t^lpj ^^m- ^^ ^^ ^"l^/^J^^^ § ^jSa^lj^gjj*^ ■ P Jy^^^ii^^ M s K.^^*^ liiToni ~it^j«t«3' Fig. 1. — Outer surface of left hemisphere of the brain (modified from Exuer). Fio. 2.-Inner (mesial) mrface of the Hght hemisphere of the brain (modified from Schiifer and Horsley). In both cases the shaded area is the motor zone. See i>af;e 47. ELEMENTS OF PSYCHOLOCT BY JAMES MARK BALDWIN Pi'ofessor-dect in Pnnceton Coaege, Professor in the University of Toronto, Author of " Handbook of Psychology."' NEW YORK HENRY HOLT AND COMPANY .1893 Copyright, 1893, BY HENRY HOLT & CO. tARYr EDUC. PSYCH. LIBRARY PSYCH. LtBRABY THE MKRSUON COMPANY PRBS8, RAHWAY, N. J. PREFACE. This book has been prepared in response to a request from a number of teachers of psychology in the universities who suggested that the expense and length of my Hand- hook of Psychology precluded its use as the text in their courses of instruction. I have, accordingly, aimed to make a book which shall present the newest essentials of the science in a single compact volume at reasonable cost. It differs from my larger work mainly in its omissions. I have endeavored, however, to simplify the exposition, throughout, often rewriting whole sections or recasting whole chapters with this in view, and adding more illustra- tive facts and explanations. The treatment of the nervous system has been put at the beginning — a pedagogical concession to my critics, to which I ask attention as unanimous as their criticism. In uegard to other alterations — respecting which the critics' opinions have largely neutralized one another — I have depended as before mainly on my own judgment. AVhat these alterations are the book is here to show. I am sorry that the doctrine of " Feeling " has not aroused the ap- proval in its readers tliat the doctrine of "Belief" has. It is stated more clearly in this book ; but it is the same doc- trine, and — may everybody be converted ! Finally, I have added before the first chapter a short glossary of terms likely to embarrass the student at the beginning of his study ; and instead of burdening the pages with references to the authorities, I have given at the outset once for all the oeneral works (Enolish mainlv) in which detailed and IV PREFACE. exhaustive expositions may be found. A reference to the corresponding fuller treatment of my own larger work is given at the beginning of each chapter. I may add that I am grateful to all who have done my w^ork the honor of reviewing, teaching, or reading it ; especially to the reviewers. One who is conscious of his own sins feels the more the humanity of the physician who forbears to probe them too deeply. J. Mark Baldwin. Toronto, January, 1893. CONTENTS. PAGES Glossary of Terms, xv References, xvi INTRODUCTION. CHAPTER I. NATURE OF PSYCHOLOGY. i^ 1. i)e^/^^7^o?^.— Subject-matter of psychology.— Distinc- tion between psychological and physiological facts. — True relation of psychology to physiology, . . 1-5 § 2. Difficulties and Errors in Psychology.— Use of reflection. —Means of remedying these difficulties : supplemen- tary psychological sources. — External sources, . 5-11 §3. Unity of Psychological Sources in Consciousness, . . 11 CHAPTER II. PSYCHOLOGICAL METHOD. § 1. Principles of Scientific MetluxJ. — In general, . . 12-13 § 2. Application of Scientific Method to PsycJiology.— Psycho- logical observation, 13-15 § 3. Experiment in Psychology. — General conclusion, . . 15-18 CHAPTER III. THE NERVOUS SYSTEM. § 1. Structure of the Nervous System. — Nerve-elements. — Combination of elements into a S3"stem. — The receiv- ing apparatus. — The reacting apparatus. — The regis- tering apparatus, 19-32 § 2, Functions of the Nervous System. — Fundamental pro- perties of nervous tissue. — Neurility. — Sentience : integration, retention, selection. — Law of nervous dynamogenesis, 32-39 V CONTENTS. PAGES § 3. Kindsof Nervous lieactio)!.— Automatic. — Reflex. — Vol- untary. — Negative : inhibition, .... 39-44 § 4. Principles of Nerwus Action. — Specialization. — Cerebral localization. — Indifference. — Substitution. — Specific connection. — Summation, 44-51 § 5. Final Statement of Nervous Fimction. — Habit. — Accom- modation, , . . 51 CHAPTER lY. CLASSIFICATION AND DIVISION. § 1. Three Great Classes 52-53 § 2. Unity of the Three Classes in Consciousness, . . 54-55 § 3. Division of the Subject, 55 PART I. GENERAL CHARACTERISTICS OF MIND. CHAPTER y. CONSCIOUSNESS. § 1. Nature of Consciousness, 56-57 § 2. Area of Consciousness. — Degrees of consciousness. — Apperception, 57-60 § 3. Development of Consciousness, 60-62 § 4. Nervous Conditions of Consciousness, . . . 62-64 § 5. Sentience and Sensibility, 64-65 § 6. Kinds of Consciousness as Dependent on Nervous Func- tion. — Passive consciousness. — Reactive conscious- ness. — Voluntary consciousness. — Fundamental prop- erties of consciousness, 65-70 § 7. The Nervous System and the Unity of Consciousness, . 70-71 CHAPTER VI. ATTENTION. § 1. Definition of Attention. — Reflex or involuntary atten- tion. — Voluntary attention, 71-74 §2. Bearings of Attention in tlie Menial Life. — Relation of attention to sensation. — To movement. — To the intel- lect.— To feeling.— To the bodily functions, . 75-79 § 3. Educational Bearings of the Doctrine of Attention.