concepts. Their presence in the usual way and under usual conditions involves so little consciousness that it is almost impossible to observe mental processes sufl[iciently to describe them except when they are in some way changing or being carried on under l8o GENETIC PSYCHOLOGY unusual conditions. The ability to observe one's own mental processes has to be cultivated. One reason why experimental psychology has led to the discovery of many important facts in the course of the experiments is because the special conditions of the experiments make the conscious processes more noticeable. The law of change is probably not limited to conscious phenomena, for nervous processes usually supposed to be unconscious conform to the same law. The physiologist, in his experiments upon nerves and muscles separated from the central nervous system, finds that sudden though slight changes in the strength of a stimulus produce greater reac- tion than larger but more gradual changes. A continuous current of electricity produces no reaction at all, though it may modify other reactions, contractions being made only when it is first sent in and when it is shut off. The same phenomenon of response to sudden changes in stimuli is shown in all forms of animal life, including those without any specialized nerve tissue, as is illustrated by the first reaction of a Paramecium to warmer or colder water. It is claimed that a frog may be boiled alive without struggling if the water is heated very gradually. It is a familiar fact that sudden changes in stimuli keep one awake, while continuous and monotonous stimuli often produce sleepiness. Turning now to the various forms of activity we find that the physiological processes of respiration, circulation, and digestion are usually performed without sudden changes and without consciousness. If air, food, or other conditions are changed, so that great and sudden variations in these processes occur, as when the air is shut off or gas is taken, CONSCIOUSNESS l8l or when poisonous drugs or excessive amounts of food are taken, consciousness becomes intense. Reflex, instinctive, and habitual movements, such as winking, walking, and dressing in the usual way under usual conditions also have little conscious accompaniment ; but we become acutely conscious of any interference with these activities. The details of nearly all familiar voluntary movements also have little place in consciousness, which is usually occupied with the new phases of the situation which vary with each performance. If the situation and modes of performance remain the same the act soon becomes an unconscious habit. It seems therefore that consciousness has no part in physio- logical, reflex, and instinctive behavior common to the species except as these processes are modified by the special experiences of the individual, and also that acquired modes of behavior almost or entirely cease to be conscious when they become uniform. Since the changes producing intensity of consciousness may be primarily either in the external stimulation or condition or in changes in the mode of action of the organs responding, we need to notice the role of consciousness in each case. In walking in the habitual way, consciousness is prominent only when we meet with obstructions or unusual variations in the surface. A child's first move- ments of every type doubtless produce conscious states, for they are producing changes in his nervous system ; but they certainly are not directed by consciousness. In combining mo\ements in various series and reacting to the constantly varying phases of environment there is continual occasion for and need of consciousness. As we have already seen in the process of learning, even l82 GENETIC PSYCHOLOGY when external conditions remain uniform, there is consider- able variety in the way in which a thing is done until some one mode of reaction is perfected and established as a habit. This means of course that the parts concerned are being modified during the learning process. Such modifica- tion is doubtless a stronger stimulus to consciousness than mere variation in objective stimulation. Where the changes in the situation are such as have been frequently reacted to in the same way they may occur almost without consciousness even in a complex series. A striking example of this is shown when a per- son reading aloud and thinking of something else per- forms the very complex mental operation of perceiving all the different words and speaking them in the proper order and perhaps with fairly good inflection. When, however, the act involves the reaction to a new situation or a modification in the mode of reaction, even a very slight change, such as a new pronunciation of a word, demands a considerable degree of consciousness. Again, while one could walk a long distance climbing stairs and making various turns almost without consciousness of the complex but familiar adjustments involved, it would re- quire his whole attention to learn a new movement, such as a step in dancing. It is evident, therefore, that the acts accompanied by most consciousness are those involving the functioning of new apparatus or the functioning of formerly used appara- tus in new ways, while a change from using one apparatus to using another, if the transition is a habitual one, may be almost without consciousness. There is therefore good reason for saying that since CONSCIOUSNESS 1 83 consciousness is especially i)rominent in all new reactions it is probably most prominent in the actions of animals which are able to learn most by experience, or, in other words, in animals whose nervous system is subject to the greatest amount of modification. It is not true however that no modification of the nervous system can take place without consciousness. Very great changes may thus take place if they are sufficiently gradual. We find this to be true of a large number of physical and mental habits which develop or change without our knowing it until our attention is called to the matter by some friend or by some event that makes us recall what we used to do under the same circumstances. The same thing is shown in a striking way by a series of experiments made by Pro- fessor Judd upon a common illusion regarding the length of lines. The subjects who were attempting to reproduce the lines shown them did not know that they were making an error ; but after many hundreds of experiments, the error, which at first had been very great, was reduced almost to zero. Other experiments have shown that when a subject knows that he is making an error and is told each time its character and amount, he corrects it much more quickly than when he has no definite knowledge of the results of his attempts. Evidently, therefore, consciousness is not absolutely necessary in producing helpful modifications in behavior, yet modification of behavior without directive consciousness, like trial movements, is a very uneconomical mode of i)rocedure. Consciousness, therefore, if not in- volved in all modifications, is at lea^t a means to more rapid and efficient modifications of behavior, and hence is probably present in all animals capable of rapid learning. l84 GENETIC PSYCHOLOGY Teachers should remember that when children know the end for which they are working and are aware of the prog- ress that they are making, they will learn much more rapidly than when they are simply told what they must do and how it must be done without being made conscious of the success of their attempts. Observing a little more closely our mental processes when acquiring a new movement or attempting to solve a problem, we notice that consciousness in all instances is not concerned so much with the act of doing as with the results of the act. For example, in reproducing a drawing, as we try again and again, consciousness tells us of the re- sult rather than of the movements made. The same is true in articulation of words, learning to skate, in manual occu- pations of all kinds, and also in the more purely mental activities of seeking a solution of a problem in mathematics, and in writing a satisfactory composition or article. Consciousness, however, is not concerned simply with the result of individual movements or series but with the end toward which we are aiming and the relation of the results of each act to that end. This is often shown in the feeling that we are progressing toward an end even when we do not know just what we are doing that is helping us toward that goal. We feel that we are getting the mastery of a tool or of a topic without knowing in just what way we are changing our activity. The relating of means to ends is not however in all prob- ability a purely conscious process, but is characteristic of all organic activity. As we have already seen, what an animal even of the lowest type does after reacting to a stimulus depends upon whether the result of the previous action is CONSCIOUSNESS 185 favorable or unfavorable. If such creatures have any consciousness it must be in the primitive and vague form of an indefinite feeling of dissatisfaction or of satisfaction. If consciousness is of any value whatever to such creatures it must be because this feeling produces a change of action when the results are unfa\orable. When consciousness appears it must perform this function and thus facilitate the proper reaction. We may say, therefore, that the primary function of consciousness in the evolution of behavior is to emphasize the results of an action with reference to the end to be ob- tained. Again we note the fact that consciousness is most in- tense, not when we are trying to achieve some one end by a certain means but when we are doubtful as to which of two or more ends we shall attempt to gain, or as to which of several means we shall use. Evidently, where there is a tendency to react to several stimuli in varied and perhaps opposite ways, the difficulty of making a reaction which is of advantage to the organism as a whole is very much increased. It is in just such cases therefore that consciousness may be of the most assistance. If, to its power of emphasizing the results of action with reference to an end, be added the power to emphasize one result with reference to one end rather than to any other, we have a second important function of consciousness which may be designated as its selective function, which of course in- volves discrimination and comparison and is especially manifested in acts of attention. In order that consciousness may thus effectively direct behavior it is necessary that it shall be occupied with some- l86 GENETIC PSYCHOLOGY thing besides the results of present stimulation. To act effectively it must be able to represent the results of past stimulations and reactions in order that the end and the means of reaching it may be selected. The more per- fectly the elements of past experience may be reproduced and freed from the connections in which they formerly occurred, so as to be combined into representations of results and of means of obtaining them, the greater the possibility of consciousness directing action in many and varied ways. The ability to form free images, which is closely correlated with the tendency to imitate new move- ments, is necessary to any considerable use of conscious- ness in directing new reactions. If this is true, the part played by consciousness in direct- ing the actions of animals in the performance of new acts must be very small even in the case of the most intelligent. The chief way in which consciousness helps them to learn is in emphasizing results after the act has been performed, thus increasing the tendency to act in the same way again if the results are favorable, and decreasing it if they are not. Consciousness in animals is probably concerned chiefly with results as they occur rather than with the various ones that may appear after the action is performed. For ex- ample, the dog that was cold and went to his mistress's door and pawed until she came and covered him, was doubtless directed more by the present feeling of being cold than by a representation of being warm. It is also probable that the animal did not first represent various means of getting rid of the disagreeable feeling and then select the one of going to the mistress's door and pawing, instead of any other, but it performed that act because in past experience CONSCIOUSNESS 187 the tendency to go to his mistress when uncomfortable had been increased by the favorable results of such action. It is evident from the preceding discussion that although all organisms possess unity, and all their activity is unifying, yet that consciousness is helpful in coordinating activities when they are many and varied so as to make them all contribute to one end. To unify and coordinate in rela- tion to an end may therefore be considered as the third and most important function of consciousness. This function involves to some extent the other two, the feeling of the results of activity, and the selection of some activities for continuance. We have in these functions of consciousness the basis for the common classification of mental facts into three divi- sions: feeling, intellect, and will. In its elementary form, consciousness is a mere feeling which indicates whether reaction is needed or not. In its next higher form of intellect it discriminates ends to be reached and the means by which they may be gained, while in the act of choosing, enforcing, and harmonizing activities in the attainment of ends we have the phenomenon of conscious ivilling. In order that consciousness may function effectively in an intellectual and volitional way it is necessary that there shall be not only sensory apparatus to present to conscious- ness the effects of stimulation, and a motor apparatus to execute movement, but there must be a central nervous structure by means of which the results of past experiences may be represented in consciousness and the [possible re- sults of future actions presented. As we have already seen, such additional nervous structures are provided in the cor- tex of man to a much greater extent than in that of any l88 GENETIC PSYCHOLOGY Other animal. Such mechanisms for reproducing the resuhs of past experience and directing new combinations must not only be present, but must have been trained in order that consciousness may function effectively. Just as a general must not only have men but must organize and train them in all the activities of warfare, so must a crea- ture whose consciousness works effectively have not only a modifiable nervous apparatus but this apparatus must be properly organized. Consciousness helps in directing the organization of nervous structure, and then after such structure has be- come well organized, it uses it in various complex activities without directing in detail what shall be done. Injury to the sensory, motor, or representative apparatus usually involved in an act may leave consciousness helpless so far as the performance of that act is concerned. In some instances, however, consciousness may train other nerve centers to perform the acts of that which has been injured, as when one who has lost the power of movement in the right arm trains the nerve centers governing the left arm to direct similar movements, or when visual centers are injured and auditory images are substituted in memory and thinking. In racial development consciousness in the form of rudimentary feeling indicating the necessity or non- necessity of movement may be present momentarily even in the lowest organisms and help to produce more prompt and effective reactions. In the case of larger animals with various sensory-motor structures such a consciousness corresponding to favorable or unfavorable relations of all parts would surely be useful, if not absolutely necessary. CONSCIOUSNESS 1 89 It is also necessary in such creatures that there shall be a large amount of modifiable nervous tissue if directive control by consciousness is to be acquired. Consciousness as a mere feeling may help to unify the various processes taking place in a complex organism, but consciousness as a discriminative and representative process is especially needed in unifying not simply present activities but present and past experiences in relation to each other and a possible future. The great function of consciousness in all its forms is to help unify behavior by "dislocating experiences," as Minot puts it, from their set- ting, thus making single elements of several past experiences combine for the good of the creature in the present and for the future. In its higher forms, as exhibited in man, it is chiefly concerned with bringing together, connecting, and unifying the results of past experience in relation to future ends rather than in relating the activities to present con- ditions only. Just as consciousness may be helpful in co- ordinating new movements in the present so it is still more helpful in coordinating the actions of to-day with those of yesterday and to-morrow. Consciousness may very well be regarded as a more eflicient and economical means of performing in the life of the individual wliat in the life of the species is effected by means of natural selection. Natural selection proceeds by the very wasteful method of killing off all individuals of the species whose actions are least effective, while conscious- ness in the individual, by means of feelings of pain, elimi- nates ineffective movements and causes more economical ones to be selected for repetition and thus to become established as habits. By means of pleasurable feelings, 190 GENETIC PSYCHOLOGY eflfective modes of reaction are more quickly established than would otherwise be the case. Consciousness thus differs from natural selection in being a positive as well as a negative factor in modifying behavior. In its higher forms consciousness selects not only accord- ing to results that have just been experienced, but also to results of more remote experiences; and selects, not blindly but intelligently, by means of conscious representation of the ends to be gained and the means to be used. So effec- tive is consciousness in directing the evolution of behavior that it produces in the lifetime of a single individual more varied and complex modifications than are produced in thousands of generations of the species by the slow and wasteful process of natural selection. The function of consciousness may be compared to that of a complex machine like a printing press or the harvester, which does with infinitely greater speed and ease that which was formerly done slowly and laboriously with very simple tools. Note. — For convenience and clearness consciousness is treated as if it were an entity added to and presiding over the ner\'ous mech- anism. The author, however, does not wish to assert or imply any philosophy or theory in regard to the relation of mind and matter. He wishes merely to describe the phenomenon so that others shall know to what he refers. Whether consciousness is a distinct entity or only a phenomenon that appears as a result of a certain kind of nervous functioning is not the most important question from the purely psychological standpoint. The important fact to be noted is that where there is a certain type of nervous functioning there is usually consciousness and a different and more effective form of activity. This new type of functioning implied by the word con- sciousness must be an important factor in the evolution of creatures showing it, otherwise it would not have been developed to the re- CONSCIOUSNESS 191 markable extent that it has in man. The important thing for the psychologist to find out is not what it is but what it does and how it docs it, making all use that he can of both subjective and objective facts. ORGANIC UNITY AND CONTINUITY The physiological activity of all organisms is unifying to a greater or less degree. In the case of the lower animals, such as worms, insects, and the lower vertebrates, the unity is comparatively slight, especially as regards the immedi- ate activities. An animal may be divided symmetrically into two parts, each of which will perform its special func- tions nearly as well as before. In some creatures, as for instance the angleworm, each part produces new segments and becomes a complete individual. In the case of a very small organism with no specialized sense organs it is quite reasonable to suppose that the mere fact of lack of physical and physiological equilibrium leads to movements that produce more favorable results. In the case of larger animals with more specialized sense and motor organs but with only a few unvarying forms of reaction it is also conceivable that the behavior may be without consciousness. In the case of human beings the physiological processes of respiration, digestion, etc., are unified very completely. A change in the functioning of one organ is always fol- lowed by correlative changes in other organs. In the case of sudden changes in air or food or when there is imperfect working of the vital organs, we are conscious that something is wrong, but ordinarily consciousness exercises no direct control over the correlated and unified activities of the vital organs. This is true not only under constant condi- 192 GENETIC PSYCHOLOGY tions but when organisms are being adapted to changes in the environment and when all portions of the body are growing and developing. A change in rate of breathing is met by change in rate of heart beat, blood pressure, etc. The unconscious unification and adjustment of activities, by which the temperature is kept almost constant as we pass from a furnace-heated room to the zero air outside, are far more complex than any heating apparatus by means of which the temperature of a house is regulated. Again, purely physiological activities are correlated not only with other activities taking place at the same time, but with activities that have taken place in the past or are to take place in the future. This is shown in the growth of all organisms, both plant and animal. Each stage of de- velopment is preparatory to the one that is to follow, and a failure in any portion or stage of the growth affects other parts in other stages of development. This is true even in the case of animals in which there is a distinct break in the stages of development, the adult frog or insect vary- ing greatly according to the temperature and food condi- tions to which the tadpole or larva, from which it devel- oped, was subjected. We usually think of physiological activities in animals as being continuous, but in them as well as in plants there may be complete suspension of activity for a considerable time without death. This is especially true of the lower animals. The caterpillar may be frozen solid, and when thawed out be as active as ever. Frogs and snakes can also remain inactive because of cold, for long periods, without destruc- tion to their lives. In the higher animals and in man com- plete suspension for a short time of the vital functions, as CONSCIOUSNESS 193 in drowning, may occur, with subsequent reanimation. In general, however, the chief physiological processes are continuous, although in sleep some of the nervous processes apparently cease. SEEMING CONTINUITY OF CONSCIOUSNESS In our own experience we know that there is a paral- lel series of conscious or subjective experiences corre- sponding to the physiological and objective movements that we are making. It seems to us as if the subjective phenomena formed a continuous series. There must be large gaps during sleep, but our conscious states seem to begin where they left off. In cases of injury to the brain, consciousness has, in individual cases, returned after weeks or months without the individual being aware of any break in his conscious life until he has been informed of events that have occurred in the meantime. Notwithstand- ing that there really are breaks in consciousness it always seems to us to be unified and continuous. Whether this is true of consciousness other than human we cannot say. It is conceivable and quite probable that consciousness in the lower animals may have many more and much longer breaks or blanks than in the case of human beings. It may be that their subjective life consists in only occasional flashes of consciousness preceded and followed by long intervals that are blank. When complex activities are performed and unified, consciousness may be present and help produce such unification, and then as soon as some of the varied stimuli have ceased, it may disappear. It may very well be questioned whether even the higher 194 GENETIC PSYCHOLOGY birds and mammals have a continuous consciousness like that of man. To have a continuous consciousness it would seem as if there must be not only many and varied sensations, but memories of past experiences as a constant part of the content of consciousness. When we look into our own consciousness we rarely find it occupied with sensations only. They usually form only a small part of its content. If all images and ideas were dropped out of consciousness we should have, if conscious at all, a very different con- sciousness from what we now have most of the time. A dog or a cat resting quietly is having but few changes in sensory stimulation, and if he has no free images of past and possible future experiences, the contents of his con- sciousness, if any, must be very meager, perhaps more so than our own when we are falling into a comfortable sleep ; for then our consciousness is occupied with images rather than sensations. When we awake, although our con- sciousness seems to begin where it left off, yet, since we possess free ideas, we can be convinced that events have taken place without our being aware of them. It would seem to be impossible for a creature without memory in some form to possess a continuous conscious- ness and be av.-are of its own subjective life as continuous. Where the memory is merely a reproduction of a series of experiences in the same order in which they occurred, the consciousness must be quite different from that of man. This is perhaps illustrated by the incident of Dar- win's dogs. They were in the habit of meeting him some distance from the house and playing around him as he walked up the path. After an absence of several years their behavior when he came was exactly the same. This CONSCIOUSNESS 195 shows remarkable memory in the sense of retaining modifications of behavior after a long interval. But evidently the consciousness must be quite different from that of man. It is safe to say that no human friend of Darwin's met him after years of absence and treated him in exactly the same way as when they were meeting every day. In the case of man an acquired mode of behavior is not only retained but in his memory the present situation is contrasted with that which accompanied the act being reproduced. The possession of a continuous consciousness such as man's would scarcely be possible without the ability to form free ideas and represent not only past experiences but one's mental states and the surroundings in which they occurred. Speaking figuratively, the physiological ac- tivities furnish the canvas, the reflex and habitual activi- ties the background, and present situations the moving pictures in the panorama of consciousness. All of this may be represented in the consciousness of a dog, but when he is passive and has little variation in external stimulation, the whole scene may almost disappear. In man's con- sciousness there is present all that there is in the dog's, and in addition free images and ideas that are appearing and being combined in all sorts of ways to represent past and possible future pictures that are contrasted with those of the present. When an animal has new experiences, the panorama presented to his consciousness changes ; but probably there is no consciousness of the former state that has been changed, no distinguishing between present stimu- lations and a reproduction of a series of past stimula- tions in the form of anticipatory images. The dog which 196 GENETIC PSYCHOLOGY chased a squirrel up a tree and barked at it was modified by the experience so that the next time he passed that way he ran to the tree and barked as before. Not having free ideas he had not analyzed the situation and could not represent the elements of the former experience so as to distinguish and contrast the present experience with the former one. His mental state was probably similar to that of the normal school teacher who, when the hymn was announced at chapel exercises, opened the book of scrip- tural selections at the page named. In general, the per- ceptual recognitions or so-called "memories" of animals are in consciousness probably very similar to habitual and semi-mechanical acts in human beings. In the case of man, experiences not only modify behavior and the pictures presented to consciousness but those experiences may be reproduced, distinguished from, and contrasted with, present experiences. He is thus able to recognize changes in his mental pictures and to fill in, from the reports of others, pictures of events that have taken place while he was unconscious. He can also look back upon his consciousness as it was, under certain con- ditions, and discern in what respect it differs from what it is now. It is important therefore to a continuous sub- jective life that one shall be able not only to reproduce former experiences, but that he shall also be able to repro- duce the background against which they appeared and be able to shift images freely from one background to another. The physiological functioning that provides the con- scious background of subjective life is of great significance in the individual consciousness. This is clearly shown in alterations of behavior and in conscious mental states CONSCIOUSNESS 197 when health is seriously impaired or when there are im- portant changes in physiological processes, such as may be produced, for instance, by taking food and rest when extremely hungry and tired. The comparatively perma- nent groundwork of our subjective life is often thus so completely changed within a short time that we seem to be looking upon a different world. In pathological cases, where physiological disturbances involve loss of sen- sory and motor powers, a patient frequently shows com- plete and perhaps permanent change of personality. Sometimes he is conscious of the change and because of his loss of sensitivity he may have the idea that he has lost his personal identity, that he is dead, or that his body has been transformed into some inanimate thing. Sudden changes in instinctive and habitual acts may also result in important changes in consciousness. The individual appears to himself and to those who know him to be en- tirely transformed in character either for the better or the worse. The ideas that were associated with the former physiological and habitual reactions are either replaced by or contrasted with those associated with the present mode of life. When the old ideas persist there is not a complete transformation in character although there is in bodily condition and outward behavior. Frequently, however, the ideas correspond to the situation and the behavior. For example, he who assumes the clothes and behavior of a beggar is likely to take on his consciousness. It is for this reason that men are often scarcely recognizable after they have engaged in a new occupation or sometimes when seen on a vacation. Sudden changes in physiologi- cal, instinctive, and habitual acts may therefore produce 198 GENETIC PSYCHOLOGY greater breaks in the seeming continuity of consciousness than complete blanks in the conscious life. OBJECTIVE AND SUBJECTIVE TERMS The purely objective study of reactions is well illustrated by experiments of Paplow and Nicoli to discover the effects of various stimuli upon glandular action in a dog. A means was devised by which the amount and rate of flow of saliva could be measured. It was found that under certain definite conditions each stimulus produced a specific reaction, which was modified by repeated association and repetition. After a certain odor, color, or sound had been presented to the dog just before feeding, a number of times, there resulted an increased flow of saliva whenever that stimulus was given, while no such response was made to other stimuli, though only slightly different. In reac- tion to sound stimulations the glands seemed to be more discriminating than the consciousness of man, a tone only one fourth of a tone abo\'e or below that associated with feeding not being reacted to by increased flow of saliva as was the exact tone associated with being fed. In our own experience there may be an activity produced by a repeated stimulus, that we call a perception, without stopping to inquire as to just what nervous, muscular, or glandular reactions have been made. With complete knowledge of the subject one might specify in detail all the physiological and psychical changes produced by the stimulus but such accuracy of expression would be a painfully cumbersome mode of describing behavior. With our present knowledge it is convenient to indicate by some CONSCIOUSNESS 1 99 subjective term, as " sensation," " perception," or " image, " the reaction that takes place without specifying its elements. This may even be done when one docs not know posi- tively that any change in consciousness has been produced, though not unless such reactions are supposed to have in- volved consciousness at some time. Since the behavior of animals is so largely under the influence of immediate surroundings, it is possible to use objective terms alone in describing it, though it is rather awkward to so confine one's self. To speak accurately in objective terms, instead of saying that an animal dis- criminates sensations of red from sensations of violet, we should say that he reacts differently to vibrations of light of the vibration rate of 435 billion per second from those of the vibration rate of 769 billion. When sub- jective terms are used in describing animal behavior it should always be understood that they do not imply the same conscious states as we have, but merely that the stimuli producing different conscious states in us produce different reactions and probably correspondingly different conscious states in animals. It is not at all likely that the color sensations, for example, are just the same in even the highest animals as they are in ourselves. In describing the behavior of man it is not only con- venient but absolutely necessary to use subjective terms. A large part of the mental activity of man is independent of external stimulation and its real nature is not mani- fested by outward movement. Careful experiments show that mental activity is associated with changes in nervous, muscular, and glandular processes, but in many instances these objective reactions are known only by inference 200 GENETIC PSYCHOLOGY from other cases of a similar character, in which a direct correlation has been found. Even when describing ner- vous processes it is often convenient to use subjective terms which are generally recognized as being correlated with those processes. On the other hand, it is sometimes convenient to express the activities of consciousness in physiological terms, as when we speak of association of ideas in terms of connections between brain centers. Although inaccurate there is considerable justification for the use of words in these ways. This is found in the fact that almost the same nervous process may take place at one time with consciousness and at another time without. As we have already seen, consciousness is most prominent in new adjustments of behavior and least prominent or entirely absent in reflex, instinctive, and habitual adjust- ments. It is therefore doubtless true that a great many nervous processes which at one time in the life of the indi- vidual were represented in consciousness may at another time proceed almost, if not wholly, w' ithout such representa- tion. In such cases it is convenient to use the subjective term implying consciousness, but it is well to have it understood that the process may take place without any such representation in consciousness as may at one time have occurred and as the words now imply. When we are learning new movements we are conscious of many sensations and images of which, at a later stage, we are not at all conscious. The same is true of perceptions. Relatively unfamiliar perceptions involve images to a far greater extent than when they become habitual, e.g. a voice not often heard may call up several images before we recognize to whom it belongs, while a familiar voice is CONSCIOUSNESS 20I recognized at once without any preliminary images. The question as to whether images are used in perceptions of any given kind should be regarded largely as a genetic problem rather than as a problem of fixed modes of mental procedure, for the imagery connected with any perception may vary indefinitely with needs, interests, and practice. For example, the sound of approaching footsteps may excite many and definite images in some and no appre- ciable images of any kind in others according to different interests, needs, and degree of familiarity. The images involved in most perceptions are usually not free images, but, as already suggested, anticipatory and of the nature of secondary or mediated sensations. Not only do processes that are at first conscious become, with repetition, unconscious under ordinary circumstances, though they may usually at will be performed consciously, but the opposite condition is found, of processes which were originally performed without consciousness that may also be performed with consciousness. This is true of nearly all the physiological processes. We breathe either con- sciously or unconsciously and within certain limits we can control the rate of breathing as we choose. A few indi- viduals have acquired control over the movements of the heart so that they can increase or decrease its rate of move- ment and can stop or start it at pleasure. Glands such as the tear glands are in some persons under the control of consciousness. Consciousness can also acquire control over muscles that are ordinarily classed as non-voluntary, e.g. the muscles of the ear. The circulation of the blood in any part of the body may also be increased by conscious attention to that portion of the body, and the representation 202 GENETIC PSYCHOLOGY of a burn has been known in some instances to produce physiological effects similar to that produced by a hot iron. The distinction between voluntary and non-volun- tary action and between mere conscious accompaniment and conscious direction of activities, cannot be closely drawn. Neither are the possibilities of acquisition of voluntary control well known. If an individual gave as much attention to acquiring conscious control of the physiological processes as he gives to acquiring control of the muscles of his hand it may be that he could gain almost as much control over the processes of circulation, digestion, repair, and growth as he now has over his fingers or his vocal organs. Again, as we analyze wholes into their elements and form new combinations we become conscious of an infinite number of things of which under the same external cir- cumstances we were not previously conscious. All mental development involves the continual emergence of new states of consciousness, just as the formation of habits involves their disappearance. The result is that as long as we are developing we are increasing the number and variety of actual and possible conscious states, though continually becoming less conscious of activities often repeated. The tendency on the part of physiologists is to emphasize the importance of nervous processes and to seek to find a complete explanation of all behavior in the laws of physio- logical activity. The tendency on the part of the psy- chologist, on the other hand, is to seek to explain what takes place in subjective terms and as the result of psy- chological laws. From neither point of view is it possible CONSCIOUSNESS 203 to gain a complete idea of all that is taking place. A large proportion of the activity of the nervous centers is not ac- companied by consciousness and hence the psychological account is quite inadequate. On the other hand, it is possible to determine to only a slight extent what is taking place in the nervous centers, except so far as it is repre- sented in consciousness and in so far as changes in nerve centers produce changes in external movements or condi- tions. Neither the physiologist nor the psychologist should push his explanations too far into the field that is open only from the other point of view. Both, however, should feel at liberty to use the terms that best serve their purpose in describing and explaining, providing it is understood or made clear by the context, that a certain type of activity which may be conceived either as a physiological or as a conscious process, is taking place, without implying that consciousness either is or is not present in the particular instance described. Words must be used in this somewhat loose