— Training of the attention. — Habits of attention, . 79-80 C0NTt:NT8. PART II. INTELLECT. CHAPTER YII. DIVISION OF THE INTELLECTUAL FUNCTIONS. 1. The Apperceptive Function, 2. The national Function, . PAGES 81 83 §6. §8. THE APPERCEPTIVE FUNCTIOK PRESENTATION. CHAPTER Vni. SENSATION. General Nature of Sensation. — Distinction between sensation and impression. — Affective and presenta- tive elements in sensation, Characters of Sensation, Quality of Sensation. — Relativity of. — Contrast, Special Sensations. — Smell, — Taste. — Hearing. — Pre- sentative elements in sensations of sound.— Sight, Common Sensations.— Organic . — Cutaneous. — Touch. — Temperature sense. — Muscular sensations. — Kin- aesthetic. — Innervation sensations. — Effort and re- sistance. — Presentative element in muscular sensa- tions. — Nervous sensations. — Physiological basis of common sensations, Quantity of Sensation : Psychophysics. — Wobfi's law. — Extensive or massive sensations. Duration of Sensation and Tlwught : Psychometry. — Effect of attention upon the duration and quantity- of sensation. — Effect of duration upon the intensity of sensation, Tone of Sensation, . . . . . CHAPTER IX. PERCEPTION. 83-84 84-85 85-87 87-93 Definition of Perception, Analysis of Perception, 93-103 103-106 106-110 110 111 111-113 CONTENTS. \ 3. Differentiation, 112-113 5 4. Localization. — The perception of space. — Data for the perception of space. — Synthesis of data ; tactual space, — Visual perception of space. — Presentation of foreign body. — Visual perception of distance. — Localization of sounds in space. — Feeling of equi- librium from the ear. — Ideal product of localiza- tion : idea of space, 113-123 5 5. Sense-Intuition. — Motor-intuition, .... 123-126 \JS^ Reflection or Self -consciousness. — Ideal product of reflection ; idea of self, 126-127 REPRESENTATION. Pernors. CHAPTER X. RETENTION AND REPRODUCTION. Memory. — Difference between representation. — Definition of General Nature of presentation and memory, 128-134 Retention. — Theories of retention. — Physiological theory. — Physical basis of memory. — Mental con- ditions of retention, 134-143 Reproduction. — Its primary condition. — Supplemen- tary condition. — Secondary aids to reproduction. — Power of imaging.— Retention and reproduction as mental growth, . . • , • • • • 143-148 CHAPTER XI. RECOGNITION AND LOCALIZATION. § 1. Recognition. — Feeling of familiarity. — Distinction be- tween recognition of an object and of an image, . 149-152 §2. Ideal Product of Recognition : Personal Identity, . 152 § 3. Localization in Time. — Data for the reconstruction of time. — Intensity as an indication of time. — Move- ments of attention as indicating position in time. — Units of duration.— Perception of time by the ear, 152-159 § 4. Ideal Product of Temporal Localization : Idea of Time, 159 §5. Kinds of Memory : Local, Logical, .... 159-160 CONTEXTS. IX COMBINATION. CHAPTER XII. ASSOCIATION. § 1. General Nature of Association. — Definition. — Ground or reason of association : the preceding idea. — Physiological basis of association, § 2. Laics of Association. — Particular or secondary laws. — Association by contrast. — Universal or primary law. — Law of correlation. — Interest as influenc- ing association, §3. For^ns of Association . — Complex associations, . § 4. Force of Association, 161-163 163-171 171-174 174 §1- §3. §3. §4. §5. CHAPTER XIII. IMAGINATION. Passive Imagination. — Material of the imagination. — Presuppositions : memory and association, . Modes of Passive Imagination. — Dissociation. — Com- position. — Fancy. — Relation of fancy to reality, Active or Constructive Imagination. — Definition, Analysis of Constructive Imagination. — Natural im- pulse or appetence. — Intention. — Selective atten- tion. — Feeling of fitness, Kinds of Constructive Imagination. — Scientific imag- ination. — Relation of scientific imagination to reality : Esthetic imagination. — Law of construc- tive imagination : correlation, .... Ideal Product of the Imagination : the Infinite, 175-178 178-182 182 182-187 18i -191 191 CHAPTER XIV. ILLUSIONS. § 1. Nature of Illusion. — General character of illusion. — Illusion due to interpretation, .... 192-194 § 2. Grounds of Illusion. — Similarity of presentations and representations. — Absence of internal stimulus. — Intra-organic stimulus : Mental predisposition to illusion 194-198 § 3. Kinds of Illusion. — Illusion proper. — Elements of reality in illusion proper.— Hallucination, . . 198-201 CONTENTS. PAGKS 4. Detection and Rectification of Illusion. — Diminished intensity. — Absence of locality. — Inappropriate escort. — Voluntary control, 201-204 ELABORATION. CHAPTER XV. THOUGH^. 1. Nature of ThougJit.— General character.— Stages, . 205-206 2. Conception. — Process of conception. — Abstraction. — Generalization. — Products of conception. — Lan- guage in its relation to conception. — The use of images in conception, 206-211 3. Judgment. — Its nature. — Law of identity. — Unity of the judgment. — Parts of the proposition, . . 211-214 4. Kinds of Judgment. — According to intention. — Ac- cording to belief : categorical judgments. — Law of sufficient reason. — Hypothetical judgments, . 