way in describing the behavior of men and animals or else a new set of terms must be invented. Attempts have been made to invent terms that are wholly objective, but this is open to the same objection as is the use of strictly psychologi- cal terms to describe conscious states. If we had both objective and subjective terms we would still be at a loss to describe processes that may or may not be accompanied by consciousness, and processes that at one time may be accompanied by consciousness and at another time per- formed without it either in the same or in different creatures. Terms indicating the process meant, but not necessarily implying that it is with or is without consciousness, are 204 GENETIC PSYCHOLOGY necessary until we know more regarding what kinds of processes may be performed witliout consciousness and what kinds must be so accompanied, and in what stages of development and under just what circumstances must consciousness continue to be present in order that the process may be performed. The term "subconsciousness" has come into extensive use recently, but has probably added to, rather than de- creased, the difficulties of the situation. It is used to de- scribe processes that take place outside of the ordinary consciousness, and usually implies that a consciousness in some way distinct from the primary, normal consciousness of an individual is directing some of his activities. This supposition is easily made and difficult to disprove. It would be safer to use subjective terms when convenient in describing what a hypnotic subject does, without neces- sarily implying that there is any consciousness accompany- ing the process. It is better to do this and then investi- gate more fully as to what kinds of acts may be performed without consciousness. It may be found that all the cases of subconsciousness, or supposed cases of a consciousness separate from the ordinary consciousness, are really cases of acts that may be performed without conscious direction or that they are supervised by an alternating consciousness. This may well be illustrated by a case reported by Dr. Prince of an individual who was able to perform complex processes of which his ordinary consciousness seemed to know noth- ing. Dr. Prince asked the subject, when in a state desig- nated as "consciousness B," to work a problem in the com- putation of time, whenever the figures indicating the hours should be presented. The ordinary consciousness known CONSCIOUSNESS 205 as "A" was then given the task of writing a poem on a sheet of paper that had in the margin the figures to be used as data by consciousness B. So far as could be determined, consciousness A took no notice of these numbers, but as soon as consciousness B was evoked by hypnotism, the solution of the problem was given. Dr. Prince sui)posed that there really must have been a consciousness B direct- ing the solution of this problem while consciousness A was engrossed with the writing of the poem. It is pos- sible, however, and equally reasonable to suppose, that the brain was consciously adjusted to perform the problem at the time of receiving directions to do so whenever the figures were presented, and that the actual working of the problem was done automatically while the only conscious- ness present, viz., the normal consciousness, was occupied with the poem, in much the same way as a person may adjust himself to reading aloud and then read a whole page while intently thinking of something else. In general, the function of consciousness is not to actually do things but to adjust apparatus for doing them, note the results, and readjust as needed. It is not wise therefore to assume that what is done without the knowledge of the ordinary consciousness must have been directed by another consciousness. The term "subconscious" often implies this. Such use of the word opens the way for all kinds of suppositions regarding the action of one or more separate consciousnesses, a reliable knowledge of which is, in the nature of the case, unattainable. The word has therefore been more of a stimulus to the imagination than a contribution to accurate thinking, and should be used with caution if at all. 2o6 GENETIC PSYCHOLOGY PROBABLE GENERAL CHARACTERISTICS OF THE CON- SCIOUSNESS OF ANIMALS No progress can be made in understanding the minds of animals by supposing that they have a consciousness entirely different from our own; and we are led into error if we suppose their consciousness to be exactly like ours, especially in its more highly developed phases. We can only hope to attain some knowledge of the truth by study- ing carefully the variations in our own consciousness and inferring from all known facts the nature and extent of such variations in the consciousness of animals, giving special attention to the least distinct and highly developed of our own conscious states. We have already found that the fundamental function of consciousness is to unify experiences, and that to itself, human consciousness is always unified and continuous, although there are actual breaks in the conscious life dur- ing sleep. In recalling the events of the day or the week the larger number are not recalled, yet the omissions give no sense of the lack of continuity. This may or may not be true of the consciousness of animals. The breaks in their consciousness maybe much longer and more frequent, but to the consciousness of an animal there may be con- tinuity and unity but probably a continuity not involving a past and a future related to the present, — a mere negative continuity in which no break is felt, because only the pres- ent is cognized. Observing our own consciousness at different times and comparing the consciousness of persons of varying age and culture, we find that there are immense differences CONSCIOUSNESS 207 in the content of consciousness. In some instances it is crowded with sensations, images, and ideas, each carrying with it a host of other images and ideas as a background, while in other cases consciousness is comparatively bare of content. In the case of animals with few sense organs and little change in external surroundings and no power of representation, consciousness, if present, must be of a simpler character than any that we have ever experienced. It is probable that the content of consciousness of even the higher animals at their best is far more meager than that of human beings at their lowest. It is a well-known fact that the span of consciousness increases greatly with age, experience, and familiarity with the experience being held in mind. Where a child can think of two objects, numbers, or words so as to name or repeat them, an adult would readily name or repeat three or four times as many. In observing trains of as- sociation the same fact may be noticed. The child's trains of thought are very short and usually initiated by external stimulation, while the adult's trains of thought are frequently very long and almost independent of external stimulation. The content of an adult's consciousness is still further increased by arrangement into groups and scries without trying to focalize individual elements. From the actions of animals it is fair to infer that their span of consciousness and their trains of thought are very brief compared with those of even a two-year-old child. In fact, most of their behavior and probably their conscious states are the result of immediate sensory stimulation. We know that our own consciousness may be of a higher or lower degree of intensity and more or less dear and 2o8 GENETIC PSYCHOLOGY discriminating. Clearness in the form of accurate discrim- ination, and intensity in the form of feeling, do not neces- sarily occur together, but frequently, if not usually, is the reverse true. The fact that the behavior of animals is much less modified by severe injuries than in the case of man would suggest the probability that the intensity of conscious feeling is in them very much less than it is in man. On the other hand, the wonderful accuracy of dis- crimination in special lines, notably in that of smell, indicates that in some cases at least animals do not lack in clearness of consciousness. This may not, however, indicate a generally highly illuminated consciousness. Just as a light is much more easily and clearly discrimi- nated in darkness than in the broad light of the noon- day sun, so some stimulations may stand out with great clearness in a consciousness otherwise comparatively dim. It is worthy of note also that our finest tactual, visual, and auditory discriminations are not of stimuli that produce pain or pleasure, but rather of those that do not, though they may be suggestive of painful or pleasurable stimuli to follow. Perhaps the most common and marked variation in human consciousness is in the unevenness of its content, or, in other words, in its characteristic of being focalized upon a portion of its contents while other portions are but dimly felt. Not only is this focus being changed from one element to another, but the degree of focalization or of concentration of attention varies immensely in different minds and in the same mind at different times. In idle moments of day dreaming there may be almost if not entire lack of focalization. In cases of fatigue also it often be- CONSCIOUSNESS 209 comes impossn)le to keep the attention fixed upon the subject in hand. Diffusion of attention is usually more marked in children than in adults, although the difference is perhaps not as great as is usually suj)posed. The child's attention changes much more frequently than an adult's and he has less power to direct it in any required way; but in some instances, at any rate, there is every evidence of very complete momentary concentration of attention upon one thing on the part of even very young children. What is true of children is true of animals in a greater degree. We cannot therefore say positively that their consciousness is lacking in focalization, but it may be in power of sustaining it. The difference perhaps between human and animal focalization is in the extent and variety of the content involved. It may very well be that when the consciousness of an animal is focalized there is little or no other content besides that which is focalized. Thus far our discussion has been concerned chiefly with the content of consciousness, and it is of this that we know most. Of consciousness as such, apart from its content, we know little or nothing. It is difficult to describe the difference between consciousness when it has much content and when it is comparatively empty. Some persons maintain that they are at times conscious but not conscious of any definite thing. A few claim to be able at will to em])ty their consciousness of all content. To most persons this condition is almost if not quite inconceivable. Since, however, creditable observers claim that this is true of themselves we are not justified in arbitrarily deny- ing its possibility. It is probable, however, that this seem- ing absence of content is merely an extreme case of dilTu- p OF —-iC. Of 2IO GENETIC PSYCHOLOGY sion of attention under conditions in which there is little variety in kind and degree of stimulation. If so, then the seeming bareness of consciousness is due to the fact that there is no focalization upon any one part. Whether animals have this kind of conscious state frequently we cannot say, but it is not improbable that in many instances such states alternate in the same animal with states in which there is almost complete focalization upon one prom- inent conscious experience. Speaking figuratively, the consciousness of the lower animals may be like a drop of ink when focalized, and like the same drop of ink spread over a surface when there is no focalization; while a highly developed human conscious- ness is like a kaleidoscopic view, always presenting unified variety that changes with every change of attention, yet is always a complex and distinct unity. Note. — It is often emphasized that the subjective phenomena occurring after physical stimulations and neural activity are entirely new and in no respect like their supposed cause. Such a statement, when looked at in the light of scientific observation in other fields, would seem to be scarcely worthy of the mention and certainly not of the attention which it has received. In all scientific investiga- tions new phenomena that have no resemblance to their causes are appearing. There is no resemblance between a blow on a piece of rock and the spark that results. In all chemical combinations the in- troduction of a new element or condition may call forth a phenomenon that bears no resemblance to the element occasioning it. The new phenomena of neural activity are as different from the stimulus calling them forth as are the conscious states that follow and accom- pany the neural activity. The peculiar thing about the new phe- nomena of consciousness that appear as the result of nervous activity in the human cortex is not that they in no respect resemble the physical stimulus nor the physiological activity, but that the new CONSCIOUSNESS 211 phenomena appear only to the consciousness of the individual pos- sessing the nervous structure thus stimulated. Other consciousnesses may have corresponding or similar facts just as other worlds may have the same elements as our own earth, but direct examination of them is possible only for the individual to whose world they belong. Just as the organism is a unity and all of its behavior is governed by the necessity of preserving that unity amidst external influences of various kinds, so the inner conscious life is a unity and all that takes place in it has reference to its own preserv^ation and development. With the appearance of a highly developed consciousness, as has already been suggested, the objective factor in evolution — natural selection — is replaced by the subjective factor of pleasure and pain, and the development of the individual be havior is governed by con- scious selection of the most effective reactions. In the simpler forms of mental life there is little subjective activity that is not manifested in objective movement, but in a highly developed human mind a large part of the subjective life is not manifested outwardly in be- havior, though it may be indicated by words; hence there are extensive fields of consciousness to be studied in human beings besides that of objective behavior, which is common to men and animals. This is the distinctive field of psychology, and its problem is to determine how activities are related to each other in individual consciousness, and not to wonder at or dispute over the fact that the phenomena of consciousness are different from those of physics or physiology. REFERENCES ♦Angell. Psychology, Chapter XXIII. Bolton. The Relation of Motor Power to Intelligence, Am. Jr. Psych., Vol. XIV, pp. 357-367. BuRNHAM, W. H. Retroactive Amnesia, Am. Jr. Psych., Vol. XIV, pp. 118-132. *Child, Chas. M. Statistics of Unconscious Cerebration, Am. Jr. Psych., Vol. V, pp. 248-257. Dearborn', G. V. N. Consciousness in the Brutes, Jr. of Nerv. 6* Ment. Dis., 1907, Vol. XXXIV, pp. 31-41, 128-140. 212 GENETIC PSYCHOLOGY *DowNEY, June. Automatic Phenomena of Muscle Reading, Jr. Phil. Psych, df Sci. Meth., Vol. V, pp. 650-658. Gilbert. Researches on Physical and Mental Developments of School Children, Yale Studies, Vol. II, pp. 40-100. GoDDARD, H. H. The Effects of Mind and Body as Evidenced by Faith Cures, Am. Jr. Psych., Vol. X, pp. 431-502. *James. Psychology, Chapter XL Jastrow. The Subconscious. *JuDD, C. H. Psychology, Chapter XIV. Movement and Consciousness, Yale Psych. Studies. N. S., Vol. I, p. 199. Practice without Knowledge of Results, Monograph Sup p., N. S., Vol. I, No. I, pp. 185-198. * Practice and its Effects on the Perception of Illusions, Psych. Rev., Vol. IX, pp. 27-39. Kjng, Irving. The Problem of the Subconscious, P^yc/j. Rev.,YQ\. XIII, pp. 35-49- KiRKPATRiCK. Individual Tests of School Children, Psych. Rev., Vol. VII, pp. 274-280. * The Part Played by Consciousness in Mental Operations, Jr. Phil. Psych, df Sci. Meth., Vol. V, pp. 421-429. *MiNOT, C. S. Problem of Consciousness in its Biological Aspects, Science, Vol. XVI, pp. 1-12. *MoRGAN, Lloyd. Comparative Psychology, Chapters I, II, III. Animal Life and Intelligence, Chapter XII. *Pierce, a. H. An Appeal from the Prevailing Doctrine of a De- tached Subconsciousness, Garman Studies in Phil. & Psych., p. 315. Boston, 1906. Prince, Morton. The Dissociation of a Personality. * Pierce's Version of the late "Symposium on the Subconscious," Jr. Phil. Psych. &f Sci. Meth., Jan. 30, 1908. Symposium on the Subconscious, Jr. of Abnormal Psych., 1907, pp. 2-80. SiDis, Boris. The Psychology of Suggestion. Psycho-pathological Researches in Mental Dissociation. SiDis and Goodhart. Multiple Personality. / CONSCIOUSNESS 213 *SrEARMAN, C. General Intelligence Objectively Determined and Measured, Ai>i. Jr. Psych., Vol. XV, pp. 201-293. Stanley, H. M. Evolutionary Psychology of Feeling, Chapter II. *SwiFT. Mind in the Making, Chapters I and IX. Stratton. Experimental Psychology and Culture, Chapters IV and V. Waldstein, Lewis. The Subconscious Self. Thorndike. Elements of Psychology, Chapter XIX. Educational Psychology. *Washburn. Animal Mind, Chapter II. Whipple. Reaction Times as a Test of Mental Ability, Am. Jr. Psych., Vol. XV, p. 489. *WissLER, C. Correlation of Mental and Physical Tests, Psych. Rev., Monograph Supp., Vol. Ill, No. 6, whole No. 16. Yerkes, R. M. Objective Nomenclature, Comp. Psych, and Animal Behavior, Jr. Comp. Neu. b^ Psych., Vol. XVI, p. 380. CHAPTER VIII SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN GENERAL CHARACTER OF FEELING IN ANIMALS Even the lowest forms of animal life show two kinds of reaction, negative and positive. Where a creature pos- sesses consciousness these two forms of reaction are doubt- less correlated with feelings of the disagreeable and the agreeable. It may be asserted that the feelings of the agreeable and the disagreeable are results instead of causes of the increase or decrease of activity associated with them. This is doubtless true to a certain extent, but it is reasonable to suppose that the feelings exert a reciprocal influence upon the physiological activities ; otherwise there would be no reason for creatures possessing consciousness to be se- lected for survival, and consciousness could never have become such a prominent characteristic as we know that it has become in man. Feelings of attraction and repulsion are doubtless promi- nent features of the consciousness of all animals that learn quickly. These do not necessarily involve any definite representation of what is to be experienced. We have an impulse to touch, pick up, or eat some objects and to draw away from others, without any distinct representa- tion of the results of such movements. It is only when we delay a movement that we are likely to form images of 214 SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 21 5 results to be obtained. In animals, conscious represen- tation is doubtless even less prominent in such cases than in man. Even strong emotions, such as fear and anger, which appear to be manifested in some form in all animals, are probably entirely different in their consciousness, when they possess any, from what they are in ours. Fear in man is largely a matter of imagination, while in animals it is chiefly a form of reaction. A person who is actively getting out of harm's way usually feels at the time merely increased activity. It is only when one is keeping still, or relatively so, and representing what may happen or has happened, that he suffers acutely from fear. Men of action suffer very little from fear. When danger threatens they act, and when it does not, they do not think about it. This is true of animals, only in a greater degree. However often a wild animal may be frightened, as soon as the heightened activities become normal, he appears to be entirely comfortable till another danger stimulus is received. What is true of fear is also true to a large extent of anger. The so-called "grief" of animals is also largely motor rather than psychic, as it is also in some people. An im- portant object of activity is lacking when a companion or a master is taken away, and apathy, or a wild form of un- directed acti\'ity, is likely to take the place of the orderly, directed activity that has been concerned with the absent individual. A horse may be as much disturbed by the absence of a mate with whom he fights a great deal, as of one with whom he is on good terms. A new object of activity is the best solace for grief in men and animals. 2l6 GENETIC PSYCHOLOGY because it substitutes directed for undirected activity. It also gives less opportunity for the representative activity, which is so likely to be carried on by man, and which in him is the chief source of emotion. The readiness with which grief may be consoled in some instances is well illustrated by Morgan's incident of the cow that was frantic because her calf had been taken away but was quieted by a stuffed calf to lick, and was soon calmly engaged in eating the hay with which it was stuffed. Similar statements might be made of other forms of instinctive emotion. Animals are supposed to show sympathy for wounded companions, but the reaction is largely motor rather than mental, as is also sometimes the case in man. The smell of blood greatly excites a herd of cattle, and if the enemy that spilled the blood of a com- rade is seen, it may be fiercely attacked ; but if it is not found it is not unusual for the excitement to expend itself upon the wounded individual. In their primitive form instinc- tive emotions are merely native tendencies to act in certain ways under certain circumstances, and only when represen- tation takes the place of action, either for the time being or permanently, do they become genuine emotions involv- ing intense feelings. The above statements do not mean that animals do not experience any emotions in connection with their instinc- tive acts, or that man experiences none when he imme- diately makes the instinctive movements. Where the de- velopment of a situation does not lead too quickly to the instinctive reaction, anticipatory images may be formed by animals as a result of a series of stimuli which cause them to feel as well as to act. On the other hand, when men SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 21 7 arc making instincti\'c reactions that arc not too vigorous, the apparatus concerned in imaging may also be suffi- ciently active to produce strong emotional states. The point to be emphasized is that in both men and animals prompt and unimpeded instinctive reaction doubtless has less feeling accompanying it than when there is delay, obstruction, and conflict of motor tendencies, with more or less imaging of some sort. It must not be supposed, however, that since represen- tation is necessary to emotion the feeling is strongest when representation is most definite. On the contrary, defi- nite and specific representation, like prompt imobstructed movement, may be accompanied by less feeling than less clearly defined imagery. It is generally true that an emotion is stronger when the general character of what is to happen is anticipated, but not definitely known and specifically represented. This is especially true in fear, for unknown dangers produce more agonizing fears than any known consequence that can be clearly represented. In man there are a great variety of emotions associated with imagery that are probably entirely unknown to ani- mals. ]\Ian has emotions also associated with concepts, but except as the concepts are accompanied by concrete images the emotions are not likely to be intense. PAIN Pain as a sensation is probably a difi"erentiation of the feeling of the disagreeable which serves as a stimulus to negative reactions. In man, ])ain sensations are differen- tiated from states that are disagreeable, and there is some 2l8 GENETIC PSYCHOLOGY ground for claiming that physiologically they are due to the excitation of specific nerve elements. To what extent pain sensations in animals are differentiated from the generally disagreeable we do not know, nor is it possible to assert, without fear of contradiction, how the intensity of pain in animals compares with that in man. We can reason as to the probabilities of the case from the function of pain in promoting self-preservative reactions and the part it plays in our own lives. Pain, like the general feeling of the disagreeable, serves as a stimulus to do something to obtain relief. The re- actions to pain stimulation are usually of a trial character, and experiment shows that in man, reactions to pain sensations, though more vigorous, are slower, less dis- criminative, and less accurate than to stimuli that have a suggestive value. Fine discrimination of suggestive stim- uli which are neither agreeable nor disagreeable, and accurate and prompt response to such stimuli, are the most effective means of avoiding painful stimuli and of preserving life. Painful stimulations best serve their function when they produce many varied and vigorous movements, by means of one or all of which relief may be obtained. Fine discrimination as to the degree and qual- ity of pain would not be of great value after the unfavorable stimulus had already begun to act. It matters not whether pain is caused by heat, cold, or contact. The only thing to do is to get away from the painful stimulus, while successful reaction to a suggestive stimulus involves ac- curate discrimination. It does not follow therefore that, because a creature reacts very quickly and accurately to a stimulus, it is experiencing pain. Pain is more prob- SPKCIFIC CONSCIOUS STATES OF ANIMALS AND MAN 219 ably present when the reactions are varied and vigorous than when rapid and finely adjusted. It is not to be sup- posed, however, that the pain is always proportional to the vigor of the reactions. It is true of ourselves only within certain limits that the greater the pain the more vigorous the reaction. Vigorous reaction probably serves of itself as a relief from the slighter stimuli, but when the pain becomes intense, relief cannot thus be obtained and there is often marked decrease in physiological activity as well as of movements. This decreased activity probably serves to decrease the capacity to feel pain. One means of judging of the relative importance of sensory stimuli is to observe what stimulus dominates action when several are being given. This furnishes something of a basis for comparison between men and animals. It is a well-known fact that a severe wound in man produces loss of appetite and less ready response to all forms of external stimulation. This is true to some extent of the higher animals and to only a slight extent of the lower. A shark or a bee may continue to feed after a considerable portion of the body has been cut away so that the food cannot be retained. Frogs and fishes will again and again take a bait though severely lacerated by the hook each time they do so. These facts indicate that pain does not play such a prominent part in determining the activity of animals as of men. Vigorous and varied movements may be the result of the overwhelming dominance of a painful sensation, or they may result merely from a disturbance of equilibrium in the relation of part to part, upon which definite movements depend. The latter rather than the former is almost surely 220 GENETIC PSYCHOLOGY the explanation of tlie beha\'ior of the angleworm when cut in two. If cut in two (juickly, while crawling, the front part is likely to continue to move forward as if nothing had hap])ened, while the posterior portion curls up and makes all kinds of irregular movements, after which it may move in the opposite direction. If this portion is again cut in two the part that is leading continues to move for- ward while the part that is following makes irregular move- ments. This is because each segment in crawling responds to the stimulus of the segment in front of it, and when that is removed equilibrium is destroyed and movements are very irregular. Injuries on one side of the cerebellum in higher animals produce for a similar reason incoordinated or "forced" movements of the whole body. Putting these facts together it seems quite probable that pain in animals is not clearly differentiated from the feeling of the disagreeable, and that the feeling is less intense the lower we go in the scale of animal life. Man probably experiences pain in a distinct and intense form more than any other creature, and the more highly developed man more than those with less highly developed nervous or- ganizations. Idiots are frequently so insensitive to pain that what would be a severe surgical operation to a normal individual appears to be to them merely an interesting and novel experience. It is probable that pain is a prominent feature in the mental life, not so much because of the value of the sen- sation in itself in the preservation of life and health, as because of its relation to other mental states. The gen- eral refinement of nervous organization in man is probably necessarily correlated with some increase in sensitiveness SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 221 to painful stimuli. It is probable also that more intense feelings of pain are needed in man to prevent actions that are not for the good of his body, than in animals, nearly all of whose conscious states are related to their physical well-being. In man, as we shall see later, there are many positive feelings of pleasure stimulating him to do things that are not for the good of the body and may possibly be of injury to it. A very slight disagreeable feeling of hunger may be sufficient to insure that an animal shall take food, but a very much greater feeling of discomfort may be needed to induce a man to cease the interesting occupa- tion of painting or writing in order to partake of food. It is probably because man is capable of experiencing so many more agreeable feelings, that are not of great biologi- cal value, than are animals, that he is capable of expe- riencing more intense feelings of pain, because they are needed in order to preserve a proper balance and induce him to act with reference to bodily needs as well as with reference to mental pleasures. Those who read into the actions of animals the same degree of suffering of which they are themselves capable, are probably wholly misinterpreting the phenomena. On the principles of evolution we can see no reason why great capacity for suffering should be of any use to the lower animals, and being of no use, there is no reason to suppose that such capacity would have been developed by natural selection. All that is needed in the way of painful experience in the life of animals is a feeling of dis- comfort strong enough to produce vigorous action when an unfavorable stimulus is being received, and to dominate behavior in so far as the well-being of the body demands 222 GENETIC PSYCHOLOGY that it shall dominate. In man, however, aesthetic, moral, and religious feelings often produce action injurious to the body, even in the face of pain which prompts to beha- vior favorable to bodily needs. INTELLECTUAL STATES Sensations In man, sensations have the quality of being not only painful or pleasurable, or at least agreeable or disagreeable, but they have many other qualities by which the sensa- tions due to one sense organ are distinguished from those caused by the stimulus of other sense organs. In addition to this, difference in sensations due to different stimulat- ing objects affecting the same sense organ, is clearly dis- criminated, e.g. various colors by the eye and many odors by the nose. We are confronted with the question as to how far animals discriminate in consciousness the dif- ference between the results of stimulation of the different sense organs and between the different kinds of stimuli affecting the same organ. In trying to answer this question we should consider our least highly developed senses rather than those that are most highly developed, and especially than those giving characteristic sensations that have been named and specifically analyzed and separated from the general mass of sensations accompanying them. Touch, taste, and smell are the least highly developed of our senses and are by us least accurately discriminated, and hence are most profitably studied as a basis for under- standing the mental states of animals. In many of our experiences we are conscious of the effects of the stimula- tion of one or more of these senses without knowing ac- SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 223 curately which ones are affected. When we drink coffee or eat ice cream, we say that the taste is agreeable or dis- agreeable, when in reality the feeling that we experience is due to the stimulus of three senses instead of one. If the temperature of these objects is changed, we realize that their agrecableness or disagrecableness depends largely upon tactile sensations, while if we have a severe cold, we find that one of the essential qualities of agrecableness, that of flavor, is lacking, because the sense of smell is not acting effectively. Because of our varied mental life we are able by practice and effort to analyze the complex mental state produced by simultaneous stimulation of all of these senses into sensations having the qualities of sweetness, bitterness, saltiness, sourness, warmth, cold- ness, smoothness, roughness, and into a variety of odor sensations. In our ordinary experience, however, we make very few of these analyses. The ordinary individual notices in eating that the food is agreeable or disagreeable, and sometimes recognizes that it has some quality which he likes in food or that that quality is not present, and yet there is no complete and clear analysis of just what the quality is. One who has given no attention to cookery may say that the cake is not good, realizing that it lacks some essential quality, but be utterly unable to tell what that quality is, though the cook who has given attention to such things may say at once, "It has not enough salt," or "It is not sweet enough." Even an experienced cook may, however, detect a lack with- out knowing at once what is missing, e.g. a lady said that something was lacking in her lemon pie, and later remem- bered that she had not as usual put salt into the filling. 224 GENETIC PSYCHOLOGY Where varied experiences and practical needs have made it convenient to analyze complex sensations into their ele- ments, such analyses have been made, but not otherwise. One of the most common mistakes in attempting to inter- pret the mental states of creatures whose experience and needs are different from our own is in supposing that ele- ments of mental states, which we have analyzed from the complex in which they are always found, have also been analyzed by them. This vitiates the reasoning of many writers on animal behavior as well as that of many writers on general psychology. A mental state becomes an entirely different mental state after it has been analyzed from what it was before such analysis. All the elements were there at first, in the total experience of the whole, but after the analysis they are there as individual factors and not simply as influencing the general character of the mental state. A person who prefers one picture, poem, or speech to another, may have exactly the same preference after he has learned to analyze pictures, poems, and speeches so as to know in just what characteristics they differ from each other ; but the mental state produced by the picture, poem, or speech will never again be the same as it was be- fore such analysis, and soon he will be unable to under- stand how an individual who distinguishes between two pictures as wholes, can fail to perceive the exact character- istics that he knows are possessed by one and lacking in the other. It is this that makes it so difficult for adults to understand the mental condition of children. A soldier who does not know a single note may learn to respond accurately to the bugle call, no matter how many other sounds are being made at the same time. If we SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 225 apply the same principle to the behavior of animals, we shall have to adopt an entirely different principle of inter- pretation from that taken by many writers. A striking example of the discriminali\-e ability of a dog is given by Romanes. He found that it could follow his track, al- though a dozen other men had followed in his footsteps and seven of them had diverged later from the path taken by himself and the others. This is interpreted by one of the most recent and acute students of animal behavior, Miss Washburn, as an instance of the analysis of a sensa- tion from the complex in which it occurs, similar to that of the expert musician who detects the instrument and the exact error made by a performer in an orchestra. To the author it does not seem probable that the mental state of the dog in following his master's track is at all like that of the musician in detecting a false note. The mental state of the dog is probably very much more like that of the unmusical soldier who knows the bugle call for advance of his own regiment, from any other signal and from the same signal made by another bugler, although he knows not a single element of music. To the dog, the sum total of odors with that of the master is different from any sum total of odors in wliich tliat of the master is not included, hence he knows whicli track to follow. He follows that track just as a man eats cake that has the (juality that he likes, although he does not know just what the quality is; or the reader still prefers the poem that apjjeals to him rallier than the one that does not, although he is utterly unable to tell the characteristic u])on which his preference depends. The fact that an animal acts differently when a certain Q 226 GENETIC PSYCHOLOGY stimulus is present, even in a very slight degree, from what he does when it is absent, does not prove that he has a distinct sensation corresponding to that stimulus, but only that his mental state in its total character, when that stimulus is present, is different from what it is when it is absent. Nature provides the sense organs for special sensations but they come into actual existence in conscious- ness as separate elements only when the results of expe- rience make this separate recognition valuable. The fact that Japanese mice learn to go in at the entrance illumi- nated with red instead of one illuminated with green, does not prove that there is a conscious sensation of red and of green as analyzed elements in the general mental state involved in the action being performed. The fact that a monkey goes to a box covered with red instead of some other box for food, does not prove that he consciously discriminates the sensation of red as an element in the sum total of his experience. It is altogether probable that children learn to discriminate objects with a specific color from objects not having that color, before they analyze the mental state produced by the object and become con- scious of redness as one of its characteristics. So long as red or any other characteristic is simply part of a situation leading to food it is not likely to be recog- nized as an element in itself. If its presence means food, not only under those conditions but under a great variety of other conditions, so that it appears as a part of many wholes, notice may be attracted to it specifically. If it ap- pears not only as a means to food but as a means to other ends, it is still further dissociated from any particular combination of conditions and ends. This occurs very SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 227 frequently in human beings who have a great variety of interests and needs, while it occurs very rarely in even the higher animals. It is probable, therefore, that none but a few specifically trained animals of the higher type have specific sensations of any kind such as we have. The various sensations that they experience probably form a complex similar to that produced in us by articles of food, only less definite and specific as to the elements constituting the complex. Space Perceptions The space sensations of animals rank in importance with the feelings of the agreeable and the disagreeable. Dis- agreeable sensations as signs of unfavorable stimuli are valuable because they indicate the need of doing something. The thing to be done usually involves some kind of a space reaction. To get relief the creature must move in a definite way and the more quickly it moves in the right direction the sooner is the reaction efl'ective. It is therefore just as important that there should be means of determining the direction of movement as it is that there should be a feeling of the disagreeable to induce movement. In a general way the sensations upon which space re- actions depend are of the same general character as those by which equilibrium is maintained. The sensations by which equilibrium is maintained vary with the position of the body and the relation of one part to another, while space reactions are usually made in response to stimula- tions coming from objects in the environment. In their more primitive form, space reactions depend to a consid- erable extent upon inequality of stimulation and upon 228 GENETIC PSYCHOLOGY inequality of sensitiveness to stimulation in different parts of the body. A creature with one portion of the body as sensitive as another and equally affected on all sides by light, heat, and other stimulations would have no occasion for movement. Just as soon, however, as it is stimulated more on one side than on the other there is occasion for spatial reaction. A greater sensitiveness on one side may also call forth reaction. When a creature responds by a different movement according to the portion stim- ulated, it is reasonable to suppose that there is some dif- ferentiation of the sensitive surface so that the eft"ect of the stimulus is different. As we have already seen, this appears very low in the scale of animal life. These two principles are probably the basis of all "tropisms." Experiment shows that the lower animals are influenced in a spatial way by light, heat, and gravity, sometimes one being dominant and sometimes another. The sensitive- ness to these different kinds of stimuli varies also with the internal conditions of the creature, the reactions of the same animal being at one time positive and at another negative to the same stimulus. It is probable that such changes are of advantage to the creature, perhaps at one time leading to food and at another to safety from enemies. We may therefore best conceive of an animal as being in equilibrium and motionless when all the stimuli tending to produce movement are in equilibrium. If he is moving and all these stimuli are in equilibrium, he continues the same form of movement, whether it be in a straight line or in a circle. Variations from this motionless condi- tion or uniform movement are produced by any stimulus that disturbs the equilibrium and becomes for the time being the dominant director of activity. I SPECIFIC CONSCIOUS STATES OF ANIMALS AND :MAN 229 Human experience may Ix' helj^ful in forming an idea of the character of space sensation in animals. A person who has been used to working for many years in a certain room, facing in a certain direction, and surrounded by the same objects, is h'kely to be somewhat disconcerted if he attempts to do the same kind of work facing another way or with the position of objects in the room changed. He does not seem to be rightly adjusted to his environment and prefers to re- sume his old position. Perhai)s many persons will ilnd the most vivid illustration of spatial adjustments in their memories of having waked in a bed in a new position. On the conscious side a condition of equilibrium in relation to surrounding objects is accompanied by a feeling of the agreeable, while disturbance of ecjuilibrium produces a feeling relatively disagreeable, although the reaction may be positive in its character and secure an agreeable result. Space discrimination depends upon the accuracy with which the various stimuli may be coordinated so as to maintain proper relations between different parts of the body and with various objects in the environment. This does not mean, however, that the sensations coordi- nated are represented separately and distinctly in conscious- ness. Experiment shows that this is not the case e\-en in man. We are guided with great precision by sensations coming from the hand and from the eye, without being distinctly conscious of what those guiding sensations are. Experiment shows that space judgments are greatly in- fluenced by variations in sensation of which the subject is entirely unconscious. This is especially true of the move- ments of the eye in bringing the image upon the point of clearest vision, in fusing the two images upon the retinae, 230 GENETIC PSYCHOLOGY and in accommodating for different distances and degrees of light. A certain sensation complex made up of all the stimuli affecting us at the moment means an object in a certain place to be reacted to by a certain kind of movement, and any variation in this complex calls for a variation in movement, but it is exceedingly difficult for us to become conscious of the exact sensations by means of which our movements are coordinated and adjusted. A slight variation from the usual in this complex may disturb the accuracy of our movements and the accuracy of our space judgments, but we are slightly or not at all conscious of the specific changes in sensations that are influencing our spatial perceptions and movements. The effect of surrounding objects that have no direct re- lation to the objects with which we are dealing, has long been recognized in a practical way by sportsmen. Tennis players change sides because the objects surrounding the tennis court within their field of view aft'ect the playing. If one were to play for a long time on one side of the court only, he would find it very difficult to play on the other side without error. He reacts not only to the ball moving from a certain point, in a certain direction, at a certain rate, to the net and the side lines, and to his own movements and position, but also to any buildings, trees, or spectators that may be in the neighborhood of the court. All spatial reactions are determined by the sum total of the surroundings affecting one. This is true not only of single reactions but also of a long series of reactions by means of which one finds his way. Not only do the sun and wind and one's own movements serve as guides, but all objects characteristic of the environment, whether individu- SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 23 1 ally and specifically known or not. For example, one who has lived much of his life in a place where roads usually run according to the points of the compass generally uses the roads as reference points in guiding his movements, although he may not be aware of the fact. When he strikes into the timber from the road, he is continually judging his direction by the relation of his movements to the direction in which the road runs that he has just left. This is true of the writer, although he did not realize it until after living for a while in a section of the country where the roads run in every direction. In trying to find why he made mistakes in direction when hunting, he was led to ascribe them to the fact that he somewhat unconsciously used the roads as guiding standards and was led into error because these roads were entirely uncertain in their direc- tion. Every individual who is able to find his way is doubtless influenced in a similar manner by something in his environment. Often he docs not know what it is but simply feels that this is the direction to take, that this is north, or that this way seems familiar. It is probable that the spatial reactions of animals are guided in a similar way by the objects characteristic of the usual environment of their species even though they are not individually familiar. A mountain sheep, for example, transported to a new range of mountains, could doubtless find food and avoid enemies very successfully. Creatures very low in the scale may have their reactions to specific objects in their immediate environment modified by becoming accommodated to them, in a way similar to that by whicli man becomes used to working in a certain room facing in a certain direction. This is probably the explana- 232 GENETIC PSYCHOLOGY lion of what is sometimes called the "homing instinct" of animals very low in the scale. Experiments show that when they are moved from their usual environment they find their way back again. This is probably because they are not in equilibrium with the new environment. They make various trial movements, then continue the movements that help to restore the equilibrium until they reach their former position. In higher animals, such as bees, wasps, dogs, and pigeons, the same factor doubtless exercises some influence. The chief difference is that in the higher animals the modification produced by all the objects surrounding the place where food has been found is produced by one or two perceptions instead of by long and repeated exposure to the objects. The wasp that has left food in a certain place has, we may say, been polarized with reference to that spot and the objects surrounding it, so that she reacts to them in a different way from what she does to any other set of objects. The nervous system of the homing pigeon is doubtless polarized with reference to the objects within the neighborhood. When carried many miles and released, his movements are often at first of a trial character; but frequently he knows the general direction of home, probably in much the same way as many men are able to tell with considerable assurance, as soon as they step off a train, which w^ay is north, although they may not know how they know it. In flying, the pigeon is also probably guided by the general character of objects in the landscape, hills, forests, etc., in the same way in which his race has reacted to them. When he approaches the neighborhood of home, so that any portion of its familiar environment can be SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 233 perceived, he finds that direction the more agreeable, and thus guided, soon reaches his old home. There is much that is mysterious in the reactions of ani- mals in finding their way, but probably nothing more mys- terious than in man's modes of distinguishing direction. He himself usually knows little of the specific sensations that guide him and that are the most important factors in his success. It has been suggested that men and animals may be subject to magnetic influences as is the needle of the compass, and this is the only explanation yet suggested of how some individuals know in every situation the points of the compass. When men are able to explain how they know directions, it is often by memory images; hence they are inclined to think that movements are in general guided in that way, when, as a matter of fact, men and all animals are guided much of the time without conscious memories and by sensations that have little or no separate representation in consciousness. Guidance by images in the form of rep- resentation of the relation of roads or objects that are not in the field of view is often possible to men but is by no means universal. Many people can act very suc- cessfully as guides who cannot describe the course to be taken. In a similar way animals are very skillful in finding their way, though they probably never image the relation of objects to each other or mentally pass over a route. Perception of Objects No absolute line of distinction can be drawn ])etween sensation and perception, either when viewed objectively 234 GENETIC PSYCHOLOGY in the form of stimulus and movement or as observed subjectively in our own consciousness. The more im- mediate the effects of the stimulus, either favorable or un- favorable, the more are we inclined to call them sensations. When, however, the stimulus is not in itself especially agreeable, but is suggestive of something to follow that is significant for our welfare we are more likely to use the word "perception." Taste and smell are more frequently named as sensations than are sights and sounds, although if an odor or a taste suggests other sensations associated with it we may use the term " perception." We may also use the term. " sensation " to indicate the effects of visual and auditory stimulation when we mean that the light, color, or sound is in itself agreeable or disagreeable instead of signifying some object that as a whole is pleasing or otherwise. On the motor side the movements in response to sensa- tions are usually less complex and definitely coordinated than those in response to suggestive stimuli and involving perception. In perception there is not only response to the stimulus received but an adjustment to the object or situation suggested by it. On the mental side in perception there is not simply a feeling of agreeableness or disagreeableness, but a mental attitude toward the situation or object suggested which in the higher animals may involve anticipatory images of what is to come, and in man in a certain stage of development may arouse memory images of past experiences in similar situations. Where the response to a stimulus is clearly of a reflex or instinctive character, we are more likely to use the term " sen- sation " to describe the mental state than when the reac- SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 235 tion is one that has been acquired by previous experience. There is no doubt that animals often make fitting responses to complex situations in an instinctive way, and hence may, in one sense of the word, be said to have instinctive per- ceptions. This is especially true of what are usually de- scribed as space perceptions. Without i)revious practice a chicken can peck with considerable accuracy at a particle of food, and young pigs either seeing or hearing their mother can guide themselves directly toward her. They can also judge distance with sufficient accuracy to jump success- fully from a higher to a lower position. The response of chickens to a danger call is also evidence of instinctive perception if we admit that the term may be applied to that which is native instead of limiting it to that which has been acquired by experience. It is probably well to recognize two kinds of perceptions, the instinctive and the acquired; although it may be convenient in describing the behavior of the higher animals and of man to use the term "per- ception" in the narrower sense of acquired perceptual motor reactions and tendencies, while in a still narrower sense it refers only to reactions represented in consciousness. On the mental side there can be no anticipatory images (or mediated sensations) except in the case of acquired per- ceptions. There is an instinctive basis, however, c\en in man for many acquired perceptions. The response of a dog to food placed in its mouth is largely sensory in charac- ter, althougli the swallowing or ejecting of the food, accord- ing to its character, suggests that there may be some reac- tion to the object as a whole rather than simply to the sensation that has already been experienced. The response of the dog to the stimulus of the odor of meat is of a similar 236 GENETIC PSYCHOLOGY character but slightly more perceptual. His response to meat that he can see but cannot smell, if he makes such a response, is without question an instance of acquired per- ception, though the movements he makes are largely in- stinctive. His reaction to the sight of a running cat indi- cates an instinctive perception, but his pause when the cat turns and faces him may indicate an acquired perception gained from previous painful experience in a similar situa- tion. It is not necessary to suppose that he has a distinct memory of the former experience, but merely that the pain previously experienced in that situation has modified his instinctive mode of action and perhaps produced some vague anticipatory images of disagreeable results that may follow continued pursuit. In our own experience we acquire new modes of behavior without any distinct recognition of the exact changes made and their results. This is perhaps best illustrated by the experience of one who is learning to ride a bicycle. He learns to make certain adjustments and avoid others without knowing just how he does it. In the case of more sudden and marked modifications the attitude and feeling toward an object may persist long after it is impossible to recall any former experience with it. This is well illustrated by a case mentioned by Professor Judd of a man who was very much afraid of horses without knowing why. Inquiry revealed the fact, however, that he had been severely bitten by a horse when he was a small boy. One's feeling of liking or dislike for persons, places, names, and things, that cannot be accounted for by any memories of experiences with them, is doubtless due to similar causes. Attitude toward objects as shown in SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 237 perceptions is much more fundamental than memory, being produced in creatures incapable of memory and persisting in higher creatures long after memory has failed. Again, a child who has seen a companion make an exclamation or gesture of horror at being touched or approached by a worm or a spider, may have its attitude towards those creatures completely changed, although it re- tains no memory of the experience that produced the change. It is probable that nearly all the acquired perceptions of animals are of this type in which there is no memory of the past experience, but only a mental attitude of attraction or repulsion excited by the object, with possibly some anticipa- tory images of the general character of the result to be ob- tained as agreeable or disagreeable. In man, in addition to these characteristics of perception, there are often definite images of just what is to be expe- rienced, and sometimes memory images of former ex- perience. These, in the cases of delayed perception, which are most readily observed, are usually the prominent elements. Hence there is a tendency for psychologists to ignore the less prominent phases of perception and to attempt to explain the perceptions of animals in terms of definite images and memories. As a result of acquired perceptions a change in the adjustment of the nervous and muscular apparatus has been produced so that the creature is modified and his states of consciousness are changed ; but there is no reason to suppose that animals are conscious that these changes have taken place. In man, such a consciousness is probably lacking in the majority of his perceptions. We are surprised at the sensation we get when we take salt from the sugar bowl, but this does not 238 GENETIC PSYCHOLOGY necessarily mean that before tasting we had formed an image of the sweet taste to be experienced. We are often surprised at the weight of objects, although we are not conscious of having formed an image of their weight. In general, the changes in acquired perception are in the reaction and attitude toward the situation as a whole, but where one feature dominates the situation the change may be chiefly with reference to that one element. In such a case the object or sensation may excite the same reaction whenever experienced. A dog that has been whipped by his master when hunting may show signs of fear when he sees the whip in the master's hand at home, or perhaps when he sees it in the hand of any person. It is not likely, however, that he will show any fear of it when it is not in the hands of some person, and then perhaps only when it is being held or moved in a certain way. In the case of acquired reactions to the more direct stimulus of an odor, which is in a way a sample of the object itself, the reaction is likely to be of a specific kind no matter what the situation is when that odor is experienced. A horse that is gun shy may show fear at sight of a gun only when it is being pointed, but if his fear is due to the odor, it is more likely to be aroused by that alone, whatever the situation. Images and Memories Since the actions of all creatures are dominated by the end to be gained, and since association of impressions is much stronger in the order in which they occurred than in the reverse order, it is clear that anticipatory images would be formed easier and earlier than reminiscent images. SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 239 Where a stimulus is always immediately followed by the same movement, there is not in our own case any conscious image formed and there is no reason to see why there should be in the case of any creature. When movements are directed toward an end but \-ary in ways that result in reaching that end by shorter means, as is the case in the learning of many of the higher animals, it would seem that an image of the result to be obtained may be dominating the movements. If, however, the movements follow the stimulus immediately, it is difficult to see how an image could be formed, or be of any service if formed. An animal that is stimulated by objects at a distance, as, for instance, a deer by the form of a hunter, may not make any considerable reaction to that stimulus for some time. It may wait until the stimulus is repeated and intensified by nearer approach and perhaps supplemented by sound or odor before it reacts strongly by running away. Evidently the conditions in this case are favorable for the production of modifications in portions of the nervous system not directly connected with the motor centers, and hence for the formation of images. Such images of results that may follow the various stimuli being received from ob- jects at a distance would be likely to be of service in directing movements. We should expect therefore that images of some sort would be formed in response to sug- gestive stimuli, especially when immediate movement is not necessary, rather than in response to direct stimuli and to suggestive stimuli requiring immediate response. The images excited in the deer, however, are probably anticipa- tory and of tlie same type as secondary sensations or per- ceptual images. In order to become free images they 240 GENETIC PSYCHOLOGY must appear under various circumstances and must be aroused in some other way than by associated sensory activity. Most of our free images are from the sugges- tive senses of sight and hearing, while images of taste and pain are rare, and to many persons impossible. In the case of the suggestive senses an image of the sen- sation to be experienced may serve the same purpose as the movements by which the sensation could be secured; hence the power of forming such images has been highly developed, while that of forming images of immediate sensations has been but slightly developed. In learning, images sometimes play a prominent part. Where the process of learning is very gradual, there is no reason to suppose that images aid in the process, for they do not in our own case. When, however, all useless and indirect movements are dropped as soon as the successful one has been made once, it is probable that images aid in the process of learning. The service rendered by images must be still greater when all movements are inhibited for a time and then the right one made at once. In all but the higher animals learning seems to be a very gradual process. Hence there is no reason to suppose that images play any considerable part in the learning of lower animals. Much of the learning of monkeys, raccoons, and other of the higher animals and some of that of human beings is not rapid enough to indicate that images assist in the process. In Cole's experiments the raccoons learned to get up on the box for food when white, orange, and blue cards were shown successively, but to remain down when blue was shown three times in succession. In other words, the reaction was not made to blue alone or blue repeated three SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 241 times in succession, l)ut only when it was preceded by white and orange. The animals often began to get up on the box after white appeared, which suggests that they had an anticipatory image of what was to follow. This is perhaps further indicated by the fact that they would sometimes get down and wait for the blue to appear before getting up on the box again. It is not certain, however, that this indicates a definite image of just w'hat was to appear. It may be interj)rcte(l merely as an indefinite image of pleas- ant results to be obtained, with a waiting for the proper signal, which is recognized when it appears, though it may not have been imaged previously. It is certainly true of persons that they are able to anticipate and react to the proper signal when it appears wdthout having held in mind an image of it. The pause involved in waiting for the proper stimulus is doubtless, how^ever, a favorable condition for developing an image of the stimulus that is to appear. Whether such an image actually is developed in the consciousness of the raccoon cannot be stated positively. Should an image be formed under such circumstances as stated above it would not necessarily be a free image or reminiscent image, since it is brought into mind only, as fax as can be judged, by the general conditions of the ex- periment and the immediately preceding stimulus of white and orange cards. Where an animal learns to perform a long series of movements it is possible but not probable that anticipatory images of the next stimulus to be reacted to are formed in the animal's mind and aid him in per- forming the movements when the trick has only been partly learned. For example, where a monkey or a raccoon is to undo several fastenings in the same order he has pre- R 242 GENETIC PSYCHOLOGY viously followed, he might image the next fastening, but at most there is probably nothing more than an image of the place toward which he is next to turn, as is often the case in our own hal:>itual acts. It is not at all likely that the animal forms a reminiscent image of what he did the other time and then thinks, "I must do the same again," as a person sometimes does. In learning a series of manual movements or in learning a selection of poetry, images of what one did before are in us the exception rather than the rule. If one cannot go on he is likely to begin again the series and may then know what to do when he comes to the place at which he was previously obliged to stop. If he stops to think instead of beginning to repeat again, he is likely to mentally repeat the first part of the series and may then think of the next thing to do. It is doubtful if animals are ever able to form an anticipatory image of a series of actions to be performed so as to mentally repeat it. If they are, that is one step beyond the anticipatory stage in which images are aroused after part of the series has been reproduced. In other words, animals rarely or never have a train of thought. It is true that animals do frequently repeat the first part of a series of movements when at any stage they are unable to go on successfully. This was an espe- cially marked feature of the behavior of Watson's rats, which when placed in the maze at some other point than at the usual entrance, if they could not at once find their way to the center where the food was, nearly always went back to the original starting point. This motor repetition is an earlier stage of development than that of mental repetition, which is probably possible to man only. SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 243 Evidently the kind of associalion formed in lliis type of image formation is that of contiguity only, and there is not necessarily any analysis of the whole situation into the elements involved in the situation or the series. In our own case images are frequently brought to mind by concentration of attention upon some one element of what is in consciousness until that brings into mind an image connected with that element in some other situation. In other words, images are brought to our mind b}- association of similarity. Images when thus brought into mind are to some extent free images since they are brought in by a portion of a new situation instead of by a reproduction of a group, a series, or situation in which they had originally occurred. It is probable that images are rarely or never brought into the minds of animals in this way and conse- quently they have few if any free images. It is difficult, however, to distinguish clearly between images that are brought into consciousness by analysis of the present situation and those that are brought in by the similarity of the whole situation or of the dominant portion of it to the situation with which the image had been associated and of which it was a prominent feature. It is also sometimes difficult to distinguish between a case of association by similarity and a case of lack of dis- crimination between two things that resemble each other as wholes though they differ in many respects. Several experimenters with animals report tliat animals that have been drilled in undoing fastenings attack entirely new fastenings by methods that have been found successful with the old and thus usually learn to undo them more quickly. This indicates a partial analysis of the situation. 2 44 GENETIC PSYCHOLOGY The fact, however, that if the new fastening demands an opposite mode of treatment, the animal requires a longer time than usual to learn it, indicates that he has not ana- lyzed the situation so as to find the exact points of simi- larity and dissimilarity as a person might do. He has perhaps analyzed the case sufficiently to at once attack the fastening, but not definitely enough to know in what direction to move it. Most of the so-called memories of animals probably do not involve images, and are therefore more nearly allied to habit reactions. The animal is readily changed by an experience and may retain the modification for a consid- erable time, so that when a portion of the situation is re- produced the appropriate reaction at once follows. An animal that has quickly learned a trick may perform it after a long interval when again confronted with the proper situation. This docs not necessarily imply, however, that he has ever mentally performed the trick in the meantime ; nor does it necessarily imply that the performance of other tricks at another time and place has caused him to form images of the one previously learned. Mental images of animals, so far as they have any, are evidently closely re- lated to the suggesting situation which is being repeated, especially to the movements which the animal himself is to make. The fact that dogs sometimes seem to dream is not a positive proof of image formation and memory. It is more probable that the movements are produced by sen- sations arising from the physiological condition of the animal and from external stimulation. Movements of various kinds may be produced in persons who are SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 245 asleep, especially habitual ones, such as turning over in response to a certain touch. It is worthy of note that in such cases there is usually no memory of dreaming; while in most instances of dreaming, with its image formation, there is no movement, and if movement occurs, the dream usually ceases. This is additional evidence that the ap- paratus concerned in image formation is different from that directly concerned in performing movements. Memory usually involves the production of images, and the process by which they are brought into consciousness conforms to the same laws that govern habitual acts. When not only movements but images are reproduced, the term " memory " maybe used instead of that of " habit." In the common characteristic of retaining and reproducing former experiences there is no difference between memory and habit. Memory is usually the result of few repetitions, while habits are the result of many. Habits when fully developed involve no images, while memory involves images or concepts. There is another characteristic of memory which is probably more primitive than that of image formation. It is recognition or a feeling of familiarity. This feeling differs somewhat from anticipatory images in that some of the things leading to the result produce a feeling of familiarity as they are experienced, which may or may not be accompanied by anticipatory images. Memory of this type differs but little from recognition in perception. This feeling of familiarity doubtless appears very early in animal life. It is contrasted with the feeling of strange- ness, which, as we have already seen, is one of the most common excitants of fear. Animals probably ha\e this 246 GENETIC PSYCHOLOGY feeling of familiarity to as great an extent as do men, but it is probably not accompanied in their consciousness, as it often is in ours, by the thought that the object has been experienced before. Recognition may occur for things that have been perceived once or many times, and one's attitude toward the object may persist without definite intellectual accompaniments. For example, the writer once recognized a face in an audience as familiar, was sure that the person had been well known to him and was re- garded in a friendly but not wholly trustful way, but was unable to recollect any one definite thing regarding the person until afterward, when he met him and heard his name. Recognition in the form of persistence in an atti- tude toward a person or thing is doubtless a prominent feature of animal memory, which the many stories of ele- phants and other creatures revenging themselves upon persons who have injured them years before, illustrate. In human psychology a mental process is not supposed to be a memory unless it is not only reproduced but is known as a former mental state that can be contrasted with the present one. This kind of memory probably involves not only consciousness but self-consciousness. Only when this kind of memory is possible are there produced what may be called reminiscent images, in the production of which one does not entirely lose conscious- ness of the present but has a feeling of contrast between the past and the present circumstances. There is no good reason for believing that any animal possesses mem- ory in this, its true form. Another element in memory of great importance in man is that of location of the reproduced experience as having J SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 247 occurred at a certain time or place or in connection with certain other experiences of one's own. This kind of memory implies the existence of free images and a further consciousness of the relation of images to each other. Hence memory in this sense is probably not found in animals. Concepts and Reasoning Since concepts represent a higher stage of psychical development than free images, and since we have already decided that animals can have very few free images, it at once follows that we conclude that they have no concepts. It is worth while, however, to devote a few paragraphs to the consideration of behavior which has been supposed to indicate that animals have concepts or general ideas, or at least what Romanes calls "recepts." There is no question whatever that animals do react to classes of objects in ways as definitely fitting as they do to individual objects. Each species of animals reacts to the enemies of its species and to classes of food suitable to it. Birds react to liquids, when alighting, in a different way from what they do to solids. This has been supposed by Romanes to indicate the existence of general ideas of each group of objects as a class. The term " instinctive per- cepts " is doubtless however a better name to apply to the mental state involved in the action. There is no reason to suppose that the mental state arises except when a sensory stimulus is received and a reaction is to be made. In many cases a reaction to the members of a class does not diflfer from the reactions to an individual of the class simply because there is no discrimination of the finer differences 248 GENETIC PSYCHOLOGY between individuals, but only of those that distinguish one class from another. In cases of acquired modes of reaction to a class of ob- jects, as, for example, the avoidance of all men by birds, the mental state is probably better described by the term "acquired perception" than by the word "concept." If an individual bird has learned to respond to one specific individual in a different manner from that used to other members of the class, we have simply an instance of an acquired perception more definite in its character than that indicated by the reaction to the members of a group. In this, as in the other case, the mental state is probably never aroused except by sensory stimulation. Reasoning, in the sense of responding to a situation in a way that has previously brought satisfactory results, is shown by animals as well as by man ; but reasoning in the sense of analyzing a situation, and identifying the element upon which results depend, is probably never shown. Most untrained persons do much of their reasoning from particu- lar to particular without consciously starting or ending with a clearly represented general truth, and the same is true of a good deal of the reasoning of many cultured people. The so-called "reasoning" of animals is somewhat similar to this kind of reasoning in man, the chief difference being that similarity of the situation as a whole to a previous situation is to a greater extent the basis of reasoning in animals, while in man it is not only the situation as a whole but specific things or characteristics in that situation that are made the basis of the inferences. In both men and animals the most fundamental basis of all reasoning is found in the general law of habit, which SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 249 produces a tendency to do the same thing under the same circumstances, that is strong in proportion as the situation and act have been repeated many times, recently and with intensity. Where the situation and the act arc exactly the same, we speak of any particular performance as an habitual act. When there are many new elements in the situation and in the act, and when some specific element in the situation is met by a mode of action that has never previously been associated with the present situation, the act is usually supposed to indicate reasoning. Much of the discussion regarding the possibility of animals reasoning is meaningless because of differing conceptions of what constitutes reasoning. There are many instances of animal and human behavior that on the surface look like reasoning, in the sense that a situation only partly like one previously met is reacted to in the way that previously brought favorable results. The stricter psy- chological definition of reasoning, however, demands that the situations shall have been analyzed and a free idea of its essential element compared with an abstract general truth regarding such element and situation. Our previous study has shown that free ideas are rarely or never pos- sessed by animals, and that abstract ideas are utterly im- possible to them. It follows, therefore, that they cannot reason in the stricter meaning of the word "reason." That animals and persons who can do little or no reason- ing, in the strict meaning of the word, can profit by former experience when they meet situations that are partly new, cannot be doubted. In the case of animals this can only be done when their senses are actually being affected, while in human beings it may be done by means of images of 250 GENETIC PSYCHOLOGY concrete situations. The real difference between reason- ing and other processes that accomplish similar results is much the same as is recognized in general psychology in distinguishing thinking from perception and imagina- tion, and as is emphasized in a subsequent chapter in dis- tinguishing the conceptual from the representative and sensory motor types of intelligence. VOLITIONAL ACTIVITY Interest and attention are objectively indicated when one stimulus appears to dominate the activity of an animal in spite of other stimuli that are being received. Even as low a creature as the Paramecium may, when feeding, fail to react to rather intense stimulations of heat or light that would ordinarily produce marked reactions. When there is any consciousness accompanying this objective attitude of interest and attention it is doubtless concerned "wholly with the dominant stimulus and the reaction being made to it. In such cases as this, however, where the stimulus is itself immediately favorable or unfavorable, it is very doubtful whether there is any mental state ac- companying the act. Where the stimulus dominating activity is suggestive rather than immediate, as when a cat is watching and creeping toward a bird, it is probable that there is a con- scious state accompanying the attitude and that this con- scious state consists largely of a feeling of attraction and expectation and a more or less definite anticipatory image of the result to be obtained. Attention to immediate stimuli is probably always SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 25 1 reflex or instinctive, while that to suggestive stimuli may be either instinctive or acquired. Interest is instinctive in the sense that the creature is so organized that certain kinds of stimuli tend to dominate his activity even though others of equal or greater intensity are being received at the same time. The structure and conditions of life of each species have made it necessary that they should be more sensitive to some kinds of stimuli than to others. For example, a small moving object of any kind is an especially strong stimulus to a cat, and for the time being is likely to completely dominate his behavior. Chickens have an instinctive interest in objects moving swiftly