214-216 5. Reasoning. — Deduction : the syllogism. — Conceptual interpretation of the syllogism, .... 216-219 6. Induction. — Relation of induction and deduction, 219 7. Proof, 219-220 8. Ideal Product of Thought 220-221 §1 PART III. FEELING, CHAPTER XVI. NATURE AND DIVISIONS OF SENSIBTLTY. Nature of Sensibility. — Definition. — Most general mark of sensibility, § 2. Division, CHAPTER XVII. PLEASURE AND PAIN. § 1. Physical Condition^ k)f PimWU aiutTain, § 2. Resulting Conception.— General conclusion on sen- suous pleasure and pain, 222-224 225 226-233 233-236 CONTENTS. XI PAGES § 3. Primary Ideal Conditions, 236-237 § 4. Secondary Conditions, 237-239 § 5, Final Conclusion on Pleasure and Pain, . . - 240 IDEAL FEELING. CHAPTER XVIII. NATTJRE AND DIVISIONS OF IDEAL FEELING. § 1. Nature. — Ideal vs. sensuous feelings, . . . 241 § 2. Division. — Ideal feelings as special and common. — Ideal pleasure and pain, 241-242 COMMON IDEAL FEELING. CHAPTER XIX. INTEREST, REALITY, AND BELIEF. § 1. General Character of Common Ideal Feeling: Interest. — Conditions of interest. — Interest of discrimination. — Active interest. — Interest of custom or habit. — Definition of interest. — Interest as ideal emotion, 243-249 § 2. Beality-feeling. — Distinction between belief and real- ity-feeling. — Rise of reality-feeling. — Rise of un- reality-feeling. — Degrees of reality- and unreality- feeling, 249-253 § 3. Belief. — Doubt. — Development of doubt. — Resolution of doubt. — Nature of belief. — Reaction of belief on reality.— Kinds of belief , 253-257 § 4. Belief in External Reality. — Its coefficient. — Primacy of muscular sensations. — Criteria of external reality, 257-258 § 5. Belief in Memory. — Memory-coefficient, — Completed criterion of reality, 259-261 § 6. Belief in Concepts and ThougJit.—Thought-coemciQnt, 261-262 § 7. Emotional Belief, 262 § 8. General Conclusion. — Composite realities, — Self the ultimate reality, — Existence, — Relation of belief to will, — Definition of belief, — Interest and belief, 262-265 xii CONTENTS. SPECIAL IDEAL FEELINGS. (Sluallt^, or 1kln&0, CHAPTER XX. DIVISION : PRESENTATIVE EMOTIONS, PAGES § 1. Duision. — General nature. — Kinds, .... 266-267 § 2. Emotions of Activity. — Of adjustment. — Of function, 267 § 3. Emotions of Content, 268 §4. Self- Emotions, 269-270 § 5. Objective Emotions, 270 § 6. Expressive Emotions. — Emotions of attraction. — Of repulsion, 270-273 § 7. SympatJietic Emotion. — Its nature and development. —Social feeling, 273-278 § 8. Bepresentative Emotions, 278 §1- §3. §3. §4. §5. §7. CHAPTER XXI. EMOTIONS OF RELATION. Logical Emotion, Conceptual Emotion Construction of Ideals.. — Nature of ideals. — Feeling of fitness Range of Conceptual Feeling, Feelings for System. — In science. — In philosophy, Etliicdl Feeling. — Its coefficient. — Moral quality. — Moral sympathy. — Moral authority. — Moral ideal. — Rules of conduct, JEstlietic Feeling. — Lower. — Higher. — Varieties in, . General Table of Feelings, 279-280 280-281 281-284 284 284 284-293 293-298 §2. CHAPTER XXII. QUANTITY AND DURATION OF EMOTION. Quantity or Intensity. — Relativity. — Emotional Ex- pression. — Diifusion of emotion. — Passion. — The- ories of emotion. — Reproduction of emotion. — Association and conflict of emotions, Duration of Emotion, 299-306 306-307 CONTENTS. §3. §3. §4. §5. §6. PART IV. MOTOR ASPECTS OF SENSUOUS FEELING. CHAPTER XXIII. THE MOTOR CONSCIOUSNESS. PAGES . Idea of tJie Motor Consciousness. — Law of mental dy- namogenesis. — Varieties of the motor conscious- ness, 308-309 Motor Value of tJie Subconscious, .... 309-311 Motor Value of Reactive Consciousness. — Elements involved, 311-313 Feeling of Expenditure in Reflex Attention. — Sensorial and intellectual attention, 313-314 Theory of Refl£x Attention, 314-316 Conclusion on Reflex Attention, .... 316-317 CHAPTER XXIV. STIMULI TO INVOLUNTARY MOVEMENT. Notion of Stimulus. — Kinds of motor stimuli. — Extra- organic. — Reflex. — Suggestion as motor stimulus. — Organic stimuli. — Expressive reactions. — Pleas- , ure and pain as stimuli. — Nature of pleasure and pain reactions. — Motor spontaneity, . . . 318-324 Impulse and Instinct. — Impulse. — Definition. — In- stinct. — Complexity of instinct. — Definition of instinct. — Variability of instinct, . . 324^330 Affective Nature of all Stimuli to Movement. — Affects. —Division of affects, 330-331 MOTOR ASPECTS OF IDEAL FEELING. CHAPTER XXV. STIMULI TO VOLUNTARY MOVEMENT. § 1. The Voluntary Motor Consciousness : General Stim- uli. — Interest. — Affects as voluntary stimuli, . 332-334 § 2. Special Stimulus : Desire. — Impulse in desire. — Desire and its objects. — Rise of desire. — Tone of desire. — Coefficient of desire. — Physical basis of desire, 334-338 § 3. Motive, ,,....,., 338 CONTENTS. §3. §3. §4. §5. §6. CHAPTER XXVI. VOLUNTARY MOVEMENT. FAGES Feelings of Effort and Consent. — Fiat, psychological and physiological. — Neget, psychological and phys- iological. — Consent. — Summary on muscular effort. — Muscular effort and the attention. — Develop- ment of voluntary movement. — Theory of innerva- tion, 339-346 CHAPTER XXVII. VOLITION. Purpose : Voluntary Attention as Choice. — Law of motive, — Nature of motives. — Volitional appercep- tion. — Controlling motive. — Deliberation. — Choice. — Potential and final choice. — Feeling of alterna- tives. — Moral choice. — Choice and habit. — Intellec- tual effort, Character. — Development of character, through choice, Initiation of Motives by Attention, .... Freedom of the M7^.