over them, while they have an acquired interest in the move- ments of persons who have frequently brought them food. In general, both instinctive and acquired interest are more or less closely connected, either with the immediate satis- faction of needs or with things that are means to the satis- faction of some instinctive need. In animals, therefore, interest and attention are connected almost exclusively with the satisfaction of biological needs, while in man, interest in the satisfaction of mental needs plays a large part. On the mental side the most elementary ])henomenon of interest probably consists in a mere feeling of attraction. In a higher stage of development there is a vague antici- patory image of the general character of the result to be experienced. In a still higher stage of development there is a more definite anticipatory image of the result and some images of what will lead to it. The higher animals may have some interest of this sort, though representa- tions of just what leads to the result are probably few 252 GENETIC PSYCHOLOGY and transient, even when the suggesting object or antece- dent stimulus is present. In man the exact result to be obtained and the elements leading to that result may be represented with a great deal of definiteness, and memory images may be formed of parts of a number of experiences, and related to each other in such a way as to bring about the desired result in the present situation. Such a mental state is by no means universal in the attentive activity of man. Much of our attention is not accompanied by these conscious states, although the fact that when observed they are prominent features of consciousness is likely to lead us to think that they are always so. Such attention as this evidently involves association of similarity and numerous free images and ideas. Hence attention in this sense is almost if not wholly impossible for animals. Animals usually respond almost immediately to the stimulus that, because of its objective strength or because of the instinctive or acquired tendency in the animal, is at the time the strongest. There is therefore no oppor- tunity for deliberation and formation of images of other acts that might be performed or results obtained under the present circumstances. Occasionally, animals do pause for a moment under the influence of two stimuli, either of which if received alone would immediately dom- inate action. For example, a dog that is chasing some hogs may stop when he hears his master's call, and for a while it is uncertain as to whether he will continue chasing the hogs or return to his master. Such a pause might be supposed to be occupied with the formation of images of the results of the two courses of action, but it is probable SPECIFIC CONSCIOUS STATES OF ANIMALS AND MAN 253 that such imagery is almost if not wholly lacking. That the action of the animal is dominated by sensory stimuli rather than by images, is indicated by the fact that the pause is readily converted into vigorous action in one di- rection or the other by a supplementary stimulus, such as the passing of a hog near the dog, or a louder call from the master. In some instances, however, when there is no ])rominent external stimulus perce])tible to man, a dog will stand as if considering what to do and then go and do something. In such cases there may be a sensory stimulus uni)er- ceived by the human observer that directs the action of the animal, but it is also possible that in some instances imagery of some kind may play a part in initiating and directing the activity of the animal. It is probably true that in many instances the physiological condition of the animal, as for example a state of hunger, initiates the action. Perhaps there is an anticipatory image of the place or direction in which to go to find satisfaction of the physiological need, but the more specific direction of move- ments is later determined by the stimuli that are received as the animal moves from place to place. An animal may thus go where he has previously hunted, but the actual hunting is probably directed, not by images, but by sensory stimulations as they come to him. Instinct and habit, rather than memory, usually if not al- ways direct the action of even the higher animals. A dog when hungry will go to the place where he has previously found food, but he may sec food placed in a new position and show no evidence of any consciousness of it afterward unless his senses are actuallv affected bv it. This was 254 GENETIC PSYCHOLOGY clearly shown by experiments upon a very clever dog that was very fond of candy. When the word "candy" was spoken he would go to places where he had previously obtained candy; but if a piece of candy were given him from a bag and the bag placed on a chair, the word " candy," uttered a few minutes later, would not cause him to go to the bag but to the usual place where candy had been found. From the above, it is clear that if representation of more than one end or of more than one means of obtaining an end is necessary to an act of will, then animals can show very little if any volitional activity. They may persist in trying to reach an end, and in doing so use various means ; but the means to be used are usually suggested by the stimulating conditions and the previous habits of the animal rather than by specific images and memories. It is true that the actions of human beings, especially of children, are directed in a similar manner; but it is also true that in their minds specific images are likely to play some part in all deliberative action, and in many instances images and ideas play the whole part at the time, the movements corresponding to the decision being made only after a long interval. REFERENCES Allen, A. The Recognition Theory of Perception, Am. Jr. Psych., Vol. VII, pp. 237-273. *Angell. Psychology, Chapters IV to XIV. Bentley, I. M., 1899. The Memory Image and Its Qualitative Fidelity, Am. Jr. Psych., Vol. XI, pp. 1-48. *BoLTON, T. L. A Biological View of Perception, Psych. Rev., Vol. IX, pp. 537-548- SPECIFIC CONSCIOUS STATKS OF ANIMALS AND MAN 255 *Daxa, Chas. L. The Study of a Case of Amnesia or Double Con- sciousness, Psych. Rev., Vol. I, p]x 570-580. *HoBHOUSE, L. T. Mind in Evolution, Chapters VIII, IX, X. *HoDGE, C. F. Method of Homing Pigeons, Pop. Set. Mo., 1894, PP- 758-775- *James. Psychology, Chapters XIII to XXIV. *Jastrow, J. Fact and Fable in Psychology, pp. 275-295. A Study of Involuntary Movements, Am. Jr. Psych., Vol. IV, p. 398. JuDD. Psychology, Chapters VI, VII, IX, X, XL A Typical Case of Perceptual Development, /r. Ped., Vol. XIX, PP- 34-45- *JuDD, C. H. Genetic Psychology, Chapters I, II, III. JuDD and Cowling. Studies in Perceptual Development, Mono- graph Slip p., No. 34, 1907, pp. 349-369. ♦KiRKPATRiCK. A Genetic View of Space Perception, Psych. Rev., Vol. VIII, pp. 565-577- Mead, Geo. H. Concerning Animal Perception, Psych. Rev., Vol. XIV, pp. 383-390- *MoRGAN, C. L. Comparative Psychology, Chapters I to XVI and Chapter XX. Animal Life and Intelligence, Chapter X. MuNCEY, Elsie. Peripheral and Central Factors in Memory Image and Visual Form and Color, Arn. Jr. Psych., Vol. XVII, pp. 227-247. Norman, W. W. Do the Reactions of the Lower Animals Against In- jury Indicate Pain Sensations? Am. Jr. Psych., Vol. Ill, p. 271. PiLLSBLTRY. Psychology of Attention, Chapters VII and X. *PiLLSBURY, Calvin, Bolton, and Boodin. Symposium on Mean- ing, Psych. Rev., Vol. XV, pp. 150-196. *PiTKiN, W. B. Reasons for the Slight ^Esthetic Value of the Lower Senses, Psych. Rev., Vol. XIII, pp. 363-377. Romanes. Mental Evolution in Man. Stanley, H. M. Evolutionary Psychology of Feeling. Language and Image, Psych. Rev., Vol. IV, pp. 66-71. *Thorndike. Elements of Psychology, Chapters XV, XVI, XVII, XVIII. 256 GENETIC PSYCHOLOGY Town, Clara H. The Negative Character of Hallucinations, Am. Jr. Psych., Vol. XVII, pp. 134-136. ♦Washburn. The Animal Mind, Chapters VIII, IX, XII, XIII. WooDWORTH, R. S. The Cause of a Voluntary Movement, Garman Commemorative Studies in Psych, and Phil. Accuracy of Voluntary Movement, Monograph Supp., Vol. Ill, No. 2. Non-Sensory Components of Sense Perceptions, Jr. Phil. Pysch. &^ Sci. Melh., Vol. IV, pp. 169-176. * Imageless Thought, Jr. Phil. Psych. &- Sci. Meth., Vol. Ill, 701. WuNDT. Human and Animal Psychology, Chapters XXIV, XXVI. CHAPTER IX TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE A BROADER CONCEPTION OF INTELLIGENCE The word "intelligence "always implies the adaptation of means to ends, but it has usually been limited to conscious processes. In order that psychology, physiology, and biology may find a common ground for the consideration of behavior it is necessary that either the term " intelligence" shall be given a broader meaning, some differentiating term like " adaptation " be used, or some new term invented to indicate the most prominent characteristic of all organs and organisms, i.e. that of activity suited to self-preserva- tion. The word "Organoses" would be a good word to indicate organic activity, whether conscious or unconscious, including the original meanings of the two terms " neuroses " and "psychoses." The author for present purposes, how- ever, prefers to extend the meaning of the word " intelli- gence " so as to include unconscious as well as conscious activities that are suited to the preservation of organic unity. Having recognized the common characteristic of all organic activity, it will be possible to classify activities according to the way in which they secure the preservation of the organisms. Our previous study of behavior has shown that the difference between actions of lower and higher animals is not in the end gained but in the mode of activity by which it is gained. Plants gain the end of s 257 258 GENETIC PSYCHOLOGY preservation chiefly by means of slow growth activities, while animals use to a considerable extent organs of move- ment in preserving life. Higher animals store up in their systems the results of activity in such a way as to be helpful in future preservative acts, and if acts are varied and complex and must be quickly modified to meet changing conditions, as is the case in man, consciousness plays an important part. All of these kinds of activity are intelligent in a high degree in the sense of adapting means to ends. The differences viewed objectively consist chiefly in the number of adaptations and the quickness and accuracy with which they are made and modified. By thus extending the meaning of the word " intelli- gence" the truths of several sciences may be brought into intimate relation and their significance better appreciated. In thus classifying the various types of intelligence, famil- iar psychological classifications may be used and shown to have a more fundamental basis than has usually been supposed. It has long been recognized that physiological processes have important influences upon mental processes, determining whether conscious processes shall or shall not be intelligent in the sense of being w^ell adapted to the se- curing of ends. In the treatment here proposed, physio- logical activity, instead of being regarded simply as injlu- encing mental activity, will be considered as one type of intelligence. The other types of intelligence will corre- spond quite closely with the old division of intelligence into presentative, representative, and thinking processes. The term "sensory motor" intelligence will be used for the first, " representative " for the second, and " conceptual " for the third. TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 259 In our study of typical forms of behavior wc found that the dominant form of intelligence in the lower organisms is physiological, while in those a little higher sensory motor intelligence becomes prominent. In the higher species of animals there is perhaps a slight development of rep- resentative intelligence, while in man this form of intelli- gence is very prominent and is supplemented by concep- tual intelligence. In our study of the structural basis of behavior we found that the lowest organisms were without nervous tissue, and that the nervous system became a more prominent ele- ment of the organism as we went upward in the scale of animal life. We found that in man there is a nervous apparatus at different levels, concerned in different kinds of behavior similar to those of the lower animals, and in addition certain apparatus in the cerebrum, either not pos- sessed or possessed only in a slight degree by any other creature than man. With such conceptions and classifications it will be much easier to correlate the truths of physiology and psychology, to compare the behavior of lower animals with that of the higher and with that of human beings, and to trace the de- velopment of behavior and ideas in individuals. PHYSIOLOGICAL INTELLIGENCE Physiological intelligence is shown especially in nutritive and growth processes. At first thought it seems incon- gruous to speak of physiological processes as intelligent. When, however, wc view intelligence in an entirely objec- tive way as the adaptation of means to ends, v;c find good 26o GENETIC PSYCHOLOGY reason for looking upon physiological processes as highly intelligent. As a builder, physiological intelligence is not surpassed by the greatest mechanic or architect. A tree with its beauty and strength may well compare with any structure planned by an architect, and the human body as a machine is far suj)erior to any as yet constructed by man. The engineer who tears down an old bridge and erects a new one while trains are running over it, has performed a remarkable feat, but not so great as that performed by physiological intelligence in directing the processes of growth in which a large number of complex organs are torn down, built up, and increased in size without any interference whatever with their activities or the harmony of their working. Discriminative and selective activity, which chooses from the various substances introduced into the body just the right elements for the building of each organ, is certainly comparable in accuracy to the perceptive judgment of the human builder. The physiological processes by which life and health are maintained are comparable, in the complexity of activities that must be related and harmonized, to the most complex machine constructed by man and even to the activities unified in consciousness. To give a single illustration, no heat-regulating device as yet invented by man will keep a building at a temperature so nearly uniform, amid rapidly changing external conditions, as is the temperature of the body, maintained by physiological intelligence. So per- fectly does it perform this function that a variation of only a few degrees in the temperature of the body indicates a serious derangement in the physiological activities. TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 261 Physiological processes, as well as other forms of intelli- gent acti\'ity, are subject to modljlcation by experience. The physiological j)rocesses correspond to the food, exer- cise, and climate usual to tlie indixidual, but they (juickly adjust themselves to changes in any or all of these respects, although such adjustment probably involves a modification of the activity of nearly every gland and organ in the body. The organism may become habituated to the use of drugs to such an extent that a dose that would produce instant death in one unhabituated to their use will have but little effect. Not only may the physiological processes be passively habituated to new conditions and substances, but what correspond to active habits may be formed. In some instances, instead of becoming accommodated to certain drugs or conditions, there is increased sensitiveness, so that smaller quantities will produce greater effects in an individual who has prcNiously taken the poison or the food in excess than would be produced upon an individ- ual that had never had such experience. This is quite analogous to growth in sensitiveness and discrimination by the senses. In such cases as this, and also in cases of disease, single experiences may produce permanent effects similar to those in conscious memory. A single attack of certain diseases, such as measles, usually renders the individual forever immune to further attacks, just as if the experi- ence were remembered and avoided. In the case of other diseases a single attack renders one ever after more sus- ceptible to the disease, e.g. pneumonia. When subjected to unfavorable conditions, the vital 262 GENETIC PSYCHOLOGY organs modify their activity until relief is obtained in ways that arc analogous to the behavior of the stentor under continued unfavorable stimulation. It is probable that in reacting to new situations the various organs and glands not only have fixed reflex-like modes of reaction, but that they vary their activity in a way analogous to that of trial movement. However this may be, we know that a change in the activity of any organ or gland is met by corresponding changes in every other part of the body, especially in those parts whose function is most intimately associated with the one first affected, e.g. change in lung activity affects also the organs of circulation and nutrition. The complexity of correlation thus involved is quite com- parable to that revealed in the relation of conscious states to each other. We see, therefore, that the phenomenon of physiological intelligence is very similar to that of conscious intelligence. The difference is not so much in the complexity of the activities related and unified in the accomplishment of an end as in the rapidity with which it is done. Where a physiological process requires hours or years, the con- scious process may only require seconds or minutes. For example, the various qualities of an article of food may be consciously discriminated in a few seconds and some of the elements combined to form a new concept in a few minutes, while the physiological process of separating the particles of food and building them up into the tissues of the body would require hours and days. The physiological processes are worthy of study, not only in themselves, as instances of a high degree of objective intelligence, but because other forms of intelligence are TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 263 dependent upon the perfect working of apparatus that is built up and kept in working order by means of physiologi- cal processes. The circulatory, respiratory, and digestive organs, together with the sympathetic nervous system, constitute the apparatus especially concerned in physio- logical activities. The other portions of the nervous sys- tem that are especially concerned in other forms of intelli- gent activity are perfected and kept in good working order by means of the physiological activities. The physio- logical apparatus bears much the same relation to the rest of the body that the heating and power plant bears to the various machines in a manufacturing establishment. The relation is more close, however, for not only is power furnished each apparatus in the human body, but it is kept in repair and in good working condition by the physio- logical intelligence. The special physiological activity in- volved in the functioning of the higher nerve centers must be exceedingly delicate and rapid to make possible the precise and lightning-like activity of conscious processes. In tracing the development from the lower forms upward we note that the chief type of intelligence manifested by the lower animals is physiological ; yet the apparatus con- cerned in maintaining the life processes becomes more and more complex. The evolution of organs concerned in the higher types of intelligence does not greatly surpass in complexity that shown in the differentiation of vital organs, by means of which physiological intelligence is manifested in the higher animals and in man. In other words, there has been almost as much increase in physio- logical intelligence, from the lowest animals to man, as there has been in the higher forms of conscious intelligence. 264 GENETIC PSYCHOLOGY SENSORY MOTOR INTELLIGENCE While physiological intelligence is concerned with the direction of activities taking place within the body in such a way as to preserve life, the sensory motor intelligence is concerned with directing movements of a part or all of the body in response to external stimulation in such a way that favorable results may be secured. All immediate responses to sensory stimulation, such as reflexes and per- ceptions, are under the direction of sensory motor intelli- gence. Plants and some forms of animals that remain constantly fixed in the same environment and subjected to the same influences, are able to preserve life by means of the slower growth processes of physiological intelli- gence. Creatures that move, however, are constantly being subjected to new stimulations, which must be re- sponded to in order that life may be successfully main- tained. Hence a high degree of development of the sen- sory motor intelligence, by means of which fitting reactions may be made, is of great advantage in the struggle for existence. Sensory motor intelligence is manifested to some extent by creatures not possessing a distinct nervous and muscular system, but is much more prominent in creatures thus en- dowed. In its simplest form this kind of intelligence is shown in comparatively uniform reflex movement in re- sponse to stimulation and in trial movements. It is best manifested, not so much in single reflex movements, as in a series or combination of such movements that are so related to each other that they all contribute to the same end. This is shown in a remarkable way in instinctive TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 265 reactions of all kinds, especially in those made in response to suggestive stimuli and in proj)er correlation with the physiological condition of the animal at the time. Sen- sory motor intelligence may be regarded as greatest in acquired reactions to complex and varied situations and in perceptual activity of all kinds. It is manifested in a high degree in all forms of manual work and athletics. The apparatus concerned in sensory njotor intelligence in the higher animal consists (i) of specialized nerve end- ings, (2) muscles, (3) nerve fibers, and (4) a nerve center. This is the apparatus used in the simplest form of reflex action. In more complex forms of instinctive and percep- tual reaction several sense organs, thousands of nerve fibers, a number of nerve centers, and many muscles act together in a unified way so as to accomplish a definite result. In order that there may be a high degree of sensory motor intelligence manifested, there must be not only highly specialized sense organs, many muscles, nerve fibers, and nerve centers, but they must all be related to each other in such a way that there is a proper balance or equilibrium of activity, and so that all may act together harmoniously in the accomplishment of an end. Any over-development of any portion of a complex and closely related sensory motor apparatus will give that part undue prominence in determining the direction of activity, while any lack of perfect connection between the parts or in the various ad- justments for meeting changing situations will interfere with the successful attainment of ends, e.g. cross eyes may result from o\'er-action of one of two opposing muscles, with the result that the two images are not properly com- bined and vision is poor. 266 GENETIC PSYCHOLOGY Although considerable changes in the character of sen- sory motor reactions may be produced by decrease or increase in the perfectncss of the peripheral organs of sensation and motion, yet the most important modifica- tions in activity are produced by changes in the nerve cen- ters and their connections. These are the parts also most readily changed by exercise, a single unfavorable or favor- able experience often producing marked changes in sub- sequent activity; e.g. the sight of medicine after a single experience may produce nausea. The connections be- tween centers become more or less close according as impulses passing between them have had favorable or un- favorable results. The close connection between all parts of the nervous system and the readiness with which even the most elementary reflex-like actions are modified by experience so that they can be called into action by impulses from other centers, are well illustrated by experiments up- on the tendon reflex or knee jerk. Stratton, who had been carrying on such experiments for some time, accidentally discovered that the mechanism concerned had learned to respond to a suggestive stimulus. In the apparatus used a sound w^as always made just before the tendon was struck, and after a great many experiments had been made, the apparatus failed to work properly, so that the sound was made but the tendon was not struck; yet, much to his sur- prise, the reaction was the same as if the tendon had been directly stimulated. Since the reflex is involuntary and without conscious direction, it must be that the change in reaction so that the movement is made in response to an associated stimulus is a case of unconscious learning by the sensory motor apparatus. I TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 267 The sensory motor intelligence becomes greater, not only in proportion to the number, variety, complexity, and unity of action of the mechanisms concerned, but in proportion to the readiness with which the apparatus is modified by experience. Since the modification depends largely upon changes in the nerve centers, an increase in the number of ner\e centers connected with the sensory motor apparatus would naturally increase the number and rapidity of modifications in activity. In the higher ani- mals and in man there is, therefore, a high degree of sen- sory motor intelligence. For example, the sensory motor mechanism by means of which a man catches a flying ball, or a swallow a flying insect, is more perfectly adapted for the purpose than any machine constructed by man. In animals the proper connection between parts, in order that successful reactions may be made to the various situations likely to be met with, is partly developed at birth, while in man it is to a greater extent acquired by experience. The sensory motor intelligence of the bee, by means of which it constructs its comb in such a way as to secure the greatest strength with the smallest amount of material, is, in its success in securing an end, quite com- parable to the calculation of the engineer. The bee suc- ceeds in doing this because his sensory motor apparatus is constructed and adjusted in such a way as to produce this definite result. The hawk in swooping upon his prey takes a course which, according to mechanical principles, is known to be most favorable for securing success. In this case success depends not so much upon the structure of the apparatus as upon the rapid making of the proper 268 GENETIC PSYCHOLOGY adjustments, as the situation varies at each moment. The sensory motor intelligence shown by the goat in leaping with absolute accuracy from rock to rock involves an accuracy of adjustment of apparatus quite comparable to that of the instruments used by the engineer. Such adjustments as these, and others shown by animals in seeking prey or in avoiding enemies, are marvelous examples of the adap- tation of means to ends favorable to the existence of the animal, that are largely inherited. They are scarcely surpassed by anything that man can do in the way of sen- sory motor adjustments and only slightly surpassed by his more conscious intellectual activities. Sensory motor activity may or may not be accompanied by consciousness. The accuracy with which such activity is carried on is in many instances decreased rather than in- creased by consciousness of what is being done, or more especially, consciousness of just how the movements are being made. Instinctive and mechanically habitual acts are usually more perfectly performed when there is little or no consciousness of how they are being done. In the acquisition of new modes of reaction, as previously indicated, consciousness is not necessary, although it may be very helpful. When it is helpful, it is not so much by revealing just what is being done and the exact character of the stimuli and movements involved, as it is in showing the results of what has been done and their relation to the end to be gained. The ball player who sees a ball start in a certain direction runs to the exact spot where the ball is to alight, puts out his hands at just the right time, and moves them in just the right way to catch the ball without pain to himself, is not con- TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 269 scious of the exact visual and kinaesthetic sensations he is experiencing and the kinds of movement he is making. His consciousness simply tells him what he is trying to do and whether he is approaching success or not. When learning to catch, he was conscious of some of the sen- sations involved and the kinds of movement to be made, but only of those that were most necessary in modifying his movements so as to be successful. The same truth holds regarding our more conscious ac- tivities of perception in which movement is not so promi- nent. In perceiving objects we are not conscious of the exact sensations that they give us, but only of what they mean in relation to purposes that we are seeking to realize. The same object in different positions and at different dis- tances gives us different sensations, but we are not con- scious of these differences only in so far as some practical need may have made discrimination necessary. The image produced on the retina by a rectangular object varies greatly, but the object seems the same to us. It is also true that we may judge with a good deal of accuracy the distance of an object from us and yet be entirely uncon- scious of the sensations that are the basis of that judgment. The amount of retinal surface affected, the movements of accommodation, fixation, and the fusion of the two images, as well as variations in brightness and in relation to other stimulating objects, influence our judgments, as is shown by varying the stimulations and movements; but we are not conscious of the exact sensations involved and of the precise nature of the change that has been produced, but only of the significance of the results of all of these. 270 GENETIC PSYCHOLOGY REPRESENTATIVE INTELLIGENCE Imagination and memory are characteristic manifesta- tions of representative intelligence. Unlike sensory motor intelligence, this form is not concerned with present stimulations, but functions by means of stored up impres- sions received at other times and places. In sensory motor intelligence there is more or less immediate movement so as to properly adjust the body to external stimulations. In representative intelligence there may be no motion made, or if there is, it may be directed in accordance with past impressions rather than according to the stimulations be- ing received at the time. The apparatus concerned in representative intelligence, if not wholly different from that concerned in sensory motor intelligence, at least functions in a different way, so that the result is the same as if the apparatus were wholly different. The apparatus of sensory motor intelligence is modified by experience so that the next time the same external stimuli are received the reaction is different be- cause of the change in the mechanism. For example, a child sees its mother sweeping without making any response at the time, but the next day it may go through the motions of sweeping. Thus the representative apparatus serves as a means of disconnecting sensory activity from motor activity. When the sensory apparatus is stimulated, the motor apparatus is usually called into play ; but where there is a representative apparatus, the impulses originated may pass almost wholly to the representative center and produce modifications in that apparatus with little or no activity of the motor centers. At some future time this activity TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 271 of the representative center may be re-excited and impulses sent to the motor center, ])roducing movements which might have occurred in the original experience had there been no representative center to divert the impulse and disconnect the sensory stimulus and the motor response. The possession of representative intelligence makes it possible, not only for movements to be directed by past experiences instead of by present stimulations, but it makes economy of movement possible, images taking the place of actual movement. In trying to open a fastening, an animal or a child manipulates it in various ways, until, by chance, the right movement is made; while an adult may look at it, note what holds it, and represent the effect of moving any part of it, and then make just the one move- ment necessary to undo the fastening. A small child, in putting boxes of different sizes one within another, pushes them together in various ways until they happen to be properly turned and one goes inside of the other. In piling up blocks he also tries various blocks for a given ])lace. An older child will look at the boxes and see how they must be turned in order that one may go inside of the other, without making the various trial movements ; and in using blocks he looks at the various blocks before him and, without picking up each one and trying it, selects the right one to fill the place. If there is none before him that will fit, he may go into another room and get a block which he remembers to have left there and put it in place. Lindley, in his experiments with a puzzle, the lines of which were traced without raising the pencil, found that children began at once to draw lines, while older people represented the result of drawing lines from various points and sometimes 272 GENETIC PSYCHOLOGY drew only after they had solved the puzzle by means of mental images or concepts. Representative intelligence is not only a means of direct- ing movements without present stimulation and of econ- omizing movements, both of which are of considerable value in the struggle for existence, but it also serves as a means of satisfying psychical needs. When this form of intelligence has developed, pleasure and pain not only have a biologi- cal value in promoting activity that is favorable to self- preservation, but they have a psychical value, ministering to the mental needs of the individual. Representation of past experiences makes it possible to experience again the pleasure and pain that formerly accompanied them. These feelings are often heightened by contrast between the present and former situation. In thus reproducing past experience a pleasurable outcome may be emphasized and the painful experience leading to it utilized for contrast, so the memories of painful experiences may sometimes be enjoyed in retrospect. It is also possible to select from past experiences pleas- urable elements, and combine them in our daydreams and in our ambitious plannings into representations of a possible future. In man it is certainly true that the pleas- ures of reminiscence and of imagination are, in the sum total, greater than the pleasure of actual sensory experience. ^Esthetic pleasure also depends largely upon representative activity. It is impossible for animals, none of which have repre- sentative intelligence developed to any considerable extent, to experience the pleasures of reminiscence or dreams of the future. Their pleasures must be derived from sen- TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 273 sory stimulations and anticipatory or perceptual images immediately excited by such stimulation. This is all that is required for the biological ends of self-preservation in animals, but man's psychical welfare demands more. The practical value to man of representative intelligence is shown not only in directing and economizing movements in the usual situations, but also in learning to meet new ones. Without this form of intelligence, little or nothing can be learned except by actual, performance by the in- dividual, resulting more or less accidentally in success. A creature possessing representative intelligence can learn by observing the actions of others, or, in other words, by imitation. It is possible thus to gain images by which movements may be directed without the more direct sen- sory experience of making the movement. This is of great help, not only in eliminating useless, trial movements in learning any given mode of reaction, but it is a short cut to developing the representative apparatus so that it may, under various circumstances, effectively direct movements in new situations involving some of the same elements. The possibilities of representative intelligence are very much increased by the fact that impressions may be as- sociated with sensory symbols which will serve to arouse representative activity in the same way as do sensory experiences of the objects and movements themselves. There is almost no limit to the possibility of arousing the representative a])paratus to activity in any desired way by means of symbols, especially visual and auditory words. It is possible for a creature possessing representative intelligence to thus learn from the experiences of others without himself observing those experiences. Knowledge 274 GENETIC PSYCHOLOGY of favorable or unfavorable conditions and modes of effec- tively securing or avoiding each, may thus be gained without actually going through the experience and even without seeing another go through it. Representative intelligence therefore has great biological value as well as psychical value to a social creature such as man. Animals may receive warning of danger by seeing or hearing com- panions trying to escape, but man may get a very definite idea of a danger and of how to avoid it by means of oral or written words. The difference between man and even the highest ani- mals is very clearly evident when we review what may be done by a creature possessing representative intelligence and observe to how slight an extent do animals show evi- dence of any such form of activity. Even the very simplest form of representative intelligence, that of learning by the experience of another, is, as we have already seen, not shown in the imitation of new acts by animals observed under experimental conditions. The common experience of persons familiar with animals will also verify this statement, that one animal rarely learns by the experience of another. If one horse, dog, or cat does something and is punished in the presence of a companion, he alone, and not the com- panion who saw the act performed, learns to avoid that act. In the lower races of man and in the lower types of individuals among civilized men, deficiency in representa- tive intelligence is shown especially in the lack of provision for the future, even though the necessity of such provision would seem to have been taught by previous painful ex- perience. Present experiences largely dominate the activ- ity, and reminiscences of the remote past and anticipations for the distant future have little influence upon conduct. TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 275 In lower grades of idiocy there is such a comj)lete ab- sence of representative intelligence that learning is wholly by the trial and success method. Such an individual may try again and again to put a large object in a small hole or a hole of a different shape. In an individual of a little higher type the lowest form of representative intelligence may be shown in a high degree of ability to imitate sounds and movements of others. In such cases, however, the imitations are usually made immediately upon the percep- tion of the act. They do not result in the power to perform the act when it is not being observed or, if they do, it is performed literally and without variation to meet new situations, and without selection of parts of the act and their combination into new and complex forms of action. CONCEPTUAL INTELLIGENCE This form of intelligence includes what is usually described in psychology as thinking processes, such as abstraction, generalization, conception, judgment, and reasoning. Like representative intelligence, it functions by means of past experiences instead of present stimula- tions. It is further removed from sensory motor activity than are representative processes. It involves a finer analysis of situations and a separation of elements, not only from many particular situations, but from any com- bination in which they have been experienced. It involves a re-grouping of elements, not as they are found grouped in objects and situations, but according to similarities and in relations by which purposes may be served. The apparatus concerned in conceptual activity is, in 276 GENETIC PSYCHOLOGY part at least, different from that concerned in representa- tive activity ; but it is primarily excited to action by impulses from the representative centers. The conceptual appara- tus is capable of more fmely differentiated activity and of very much greater capacity for rapid and various adjust- ments, and exercises a much greater influence in directing and unifying other activities. The final motor reaction to a situation may be objec- tively the same w^hen determined by conceptual intelligence as virhen directed by representative or perceptual intelli- gence. For example, in jumping from a moving car an animal or a person may respond to the sensory stimuli involved in the situation in accordance with many ex- periences of jumping from cars with more or less favorable results. A person without much experience of this kind may direct his movements in accordance with a mental image of the movements he has seen made by other persons under similar circumstances, while a person who had never had any experience in alighting from a moving ob- ject, and had never seen any other person perform the act, might direct his movements in accordance with his general knowledge of the laws governing moving bodies so as to jump in the same direction that the car is moving, just as did the others. The ideas of force, direction, gravity, etc., used by the one who directs his activity by conceptual intelligence have been derived from sensory and represen- tative experiences, but they are entirely free from connec- tion not only with any particular kind of situation but from any object or place. In performing an act like that described above, concep- tual intelligence is likely to be less successful than either TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 277 representative or sensory motor, yet it is capable of serving practical purposes in entirely new situations, while sensory motor intelligence is elTective only where the individual has himself had a great deal of experience of just that kind, and while representative intelligence would be of little value if the individual had not himself had similar experiences or had not had the opportunity to observe how others meet such a situation. The less the accomplishment of an end involves the direct placing of materials by one's own movements, the less effective his sensory motor intelligence and the more effective the conceptual intelligence, while representative intelligence is intermediate between the two. If a way is to be found across a stream, a creature possessing per- ceptive intelligence only will run up and down the stream, going out on points, stones, or logs, and may thus acci- dentally find a means of getting across. A person pos- sessing representative intelligence, without necessarily going to the various projecting points, would look to see if there were any passage across. If there were not, he might, without going to them, look to see if there were any boards or logs that could be placed across projecting points and stones in such a way as to make a bridge, or he might remember that there was such material to be ob- tained, and judge of its fitness by comparing his mental image of it with the spaces to be bridged. An engineer, on the other hand, directing his activities by conceptual intelligence, might, by the use of his transit and mathemati- cal calculations, determine the distance to be bridged, and kind and dimensions of materials needed to construct a bridge that would sustain itself and the person or vehicles 278 GENETIC PSYCHOLOGY that would pass over it, and send an order to the city for the materials and workmen. He could do this without definitely imaging the materials needed and the movements involved in placing them. The symbols used by him take the place of objects, and in his consciousness concepts may wholly take the place of images. If a fire breaks out in a city, a creature possessing sen- sory motor intelligence acts only when his senses are directly affected by the fire or the actions of compan- ions, while one possessing representative intelligence may respond to the cry of fire without directly perceiving it, perhaps by sitting still and picturing in detail the flames, curling smoke, falling buildings, the rushing crowd, etc. ; while one dominated by conceptual intelligence may note the number of the fire signal, think of the direction of the wind, and without any detailed imaging, know at once that the building that he is in is threatened and then take the proper means to secure his safety. He can thus grasp the essentials of the situation and begin making the proper reactions to a danger that he has neither directly per- ceived nor definitely imaged. He could perhaps image the details, but under the circumstances it would be a waste of time and energy to do so. In dealing with abstractions images may be a hindrance, e.g. in geometrical reasoning figures are conceived without color, weight, taste, etc., and reasoning is then made much simpler and more ac- curate. Many people engaged a great deal in mathemati- cal and other forms of abstract reasoning often lose the habit and sometimes the power of imaging. Conceptual activity therefore plays the same part in making images unnecessary that representative activity plays in avoiding useless movements. TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 279 Conceptual intelligence not only makes it possible to accomplish some purposes more quickly and effectively than by sensory motor or representative intelligence, and to meet new situations which could not be reacted to effec- tively by any other form of intellectual process, but it enables one to go beyond what can be experienced or even represented. It is possible to perceive or to represent two, three, five, ten, or a hundred objects, especially if they are properly grouped. It would not be possible either to perceive or to represent a million objects as a million, though it would be possible, by spending a number of days, to perceive or represent a series of objects amount- ing in number to a million. One can, however, in a mo- ment form an accurate conception of a million and almost as easily of a million million. To conceive of an object as a million times as large as the largest object that has ever been seen or one millionth the size of the smallest object that has ever been observed, is not difficult, but to represent such objects is utterly impossible. We cannot represent space as having more than three dimensions, but the mathematician readily conceives such a space and has determined the mathematical laws of its relations with as much certainty as those of a space of three dimen- sions. The fact that conceptual intelligence can deal with relation regardless of things gives it this power. As already noted, auditory and visual symbols are of great advantage to representative intelligence, helping to free elements from particular situations, and making it possible for an individual to profit by the experiences of others through the medium of words. The part played by symbols in conceptual processes is even more impor- 28o GENETIC PSYCHOLOGY tant. Without words, there could be very little conceptual activity, and some persons think there could be none. Words may be introduced into any situation, and any element or relation of elements that has received attention may be associated with a word, which then serves to present it to consciousness in the absence of that situation. Elements of various situations that have become freed from their associates by means of words may be combined in any desired way and the combination associated with and. held together by means of a word. Words thus serve to organize the elements of experience, and it becomes possible for the concept thus formed to function inde- pendently of any particular situation and obviates the necessity of forming images of the elements from which the concept was formed. Without words, by means of which elements may be more completely isolated from their associates and any combination of elements held together and organized, the development of concepts would be almost if not quite impossible. The possibilities of the human brain as a mechanism of intelligence are still further increased by grouping a large number of ideas that for certain purposes may be considered as alike, and letting some symbol stand for that group of ideas which may then be treated just as if it were a single idea. A single word thus takes the place of a large number of images. The thought of a sentence held in mind by a single word may take the place of the whole sentence. In a similar way the thoughts of a para- graph, of a chapter, of a book, or even of entire departments of science may be held in mind by means of a title or name and may be considered for certain purposes as a unit to TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 281 be compared with other paragraphs, chapters, books, or departments of science. By means of this power of se- lecting and grouping, the mind is enabled in a few seconds to deal with the most complex situations with much greater accuracy than would be possible by means of hours or pcrhajjs months of sensory motor and representa- tive activity. The architect and the engineer may thus, in a few days, plan in detail structures that will require months of sensory motor and representative activity of an army of men to execute. THE FOUR TYPES OF INTELLIGENCE IN MAN In man we find all four types of intelligence manifested. He possesses physiological intelligence in a high degree. He can live in every variety of climate, and can adapt himself to sudden changes and endure fatigue as well, if not better, than any other animal. In sensory motor intelligence, also, man is not inferior to the most gifted of the animals, although some of them surpass him in special forms of accurate movement and in discriminative ability, yet in general he is capable of acquiring variety and pre- cision of movement and discrimination not surpassed by any. As to representative and conceptual intelligence, even the highest animals show little of the former and none of the latter. Individual human beings are endowed with these various forms of intelligence in greatly dilTering degrees. Those who are favored with a high degree of physiological in- telligence have the strength, energy, and endurance for 282 GENETIC PSYCHOLOGY accomplishing many and difficult tasks. All the vital organs, the heart, lungs, and digestive system, are perfectly de\eloped, capable of sustained and harmonious activity, susceptible to adaptive changes and capable of retaining permanently, acquired modifications. The one thus endowed by heredity and by normal healthful growth and development has an admirable foundation for success in physical and mental activities. Unless thus endowed one cannot reach the highest degree of success, yet the mere possession of such a physiological endowment does not insure efficiency in other forms of intelligence. One endowed with exceptionally perfect sensory motor apparatus, accurately adjusted, is capable of responding to immediate sensory stimulation with extraordinary rapidity and accuracy. Such a one may execute with the greatest ease and accuracy the most difficult forms of re- sponsive and constructive activity. The athlete, the skilled artisan, artist, and singer are thus highly endowed with sensory motor apparatus that makes it possible for them to do with ease what would be utterly impossible, even after long practice, to others with less perfect sensory motor apparatus of the kind needed ; e.g. the construction of the throat makes the sounding of high notes easy to one and utterly impossible to others. On the other hand, deficiency in the sensory motor apparatus does not necessarily mean deficiency in the other forms of intelligence. Persons of health and vigor may be clumsy and slow in their sensory motor reactions, and those with deficient sense organs or with imperfect muscular development may possess an unusual degree of representative or conceptual intelligence. Even the entire TYPES OF ADAPTIVE ACTIVITY OR INTELLIGENCE 283 absence of some of the special senses is no absolute bar to the working of the representative and thinking intelligence. If there is sufficient external stimulation to start the de- velopment of the representative and concei)tual centers of the cortex, they may continue their activity and develop- ment independently. This is shown in a striking way in the education and development of Laura Bridgman and Helen Keller, the latter of whom, though deprived of the two senses most used by human beings, has attained a development of representative and conceptual intelligence far superior to that of the average human being. One who is highly endowed with vigorous representative centers is capable of imaging with great vividness and of reproducing past experiences after either long or short periods of time with great accuracy. There are individuals who are capable of producing such clear images, as, for instance, that of the printed page, that they can examine its parts with almost as much ease as is possible in ordinary sense perception. There have also been persons who could read a book through once, and then repeat it word for word. Other individuals possess extraordinary fa- cility in producing and combining in all sorts of ways images of various kinds, as is perhaps best shown in imaginative literature, but it is also shown in many practical and scien- tific inventions. Conceptual intelligence, which depends upon the pos- session and effective working of the conceptual centers, may be possessed in a very high degree by persons who are not especially endowed with the other forms of intel- ligence, and even in cases where they are deficient in physiological, sensory motor and imaginative acti\'ity. A 284 GENETIC PSYCHOLOGY good philosopher may have little physical endurance, slight sensory motor skill and little or no power of imagina- tion, and yet he may reason correctly regarding all forms of activity. When, however, the physiological intelligence fails to keep the conceptual apparatus in good working order, there is immediate decrease in conceptual intelligence. It is safe to say that the great men of the world have usually been highly endowed with all forms of intelligence. They have been able to produce and expend in the most economical way a large amount of muscular and nervous energy, have possessed strength and skill, and have been able to direct their imaging and thinking effectively, not only because they possessed all types of intelligence, but because these types were harmoniously combined. REFERENCES BooDiN, John E. Mind as Instinct, Psych. Rev., Vol. XIII, pp. 121-139. *BoLTON, T. L. A Genetic Study of Make-believe, Jr. Phil. Psych. b'Sci. Meth., Vol. V, pp. 281-288. ♦BtTRROUGHS, John. The Reasonable but Unreasoning Animals, Otitlook, Vol. 85, pp. 809-815. Burke, F. From Fundamentals to Accessory in the Development of the Nervous System and of Movements, Ped. Sent., Vol. VI, pp. 5-64. BuRNHAM, W. H. The Hygiene and Psychology of Spelling, Ped. Sent., Vol. XIII, pp. 474-501. Brown, H. W. Some Records of Thoughts and Reasonings of Children, Ped. Sent., Vol. II, pp. 356-396. *Dawson. Levels of Development, Jr. Ped., Vol. XVIII, pp. 9-24. Dewey, John. The Reflex Arc Concepts in Psychology, Psych. Rev., Vol. Ill, pp. 357-370- TYPES OF ADAPTIVE ACTIVITY OR INTELLKiENCE 285 ♦HoBHOUSE, L. T. Mind in Evolution, Chapters V, XI, XII, XIII. Mitchell. Mathematical Prodigies, Am. Jr. Psych., Vol. XVII, pp. 61-143. Morgan, C. L. Comparative Psychology, Chapters X, XIII, XIV, XV, XVI. PiLLSBURY. The Psychology of Attention, Chapters VII, X, XIV, XV. RiBOT, Th. Creative Imagination, Open Court, 1899, p. 231. Rowland, E. H. The Psychological Experience connected with the Different Parts of Speech, Psych. Rev., Monograph Supp., No. 32, 1907. Scripture. Arithmetical Prodigies, Am. Jr. Psych., Vol. IX, pp. 1-59- *Shepardson, E. a Preliminary Critique of the Doctrine of Funda- mental and Accessory Movements, Ped. Sem., Vol. XIV, pp. 101-116. Thorndike, E. L. Educational Psychology, Chapter IV. *Wasmann, E. Instinct and Intelligence. Psychology of Ants and of Higher Animals. Winch, W. H. The Function of Images, Jr. Phil. Psych. &= Sci. Meth., Vol. V, pp. 337-352- CHAPTER X TYPES OF LEARNING ACTIVITY NATURE OF LEARNING In correspondence with the broader meaning of intelli- gence adopted in the preceding chapter, the idea of what is meant by learning must be enlarged. Each organism and each organ has characteristic modes of functioning, and any change produced by experience in the usual mode of functioning, whether it be in an amoeba or in man, in a vital organ like the heart, or in an organ of consciousness such as the cortex, is, in the broader meaning of the word, an instance of learning. In this broader sense the stomach learns to digest certain kinds of food and the lungs to function in a certain kind of air, as truly as the conceptual centers learn to deal with the truths of a special science. The chief difference in the different types of learning is that in some cases activities already organized are modified by experience, while in others the activities are organized by experience. The organization of the physiological apparatus and, to a considerable extent, of the sensory motor apparatus is nearly complete at an early age in animals and children, largely as the result of inherited growth tendencies, while the activities of the representa- tive and conceptual centers are for a long period being organized chiefly by experience. For this reason physio- logical learning and sensory motor learning are largely a 286 TYPES OF LEARNING ACTIVITY 287 matter of perfecting the existing organization of activities, and then later of modifying the activities of parts and their relations to each other, while representative and conceptual learning consist mainly of acquiring new forms of organized activity. In the lower animals learning consists chiefly of modification of apparatus already organized, but in the higher there is much more organization of new activities. In a broad way all learning is the result of activity in response to the particular environment in which the crea- ture lives. It is brought about by variations in the kind, relative strength, and order of stimuli exciting activity. In the case of the various organs of the body the learn- ing is frequently not in direct response to a stimulating environment, but is produced indirectly by the modified activity of some other organ or organs. The stomach functions somewhat differently when one uses his brain a great deal than it does when he is engaged in hard man- ual labor; the muscles of one arm are modified by the exercise of the other, and the development of conceptual and sensory centers is closely correlated with the develop- ment of the representative centers. Since the general character of all activities is somewhat different in different stages of development, the modifica- tion produced by a certain kind of stimulus will not be the same at one stage as at another. Foods and modes of treatment favorable to the physical and mental develop- ment in one stage of growth may be very harmful in a different stage, hence an effective mode of learning in one stage of development may be very ineffective when a differ- ent stage has been reached. 288 GENETIC PSYCHOLOGY For the purposes of this chapter, learning is used broadly to include haljit formation as well as the more or less consciously directed activities that precede the formation of many habits. THE PHYSIOLOGICAL TYPE OF LEARNING Physiological processes are sufificiently organized at birth to maintain life. The lungs begin to function as soon as the air enters them, and in a similar way appro- priate food is digested and assimilated. These processes are doubtless perfected somewhat by exercise, but physio- logical learning consists chiefly in adaptation of these processes for the good of the organism, according to the kind and amount of food taken and the time of taking it, the climatic influences of heat, light, and moisture, electric conditions, density and purity of air, etc., and according to the kind and amount of exercise given the various or- gans directly and in correlated, activity with other organs. Very important physiological changes are produced by residing in different climates and by engaging in different forms of activity, but physiological intelligence directs and unifies these changes for the good of the organism. People living in different parts of the world and engaged in differ- ent occupations are on the whole surprisingly similar in size, strength, and length of life, although differences in complexion and other minor characteristics are marked. This is one evidence of the extent to which physiological intelligence unifies and adapts changed activities so as to preserve life and health. Other evidence is furnished by cases in which the most harmful drugs, vitiated air, and TYPES OF LEARNING ACTIVITY 289 improper exercise are sometimes taken for a long period of time without destroying life. So great are the gradual modifications sometimes produced that a sudden change to normal food conditions as regards air and exercise may produce sickness and death. Because of this extraordinary power of the physiological activities to become adapted to the conditions to which they are exposed for a long time, it is difficult for physiologists to determine even by careful experiment what kinds of food and exercise arc best for an individual. It is hard to tell whether the seem- ingly favorable or unfavorable results of a change in food and exercise are an indication of their natural suitability or unsuitability, or are merely the result of a change in previous physiological habits. As a result of experience every organ, muscle, and gland, even to the smallest blood vessel, forms habits of acting in a certain way with a certain degree of vigor and perhaps at certain times. Any change in hours of sleeping, eat- ing, or working may therefore produce considerable de- rangement of the physiological processes. Irregular eat- ing and spasmodic activity arc therefore very unfavorable to health, especially in individuals who have been very systematic and regular. Physiological learning involves not only the perfecting and modification of the activities of the vital organs and their relation to each other, but a proj)cr relation of their activities to the activities of other organs, especially to those of the various nerve centers. It is a well-established fact that whenever any portion of the body is active, whether it be a gland, a muscle, or a nerve center, there is increased circulation of blood in that part. Although changes in u 290 GENETIC PSYCHOLOGY circulation take place with considerable rapidity, there is reason to believe that habits of sending blood in increased quantities to certain organs may be established by using those organs at certain times. The greater effectiveness with which the brain works at certain times of the day may therefore be regarded as a result, in part at least, of circulatory habits that have been established. So closely are all activities influenced by physiological habits that expenditure and conservation of energy, sobriety, sensu- ality, cheerfulness, melancholy, physical and mental slow- ness or quickness, are in part the result of the acquisition of certain physiological habits. Since the physiological activities are the earliest to become organized, it follows that physiological habits of a desirable kind need to be formed during the first few years. Proper food and exercise and regularity in taking them are therefore the chief forms of learning to be desired in the early years. If a child of six has good physiological habits so that every organ of his body is in good working condition and in harmonious relation with every other part, it makes little difference, so far as his future intellectual achieve- ments are concerned, what the amount or character of his knowledge may be at that age. The response of the stomach, so that the mere sight or odor of food that has previously made one ill causes nausea, is a result of physiological learning in man, quite compa- rable to the learning of the crab to respond to the placing of a screen that preceded feeding ; while the readiness of the stomach for food at accustomed times is comparable to the sensitiveness of snails and sea anemones to waves at the time of high tide and to the coming of animals for food at TYPES OF LEARNING ACTIVITY 291 certain times. In all such cases the learning is physiologi- cal rather than conscious. SENSORY MOTOR LEARNING Sensory motor learning is chiefly a process of establishing relations between sense and motor organs in the nerve centers of the spinal cord, the basal ganglia, and the sense and motor centers of the cortex. In so far as these con- nections are formed by the processes of growth without much stimulation, they are largely physiological. Reflex and instinctive movements, such as sucking, moving the eyes in a coordinated way, crying, cooing, sitting, creeping, standing, walking, and climbing, are partly provided for by inherited structure and inner laws of growth, but they are perfected more quickly by the ordinary stimuli than they would be if such stimuli were absent. If healthy activity of the nervous and muscular system is maintained, these movements may be made as the result of growth processes without any necessity of actual practice in making them. Special practice hastens the learning of movements, and in the case of human beings some of them, e.g. walking, might, without definite practice, often fail to be acquired. Sensory motor learning is shown most clearly in acquiring reactions to stimuli not usually reacted to by the species and sometimes in learning to make movements unusual for the species. Sometimes botli the stimulus and the form of movement are new, as when a dog learns to walk on his front feet in response to a word. In animals sensory motor learning consists chiefly in developing more highly than is usual for the species, the 292 GENETIC PSYCHOLOGY characteristic reflex and instinctive movements, and in learn- ing to make those movements in response to some new stimulus and in a certain series. Animal trainers always try to find some act which an animal instinctively or re- flexly performs in response to a certain stimulus. They then give him some other stimulus before the usual one, and arrange that the movement shall be followed by pleasurable results. For example, a horse instinctively raises his foot and puts it down when his shin is struck. If the striking of the shin is uniformly preceded by some other stimulus, such as a gesture, a word, or a turn of the eye, he will learn to respond to that stimulus without his leg being touched. Similar associations with other instinctive movements may be made, and then all brought together in such a way as to constitute what seems to the observer a wonderful exhibition of intelligence. Educated horses are thus made to appear to perform complicated mathematical calculations. Their performances are truly wonderful as regards refinement of discrimination of the essential stimulus. In some instances a horse responds to changes in the one directing his per- formance that are unnoticed by human observers and of which the director himself is unconscious. That they must be made, however, is proved by the fact that if the face of the one directing the performance is covered, the horse is unable to perform his tricks. In the extent to which native sensory motor reactions may be developed, the higher animals are nearly if not quite equal to man. The child has many more sensory motor reactions to perfect than most of the animals, since his reflex and in- stinctive movements are usually less perfect at birth than theirs. The child also, because of the peculiarity of his TYPES OF LKARNIXr. ACTI\-ITY 293 motor apparatus, is capable of making a very much greater variety of movements than is possible to any animal. Since every movement is stimulated and guided by sensory impulses, he has the possibility of acquiring an almost infmite number of connections between sense stimulations and movements. If all of these associations had to be ac- (juired by the incidental occurrence of the various stimuli in a certain order so as to form a series or a complex form of activity, he could acquire in the course of a lifetime only a small part of the associations that are acquired by the child of three years. If he were taught the combinations wholly by the same methods used in training animals, he would still be unable to acquire more than a small part of the sensory motor connections that are usually acquired by educated children. Fortunately another means of sensory motor learning is opened to the child. We do not in every case have to start with some simple reaction and build on to that, as in case of animals, but, thanks to his imitative ten- dency, the child may acquire new combinations of sense im- pressions and movements in certain relations to each other without having to hit upon the right combination by chance movements of his own. As has already been jjointcd out,^ the realization of the instinctive tendencies of the child depends upon certain anatomical and physiological con- nections between the various sense and motor centers of the cortex. When a child hears a sound, the path from the auditory center for that sound is more open toward the motor center concerned in producing the same sound than in any other direction. A similar truth holds regarding centers concerned in the visual perception of movement and the motor centers concerned in executing the'^ame movement. 294 GENETIC PSYCHOLOGY There is therefore an inherited basis for the organizations that seem to be produced by experience. By the help of the imitative tendency the child is soon able to acquire all the complicated movements involved in learning to dress him- self, in manipulating objects in countless ways, and in handling a variety of tools for various purposes. Learning to speak, so far as the making of the movements is concerned, is also largely a sensory motor process. A child of two who has learned to utter five hundred words has in that process alone probably acquired a greater number of sensory motor connections than is usually acquired by any of the higher animals in all forms of their activity during a lifetime. Only a very few of the animals have a sensory motor apparatus that is capable of producing the sounds involved in the pronunciation of words. It is largely because of the great variety of movement possible to the child owing to the structure of his vocal apparatus, and of his arm and hand , and because of the nervous organizat ion that permits him to learn, by means of imitation, that the sensory motor acquisitions of the child are so infinitely superior in number and variety to those of any of the animals, though in inherited organization of sensory motor appara- tus they often far surpass him. The chief mode of establishing sensory motor connec- tions is by means of repetition with favorable results. The more uniform the repetition, the more surely and quickly will an association and a series of reactions be established as a habit. In so far, therefore, as any activity is to be performed in a sensory motor way it is desirable that in learning it the method of unvarying repetition should be followed. This is one of the chief maxims of animal TYPES OF LEARNING ACTIVITY 295 trainers. Its importance is well illustrated by the incident given by Bostock of a trainer who lost control of his animals and nearly lost his life because at a critical stage in the performance of a trick by his animals, he turned to the left instead of to the right, as he had previously done when that trick was being performed. The importance of proper development and organization of sensory motor activity cannot be overestimated. This may well be illustrated by the connections between visual impressions that are perfected by experience and used during every waking moment. A moving object stimulates the periphery of the eye, and at once the head and eyes are turned so that the points of clearest vision are stimulated. In learning to read the movement of the eyes along the line and back to the beginning of the next line is a sensory motor process of considerable difficulty that must be ac- quired and perfected. A little reflection will show one how delicately accurate the movements of the eyes must be to follow the lines of ordinary print successfully. He will then perhaps agree that the more rapid learning to read by children of the present day is due as much to wider spaced printing in the readers as to better methods of teaching. In touching objects and moving them in any desired way and in making the proper movements to intercept a moving object, the most accurate adjustment of sensation and move- ment is required. Not until such sensory motor reflexes are well established can there be any considerable develop- ment of manual ability in the daily movements of walking, dressing, etc., and in any form of skill involved in work or in plays and sj)orts. If one attemj:)ts to guide his hand in tracing lines which are seen in a mirror onlv, he will 296 GENETIC PSYCHOLOGY realize how important it is that the relatively simple sensory motor reactions shall be well developed. The more complex perceptual activity that must be acquired is suggested by the following : children often confuse such words as "saw" and "was," "on" and "no," probably because in all their previous experience in gaining free ideas, objects, e.g. chairs, are of the same class when their parts are the same no matter how they are turned or from which side they are viewed, although their appearance varies greatly. This tendency is doubtless carried over into the perception of symbols, and errors are made because of ignoring differences con- sisting only of variations in arrangement of letters or digits. The writer distinctly remembers when about nine years old noticing for the first time that a number on a calendar was not the same when read backward. The simple sensory motor reactions are not only neces- sary to success in movements of all kinds, but also to accu- rate perception. This is most easily demonstrated in illusions. For example, a large object is lifted with more vigor than a small one of the same weight, resembling it except in size, and this is one reason why the weight of the smaller object is usually perceived as much greater than that of the similar large object. Many other illusions, especially of size and shape, are caused by the character of the sensory motor reaction involved in the perception, e.g. line a < > seems shorter than line b > < because the eye tends to stop sooner when following line a. It is probable that the development of perceptive power is in general very largely dependent upon the perfecting of sensory motor reactions. The play of the child by means of which the TYPES OF LEARNING ACTIVITY 297 simple sensory motor reactions arc perfected and organized in various ways is therefore one of the most important parts of his education. As we shall see later, this form of learn- ing in its more complex aspects plays an important part in the higher intellectual acquisitions of man, especially in dealing with the symbols of images and concepts. We have already given evidence that the learning of animals is largely sensory motor, since their learning is confined almost wholly to what is associated with their own movements. We therefore have an extensive iield of learning that is common to men and animals, while into another extensive field man only can enter. REPRESENTATIVE LEARNING In physiological terms representative learning involves the acquisition of tendencies on the part of the representa- tive centers in the cortex to function in certain organized ways independently of sensory stimulation. In psychical terms it involves the formation of free images of objects, movements, and symbols independently of their associates. Independent action of representative centers and the formation of free images is brought about by a method exactly the reverse of that most successful in sensory motor learning. Instead of having the sensory motor ex- perience repeated in exactly the same way with the same accompaniments, the representative centers need to be excited by sensory stimulations varying in kind, order, and relation. A square or a triangle in unvarying surroundings may serve as a sensory guide to a pigeon or other animal seeking to find its way through a maze or to food, without 298 GENETIC PSYCHOLOGY the animal having any distinct idea of the figure itself separate from its surroundings and the end to be attained. Usually animals have few experiences with squares in different surroundings or as means to different ends. They are not able, therefore, to form a separate image of the figure. The child, on the other hand, has many objects of interest to him that are square, and he has much experience in manipulating such objects and using them for various purposes. His attention is thus attracted to the character- istics of the figure in the midst of various surroundings and in the attainment of a variety of ends. He therefore soon comes to have a free image of the square. In most adults, images of geometrical figures are for this reason freer than images of other objects. This is shown by the fact that in listening to a description, the statement that a rectangle is red and is resting on its shorter side, causes no such shock of surprise or reconstruction of the mental picture as would the statement that a house previously named was blue and standing with its chimney downward. For a similar reason a mountain from a new point of view is like a new mountain. Representative learning is greatly aided by imitation. The same act is observed and repeated under various surroundings. This is especially true when the child imitates what he has seen at some other time or place. Such imitation is often of the dramatic form where objects present are used to represent other objects not present and where the movements are partially carried out in imagina- tion instead of being actually executed. The variety in the combinations of objects and acts that are experienced in imitative activities greatly hastens the formation of free TYPES OF LEARNING ACTIVITY 299 images of them. After images are partially developed, internal repetition of experiences without motor imitation hastens and perfects the process. Words are also a very great help in representative learn- ing. The same sound being used to designate an object under various circumstances makes it possible for the object to be represented when the word is heard and the object not present. In this case the representative center is excited to activity, not by the sensory stimulus of the object itself, but by another form of sensory stimulus associated with the object and given in entirely different surroundings. Words are among the most effective means of producing action of the representative centers without direct sensory stimulation, because the excitations of the center arc likely to be in new surroundings and in the absence of the original object. The first steps in forming free images are taken by children in their manipulation of objects. Manipulation of objects makes possible immediate imitation of acts as seen, and this prepares the way for delayed imitation of them under other surroundings. Following this may come association with word symbols and imaginative changes in surroundings, characteristics, and relations. In the child's manipulation of objects in a variety of ways, in his imitation of all kinds of acts, and in his dramatic play and imaging, he is organizing his representative apparatus in such a way that the elements of all his past experiences may be called into play and used in indirectly acquiring and interpreting the experience of others as expressed in words, oral and written. The apparently useless and some- times amusing, absurd, or troublesome behavior of children 300 GENETIC PSYCHOLOGY is in reality often a most important form of the learning process. After a number of free images have been formed and as- sociated with the appropriate words, a means of learning is open to the child that is not possible to any animal. Words spoken in a certain order produce a corresponding grouping of free images, and in this way new internal experiences entirely independent of present surroundings may be gained. In so far as the child has free images of the elements of all human experiences and of the fundamental elements of the external world, he can, through the medium of words, in- ternally experience what has been experienced by any person in any portion of the world in any period of its history. His learning is no longer limited by time and place, but he is introduced into an environment un- bounded in the possibilities it gives for representative learning. These facts are especially well illustrated in the study of geography and history. Animals, on the other hand, have no such means of learn- ing. It is true that they can learn to respond, in a sensory motor way, to words that may be associated with a definite movement to be made. Words are most effective to them when spoken in the same tone and under the same circum- stances, yet some of the more intelligent animals may learn to respond to the word itself under various circumstances. In no case, however, is there a record of an animal being given new knowledge by means of words. He is taught words, but words cannot be used to teach him anything new, because he has no independent action of representative centers by which the objects and experiences signified by the words may be separately represented and formed into new combinations of internal experiences. TYPES OF LEARNING ACTIVITY 301 A child may learn words even in a sensory motor way more readily than animals, because he has a vocal apparatus that enables him to respond to all words by their utterance, whether he can give any other form of motor response or not. Very young children easily learn meaningless jingles and rhymes. Children a little older readily learn long selections that they hear repeated frequently, without necessarily knowing their meaning. It is also true that children when being taught to read may seem to know a word, but fail to recognize it when it appears in a different place or surrounded by different words. A long word may be correctly distinguished from the short words with which it is learned and then be named correctly. In order that free images of visual words may be formed, it is necessary that they should be observed with a variety of associates. The same principle holds in acquiring free images of either visual or auditory symbols and in acquiring the symbolic statements of the facts of number, A child that does not know the significance of three may learn in a sensory motor way a large section of the multiplication table. In general, practice in immediate response to a series of sensory stimulations by a series of movements with little or no variation in the repetition results in sensory motor learning only, while the repetition of a stimulation under varying circumstances with different interests and move- ments results in representative learning or the formation of free images. After many free images have been formed, representative learning proceeds most rapidly and effec- tively when the images are revived and combined by means of words instead of having the original sensory 302 GENETIC PSYCHOLOGY experience repeated. In learning the essential charac- teristics of an object or class of objects, more rapid progress is made by naming the characteristics and re- peating them when the object is absent than by repeated observations without any naming of characteristics. CONCEPTUAL LEARNING Learning to think is a process of organizing conceptual centers and getting them to function independently of sense and representative centers that are excited by objects, and in association with those centers that are concerned in the production of percepts and images of words and other symbols. The organizing process is similar to that in representative learning, images serving as stimuli to the conceptual centers in much the same way as sensations stimulate the representative centers. The process of organizing the conceptual apparatus is also similar to that involved in organizing the perceptual. The conceptual apparatus is not, however, organized pre- vious to experience as is in part the perceptual in some lines, and much more freedom of adjustment is needed in con- ceptual activity. Free images instead of sensations serve as stimuli for the organization of conceptual centers, while ends to be gained determine the adjustments, and words help to emphasize these adjustments and provide for their more accurate repetition. In perceptual organization an object arousing directly one kind of sensation comes to stimulate indirectly other sense centers which it has at an- other time stimulated directly, while in conceptual activi""" a word or an image of a characteristic found in many sitUt.