—Indeterminism.— External de- terminism. — Immanent determinism. — Freedom as self-expression, — Feeling of freedom — of responsi- bility, Effects of Volition. — Expressive effects. — Effects proper.— Physical control.— Mental and moral control, ,,....... 367-371 Rational Aspects of Volition. — Intuition of power. — Intuition of obligation, 371-373 347-358 358-361 361-363 363-367 GLOSSARY OF TERMS.' Presentation : a mental picture or image, any object of knowledge or thooght. Representation : the same when remembered or revived. Presentative : having reference to an object of consciousness. Idea : a mental state of any kind, considered as subject to reproduction or revival. Subjective : belonging to the subject, i. e., to consciousness itself. Objective : belonging to things considered as objects of consciousness. Empirical : belonging to or derived from the observation of events themselves; de- rived from experience. Experiential : the same. Empiricism: the doctrine that all knowledge is derived exclusively from experi- ence. Intuition : (1) the act of looking at directly, without a medium of any kind ; (2) the information reached by euch an act ; (.3) knowledge is intuitive or rational when it is open to immediate inspection, i. e., needs no proof. Rational : applied to knowledge in about the same sense as intuitive, above. Intuitionalism : the doctrine that some knowledge is intuitive, i. e., not derived exclusively from experience ; opposed to Empiricism. Phenomenon : an event, change, happening, of any kind. Synthesis : (1) a union of elements in which these elements are themselves hidden; (2) the process of uniting elements as described. Integration : (1) a union of elements in which these elements are still evident ; (2) the process of bringing about such a union of elements. Function : (1) an activity, process, or performance (applied to organisms) ; (2) an expression for, or way of stating a thing (mathematical use) ; (3) a regular appearance of, or event in (consciousness : use in psychology). Relative : to a degree dependent. Absolute : not relative, independent. Content : material, or filling. Form : that which sets limits to a content ; that which ia filled. Postulate: si, presupposition. Hypothesis : a postulate put forth to explain a set of observed facts. Inductive : resting on observed facts. Deductive : guaranteed by a general principle. Affective : happening in consciousness but not referring to an object ; opposed to 2)resentative. Co-efficient : an essential i)eculiarity, or distinguishing mark ; a standard, or normal value. Dynamic : progressive, forceful, causal. 1 The best way for the student to become familiar with the use of these words is simply to neglect this list until he come to the terms one by one in the body of the book. xvi REFERENCES. Genetic ; belonging to the origin or birth. Reaction : response, stimulated discharge. Sensor : stimulating, or contnbuting to, sensation. Motor : stimulating, or contributing to, movement. Afferent : transmitting toward the brain ; sensor ; centripetal. Efferent : transmitting away from the brain ; motor ; centrifugal. Periphery : outside, surface (of the body). Peripheral : belonging to the periphery. Central : belonging to, or located in, the nerve centers, or gray matter of the nervous system. REFERENCES. The student may consult with profit the expositions given, from different points of view, in the following works, where full references to further literature may also be found : James, Principles Of Psychology (2 vols., Holt and Macmillan). Hbffding, Outlines of Psychology CMacmiUan'). Sully, The Human Mind (2 vols., Longmans). Ladd, Elements of Physiological Psychology (Scribners). Ribot, Germaii Psychology of To-day (Scribners). Bain, The Senses and the Intellect (3d ed., Longmans). Bain, The Emotions and the Will (3d ed., Longmans). Wundt, Grundzuge der Physiologischen Psychologie (2 vole., 3d ed., Engelmann, Leipzig). Wundt, Vorlesungen uber die Menschen und Thierseele (2d ed., Voes, Leipzig). Volkmann, Lehrhuch der Psychologie (3d ed , Schulze, Cothen). References to the author's Handbook of Psychology (2 vols.. Holt and Macmillan) are given at the beginning of the several chapters of this book. ELEMENTS OF PSYCHOLOGY. INTRODUCTION, CHAPTER I. NATURE OF PSYCHOLOGY. » § 1. Definition. Subject-matter of Psychology. We may define psy- chology as the science of the phenomena of consciousness, being careful to include consciousness wherever and in whatever stages it be found ; or, if we emphasize, not so much the facts with which we deal, as the mode of our knowledge of these facts as the science of mind as ice know it. By " phenomena of consciousness " we mean happenings or events in consciousness, everything that belongs to our minds : sensations, impulses, acts of will, reasoning proc- esses, etc. The question of psychology is : " Is there an order of mental facts apart from the phenomena of the physical sciences and especially physiology ? " This question is sometimes answered negatively. Psychology, we are told by the materialists, is properly a branch of physiology : ^ Handbook, vol. i. chap. 1. A footnote reference such as this is given at the beginning of each of the following chapters to indicate the fuller treatment of the corresponding topics in my Handbook of Psychology. Full references for further reading are to be found at the end of the several chapters of the Handbook. 