- TYPES OF LEARNING ACTIVITY 303 tions produces an adjustment of representative apparatus corresponding to the word, and there may be much or little separate activity of the representative centers thus ad- justed, according as the mental process is chiefly imagina- tive or conceptual; e.g. a person of the imaginative type may image size, color, shaj)c, and position of houses, trees, etc., when the words are heard, while another may think only of their meaning without definite imagery of objects or sensory characteristics. The method by which conceptual centers (or more properly conceptual adjustments) are most quickly devel- oped, is much the same as that by wdiich representative centers learn to function independently. The images serv- ing as stimuli to the conceptual centers must be varied as much as possible. In connection with this variation there must be the distinctive selective process of attention and facility in making and maintaining adjustments, so that cognition of relations is possible. In the selection of common characteristics, purpose is an important factor in determining what are the essential characteristics of various objects used in reaching the desired ends, or, in other words, in making and maintaining a general type of adjustment. A child that has fre- quently seen cubes in various situations may form free images of them, but in order that concepts may be derived from his experience with blocks and other objects, certain characteristics must be made objects of special attention. If the child has been using these objects for constructive purposes in connection with those of another form, his attention is likely to be directed toward their shape, and h begins to have a concept of form as a characteristic of 304 GENETIC PSYCHOLOGY objects. If the blocks have varied greatly in size, and those of one size have proved better fitted for certain purposes than those of another size, attention selects the character- istic of size, and the concept of size begins to develop. If the child is making a design of several colors in which he has to choose the block to use on the basis of color, his attention will be directed to the characteristics of red, green, etc. If he should have occasion to handle blocks of different weight, his attention would be called to that characteristic. In deriving such concepts as those of form, size, color, and weight simpler ideas are first formed. The child develops the idea of a square, triangle, rectangle, etc., and the meaning of such adjectives as square, before he gains the more completely abstract concept of form. Ideas of objects as large or small for various purposes, and for vari- ous classes of objects, are formed before there is the com- pletely abstract idea of size. Children sometimes have difficulty in understanding why a large object of one class, as, for example, a dog, should be called large when a much larger object of another class, as a horse, is called small. A child also forms ideas of red, green, blue, etc., before he forms the more abstract concept of color. Concepts of heavy and light also precede the more abstract one of weight. In the formation of all such concepts, after a number of free images have been gained, it is no longer necessary to actually or completely represent all of these images. A concept often involves a tendency to form, and a conscious- ness of the possihility of forming specific images of objects of various forms, sizes, colors, weights, etc., but it may TYPES OF LEARNING ACTIVITY 305 function with little or no actual imaging. In this way the possibility of forming distinct images, which is an essential element in the concept, takes the place of their actual formation, just as images take the place of actual move- ments. The formation of one concept prepares the way for the for- mation of another, and even the concei)t which has scarcely begun to form may help in the development of another that has given it birth ; for example, a child who distinguishes between triangles and squares does so in part because of the difference in the number of sides, and when the idea of form is fully developed, the idea of number will be an essen- tial part of the idea. It is unquestionably true, however, that children learn to distinguish triangles from squares long before they can count and before there is any other evidence that they are conscious of number differences as such. The concept of number will not be formed until the number characteristic is singled out because of some practical need or interest leading to conscious attention to number relations. The formation of every concept gives experiences that are helpful in the formation of other concepts as well as necessary to the perfect development of the concept in question, but the experiences that may serve as the basis of concepts do not actually become such basis until they have been selected by conscious attention from the complex in which they appear. This is one reason why the logical method of teaching a subject is not the psychological method and does not work well especially with young children. To a logical adult mind it seems just as impossible that any sort of a concej^t of a triangle can be developed witliout the concept of num- 3o6 GENETIC PSYCHOLOGY bcr being first formed, as it formerly seemed to teachers that it would be utterly impossible to learn words without first learning the letters of which words are composed. It may be stated as a general rule that early concepts are not formed by combining concepts already existing, but that they emerge under the stimulus of interest, purpose, and contrast from a complex that is as yet unknown spe- cifically. This is the reason why teachers are beginning to realize that the more logical the method of presenting a subject to an adult mind, the less it is suited to a young child. The help that concepts already formed render to others is well illustrated in the process of acquiring concepts of the meaning of words not associated with concrete expe- riences. If one knows the meaning of a few words of a sentence that he hears or sees, he can often form a pretty good idea of the thought of the whole sentence, and after hearing the unfamiliar words used in a variety of sentences, he comes to have a fairly clear concept of their meaning. If a wrong meaning is attached to the essential word in a sentence, incorrect concepts of words associated with it may of course be formed. When new words are definitely explained by means of known words, we have examples of the slightly different process of forming concepts by com- bining concepts already existing. In reading understanding^ there is a unifying process in which the concepts suggested by every word are related to and modified by other words, especially those immedi- ately preceding and following. A series of words produces some anticipation of the words that are to come, and the words that are to follow modify to som.e extent the signifi- TYPES OF LEARNING ACTIVITY 307 cance of those just preceding. In ordinary reading the eyes are several words ahead of the vocal organs, and read- ing with proper expression of thought is impossible without this modifying and unifying relation of all the words in the sentence. The limitations and advantages of conceptual intelli- gence are well illustrated by the experiments of Professor Judd upon fifth and sixth grade boys in two groups who were learning to strike a target under water. To one group an explanation was given of refraction, which makes an object seen under water seem to be disi)laced. In the first experiment, when the object to be touched was twelve inches under water, both groups were on an equality, seeming to learn in a sensory motor way by trial and error, but when the depth changed to four inches and all were informed of the fact, the boys who understood the prin- ciple learned much more rapidly, while the rate of the others remained about the same. Some sensory motor ex- perience is evidently necessary, but having that, one with conceptual intelligence and knowledge can apply his ex- perience to new relations, while one without such knowl- edge must continue to learn by trial. REVERSAL OF RELATION BETWEEN LOWER AND HIGHER CENTERS As we have already seen, the representative centers are primarily excited by the sensory motor centers and the conceptual centers by the representative centers, and variety in such excitation helps to get the higher centers ready for independent activity. They soon become 3o8 GENETIC PSYCHOLOGY capable of being excited by impulses passing from one representative center to another or from one conceptual center to another, and by impulses passing from the centers for perceiving and representing symbols. After they have thus become independent of immediate stimulation from the lower centers, there is need for a reversal of the process, so that the higher centers may send back stimuli to the lower, and thus excite them to activity. It is because of this that voluntary control of movements and of images becomes possible. Usually this reversal of the course of impulses so that the higher centers stimulate the lower to activity takes place gradually, and the fact that the processes are distinct has received little attention. A striking example of the two processes carried on separately is that of a little girl who began before the close of her first year to imitate words and was able to imitate with almost perfect accuracy every word that she heard. At this time she made no attempt to use words as a means of expressing her ideas. Later she began to do so, but then had as much difficulty as the ordinary child in pronouncing words correctly. Evidently her earlier imitation of words was entirely of a sensory motor character, while in her attempts at speak- ing the centers for controlling the vocal organs were being excited from the conceptual and representative centers. It is a well-known fact that associations may be very strong in one direction and have little or no suggestive force in another direction. One who can readily repeat the alphabet or a quotation may find it difficult or impos- sible to repeat the same backward. This is true in a very marked degree of reversing sensory motor series, such as TYPES OF LEARNING ACTIVITY 309 writing a word backward, while in representative and conceptual activity, where variety of combinations is com- mon, the reversal of the order of a series, as recalling the events of yesterday, beginning at the end of the day, is not difficult. It is only when a scries of ideas has frequently occurred in a certain order that reversal is difficult. In the case of series involving lower and higher centers, reversal is likely to be more difficult without practice than when the centers of higher levels only are involved. It may safely be stated as a general rule that ability to per- form an act in response to a sensory stimulus does not necessarily mean ability to perform it in a voluntary, rep- resentative, and conceptual way and vice versa. One who can perform accurately a gymnastic or manual exer- cise on occasion may find it difficult or impossible to rep- resentor describe voluntarily how it is done, and on the other hand, one who is able to describe the movements may be unable to perform them successfully. It is well known that a child who can laugh or cry perfectly in response to the proper stimulations may be unable to do so voluntarily. The same truth applies to a greater or less extent to everything that the child does. He may, under proper conditions, walk or stand gracefully, but not be able to do so voluntarily. He may use words correctly when there is the usual stimulus for their use, but be unable to put the words in sentences or tell what they mean. He may be able to repeat a verse or a selec- tion when started on it, but not have power to think of it at will. For this reason one who understands grammar well may use poor language, while one who uses good lan- guage may know little of grammar. 3IO GENETIC PSYCHOLOGY Again, one who can form appropriate pictures and con- cepts in response to the words of a poem may be quite unequal to writing such a poem. One who is able to follow accurately a course of reasoning may be utterly unable to construct a similar line of reasoning, and one who can respond accurately and tactfully to moral and social situations may be unable to state the rules of eti- quette and the principles of morality. These facts make it clear why there is such a difference between theoretical knowledge and practical ability, and why, as one college president expressed it, " college students simply flounder for about two years after they get out of college." In many processes of learning, the reversal of the direc- tion of excitation between higher and lower centers begins at once, so that the process of voluntary control is only a little behind the acquisition of sensory motor responses. Imitation plays a large part in this reversal, particularly in the transitions from immediate sensory motor imitation to the delayed and ideational forms in which acts are reproduced, not at the moment when seen, but some minutes, hours, or days later. In conscious learning the process is often facilitated by alternating the sensory motor imitation with the ideational. The child observes how some one else does a thing and tries to do it with per- haps indifferent success. He is shown again and repeats his attempt perhaps more successfully. He then practices the movement without a preliminary observation of the movement as made by some one else. The sensory stimu- lus may, however, remain for some time the most effective means of securing the right movement. This is illustrated by such movements as are made in gymnastic exercises TYPES OF LEARNING ACTIVITY 311 or in skating. One who cannot successfully execute them alone may be able to do so when he has the stimulus of perceiving others make the movements in the correct way. The same is true also to a marked extent in articulation and in singing. The child's imitative and playful tendencies lead him to effectively reverse the process of learning in most lines of incidental learning, so that he not only knows how things are done, but can do them. In school, however, where the process of learning is directed by others, the reversal often fails to take place. Many things are learned in a receptive way, and the teacher is then surprised that they cannot be repeated in any other way or, in the case of ideas which seem to be understood, that they cannot be used in doing things. It is well recognized that in the trades and professions a man may be very well trained theoretically and yet be very unsuccessful in actual execution, while another man may have no theoretical training and yet be very success- ful in practice. The first has had the higher centers trained to respond to external stimulations and to impulses coming from each other, but has had little training in sending im- pulses from the higher to the lower centers, while the second has had much training in sending impulses from the higher to the lower centers in such a way as to bring about the proper adaptations to the external conditions. In many instances success depends upon general direc- tion by higher centers and also upon quick sensory responses to the changing situations. In other words, impulses constantly passing in both directions must be coordinated in order that ends may be gained in practical affairs, in 31- GENETIC PSYCHOLOGY distinction from success in reaching conclusions in cases theoretically defined and supposedly unchanging. Movements may be the result of sensory motor stimula- tion or caused by impulses sent from the higher centers to the lower. The same is true of all forms of expression. They may be called forth by immediate external stimula- tion or they may be the result of the lower centers being stimulated by the higher. The value of manual training and of other forms of expression, in learning, is not because movements are made, but because the higher centers are gaining power to stimulate and direct the activities of the lower. This is also the psychological justification for the general principle of having impression followed by ex- pression. It should be recognized, however, that the de- velopment of the higher centers is greater in proportion as the mode of expression is different from that of the impression. The higher centers may become capable not only of reversing the course of impulses so that a person may do voluntarily what has formerly been done in response to external stimulation, but they may stimulate and direct the lower centers in the performance of activities for which they have had no direct stimulus; e.g. an oral language is usually learned through the sensory stimulus of hearing that language spoken. It is possible, however, for an individual to learn to speak a foreign language from the study of books. By means of free images, of sounds as- sociated with certain visual symbols, he can learn in a rep- resentative way the combinations of sounds constituting the words of the foreign language. He can then give the vocal organs practice in uttering combinations of sounds TYPES OF LEARNING ACTIVITY 313 that they have never had any sensory stimuKis to utter. It is also possible to learn various forms of gymnastic exercises and of constructive movements by reading de- scriptions of them and then practicing their execution. Such methods of learning demonstrate the extraordinary power of the higher centers over the lower that may be developed. It should be remembered, however, that the lower centers must have been previously well trained in some respects and have been under control of the higher, or such acts as learning new movements in a voluntary way would not be possible. In this learning of new things by lower centers under the direction of the higher, we have a most striking differ- ence between man and animals. There is no evidence whatever that higher centers ever take the lead in the learn- ing processes of animals. Whatever they learn to do is learned through external stimulation, either from their natural environment or through special training given by man. No one has even claimed that a horse ever under- takes to train himself to be a good trotter, or a l^ird a good singer, although both are readily subject to externally initiated training of this sort. In the case of man, on the other hand, ideals of what he wishes to be are among the most important sources of all learning activity. He forms ideals and then directs the learn- ing processes by which he is enabled to realize those ideals. In doing this he does not necessarily proceed by the method of training the lower centers to perform activities for which they have previously received no sensory stimulus, but he frequently takes the easier and more economical method of seeking opportunity for the reception of the proper sen- 314 GENETIC PSYCHOLOGY sory stimulations. In learning a language, for example, he does not try to train the vocal apparatus wholly by means of impulses sent from the higher centers, but he arranges to be with people who speak the language, and thus secures the training of the vocal apparatus through the much more rapid and effective means of sensory motor stimulation and immediate imitation. What is true of language is true in all lines of learning. The most effective learning is under the direction of the higher centers, but these higher centers often accomplish the purposes desired, not by attempting to directly control the practice activity of the lower centers, but by arranging that the lower centers shall have a suffi- cient amount of practice in the simpler process of respond- ing to external stimulation. SEPARATE AND COMBINATION LEARNING Although the various learning processes may be carried on separately, they are usually combined to a greater or less extent. Frequently one process dominates, yet is very much assisted by the others. When a number of persons are listening to a lecture some depend upon one and some upon another kind of mental process in learning from the speaker. A stenographer may hear the words and respond to each by making the proper character, with little or no activity of the representative and conceptual centers. Another individual may form numerous mental images as he listens to the speaker, with little attention to the words and to the thought. A third may form ideas almost without imagery and with no attention to the exact words used. Afterward the stenographer may reproduce TYPES OF LEARNING ACTIVITY 315 the words of the lecture with great accuracy and in doing so may, at the same time, form either images or concepts associated with the words. The one who formed images in the first place may translate these into words which may be quite different from the ones used by the speaker, and in doing so may give some attention to the thought connecting these images. The third may recall the line of thought pursued by the speaker, image in some detail the parts, and express the ideas in his own words. In all these cases each person seems to depend largely upon one form of learning, but it is safe to say that in nearly all cases the other forms of learning play a more or less important part. The stenographer depends chiefly upon previous training, by which each elementary sound has become associated with a definite movement. Since, however, the making of the movement does not imme- diately coincide with the hearing of the sound, but follows it at a greater or less distance, he is carrying in mind a number of sounds, while making the movements in re- sponse to those previously heard. If he has mental images or concepts corresponding to the sounds as grouped in phrases and sentences, he can do this much more success- fully than if they are to him a series of unrelated and meaningless words. Without exception, stenographers can take more accurately a series of sentences expressing familiar thought than they can either isolated words or sentences expressing ideas quite unfamiliar to them. A complete sensory motor re])roduction of words is, however, possible to a few individuals. A most remarkable instance of this kind is related by a missionary. After delivering an address to the nati\es in his own language, he noticed 3l6 GENETIC PSYCHOLOGY a crowd gathered around a native who knew nothing of that language. The man who was speaking to them, so far as the missionary was able to determine, reproduced accurately every word and gesture that he himself had used in his address shortly before. In the case of the one who relies chiefly upon mental pictures, success depends largely upon the association which he has previously formed of words and the images suggested by them, but much assistance is derived in form- ing and connecting these mental pictures from his under- standing of the general line of thought being pursued. He is probably also assisted in many cases by incipient move- ments corresponding to actions suggested by the images. The conceptual learner, although depending largely upon the abstract ideas suggested by the words, and the relation of those ideas to vvdiat he already knows of the subject being discussed, yet is also often greatly assisted by images around which some of the principal ideas are grouped or by certain word symbols under which he groups the different thoughts expressed. In many cases he is able to recall the thought either by reproducing some of the images called up by the speaker and then expressing the thought associated with them, or by reproducing certain words that serve as an outline of the topics treated. In some instances a sensory motor learning of such an outline may be used as a means of recalling the thoughts expressed. Some persons with such an outline may reproduce a lecture with great accuracy and completeness, while without it they would be able to tell little or nothing. The same combination of processes takes place to a greater extent than has just been described in nearly all TYPES OF LEARNING ACTIVITY 317 instances of studying lessons and learning selections. In learning a poem, for example, one may learn it in the sensory motor way, being helped greatly by the rhyme and rhythm but incidentally also by the imagery and the thought. Another may form an image for each line and associate the words with that imagery, while a third may get the thought of the different lines and verses in relation to the thought of the whole and then associate with it the words expressing the thought. In many cases all of these processes are carried on at once without any one of them especially predominating. Recent experiments in memory, in which the mode of memorizing was studied, emphasized the fact that most individuals have some kind of a plan or habit of memoriz- ing and often make use of some form of imagery. Im- provement in memory is usually the result either of greater facility in the use of some memory scheme or the adoption of a more effective scheme of memorizing. A detailed study of schema used in learning of various kinds will be likely to yield important results for psychology and ped- agogy. Most things that a child learns to do involve activities of both higher and lower centers and also a process of getting the sensory motor, representative, and thinking activities to act harmoniously. In learning to read, for example, the child is acquiring the sensory motor process of responding to a visual stiniulus by appropriate move- ments of the vocal organs. It is possible to do this without forming any association whatever between the visual sym- bols and the images or ideas which they are supposed to suggest. This is frequently done without the knowledge 31 8 GENETIC PSYCHOLOGY of the teacher, especially when a series of words are learned together and in one place only. Again, a child who does not know any of the words visually but who knows them auditorially, may at sight of the page be able to repeat every word on it. In order to get the sensory motor con- nection between each visual word and its vocal utterance, it is necessary that the word shall be seen in various com- binations in relation to other words. If this is not done the association may be chiefly with a certain place in the complex percept of a page, paragraph, or sentence. The association between the oral word and the visual word becomes strong just in proportion as the connections be- tween the visual word and its immediate accompaniments in perception are broken up by continual variation in the associates of the word. During the process of acquiring the sensory motor as- sociations the attention may have been fully occupied with that process so that no images were formed even in the case of words previously familiar in their auditory form. If such is the case, a distinct process of representative learning is necessary so that the visual symbol may not only call up the auditory symbols, but also the things symbolized. Again, if the sensory motor and representative processes are separately acquired, it may be necessary to give the child special training in getting thought from the series of printed symbols. Even in cases where the words are all familiar and call up appropriate ideas, he may not con- nect them in such a way as to get the thought of the phrase, clause, sentence, or paragraph as a whole. This is a very common condition in children who have just learned to TYPES OF LEARNING ACTIVITY 319 read by the method of learning elements separately. They arc frequently unable to get the true meaning of what they have read without their attention being called specifically to the relation of the different words to each other. In order to read successfully, all of these processes must be carried on simultaneously and harmoniously. It fre- quently happens that a child who knows all the words in a sensory motor way when his attention is directed especially to that process, miscalls many of the words when his attention is directed to the images or meanings suggested by them. In reading aloud, the articulation and the proper em- phasis and inflection involve a still further complication of processes ; hence a child who is able to get thought from silent reading may be unable to read clearly and with proper expression while getting the thought, though he may be able to do so in imitation of another. Again, if his attention is directed to articulation, pauses, and em- phasis, he may be unable to get the thought which should be expressed. The process of reading aloud correctly, intelligently, and expressively, involves the harmonized activity of a number of different centers at several levels, in a manner comparable to and very much more complex than the working of belts, w^heels, cranks, and pulleys in any ma- chine. As in the case of the machine, parts may run suc- cessfully alone by changes of adjustment, or a defect in one part may interfere with the working of all the other parts. The process of learning to read may be carried on in an order exactly the reverse of that which has just been de- 320 GENETIC PSYCHOLOGY scribed. Instead of acquiring the elementary processes separately at first and then their proper combination, the complex process may be attended to first and the elemen- tary process learned incidentally. From pictures, explana- tions, or talks about objects, or by dramatic representations, a child may get the idea of the thought to be expressed and then begin learning the visual symbols that express that thought. His knowledge of the thought to be expressed, and his mental images of the situations in- volved, will in many cases enable him, by the help of his knowledge of oral language, to guess at what the visual symbols stand for. If this guessing is supplemented and corrected by the teacher, the attention of the pupil being directed toward the peculiarities of the visual symbol for each word, incidentally and without withdrawing it from the thought being expressed, the child will soon form the sensory motor associations with the separate words. If the thought still is prominent in his mind as he utters the words of the sentence, he will speak them with something of the same expression that he already uses in imparting his own ideas. In this method of learning to read, thought leads and the lower centers learn under the direction of the higher, all the processes being harmoniously combined while each is being acquired. In order to learn to read successfully in this way the child's attention must be kept occupied more or less with interesting thoughts that are being gained through the reading, but it will be necessary to occasion- ally direct his attention to sensory motor activities in which he shows a deficiency. Sometimes it will be necessary to give special drill in recognition and pronunciation of TYPES OF LEARNING ACTIVITY 321 words and of elementary sounds aside from the reading exercise. Whether the method of acquiring the processes of reading separately, beginning with the lower and then learning to combine all of them after the higher have been acquired, should be used, rather than the method of learn- ing all the processes at once, with the higher thought process leading, is to be determined, not by the facility with which any one process may be acquired, and the degree of ac- curacy attained at any particular stage, but by the readiness and completeness with which all of the processes are ulti- mately acquired. In practice, a single child may be taught more successfully by the thought and combination method than can a large number, because one can be sure that he is looking at the right word. In learning to write, there is a similar combination of complex processes, but directed more toward the expression than the acquisition of thought. Much more sensory motor practice is necessary in learning to write than in learning to read, because the vocal organs have already been more completely trained for the utterance of sounds than has the hand in the making of forms. The repre- sentative process is also more important in learning to write because the child, after his first attempt at copying, must be able to form an image of the letters to be made, and he must also remember the way in which these letters are combined to form the words that he wishes to use. It is therefore much more difficult to teach a child to express thought in writing by the combined method, with the thought to be expressed leading and directing the represen- tative and sensory motor processes, than it is to pursue the same method in accjuiring ability to gain thought from y 322 GENETIC PSYCHOLOGY the printed page. Some special drill is usually necessary upon the motor process of writing and the memory process of spelling, but if these processes are carried on entirely without connection with the expression of thought in writ- ing, the child is liable not to combine the processes already acquired with the thought process, but to spell incorrectly words that he knows orally and to use quite a different style of penmanship when expressing thought from that used in the copy book. In arithmetic, the child must acquire sensory motor, representative, and conceptual facility in order to do his work successfully. The number symbols, either auditory or visual, may be acquired either singly or in their various combinations in a purely sensory motor way. A child who knows nothing whatever about numbers may learn a large section of the multiplication table in a short time, especially if it is arranged so there is some rhythm in speak- ing the numbers. Much of the learning of the multipli- cation table in school is, unknown to the teacher, of this sensory motor type. Acquisition is made in this w^ay most readily when the numbers are given in the same order every time. After they have been learned in this way the series may be broken up and the separate combinations acquired. In the process of breaking up the series the child usually acquires images of the separate symbols, and when two terms of a combination are given with the proper signs, as 3 X 4, he forms an image of the third number either as heard or seen, or both, according to his previous training. Tables thus learned may then be used in the solution of problems. The ordinary working of examples may be and often is TYPES OF LEARNING ACTIVITY 323 little more than a sensory motor and representative dealing with symbols in ways that have been acquired by imitation and direction. The symbols may not arouse any repre- sentation of groups of objects, or any concept of number relations. It is quite common for children to think it utterly impossible to perform the operation of subtraction when the subtrahend is placed above the minuend, or to work an example in long division if the mode of expressing it is changed. The process is to them wholly one of manip- ulating symbols. Later they may acquire more complete number concepts and be conscious of the fact that in thus manipulating symbols they are .representing number rela- tions. The importance of sensory motor familiarity with symbols used in arithmetical calculations w^ill be impressed upon any one who tries to multiply LXV by XXXII, using Roman numerals exclusively. Before going to school the child usually acquires first the auditory symbols that stand for number ideas and knows that series in order, to ten or perhaps a hundred. He may also be able to apply the series to objects in counting them. When learning to count, the child is likely to take the number as the specific name for the object pointed out when the number is spoken, e.g. the forefinger as having the name "one" and the little finger that of " four," but from hearing the number symbol applied to various objects in various combi- nations, he is enabled to pick out the number charac- teristic of objects from the many that they possess. This is the beginning of the number concept. This concept becomes more and more definite with his increase in abil- ity to represent the number of objects indicated by each 324 GENETIC PSYCHOLOGY symbol, when they are not present, and by his ability to represent the various combinations of smaller groups of objects that go to make up the larger groups. The child has some knowledge of "twenty" when he knows that it comes some distance along in the number series, and when he knows that it means a larger group of objects than ten, and that it comes earlier in the series than fifty and stands for a smaller group of objects. In acquiring what are called the facts of number he may get exact ideas of the relation of twenty to smaller and larger numbers. The process of getting definite ideas of numbers so that he knows just how much larger one is than another, is greatly facilitated by the various combinations of objects that may be used, but number ideas grow slowly, especially when the attention is much occupied with symbols and processes. Not unfrequently drill on processes checks entirely the growth of number concepts. After considerable experience in applying the proper symbol to small groups of objects and learning the sym- bols expressing the combination of groups into other groups, the sensory motor process may give place to the process of imaging objects. Later definite representation is un- necessary and concepts of numbers and their combinations indicated by symbols may be substituted for the longer process of imaging objects in groups. When this stage has been reached, further progress in number may be made with only occasional returns to actual imaging of objects or sensory experience with them. A knowledge of place in the number symbol series and the facts regarding the simple combinations are now of great help in acquiring the larger combinations and may profitably be used instead of manipulating objects. TYPES OF LEARNING ACTIVITY 325 The simplest stej) in making use of the number series in learning the facts of number is taken when the child learns to omit every other one of the series, or in other words, learns to count by twos. Further progress is made in learning to omit every other one of the two scries, or in other words, learning to count by fours. Another process that may come as early or earlier is that of learning to count by tens, twenties, etc., a process very similar to that of counting by ones. This is easily followed by learning to count by fives. By counting forward and backward and by noting how many times the given number was used in counting in each direction, the facts of subtraction, multiplication, and division that are necessary to the more complete and accurate concept of the various numbers, are readily acquired. After learning to count by twos beginning with one, a child can soon count by threes by adding two and one to each sum. Counting by six and by eight is also easy to one who counts readily by threes and fours. All other simple number combinations can easily be acquired by one who is familiar with those previously mentioned, e.g. seven plus eight may be thought of as one less than eight and eight. In this way each new fact is not separately memorized but recognized by means of what is already known. A child who counts on his fingers has a sensory motor series that is better for him to apply than to simply learn the answer given him, but the one who has a few combinations well learned can apply his representative and conceptual series in determining new combinations with much greater rapidity. In all learning, but especially in that of mathematics. 326 GENETIC PSYCHOLOGY some sort of schematic arrangement of what has been learned may be used as a test for each new thing. This mode of testing and grouping should change in content and form as one's acquisitions become more extensive and ^ of higher forms. For example, formulas and equations are necessary in higher mathematics. It is probable that many persons never get beyond the "finger counting" stage of testing and learning not only in mathematics but in many lines of thought. The importance of fixed "standards" or schema with which varied phenomena of the same general kind can be compared can scarcely be overestimated in considering mental development. The original standards for exten- sion, "span," "cubit," like the first standard counting series, are based upon human anatomy, while the original time measurements are based upon the "winking of an eye" and common phenomena of day and night, change of moon and of seasons. History is possible only when a definite unit and a point of reckoning are fixed. No ac- curate development of industries or science is possible without definite standards of measurement of space, time, force, value, etc. This has long been recognized in the sciences and the industries, but the importance of standards of reference in mental development has only begun to be appreciated. There is good reason for believing that the superior mental development of man is in part due to his use of mental standards. Some of the earlier standards to be formed are those of size and shape. Appearances of objects differ infinitely according to distance and point of view, but we adopt the position and distance that give us the clearest and most easily attained view, i.e. at TYPES OF LEARNING ACTIVITY 327 right angles to the line of sight and usually at a distance of about a foot, where they can be best seen and easily handled. Every geometrical figure is judged by how it would look if brought to that position rather than by its particular appearance at the moment. Every class of objects comes to have a standard appearance according to the appearance that is oftcnest and most clearly presented. Words and symbols of all kinds also serve as standards of experiences. The importance of standards of measure- ment is appreciated when one attempts to estimate distance in unfamiliar units, e.g. centimeters. One who has es- timated larger distances in yards may even find it hard to do so in rods or feet. In music the notes and their arrangement in a scale must be learned as a standard before progress in the science of music is possible. In physics, units of weight, force, etc., are necessary to clear conception, and in every sphere of knowledge definitions, formulas, and general truths must be acquired before accurate conceptual thinking can be carried on. The standards may differ greatly for different things in the same individual, but whatever kind of stand- ard is most frequently used indicates whether one is domi- nantly of the sensory motor, representative, or conceptual type of intelligence. In concluding the topic of learning it may be emphasized that practically everything that is learned consists, if we analyze it, of many simpler processes and usually of series not only of different sense elements but of series of activ- ities at several different levels. It is only when these series are properly linked together and adjusted to each other that success is possible. It is not enough that any or all 328 GENETIC PSYCHOLOGY of the scries of activities be acc}uired separately, but each must be brought into such relation with all the others that its performance facilitates rather than interferes with their performance. It is possible to acquire the different series separately or all together, but an intermediate course is probably often most economical, some elementary series being acquired alone or in combination with others, then the process complicated by the addition of other series. As new skill and knowledge are acquired, one series then another leads or is used as a standard of reference. Sensory motor standards are common in the earlier stages, while later representative and conceptual standards are most used. REFERENCES *Angell, Judd, and Pillsbury. On Special and General Training, Ed. Rev., Vol. XXXVI, pp. 1-42. ♦Arnold, Felix. The Initial Tendency in Ideal Revival, Am. Jr. Psych., Vol. XVIII, pp. 239-252. Bergstrom, J. A. An Experimental Study of Some of the Conditions of Mental Activity, Am. Jr. Psych., Vol. VI, pp. 246-274. *Browne, Chas. E. The Psychology of Simple Arithmetical Pro- cesses, Am. Jr. Pysch., Vol. XVII, pp. 1-37. *Bryan and Harter. Studies in the Physiology and Psychology of the Telegraphic Language, Psych. Rev., Vol. IV, pp. 27-53. BuRNHAM, W. H. The Hygiene of Drawing, Ped. Sem., Vol. XIV, pp. 289-304. ♦Chambers, W. G. The Significance of Motor Activity in Primary Education, Jr. Ped., Vol. XVIII, pp. 166-184. ♦Cleveland, Alfred A. The Psychology of Chess and of Learning to Play it, A7n. Jr. Psych., Vol. XVIII, pp. 269-308. CoovER and Angell. General Practice Effect of Special Exercise, Am. Jr. Psych., Vol. XVIII, pp. 328-340. TYPES OF LEARNING ACTIVITY 329 ♦Ellison. Children's Capacity for Abstract Thought, Am. Jr. Psych., Vol. XIX, pp. 253-260. Freeman, F. M. Preliminary Experiments on Writing Reactions, Psych. Rev., Monograph Supp., No. 34, 1907, pp. 311-333. ♦French, F. C. Mental Imagery of Students, Psych. Rev., Vol. IX, pp. 40-56. *Gard, W. L. a Preliminary Study of the Psychology of Reasoning, Am. Jr. Psych., Vol. XVIII, pp. 490-504. Gesell, a. L. Accuracy in Handwriting as Related to School In- telligence and Sex, Am. Jr. Psych., Vol. XVII, pp. 394-405. Hall, G. S. Adolescence, Chapter III. *HuEY, E. B. Psychology and Pedagogy of Reading. Jacobi, Mary P. Psychological Notes on Primary Education and the Study of Language. *KuHXMAN, F. On the Analysis of the Memory Consciousness for Pictures of Familiar Objects, Am. Jr. Psych., Vol. XVIII, pp. 389-480. On the Analysis of the Memory Consciousness, Psych. Rev., Vol. XIII, pp. 316-347- Leuba and Hyde. An Experiment in Learning to make Head Move- ments, Vol. XII, pp. 351-360. Mach, E. On the Part Played by Accident in Invention and Dis- covery, Monist, Vol. VI, pp. 161-175. ♦Meyerhardt, M. W. Economical Learning, Ped. Sem., Vol. XIII, pp. 145-184- Morgan, C. L. Comparative Psychology, Chapter XII. QuANTZ, J. O. Psychology of Reading, Monograph Supp., Vol. II, No. I, December, 1897. ♦Peterson, H. A. Correlation of Certain Mental Traits in Normal School Students, Psych. Rev., Vol. XV, pp. 322-338. Phillips, D. E. Number and its Applications Psychologically Considered, Ped. Scm., Vol. V, pp. 221-279. ♦Slack, M. Mirror Writing and Left-Handedness, Ped. Scm., Vol. II, pp. 236-244. Smedley, F. W. Child Study. Report No. 3, of the Child Study Department of the Public Schools of Chicago. 330 GENETIC PSYCHOLOGY Smith, M. K. Reading and Memorizing of Meaningless Syllables Presented at Irregular Time Intervals, Am. Jr. Psych., Vol. XVIII, pp. 504-513- Smith, W. G. The Relation of Attention to Memory, Mind, January, 1895, PP- 47-73- *SwiFT, E. J. Mind in the Making, Chapter VI. *Terman, L. W. Genius and Stupidity, Fed. Sem., Vol. XIII, pp. 307-373- Thorndike, E. L. Memory for Paired Associates, Psych. Rev., Vol. XV, pp. 122-138. CHAPTER XI RACIAL AND INDIVIDUAL DEVELOPMENT GENERAL THEORY AND PRINCIPLES In order to get a better conception of the genesis of behavior and of consciousness in the race and in the in- dividual, and to better understand the influences affecting the consciousness of individual human beings, it is nec- essary to take a survey of evolutionary processes from a new point of view, i.e. considering the elements of which organisms are composed and their relation to each other and to the external environment. The lowest form of animal life consists of a single cell, while the higher forms are composed of billions of cells. The germ, however, from which an individual of the higher forms of life develops, consists of a single cell. This simple, almost microscopic cell develops into a many celled, complex organism. Evolutionary theory supposes that in racial development there has been a similar change of simpler organisms into those of higher and higher forms. In the case of the individual this change takes place in a very short time, ranging from hours to years, while in the race the time required for such changes varies from thou- sands to millions of years. The development in the race is known as phylogeny and that of the individual as ontogeny. Since both phylogenetic and ontogenetic development 33^ ?>2>^ GENETIC PSYCHOLOGY is from very simple lo very complex forms, there must necessarily be some similarity in the changes that take place. As a matter of chance it would be expected that a human organism, which begins as a single cell, would at a certain early stage of development show some simi- larity to lower forms of animal life, such as the worm or fish. Many such resemblances have been found ; so many, that a biogenetic law has been formulated which asserts that the individual organism, in its short period of develop- ment, goes through all the chief stages of development of the race as shown in the different forms of animal life. The human embryo is not only not distinguishable from the embryos of other vertebrates at the beginning, but it resembles in its general form and prominence of parts successively higher orders of animal life until it assumes the typically human form. In building up the human form, the most obvious and direct mode of con- struction from the original germ cell does not seem to be taken, but the development proceeds as if an animal of one of the lower forms were to be produced and then another a little higher, until by a very indirect course of development the human form is finally evolved. Many extra organs, not ordinarily possessed by man, such as gill slits, a tail, and extra mammary glands, are always found in the embryo of man and all mammals, and are occasionally found in human beings at birth. By the discovery of a large number of such organs that are prom- inent in the embryo of man and either rudimentary or entirely absent at birth, a strong case has apparently been made out for the theory that the germ cells of the race have formed a habit of developing in certain ways that persist RACIAL AND INDIVIDUAL DEVELOPMENT 333 in spite of the fact that the method is indirect and un- economical. The law is recognized in studying the relationship of one species of animals to another. If there is marked similarity in embryological development, the fact is taken as one line of evidence of relationship, though no biologist relies exclusively, and some rely to only a slight extent, upon such similarity in determining the question of com- mon ancestry of various species of animals. A great many exceptions have been found to this bio- genetic law. Some stages of development that are present in lower forms are omitted in the higher, and the order of development of parts is not always the same in the higher as it is in the lower. A still more striking fact has been noted that in the development of the lower forms certain organs are sometimes much more prominent in the embryo than they are in the mature animal, just as if the embryo had started to become a creature of a higher species, with certain organs more prominent than in its own species. Such facts as these surely cannot be explained by the theory that the germ cells have got into a habit of develop- ing in a certain way unless it be supposed that the creature in question was originally of a higher form and has fallen back into a lower. It is now believed that some of these organs that are prominent in the embryo perform needed functions at that time and hence are not the useless vestigial organs that they have been supposed to be, e.g. the pituitary body in the brain. Aside from this a general explanation may be given that will more satisfactorily account for both kinds of facts. Each germ cell may be supposed to have within itself 334 GENETIC PSYCHOLOGY certain special growth tendencies that cause it to assume the form of its species rather than that of any other species. This special growth tendency possessed by each germ cell may not be absolutely fixed in its character but subject to slight variations similar to the trial movements of organ- isms. The germ cells of different orders of animal life have, to a considerable extent, different growth tendencies, although there are some common elements in all. In the case of those species that are more nearly related, a greater similarity in growth tendencies would naturally exist. In the case of a species of animal descended from a more primitive form, it would be expected that some of the growth tendencies would be the same, but that others would have been suppressed and still others made more prominent in the germ cells of later and higher forms. In this way the similarity of and also the difference between phylo- genetic and ontogenetic development may be explained without supposing that the germ cells have formed a habit of developing in a certain way, but merely that certain of their somewhat diverse growth tendencies have been suppressed and others increased by the influence of the environment on the body cells and indirectly upon the germ cells of which the body cells are the environment. Plants and some animals may be propagated by cuttings, and reproductive cells may be regarded as simply parts of the original organisms, hence the development of an in- dividual organism is a development of the same general type of organization as that of the species and we should expect a similar kind and order of development of the in- dividual and the species. WTiatever differences there may be in the two cases would be due to difference in infiuences RACIAL AND INDIVIDUAL DEVELOPMENT 335 affecting development. The development of the individual takes place in response to the direct influence of the environ- ment, the influence of which upon the species is indirect, through the reproductive cells that survive and pass on the original and perhaps also some of the acquired charac- teristics of the species from one generation to another. There is no doubt that the species may develop in a certain direction through natural and artificial selection of in- dividuals whose reproductive cells are to produce the next generation. The question most in dispute is whether evolution in the species can take place in any other way than by increasing some of the original characteristics of the species and decreasing others through natural selection of individuals. It has been held that the changes produced by the experience of the individual from which the repro- ductive cell comes, are imparted to the reproductive cell and may thus become established in the species. This sup- position has been shown to be almost if not entirely un- tenable in so far as it supposes that the specific modifications produced in the individual are imparted to the reproductive cells. It is known that reproductive cells in some animals, and probably in all, are at an early stage of embryonic de- velopment separated from those which develop into the main body of the individual. These cells are therefore almost entirely cut off from the influence of external en- vironment. Their real environment consists of the body cells and it is quite reasonable to suppose that changes in that environment may produce changes in them; but it does not follow that the change is of the same character as that taking place in the body cells. Since there is no 336 GENETIC PSYCHOLOGY nervous connection, the chief medium for the transmission of modifications is the blood. This and the variations in temperature of the body and the pressure of its cells, must be the chief influences tending to modify the repro- ductive cells so long as they remain in the body of the parent. It should be remembered that reproductive cells while in the body of the separate parents are not developing very much, and hence are probably less modifi- able than where greater changes are taking place. After two reproductive cells have united to form the germ cell from which an individual of the next generation is to be developed, development is very rapid and it is to be expected that considerable modifications in development may be produced. Experiments show that in the lower ani- mals profound modifications may be produced by changes in gravity, temperature and food. The size, coloring, etc. of butterflies and even birds may be thus greatly changed. It is probable that in human beings and other of the higher animals the development of the embryo is affected by the condition of the mother. In human beings it is well known that the presence of the embryo modifies all the physiological processes of the mother, and it is reasonable to suppose that reciprocally the physiological condition of the mother modifies the development of the embryo. Again, before reproductive cells have been united we know that they must influence the development of the body cells, since unsexing greatly modifies development, causing the male to become more feminine in appearance and the female more masculine. In view of these facts it is not improbable that body cells modify reproductive cells to some extent though probably not to nearly as great an RACIAL AND INDIVIDUAL DEVELOPMENT 337 extent as the rapidly developing embryonic cells are affected by the body cells of the mother. It does not follow, how- ever, that the modifications are of the same kind as those that occur in the body cells, nor is it certain that the modi- fications that do take place extend in any considerable degree beyond the individual in whose germ cell they occurred. It has not yet been proved that the changes produced by unusual temperature, in the color of butter- flies' wings and birds' feathers, are transmitted to the next generation. McDougall, however, found that substances injected into the ovum of a plant may not only cause the seed to produce a plant individually different from the species, but that its descendants also have the new char- acteristics. In the light of these facts it would seem probable that although the reproductive cells are not directly affected by the external environment, they may be modified to some extent by the modifications that are produced by the en- vironment or otherwise in the body cells, and that some modifications thus produced may become inheritable char- acteristics in the species. Where the environment and mode of life of a species for many generations develops in the life of each individual certain characteristics and suppresses others, it is most probable that the reproductive cells will be modified by their constant environment of changed body cells, but it is doubtful to what extent the characteristics of the species are thus permanently changed. Plants grown for many generations in new soil and climate show modification in growth tendencies for a few genera- tions when brought back to their native habitat. We are not sure, however, as to how permanent such modifications z 338 GENETIC PSYCHOLOGY arc. Neither can we say how far the modification is due to the selection of individuals for reproduction by man, and how far characteristics of the reproductive cells are increased and others decreased by the changed external and body cell environment. The discussion regarding the possibility of inheritance of acquired characteristics carried on so hotly for many years will probably be settled by experimental zoology wholly in favor of neither Weismann nor Lamarck, by proving that modifications may be produced in reproduc- tive cells by changes in body cells, but that the changes in body cells produced by experience do not necessarily, and probably not in general, produce exactly the same kind of changes in the reproductive cells and the individuals that develop from them. It will probably also be estab- lished that although there is no complete and rigid deter- mination of the course of evolution by the characteristics of the reproductive cells, yet that these characteristics are relatively permanent as compared with those of body cells. Since variations are most prominent in cross breed- ing, it is probable that the growth tendencies of one parent will conflict with some and harmonize with other growth tendencies of the other parent cell. The result is that some characteristics are increased and others decreased, and it may be that wholly new ones may thus result in somewhat the same way as is the case when two chemical molecules unite. A changed environment may favor such variations and thus help to produce mutations which are the result of changes in growth tendencies, while grad- ual increase and decrease of characteristics would usually be the result of harmony of growth tendencies in the slightly different cells of the two parents. RACIAL AND INDIVIDUAL DEVKLOPMENT 339 Variations, however produced, are at once acted u[)on by natural selection, which eliminates individuals with char- acteristics least favorable to survival in a given environ- ment. Temporary lack of correlation, however, between variations may be bridged over by modification in the individual, e.g. a deer with large horns may develop the muscles necessary to wield them successfully. In order that such muscular development may become estab- lished as a characteristic of the species there must be either a chance or mutating variation in favor of greater muscular development or else the presence of the large horns and muscles in the individual must so affect its reproductive cells that the tendency to the growth of more muscular tissue, especially in the neck, is produced in his descendants. THE CELL IN INDIVIDUAL AND RACIAL DEVELOPMENT All organisms are composed of cells. Recent studies have shown that most cells have a life history with stages of youth, maturity, and old age. In general, young cells have a large nucleus, while old cells have a smaller nucleus surrounded by a larger mass of protoplasm. In the course of development the nucleus changes little except in size, while the protoplasm differentiates to a very great extent and in a great variety of ways for different cells. In young cells, i.e. those lately developed from the germ cell, there is a great capacity for dividing and producing new cells, while in mature cells this capacity is in most cases entirely absent. In the embryological period of individual development nearly all the cells are engaged 340 GENETIC PSYCHOLOGY in a rapid production of new cells like themselves. As development proceeds the cells already produced change in character and, in proportion as any cell differentiates, does it become incapable of producing new cells. In human beings at birth the production of new cells, under ordinary conditions, has nearly ceased. The changes that take place in the course of development after birth are therefore largely due to specialization and to increase in size of cells already formed. The capacity for producing new cells under special conditions still remains, however, in some portions of the body. This is especially true of the surface cells of the skin, which are especially liable to destruction. A consid- erable amount of connective tissue that has been destroyed may be replaced, which would not be possible if the cells had entirely lost their capacity to produce new cells. In the case of muscular cells there is also some capacity for producing new cells and thus repairing injuries. A slight degree of this capacity is also retained by the cells compos- ing special organs, such as the liver. In the nerve cells, however, which are capable of such a high degree of special- ization, the capacity to produce new cells seems to be nearly, if not entirely, absent at birth, though parts of cells may be replaced, e.g. if a cell body is destroyed, its fiber dies and is not renewed ; but if the fiber only is cut or destroyed, a new one may grow out from the cell body. This power of producing new cells to take the place of cells or parts of cells that have been destroyed is known as regeneration. It is very much greater in children and young animals, which are composed of young cells, than in those that have reached the adult stage ; while in old age it R-^CIAL AND INDIVIDUAL DEVELOPMENT 341 IS sometimes almost entirely lost. This is paralleled in the development of the race by the fact that in the lower animals the capacity for regenerating parts that have been lost is very much greater than in the higher animals. Several segments may be removed from an angleworm, and the lost parts, including the head, will be regenerated. In animals still lower in the scale, such as the jellyfish and the stentor, division into several parts is followed by regeneration that makes a complete individual of each portion. Even in animals as high in the scale as crabs and some of the lower vertebrates the removal of a leg is followed by its complete regeneration. An examination of the cells composing the bodies of lower and higher animals shows that in general the cells constituting the bodies of the lower animals are less com- pletely developed and highly specialized than those com- posing higher animals. Speaking in a very general way we therefore say that the characteristics of cells in lower animals are similar to those of the cells of the young of higher animals. In general, a cell that has been matured and specialized is not capable of producing new cells. In lower animals that produce by fission, it has been found that after a certain number of generations have been produced the capacity to produce decreases, unless there is a conjuga- tion of cells, which is usually followed by increased capac- ity to produce new cells. In the case of higher animals, where there is sexual rei)roduction, the cells for that pur- pose are usually set a])art before much ditTerentiation has taken place in the embryo, and the reproductive cells re- main unspecialized. After two such cells from difTerent 342 GENETIC PSYCHOLOGY individuals have united, changes take place rapidly ; the nucleus of the germ cell thus formed divides again and again as it develops into an individual of the species. RELATIONS OF CELLS IN DEVELOPMENT In the case of lower animals death results only from the destruction or loss of vitality of all, or a considerable portion, of the cells of which they are composed. As we have already seen, if only a part of the cells of a lower animal are destroyed, the other cells produce new ones to replace the parts that have been removed. In the case of man and the higher animals, however, death rarely results from the destruction or the old age of a large portion of the in- dividual cells composing the body. Most of the cells are still vigorous and without signs of degenerative changes. Conversely it is possible to remove from the body a mus- cle or even the heart and by means of artificial circulation keep it actively functioning long after the animal as a whole is dead. Death in higher animals usually results from the injury or loss of functioning power of the cells composing some particular organ of the body, without whose activity the rest of the organs are unable to function properly. The difference between a lower animal and a higher one consists, not merely in the character of the cells composing the body, but chiefly in the relation of the various specialized cells to each other, and the same is true of the differences between an animal at birth and when mature. In single celled animals, life is maintained by harmoniza- tion of the activities of the cell with the environment im- RACIAL AND INDIVIDUAL DEVELOPMENT 343 mediately affecting it. In animals composed of more than one cell all the other cells constitute, in effect, an important stimulating environment for each individual cell. To maintain life the activity of each cell must be harmonized not only with its immediate external environment, but also with the activities of the other cells. So long as the many cells of which the organism is composed are similar and undifferentiated, their influence is less significant. This is shown by the fact that the removal of large numbers of cells from lower animals makes little difference in their activity, except that opportunity is then given for exercising more fully the capacity to produce new cells. This soon results in regeneration or replacement of the cells which have been removed. Even in these lower organisms, however, the relation of part to part is of a good deal of significance. If too many cells are removed for the re- generating power of an animal of a given degree of organi- zation, regeneration does not take place. The decreased power of regeneration in higher animals is probably due in part to the variety of cells in the different structures of the body and to a lack of correspondence in the rate of development of the various new cells when any portion of the body has been removed. The reason why a lost limb is replaced in a newt and not in man is probably because the highly differentiated cells composing the bones, muscles, blood vessels, nerves, and skin of man, cannot produce new cells at the rate necessary for the harmonious functioning of cells of one kind in relation to cells of the other kinds. As we have already seen, the less specialized cells composing the connective tissue have much greater capacity 344 GENETIC PSYCHOLOGY for producing new cells than have the highly specialized nerve cells. We may note also that the possibility of specialization as the result of exercise and growth is very much less in the connective tissue cells than in the nerve cells. In other words, the cells that have the least capacity to produce new cells have the greatest capacity for change and specialization, and the reverse. On the other hand, every organism has, within certain limits, a normal size at maturity. It has some capacity to produce new cells, as is shown in the phenomenon of regen- eration ; but new cells that might increase the size of the animal are not produced as long as the animal is uninjured, evidently because the tendency is checked by the relation of one part of the animal to other parts. Not only growth but development and specialization of structure in different parts of the body are therefore probably due to the relation of cells and organs to each other rather than to the mere character of the individual cells. It follows also from this that the changes that take place in the development of animals from lower to higher types of organization, and in the development of individuals from the embryo to infancy and from infancy to maturity, are influenced to a greater and greater extent by the relation of cells to each other, and less and less by the direct in- fluence of the external environment upon the development of individual cells. The greater the variety and degree of specialization in the cells of an organism the more will the activity and development of each part be influenced by every other part. It is a well-known fact in physiology that the removal of a single apparently insignificant organ, such as the thyroid gland, produces profound changes in RACIAL AND INDIVIDUAL DEVELOPMENT 345 the whole process of develo[)mcnt. The functioning and growth of every organ of the body is thus modified and the individual is weak and undeveloped both physically and mentally. One form of idiocy is due to deficiency in this gland, and extract of the thyroid of sheep often produces great improvement. In man the removal of the primary organs of sex at an early age causes profound modifica- tions in the physical and mental development, the second- ary physiological characteristics, such as beard, change of voice, etc., failing to appear in the male and becoming prominent in the female. It is known that the production of new individuals in lower organisms is limited by the fact that a substance un- favorable to further reproduction is produced. It has been suggested by Tayler and others that in their growth all the cells of the human body produce substances that may retard or accelerate the growth of other cells of the body. If this is true, the thyroid gland is simply an extreme ex- ample of what is true in a less degree of every organ. The importance of the relation of cells to each other and the consequences of environing influences are emphasized by the following facts. Tumors may be transplanted from one mouse to another and made to grow, but the rate and extent of growth vary not only with the variety of the mouse used, but also in the same variety, if the mice have been subjected to different food and climatic conditions. It may be that all abnormal growths, such as tumors and cancers, arc due to disturbance of normal relations in the growth processes by means of which retarding substances are not supplied to certain cells, or unusual accelerating influences are given them. When the whole organism is thus affected the result may be a dwarf or a giant. 