2 : NATURE, OF PSYCHOLOGY. since physiology, as the' science of tlie functions of the bodily organs — the lungs in respiration, the heart in circu- lation — includes the function of the brain, which is thought. Psychology thus becomes a special chapter in physiology. This identification of mental facts with organic and vital facts is wrong. There exists between the two orders of facts a radical opposition in several particulars. Distinction between Psychological and Physiological Pacts. The opposition between these two classes of facts takes several distinct phases. I. Relation to Movement. The organic functions are simply movements of the organs of the body, that is, movements of matter in space. The functions of diges- tion and circulation are the physical activity of their respective organs, and the science of such functions is nothing more than the complete knowledge of these movements. With thought or feeling the case is very different. Without doubt thought has some of its con- ditions in the brain, and yet we cannot say that thought is movement. The most that can be said, by the most ad- vanced materialism, is that thought is an effect or result of cerebral movement. Let the movement be what it may and let the mental fact be what it may, there is nothing in common between them. Something must be added to movement to give feeling. The fullest know^ledge of the brain would not lead us to suspect the existence of such a thing as thought if we did not know it already in con- sciousness. If an animal for example, says M. Rabier, ex- perienced sensations quite different from any we know, the most exact knowledge of what takes place in the brain of the animal would throw no light upon their nature ; just as full knowledge of the auditory and visual apparatus gives no idea of sound or color to the man born deaf or blind. For this reason, we cannot speak of thought as occupy- ing space or as having exact locality. All such forms of SUBJECT-MATTER. 3 expression will be seen, upon examination, to refer properly to the physiological accompaniment of thought. For ex- ample, we speak of the localization of speech in Broca's con- volution ; but it is the brain modification which accom- panies speech that is there located. Suppose all our words were impressed upon the brain, making it, as some seem to consider it, a kind of magazine of photographic plates, still the great mental essential, consciousness, might be wanting. II. Relation to measurement: mental facts, unlike physical facts, cannot be directly measured. For the meas- urement of external magnitudes extension affords us at once definite and constant standards ; but for states of con- sciousness we have no such exact means of procedure. The fact that mental events are subjective in their nature makes them liable to all the uncertainties of subjective estimation. This difficulty is further enhanced by the consideration that the mental fact is always associated with a physical fact, and it is impossible to isolate the former. Tliis is seen in both the cases in which physical measurements seem to be most successful : in the measurement of the duration of mental acts and of the quantity or intensity of sensa- tions. In the former case we proceed upon the supposi- tion that time standards can be employed for mind as space standards for body : but the time occupied by the cerebral event is so interwoven with that of the mental that it has proved impossible to separate them. III. Mental states are distinguished from physical states in the means through which they are knoicn. As modifi- cations of matter, ph^'sical facts are known through the senses. Bodily functions are thus laid open to the gaze of the physician and the anatomist. The brain itself may be observed in its activities after the operation of trepanning. But mental states escape all such observation. They are known, on the contrary, in an immediate way through the consciousness of the individual. And while we are able to 4 NATURE OF PSYCHOLOGY. observe and analyze the physical processes of others, our immediate knowledge of mind is limited to ourselves. IV. TTie most essential characteristic of mental states is their subjective nature; what we may call their inner as- X)ect, in the phraseology of late science. By this is meant that relation to a self or subject that makes them what the}^ are in distinction from outer phenomena, which, as far as we know, have an existence apart from such a reference. This distinction is admitted even by those who reduce the two classes of phenomena ultimately to a single i^rinciple. This fact of a self affected becomes in developed mental states a matter of reflection and differentiation from the not-self ; a distinction arising, as will appear, within the inner aspect, and impossible without such a subjective beginning. V. The method of mental activity is quite distinct from that of the physical forces. As we proceed we shall find a constantly recurring fact of mental sj^ntbesis whereb}'', b}" conscious mental activity, states of consciousness are gathered and unified in new products themselves appar- ently simple and original. In the physical world we find no such unifying force as that known in psychology as the activity of apperception.