346 GENETIC PSYCHOLOGY The disturbance of the function of one part during the growing period may produce disturbance of function of many other parts and thus cause profound changes in the development of all organs concerned. For example, the abnormal growth of adenoids interfering with the passage of air through the nose leads to mouth breathing and to less aeration. The secondary changes that may follow are a V-shaped palate, chisel-shaped teeth, a considerable modifi- cation of the external nose, especially at the openings and near the eyes, imperfect development of the lungs and of the muscular and bony wall inclosing them (a condition known as "pigeon breast"), changes in the middle ear, leading to partial deafness, and finally a marked retardation in the brain development. We may note again that in a creature composed of a variety of specialized cells where relation of part to part is of such significance in development, we always find a large number of nerve cells which serve the purpose of con- necting each kind of cell with every other kind. In this way the functioning of cells in one part of the body may readily be affected by and harmonized with the functioning of cells in other parts of the body. Besides this primary functioning of the nerve cells there is also a secondary function that in higher animals is of equal importance. In them, nerve cells not only connect all parts of the body with each other so that each is influenced by all the others, but the activity of the nerve cells becomes the most im- portant influence affecting the activity of other cells. This is perhaps a natural result of the high degree of modifiability possessed by the nerve cells. They are so readily changed in their functioning and structure by what they do, and retain RACIAL AND INDIVIDUAL DEVELOPMENT 347 SO perfectly the effects of previous experience, that they influence the action of other portions of the body not only because of the activity excited in them by present stimulation, but also by the stored up results of past stimulations. It is well recognized in physiology that the nerv^ous system exercises a very important trophic influence upon all parts of the body, since any lack of nervous supply or imperfect nervous functioning modiflcs, in a marked degree, growth processes. It is evident that the relation of the nerve cells to the muscle cells is especially close and that the development of the muscles is almost completely dominated by the activity of the nerve cells, at least after birth. Even more marked is the effect of the activity of each portion of the nervous system upon the activity of every other portion of that system. In general, in the early stages of life in human beings, the nerve cells in the spinal cord and lower portions of the brain excite to activity the higher centers in the cortex. In later life the influence is more in the other direction, the higher conceptual and representative centers modifying the activity of the sensory motor centers. It is evident that in the case of the nervous system the characteristics of individ- ual cells are of very slight importance compared with the relation of groups of cells in the nervous system to each other and to other portions of the body. We may say, therefore, that not only in higher species, but also in individ- uals, as cells become more specialized so does the rela- tion of part to part become of increasing importance. Not only does relation of part to part become more and more important with increased specialization of parts, but, as we have already shown, the most efl'ective form of 348 GENETIC PSYCHOLOGY nervous and motor organization is that in which compara- tively few parts may be made to act in various relations with other parts, as is the case with the two hands of man. Furthermore, the higher animals survive not only because the parts of their own bodies are properly related to each other, but because of the relation in structure and instincts between offspring and parents, and also because of the relation of individuals to others of their kind. In man this relationship to others extends beyond the immediate envi- ronment, so that physical and especially mental develop- ment depends in part upon the influence exerted by other people far distant in time and space. The forms of the athletes of to-day are determined in part by ideas associated with the activity of nerve cells in the brains of the Greeks. SELECTION IN INDIVIDUAL AND RACIAL EVOLUTION There are great differences of opinion among scientists as to the causes of variation in individuals of the same and successive generations of the same species, but there is universal agreement that natural selection is the chief factor in determining what individuals of the species with their special modes of behavior and structure shall sur- vive. It is now also recognized that of the various trial movements made by an individual, those are selected for survival which have favorable results and that the organs concerned in the production of those movements are thus developed. There are, however, important differences in the selection of behavior and structure for survival in the species and in the individual. In racial development modes of behavior and structure RACIAL AND INDIVIDUAL DEVELOPMENT 349 are selected for survival by the preservation of the lives of individuals having those characteristics long enough for them to produce descendants similar to themselves. The selection is made in a negative rather than a positive way. All individuals that at any stage of their development have characteristics of cells or of relations of cells to each other that are sufficiently unfavorable to survival are eliminated, and those characteristics never again have a chance to develop in the species, unless it be by some variation similar to that which gave rise to them before. Again, it is generally true that the individual is engaged in a struggle for existence not only against unfavorable condi- tions in the physical environment, but also against other individuals of his own and of other species. There are some exceptions to this among the lower animals and an increas- ing number among the higher. In most of the lower vertebrates, as for example fishes, there is no cooperation between individuals ; parents are even likely to destroy their own young. Survival in such creatures depends chiefly upon the enormous number of individuals produced. Among higher vertebrates the parents assist for a longer or shorter time the individuals of the next generation instead of engaging in a struggle for existence against them. In all such cases the survival of the species depends upon the correlation between the instincts of the young and the in- stincts of the parent. Any failure of the instincts of the young to match those of the parent may result in death. In social animals we have a farther development of coopera- tion, adults of the same species cooperating in their activi- ties in securing food and in repelling and escaping enemies. Even in these cases, however, there is a large amount of 350 GENETIC PSYCHOLOGY conflict between individuals of the same species, and the results of these conflicts determine to a considerable extent what ones shall obtain food and produce descendants; and hence evolutionary progress in the species is determined more by competition than by cooperation. In some cases, especially among insects, there is a sort of cooperation between different species and different varieties of the same species in a way known as symbiosis. The relation of ants and aphids, their so-called "cows," and of slave-making ants and their "slaves" are examples of different species and varieties cooperating with mutual advantage. The same may be said of some forms of parasitism, though usually in such cases the parasite species profits by the relation without giving any corresponding advantage to the host species. In the relation between insects and plants we have a remarkable example of mutually helpful structure and mode of behavior by which the insects obtain food and the plants are properly fertilized. Notwithstanding these interesting exceptions it is the general rule that the individuals of every species are in conflict, not only with other species, but also to a considerable extent with other individuals of their own species, and all evolution, so far as it depends upon natural selection, is the result of eliminating individuals and with them the modes of behavior and structure least favorable to survival. With progress to higher forms, reactions to other living creatures become more and more important as compared with reactions to the physical environment. The struggle for existence is less severe between parts of the individual than between individuals in the species. There may be something of a struggle between the different RACIAL AND INDIVIDUAL DEVELOPMENT 351 cells, but this cannot be a prominent feature of individual development, otherwise the harmony of parts which is absolutely necessary for the maintenance of life would not be possible. If there is a struggle between the different cells, it is a struggle for position or prominence in the or- ganism instead of a struggle that means survival for some cells and death for others. The same is true of the social struggles of man. In general, the relation between the different cells of the body must be that of mutual influence of each upon all the others, and cooperation must be the rule rather than the exception. In the development of an individual from the original germ cell to maturity, selection is all the time acting in such a way as to make certain activities prominent and thus develop certain types of structure and relation of part to part. In this case, however, selection is not simply a nega- tive factor in evolution. It is true that useless movements, and especially those that are harmful, are not repeated to any great extent. The useful movements are repeated, however, not merely because they are not eliminated, but because of their favorable results. They are not only repeated because of native tendencies to that form of movement, but the tendency to make such movements in- creases positively and in a very marked degree because of their repetition. Again, modes of behavior which do not prove suitable in a given environment or at a given stage in the development of an individual, are not always permanently eliminated by failure at that time, as is the individual in racial develop- ment. Modes of behavior that at one time are useless or harmful may appear again and prove useful under other 352 GENETIC PSYCHOLOGY circumstances or at another stage of development, and then become permanent characteristics of the individual. It is evident, therefore, that selection operates in a much less decisive and irrevocable way in the evolution of the individual than in the development of the race. Many varieties of behavior may therefore appear and persist in the individual for long periods of time that never become in- herited characteristics of the species. Wherever individuals are able to modify their behavior in any way it must be that they inherit the capacity for such modification. This capacity for modification in vari- ous ways may be increased indefinitely in the species, while the actual. modifications can take place only in the indi- vidual. This is the feature of development that becomes more and more prominent as we go upward in the scale of animal life and becomes almost the exclusive feature in human development. Very few definite and specific modes of behavior other than those common to animals have become established in the human race, while the ca- pacity to develop to almost any degree in an infinite variety of ways is so great that in this respect, more than any other, man is distinguished from all other animals. There is good reason to believe that the change in evolu- tion, from the development of specific structures and modes of behavior in the species to the development of capacity in the individuals of a species to acquire modes of behavior, is very closely correlated with the development of conscious- ness, which we have already found is so likely to be present when behavior is changing, and which is largely absent in fixed reflex and instinctive behavior. Selection, which works in a negative way by destroying individuals with RACIAL AND INDIVIDUAL DEVELOPMENT 353 modes of behavior unsuited to survival, is made effective in the development of the individual by the pain that accom- panies such behavior in a creature that is conscious. If, when pain is felt, the action ceases or is modified before serious injury has resulted, the individual may survive. Pain thus serves as a substitute for death. It is a more economical means of evolution in the species than death and favors variety of action in the individual. This negative action of consciousness is supplemented by the positive influence of pleasure. All the modifications in behavior produced by pain, which bring relief and pleasure, are likely to be repeated and thus developed. The variety of behavior and the rapidity and extent of development is thus greatly increased by consciousness. A further development of consciousness that makes reac- tion to suggestive stimuli more nearly perfect, enables the individual to modify its behavior before injury is actually experienced. With a further development of consciousness giving foresight as to means of avoiding painful and securing pleasurable stimuli in the future, the possibilities of varied development in the individual are greatly increased. We may expect to find in man, therefore, much greater individual differences than in animals and to find that there is a great deal in his individual development that has no parallel in the de\'elopment of the race. In many instances also we may expect to find capacities and powers that have little or no biological value because neither harmful nor helpful to the species. So long as men do nothing that brings disease and death they may take a thousand different means of avoiding painful experiences a A 354 GENETIC PSYCHOLOGY and securing pleasures without subjecting themselves to the law of natural selection. This extraordinary development of individuals in vari- ous directions under the influence of conscious pain and pleasure is not, however, entirely without effect upon the evolution of the race. Men find many of their pains and pleasures in association with each other, and individuals who find their pleasures in ways that are painful to others, if not actually eliminated by their fellow-men, may not receive as much help from others and may not have as good an opportunity to produce descendants. Again, individuals who find their pleasures in the same way are more likely to cooperate and to marry. The descendants of parents with great capacity for one kind of enjoyment, e.g. aesthetic pleasures, are likely to have more capacity for such pleasures than their parents. In this way we may account for the development of many psychical characteristics that have no biological value. It is evi- dent, therefore, that consciousness must have been one of the chief factors in the development of the human race beyond the stage reached by other animals. ENLARGEMENT OF ENVIRONMENT IN THE EVOLUTION OF THE RACE AND THE INDIVIDUAL The importance of environment in evolution does not depend upon the theory that variations are produced by environment. Natural selection is determined by the en-- vironment, and any change in environment is likely to eliminate certain modes of behavior and certain structural characteristics not affected by the previous environment^ RACIAL AND INDIVIDUAL DEVELOPMENT 355 and thus make others relatively more prominent. The characteristics that are selected for survival in the evolu- tion of the race and the individual are therefore determined by the environment in which the organism develops. In a general way environment is usually understood to refer to the immediate external surroundings of the or- ganism. In truth, however, environment, as a factor in evolution, should refer chiefly to the surroundings that in any way affect the activity of the organism and thus deter- mine its development. In this sense creatures living in immediate proximity do not necessarily have the same environment. One may be profoundly affected by some- thing in the surroundings that exercises no perceptible influence upon another. The conversation, books, and pictures in the home are immensely important phases of the environment of the child, but they play no part worth noticing in the development of the kitten having the same material surroundings. Young animals have quite a different environment from the same animals when matured. They are limited in their movements, protected from climatic influences and enemies, and supplied with food by their parents. .\s they develop, go into new surroundings, and begin to secure their own food, they meet with entirely different kinds of environ- ment to which they must react appropriately. Even in the case of mature animals it cannot be said that the en- vironment to which they are reacting remains the same even in the same locality. A bird, for example, that is building a nest, is affected by nest-building materials that, under other circumstances, would probably exercise no influence upon her behavior. In general, it may be said 356 GENETIC PSYCHOLOGY that as a creature matures it reacts to more phases of any environment in which it is at the moment, and being able to move more freely it thus meets with more varia- tions in surroundings. In racial development it is evident that the simpler or- ganisms are affected by few elements of the environment, and the higher by many. The lower organisms react chiefly to physical and chemical stimuli, while the higher organisms, with many special sense organs, react to a great variety of objects and characteristics that have little or no physical or chemical effect upon them. Every increase in variety of sense organs results in an increase in the variety of environment affecting the organism. Every increase in sensitivity and in the possibility of varied movement in- creases the number of characteristics of the environment that may affect the organism. The needs of a creature and its instinctive tendencies, which are largely determined by its structure, mark out for it the portion of the environ- ment that shall influence it most. In both the individual and the race, positive psychical needs become more and more important as higher stages of development are reached. From the above it is clear that an individual must diverge more and more in its development from that of the race as it passes from the embryological and infantile stages into more mature stages of development, and that this diver- gence must be greater in proportion as capacities for modi- fication increase and as the individual becomes subject to the influences of a wider and wider environment. Much has been said about the correspondence between the intel- lectual development of the child and of the race, but this is RACIAL AND INDIVIDUAL DEVELOPMENT 357 just where there must be least correspondence so far as the apparatus involved in the higher intellectual process is concerned. Since, in the nervous system, capacity for modification is greater than in any other part of the body, and since, as we shall see, the environment affecting the development of the child is entirely different from that affecting the race, it follows that there is little chance for the higher nerve centers to be modified in the child in the same way as they have been in the race. The child and the savage resemble each other chiefly because they are both to a considerable extent undeveloped intellectually. Both have the physiological and instinctive characteristics of the race, but they are in different stages, some instincts being more prominent in one and some in the other, e.g. imitative instincts in the child and sexual in the savage. They are like each other in that the higher nervous structures are only partially developed and hence exercise much less influence over the rest of the organism. The sensory motor apparatus is well developed in both the child and the savage, and therefore their behavior is in some respects similar. In the development of the child and the race the order in which the different kinds of intelligence appear is doubt- less the same, physiological intelligence appearing first, successively followed by sensory motor, representative, and conceptual intelligence. Since representative and con- ceptual intelligence are developed almost wholly by ex- perience, there can be a close parallel in the development of the higher forms of intelligence in the race and the child only when both have been subjected to similar and ever- broadening environments. This has been true to some 358 GENETIC PSYCHOLOGY extent, but few phases of the broader environment have acted long enough on the race or in the same way upon individuals of the species to produce an appreciable influ- ence upon the nervous structure of the species, though in the individual a complete transformation may be produced in a very short time. PHYSIOLOGICAL EVOLUTION IN MAN Man, in his physiological development, is probably influenced less by physical surroundings than any other species of animal. He is able to maintain life in every zone, and in his chief physiological features he is the same wherever found. This is due, in part, to his intelligence, which enables him to protect himself from his immediate environment and prepare for future needs. Races of men differ somewhat in size and proportion of parts, but espe- cially in color of hair, eyes, and skin, where they have not migrated and intermarried. These differences are doubt- less due to the selective influence of climate and modes of life lasting long enough to produce distinct effects. Aside from differences in climate, the most important changes in environment affecting the evolution of man are to be expected in the conditions of city life, where the environment has been entirely transformed by man and where men are engaged in a great variety of specialized activities unknown to the savage. This change to city life, which is such a marked feature in modern civilization, is like transporting the human race into a new world where it is subjected to many new environing influences. In the city, with its mechanical modes of controlling temperature, RACIAL AND INDIVIDUAL DEVELOPMENT 359 light, and means of obtaining food, latitude makes little difference. The practice, however, of having the skin subjected to little variation in temjoeraturc, and i)rotccted from air and sunlight, of breathing air deficient in oxygen, and filled with gases and germs of various kinds, and of feeding upon prcj^ared foods, while engaging in highly specialized activities involving little muscular effort, must in time exercise an important selective influence upon the human race. While it is, under these conditions, less subject to some forms of disease than under the more primitive conditions of life, it is more subject to other forms of disease, especially those due to germs that thrive under such conditions of life, e.g. tuberculosis. One of the chief factors in determining the type of phvsical organi- zation that shall survive under modern conditions is that of ability to resist the attacks of various germ diseases. Another important factor determining the physiological type of the future man and woman is the character of activity required in order to succeed in the conditions of city life. Under primitive conditions of life, vigor of skin, of muscles, and digestive apparatus were the chief factors in survival, while under modern conditions continual and varied activity of the nervous system is required. In cross- ing a few crowded streets there are a greater number and variety of sensory motor adjustments than in walking a mile in the country; while a business man in his ofi'ice, in an hour's time, may make more representative and conceptual adjustments than the savage makes in a whole year. The general result, therefore, is that those who cannot endure this continuous and varied activit}- of the nervous system fail in the struggle for existence. Hence the tendency is 360 GENETIC PSYCHOLOGY in the direction of selecting for survival the nervous type of human beings so far as such an organization is consistent with the preservation of a proper balance and harmony of relation between the nervous structure and other portions of the body. This tendency is, however, counteracted and limited in various ways. A larger central nervous system means a larger head, and since infants with large heads are likely to die at birth, this cannot become a much more prominent characteristic of the race. In modern life, also, failure to succeed does not, in most cases, mean death, as it does among animals and to a considerable extent among savage races. The individual who fails continues to live, and in a large proportion of cases produces descendants. The application of the results of medical research in such way as to protect men from elimination by disease germs, and the limitation of the hours of specialized labor and the increase in athletic and recreative activities involving muscular activity, are also counteracting influences. The changes affecting the physiological development of the human race are so slow that the effects of changed environment, as found in our modern cities, have as yet produced a scarcely discernible influence. In the case of individuals, however, the effects of environment are so rapid and profound that a few years' residence makes a very striking change in the physiological processes of the individual. Every occupation produces some modifica- tion of the physical type, while living in a special environ- ment during childhood, and engaging at an early age in an occupation involving specialized activity, produce pro- found changes in the individual. RACIAL AND INDIVIDUAL DEVELOPMENT 361 The vocal organs, which are so highly developed in the throat of man, and the nervous structure controlling them, are of little or no use in reacting to the material environ- ment, but are useful chiefly in reacting to the human and mental environment. The development of the large rep- resentative and conceptual centers of the brain is also the result of mental rather than physical needs. Since the conceptual centers acquire control over the other centers and through them of the whole body, and since one's occupation, surroundings, and conduct are determined largely by one's tastes and ideas, it follows that the physiological development of man may be greatly modified by his conceptual activity. However profound such modifications may be in the individual, they can affect the race only when the conditions remain the same for many generations, or when they lead to sexual selection favoring the development of the characteristics in question. PSYCHICAL AND SOCIAL EVOLUTION IN MAN Mental evolution is affected profoundly by that portion of the physical environment which is significant in relation to practical needs. In civilized life this physical environ- ment is entirely different from that of more primitive modes of existence. The surroundings are men and their con- structions, while nature and its products are very insig- nificant phases of the environment. We now have little need to react directly to nature's forces and products, but must understand and operate machines made by man, to utilize and transform them. The child has to adjust himself to a man-made environment in which food does 362 GENETIC PSYCHOLOGY not grow on trees or run in the forest, but must be obtained from the market and paid for by means of little round pieces of metal. Clothing, so far as he sees, is not made from vegetable and animal fibers, but is obtained from the store. If one wishes to go anywhere, he does not walk, but gets on a car and pays money, or if on water, in a boat, and pays money also. If one is cold, he must turn something and the heat will come ; if one wants light, he turns some- thing else; if he wants to know what time it is, he does not look at the sun or the stars but at a watch or a clock. Mental evolution in man is, therefore, much more pro- foundly affected by the artificial and social environment than it is by the natural. Not only is the modern city child surrounded by men and a man-made environment, but a large proportion of his reactions are to men rather than to things. He also has comparatively little contact with other living creatures than man. The chief stimuli to action are his perceptions of what people do and say. In such of these actions as express emotions, as laughing, crying, etc., there is little difference between those affecting the primitive man and the child of to-day. In responsiveness to these, therefore, the child resembles the primitive man. He also resembles him in being affected by religious and other mysterious ceremonies. In all else, there is little in what the man of the present day does that resembles the activities of the primitive man, and hence little to make the child like the primitive man. The language environment, even when it persists in the same form for many generations, affects not at all the vocal apparatus of the race, while in the development of the individual child it exercises a profound influence, RACIAL AND INDIVIDUAL DEVELOPMENT 363 If the difference between the material and physical environment of the child and that in which the primitive man developed is great, we may say that the difference in mental environment is almost infinitely greater. A primi- tive people with little or no language other than that of natural signs, with no means of measuring or keeping ac- count of time or distance or of expressing number relations, has a mental environment so small that it would hardly be recognized in the map of the mental influences affect- ing the people of a civilized country, who are responding to communications from the other side of the globe and guiding their actions by events long past, or those antici- pated for the distant future. All the actions of men constitute a mental environment, because they are interpreted in subjective terms, as ex- pressions of feeling and purpose. This is true, to only a very slight extent, of animals, flowers, and inorganic things. We may say, therefore, that the human environment is a mental and social environment in a greater degree than it is a merely physical one. With the advance in civilization, human environment becomes more and more influential in the reactions of the individual, because added to the actions of living men are the traditions and records of what men have done. The conditions of life are also such that man no longer struggles directly with nature for his live- lihood, but by some form of specialized activity in coopera- tion and competition with other human beings, he indirectly obtains the means of subsistence. There are few occupa- tions in our present complex life in which success does not depend, to a greater extent, upon one's ability to react in appropriate ways to men and to their knowledge, tastes, 364 GENETIC PSYCHOLOGY and beliefs than it docs upon one's ability to deal success- fully with things. The successful merchant and manu- facturer must know what will please men and women or he fails, whatever his practical or scientific knowledge of things may be. While this is true in a marked degree even in the attainment of the material necessities of life, it is true in a very much greater degree in the attainment of success in immaterial ways, e.g. in obtaining social and political positions. Every development of social, artistic, moral, religious, and intellectual interest, and every new mode of gratifying such interest, opens out a new line of development for the individual and the race. With advance in civilization the course of mental development is determined more and more by these human influences and less and less by the material environment and the physiological needs of the body. There is, therefore, a psychical development largely independent of physiological development and of the law of natural selection in the form of physical survival. In- tellect in both the child and the race is developed more rapidly by social and psychical stimuli than by the stimulus of things. In the associations of men with each other, especially in the cooperative action of the members of a group, some modes of reacting to the mental states of others are found effective, and because of their satisfactory results are retained. When these modes of reaction are established as customs or laws in any race of people and when there are institutions, such as governments, churches, societies, and corporations to give expression and force to them, we have in social life a mental environment that exercises RACIAL AND INDIVIDUAL DEVELOPMENT 365 a profound influence upon the development of that group of people. These modes of behavior and these institutions persist for many generations, modifying profoundly the development of each generation as it appears. These social customs and institutions determine from without the development of individuals just as effectively as structural changes in lower organisms determine their development from within. If such influences lasted long enough, the nervous structure of the race as well as of the individuals of each generation, might conceivably be modified by these cus- toms and institutions. This modification, however, if oc- curring at all, would be chiefly general in character, increas- ing only sensitiveness to human influences and the capacity for aesthetic and moral emotions and for intellectual acqui- sitions, without producing any increase in any particular kind of social, artistic, moral, religious, or intellectual tendency. The principle of selection acts in the development of customs and institutions in society just as it does in the individual in the development of habits ; those found most efficient surviving, as a rule; although, as in the case of habits, the most economical form is not always reached before they become fixed, and having become fixed, they may persist long after they have ceased to be efficient. Social organization, like consciousness, develops most when changes arc taking place. The more distinctively psychical peculiarities of a people are therefore preserved, not in their brain structure, but in their customs and institutions, knowledge, and beliefs, which, in so far as they are constant and uniform, cause the same characteristics to develop in most of the individuals of each generation. 366 GENETIC PSYCHOLOGY Changes may be much more quickly produced in the psychical characteristics of a people than in the instincts of a species of animals, because a change in the physio- logical structure of the race does not have to be produced, but only a change in the environment. Furthermore, the change of psychical environment possible to man, through his power of imitation and ability to understand words, enables a nation to acquire in a very short time many of the psychical characteristics of another nation. The amount of change in mental characteristics that may be produced in a people by such control of the social and psychical environment as man now possesses is far greater than could be achieved through any conceivable modifica- tion of the nervous structure of the race, either specific or in the form of general capacity. The future progress of the human race will therefore be more and more through psychical and social influences embodied in customs, in- stitutions, knowledge, and education. The change in the course of development from the pro- duction of specific apparatus to the production of capacity for acquisition, and the resulting increase in importance of the environment as a positive factor in development, together with increase in the part that consciousness plays in development, has tended more and more to exalt in importance the individual rather than the species. In man, who is not only conscious but self-conscious and aware of what he has been and what he may become, the indi- vidual is of supreme importance. In his conscious life is found a distinct world separate from that of every other individual and developing from a very simple state into higher and higher types of unity. To trace this develop- RACIAL AND INDIVIDUAL DEVELOPMENT 367 ment of the individual consciousness is the special problem of genetic psychology. In order to do this we must know something of the way in which environment affects this inner life and also the influence U])on the development of consciousness of the physiological and sensory motor or- gans and apparatus, whose activities are organized before consciousness has begun and which in the earlier stages have more influence upon the production and organization of conscious states than conscious states have upon them or upon the working of the representative and conceptual apparatus. The body with which the representative and conceptual apparatus is associated determines not only the type of organization but the individual temper- ament. The actual organization and development of psychical characteristics take place as the individual con- sciousness is aroused and selects for survival in its inner world various phases of the environment. Conscious selection, therefore, rather than natural selection is the chief factor in the evolution of the individual consciousness. The author hopes in a subsequent volume to treat of the working of conscious selection in the development of individual consciousness under the conditions imposed by the material and psychical environment and the physio- logical and sensory motor intelligence with which we have found the consciously directed intelligence to be so closely related. REFERENCES Baldwin, J. M. Development and Evolution. Mental Evolution, Methods and Processes, especially Chap- ter VI. 368 GENETIC PSYCHOLOGY Baldwin, J. M. Social and Ethical Interpretation, especially Chapters II, IV, XIII. Chamberlain. The Child, Chapter VII. * Conn, H. W. Evolution of To-day. Method of Evolution. Darwin, C. R. Descent of Man and Selection in Relation to Sex. Darwin, Francis. Habit Illustrated by Morphology, Science, September, 1908, pp. 385-396. Davenport, C. B. Experimental Morphology. ♦GuiLLET. Recapitulation and Education, Ped. Sent., Vol. VII, pp. 397-445- Haeckel. Evolution of Man. Headley, F. W. Life and Evolution. Kellogg, V. L. Darwinism of To-day. McDougal. Heredity and Environic Forces, Science, Jan. 24, 1908. * MiNOT, C. S. The Problem of Age, Growth, and Death, Pop. Sci. Mo., Vol. LXXI, pp. 97-120, 193-215, 359-377, 455-473, 509-523- Morgan, T. H. Regeneration. Experimental Zoology. ♦Morgan, C. L. Animal Life and Intelligence, Chapters IV, V, VI. Pearl, Raymond. Some Results of a Study of Variation and Cor- relation in Brain Weight, Jr. Comp. Neu. df Psych., Vol. XV, pp. 467-481. Reid. Principles of Heredity, Chapters V, IX, X, XI, XII, XIII, XIV, XXI. Romanes, G. J. An Examination of Weismanism. * Swift, E. J. Mind in the Making, Chapter VII. Tayler, J. L. Aspects of Social Evolution. Thomas. Sex and Society, pp. 223-314. Thomson, J. Arthur. Heredity. Watkins, G. p. Forms of Selection with Reference to Their Applica- tion to Man, Pop. Sci. Mo., Vol. LXXI, pp. 69-83. Weismann, a. The Germ Plasm. INDEX Adaptive instincts, 100-103. activities, 257-285. Adenoids, 346. ^Esthetic instinct, 104. feelings, 222. pleasure, 272, 354. Allen, 75. Amoeba, 39-43, 170, 286. Amphibia, 66-68. Anger as an emotion, 215. Angleworm, 220. Animals distinction from plants, 7, 8, 257. types of behavior of, 39-88. domestic, 81-85. Ants, 72-76. Aphasia, 149. Arithmetic, 286-289, 322-325. Association, 243, 308. Attention mechanism of, 162-168. of animals, 250-254. Baldwin, 122. Basal ganglia, 144. Beaver, 103. Bees, 267. Behavior as a common characteristic, 2. as basis of genetic psychology, 3.4- genesis of, 8-13. structural basis of, 16-37. types of, 39-88. distinguished from physiological processes, 87-88. of species, 92-109. of individuals, 111-139. structure concerned in, 141-168. Bell, 63. Bentley, 65, 128. Berry, 81, 121. Bethe, 63. Birds, 82, 102, 104, 107, 170, 204, 247. 248, 331, 355- Bohn, 61, 62. Bose, 173. Bostick, 295. Brain of vertebrates, 141-146. difference of man's, 146-152. functioning, 152-156. special processes of, 156-162. possibilities of, 280. i, 352, 354- 114, 118, 120, 250. Capacities, Cats, 81, 9^ Cattle, 97. Cell reproduction and germ, 331. in individual and racial develop- ment, 339-342. relations in development, 342-348. Cerebellum, 142, 144. Cerebrum, 141, 144. Chickens, 81, 115, 116, 120, 251. Child, 122, 124, 147, 181, 271, 292, 293, 296, 298, 301, 303, 304, 310, 317. 318, 319, 357. 361. 362. Children, 4, 117, 124, 184, 224, 286, 301, 304, 305. Creek chub, 65, 120. Clams, 60, 170. Cole, 84, 131, 240. Color sensations, 21, 22. perceptions of fish, 65. perceptions of insects, 73. perceptions, 199, 226. concepts, 304. Comparative Psychology, 2. 2B 369 37° INDEX Concepts physiological mechanism of, 162, '166-16S. and reasoning, 247-248. Conceptual centers, 151, 152, 155, 166, 167, 361. intelligence, 275-281. Consciousness as basis of genetic psychology, 2-3. to be assumed only when neces- sary, 13-14. of amoeba, 42. and learning, 127-128. objective criteria of, 169-178. subjective criteria of, 1 79-191. continuity and unity of, 193-198. of animals, 206-210. specific states of, 214-250. Cooperation of animals, 97. of men, 349, 350, 351, 363. Cord, spinal, 143. Courtis, 24. Crabs, 62, 63, 113, 115, 176, 341. Crawfish, 63-64. Crow, 82, 103. Curiosity, 102. Darwin, 104, 194. Davis, 84, 131. Death feint, 71. Deer, 237, 239, 339. Development stages of, 12. of motor structures, 31-33. of nervous structure, 33-37. of free images, 126-139. of concepts, 302-307. of race and individual, 331-367. Dog, 37, 81, 98, 99, 108, 120, 121, ^35, 136, 170. 186, 194, 195, 196, 225, 238, 244, 252, 253, 254. Ears, 26. Echinoderms, 58. Elephant, 138. Embryo, 332, 333. Emotions, 215-217. Environment enlargement of, 354-358. Evolution and genesis of behavior, 8-13. physiological of man, 358-361. psychical and social, 361-367. Expressive instinct, 106. Fear instinct of, 93, 94. relation to religion, 107, 108. as an emotion, 215. Feeling in animals, 214-217. pain, 217-222. Fi.sh, 64-66, t20. Focalization, 208-210. Form perception of, 22, 23. concept of, 305. Foxes, 103. Franz, 145. Frog, 24, 36, 66-67, 141-143. 165, 180, 192, 219. Genesis of behavior, 8-13. Germ cell, 331, 332, 233- Goat, 268. Goltz, 143. Graber, 20. Gredler, 76. Grief, 215. Guinea pigs, 76-78, 79. Habit of starfish, 59, 60. formation, 111-119. complication with instincts, 119- 126. and memory, 244-245. and reasoning, 247-248. Haggerty, 134. Hawk, 267. Hearing organs of, 23-26. Hen, 96. Heredity, 12. Hobhouse, 133, 135 Hodge, III. Holmes, 68. Horse, 97, 215, 238, 292. Hydra, 53-56. INDEX 371 Ideas free, 126-139. Image free, 126-139. loss of, 149. centers, 151. mental, 158-160. and perceptions, 200-201. and memories, 160-162, 238-247. in learning, 299-302. Imitation, loi, 123-126, 298, 310- Individual behavior, 111-139. and racial development, 331-368. Infant, 122, 136, 148. Infusoria, 43-53- Inhibition, 120. Instincts nature and differentiation, 76-93. individualistic, 93-95. "" parental, 95-96. social, 97-99. adaptive, 100-102. play, 100. imitative, loi. curiosity, 102. constructive, 102-103. aesthetic, 104. teasing, 105. jealousy, 105-106. e.xpressive, 100. regulative, 106-109. moral, 108. fear, 107. religious, 107-108. complication with habits, 119- 126. specialization of, 102-109. Intellectual states, 222-254. Intelligence objective tests of, 169-178. a broader conception of, 257-259. physiological, 259-263. sensory motor, 264-269. representative, 270-275. conceptual, 275-281. tj'pes of in man, 281-284. Interest, 250-254. Jackson, 154. Japanese mice, 21, 226. Jealousy, 105. Jelly-fish, 341. Jennings, 112, 116. Judd, 183, 236, 307. Keller, 24, 283. Kinnamcn, 85. Learning and suggestive stimuli, 28. and habit, 116. and consciousness, 183-184. nature of, 287-288. physiological, 288-291. . sensory motor, 291-297. representative, 297-302. conceptual, 302-307. reversal of processes of, 307-314. combination, 314-328. to read, 317-321. to write, 321-322. of mathematics, 322-325. Light, 20-23. Lindley, 271. Littorina, 61. McDougall, 337. Manual training, 312. Medulla, 142. Medusa, 56-58. Memory, 160-162, 238-247. Mental images, 158-160. Minot, 189. Mobius, 120. Modifiability, 176-178. Molusca, 60-62. Monkey, 83-85, 133, 134, 137. 138. 151, 170. Morgan, 115. Motion and intelligence, 172-174. Motor structure, 31-33. Natural selection, 9, 348, 354. Nervous system of man and animals, 146-152. Neuroses, 257. Nicoli, 198. 372 INDEX Objective terms, 4, 198-205. Optic thalami, 141. Ontogenetic, 331. Organisms subject of study, 2-3. characteristics of, 5-8. Organoses, 257. Pain, 217-222, 353, 354. Paplow, 198. Paramecium, 43-53, 113, 182. Parrots, 82. Penguin, 96. Perception physiology of, 156-158. and images, 158-160. of space, 227-233. of objects, 233-238. Phototropic, 20. Phylogenetic, 331. Physiological processes, 87-88. intelligence, 259-263. learning, 288-291. Pigeon, 36, 81, 82, 135, 176, 232. Pigs, 235. Plants, 7, 8, 257, 264. Play, 100. Pleasure, 353. Preyer, 116. Prince, 204. Psychic factor, 13-14. Psychoses, 257. Purpose and intelligence, 174-175. Raccoons, 83-85, 131. Racial instincts, 95-96. Ranatra, 68-71. Ransom, 63. Rat, 78-81, 118, 177, 242. Reasoning, 247-250. Recognition, 245-246. Refle.xes, 92, 93. Religious instinct, 107-108. Representative centers, 154, 155. intelligence, 270-275. learning, 297-302. Romanes, 225. Salmon, 95. Selection in individual and racial development, 348-354. Sensations, 222-227, 234. Sensitive structures, 17-26. Sensory motor centers, 157. intelligence, 264-269 learning, 291-297. Shark, 219. Sight organs of, 20-23. Smell organs of, 19. sense of, 28-29, 222-225. Smith, 113. Social instincts, 97-99, 124, 361- 367- Somatic sense organs, 30-31. motor organs, 23- Sound stimulation, 23-26. Space perception, 227-233. Sparrows, 9. Spaulding, 62. Stentor, 50-53, 116, 341. Stimuli fundamental, 18. tactile, 18. chemical, 18-19. light, 20-23. sound, 23-26. suggestive, 26-30, 239-241. Stratton, 266. Structure as a common characteristic, 2. as determining survival, 9-12. basis of behavior, 16-37. sensitive, 17-26. motor, 31-33. and complex behavior, 141-168. and consciousness, 169-170. Subconsciousness, 204-205. Subjective, 198-205. Suggestive stimuli, 26-30, 239-241. Survival, 9, 119. Sympathy, 216. INDEX 373 Taste organs, 18-19. sensations, 222-223. Teasing, 105. Tendon reflex, 164. Thorndike, 83, 131. Thyroid, 345. Toilet-making instinct, 103-104. Tortoise, 67-68. Touch organs, 17-18. sensations, 222-223. Triplett, 120. Turner, 75. Types of intelligence, 257-284. of learning, 286-328. Unity of organism, 6-7. of consciousness, 187, 193-198. Variation, 12, 328, 329. 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