* True Relation of Psychology to Physiology. These two orders of facts lead us to two distinct sciences — equall}^ sciences of fact or natural sciences. Psychology cannot be a chapter of physiology, because the methods and results of physiology do not reach nor involve mental data. One is a subjective science and the other is an objective science, and the difference is strictly experiential. The absolute separation of psychology from physiology, however, in point of matter, does not imply their independ- ence of each other in point of fact. They are united in fact by a bond which finds analogy only in that which unites the science of the inorganic, chemistry, with that of life^ biology. Life introduces a new series of phenomena ' 'i'reatcd below, DIFFICULTIES AXD ERRORS. 5 into nature, but the morphological changes it produces are accomplished only through the processes of inorganic or chemical change. So psychologv, while introducing a new order of phenomena, proceeds immediately upon the data of physiological change. The connection of the two is as real as their separation. The physiologist often finds the causes of organic modification (facial expression) in the movements of the mind, and the psychologist likewise finds causes for mental modification (sensation) in states and functions of the body. § 2. Difficulties and Errors ix Psychology. It has already been said that consciousness is the one characteristic of what we denominate mental. The diffi- culties and errors, therefore, that arise in psychology must be difficulties and errors either in the reports or in the in- terpretation of consciousness. There can be no doubt that there are such difficulties and errors, for otherwise the science would be much more developed than it is. They cannot arise in the actual reports of consciousness, for by its intimate nature as immediate feeling of inner states it reveals what actually is and happens. Considered, then, as arising from the interpretation or mental building up of the data of consciousness, several kinds of error may be pointed out. I. Difficulty of distinguishing Consciousness from Association and Inference. The primitive data of con- sciousness are no longer presented simply in adult life, but carry with them a mass of complex and derived material. "Hardly has consciousness spoken," says Mill, " when its testimony is buried under a mountain of acquired notions." The fact that there is a higher and lower in the mental life — a development from first things — is sufficient to show the reason of this confusion. For example, we shall find in studying sense-perception that the localization of things in space, which seems to be an immediate act of conscious' 6 natuhb of psychology. ness, is really due to a very complicated construction from data of sensation, and the general process of memory carries with it an instinctive belief in the reality of our images, due largely to association, which leads us often into illusion. So marked do these difficulties and confusions become in the higher processes that some additional safe- guard must be resorted to : some method of reducing com- plex mental states to the simple data of consciousness. This resort is found in Conscious Heflection. Use of Reflection. Even though the necessity spoken of did not exist, still simple consciousness, however clear, would not be sufficient for science. Consciousness is knowledge of present states, new and revived, and gives us only a play of present conditions. The scientific observa- tion of mind demands more than this. It demands the turning back of the powers of thought and reason upon our immediate knowledge for its examination, testing, system- atization. Simple observation does not suffice for the science of physics, nor will it, for the same reason, for the science of psychology. By reflection, therefore, consciousness itself becomes a matter of consciousness. To observe consciousness I must stand aside, so to speak, apart from myself and report what takes place in myself. If it is attention which I wish to observe, I must attend to the act of attention, in order to describe it. There is in such reflection a species of sec- ondary or subordinate consciousness, from the ground of which we look in upon our primary self. This apparent doubleness, or the effort to place ourselves beyond the range of our own states in reflection, leads to new sources of diffi- culty. II. Disturbing Effects of Reflection. Reflection, con- sidered as the turning in of the mental processes upon themselves, necessarilj^, by a great law of attention, exerts a disturbing influence. All our mental states are rendered more intense by the attention:^ consequently as soon as the ' Treated below. SUPPLEMEXTARY SOURCES. 7 state observed comes within the range of fruitful observa- tion, it is changed, both in its own integrity and in its rel- ative importance in the mental life. A pain attended to, for the express purpose of estimating its intensity, becomes more intense. Operations, also, which demand close appli- cation or successive mental efforts, are completely suspend- ed by reflection. A difiicult logical problem or musical performance becomes more difficult or impossible of accom- plishment when, by reflection, we note the stages of the process. Mental effectiveness seems to require a single di- rection of consciousness. On the other hand, also, certain states of mind make reflection impossible, their temporary importance in consciousness being overpowering : such as strong fear, anger, and the emotions generally. But psy- chology, as a science, cannot dispense with the complete knowledge of such states, since they are sometimes most important and enlightening. Indeed aggravated states, especially when they become manifestations of mental dis- ease, generally cast most light on the normal processes from which they arise. Means of Remedying these Difaculties: Supplemen- tary Psychological Sources. In view of these limitations, the psychologist is thrown back upon any other means he may command to correct, complement, and enlarge the scope of reflection. In general these supplementary^ sources of information are internal and external. I. Internal Source : Memory. The errors of internal re- flection which arise from the deranging effects of attention may be remedied in large part by memory. Mental states which cannot be madetlie object of immediate examination in the present, may be recalled from the past and held before the attention as reproduced images. The facility with which the mind does this is quite remarkable. Frequently an experience which is obscure or meaningless, an unknown sound, an unrecognized face, a vision, is thus recalled and given a rational explanation. The psychologist often 8 NATURE OF PSYCHOLOGY. catches liiraself just emerging from a state before almost unconscious, which, being brought back in vivid detail, is of especial value and frnitfulness for his psychological theory. This fact of memory is further strengthened by the phenomenon of after images or after sensations — traces left in the mental life after the actual stimuli have ceased to act. Of these we shall speak more in detail. There is a vibratory persistence in the nervous organism which tends to continue the central process and its accompanying mental state. And the same residuum or after-effect is also j^robably a mental necessity, since time is needed for the shifting movements of attention in its transition to new experiences ; during this period there is notliing to drive the former experience from consciousness, and it persists a noticeable time. II. External Sources. If it is impossible to deny the utility of inner observation, it is almost equally" dangerous to depend upon it exclusively. Failure to resort unceasingly and repeatedly to external observation at every stage of our stud}^ leads to tlie most chimerical subjective systems and the most one-sided views of life. So evident is this that, even when most strongly emphasizing the inner source of data, psychologists have found it necessary to la}^ hold upon whatever certified records of others' experiences in health or disease they found available, and held them up as valuable. Among these external sources we may enumerate the following, to which it will be necessary from time to time to refer : 1. JRace Psychology. This is, in the first place, the study of mind in its social characteristics, and in its prod- ucts in society, the state, religions, customs, and institu- tions. It accepts all the results of anthropology and views them as tlie manifestations of the mind. It examines ancient philosophies, cults, and civilizations ; literatures, history, laws, mythologies, traditions, the sources from EXTERNAL SOURCES. 9 whicli tlie human mind has drawn its culture in all ages. It values the reports of travelers in respect to savages, lieathen, and degenerate races ; the conditions of social life everywhere. For in all these manifestations of the life of the human mind, we have direct information respect- ing its nature and capacities. 2. Animal or Comparative Psychology. - As might be expected, the study of animals is of extreme importance for our science ; for animals show^ striking evidences of the i^lienomena of consciousness both in its lower and in many of its higher forms. It is perhaps destined, judg- ing from the contributions it has already made to some departments of research, to throw as much light upon human psychology as comparative anatomy has upon human physiology. As is tlie case with many physical functions, so certain intellectual states are seen in animals in a less developed and complex state, or in a more sharp- ened and predominant state, than in man ; and thus the necessit}^ for a genetic study of tliese states is met to a greater or less degree. Instinct, for example, attains its most perfect form in animals, memory is often remarkably developed, and certain of their senses show a degree of acuteness which we would never expect the corresponding human senses to possess. And the study of animals for psychological purposes is not limited to observation of their habits, productive as such observation is ; but the physiological method is capable of much more extended use than in experiment upon man. Condemned animals may be directly used for purposes of neurological research under conditions which rule out all pain to the creatures. The variety of problems which may thus be reached is limited only by our ability to state them and our ingenuity in planning the experiments. 3. Infant Psychology. The importance of the early study of mind is to be equally insisted upon. By it mental facts are reached, as far as ihej ever can be, at their origin 10 NATURE OF PSYCHOLOGY. and in their simplest form. It is more important to know what mind is than what it becomes. The child serves to correct the reports of adult life by opening up object les- sons in the growth of mind. At the outset the child mind is lower than the highest animal mind, since, while its human possibilities have not emerged, its instinctive equip- ment is not as'varied as that of animals ; but in its rapid development it exhibits the unfoldings of organic mental growth in correspondence with the growth of the bodily system, an advantage found in none of the other fields of observation.* 4. Abnormal Psychology. As in the former sources of information we deal with mind in health here we come to consider it in disease : that is, Ave look to all abnormal or diseased conditions of the mental life for light upon its nature and upon its legitimate operations. It includes all cases of variation from the normal and healthy activity of conscious mind : sleep-walking, dreams, insanity in its multiplied forms, loss of memory, loss of speech, hypnotism, idiocy, hallucination, disturbances of conscious- ness generally. All these variations aiford — as such varia- tions in any science afford — instructive views into the working of mind in its most intimate character. And the reason for this is plain. Such cases offer immediate occa- sion for the application of the logical method of difference^ which consists in removing part of a cause or effect and observing tlie consequent variations in the corresponding effect or cause. This procedure enables us to attach an effect to its true cause. One most general result of the study of mental disease, for example, is this, that we have learned to seek its cause in diseased conditions of the body, rather than in obscure mental movements or supernatural influences. It has been well said that a man deprived of one of his senses from birth is a subject especially prepared ' On the problem and method of Infant Psychology, see my article in Science, December 26, 1890. UNITY OF SOXTRCES. 11 by nature for the application of tlie method of difference. The science of mental disease and its cure is called Psy- chiatry. § 3. UxiTY OF Psychological Sources in Consciousness. From tlie external standpoint, psychology stands upon a level with the other sciences of observation ; but by the addition of inner experience it attains a unity they do not possess. The medium of all observation of nature, con- sciousness, which does not enter as part of the material of other sciences but often acts as a hindering cause, here serves within the circle of the science itself a useful and important role. The interpretation of facts, called in science the " personal equation," is in psychology an act of essential value, since data for psj^chology can be explained only from the point of view of mind. In short, external observation, which is necessarily of the physical, and of the mental only through the physical, must be translated into the forms of our own inner life. The ultimate basis, tlierefore, of psychological interpretation and construction is the mental experience of the individual, in so far as it is normal and typical. CHAPTER II. PSYCHOLOGICAL METHOD. » § 1. Principles of Scientific Method. In G-eneral. The question of method is an important pre- liminary to all scientific work. It involves the two great questions, first, what is the destination, and second, what is the road to the destination. In the preceding chapter, in the consideration of the subject-matter of psycliology, the for- mer has been considered. It remains to inquire into the latter ; through what means or by what kind of procedure shall we investigate tlie matter before us in order to reach the most general and exhaustive results ? This problem is practically solved for us in the method of the objective sciences. For if, as has been said, psychol- ogy is a science of fact, as they are, and proceeds by the observation of a given class of facts, as they do, then the tried method of procedure which they employ will be most productive here. True scientific method includes the three following processes, the first two of which belong more properly to Induction.^ First, Observation y by which is meant the widest possible appeal to fact, by way of an actual under- standing of the cases in hand. It must be extended to include all reliable testimony. The . broad defining marks of the material treated of become thus apparent and great classes are reached. This constitutes natural history, rather than natural science ; it describes the subject-matter but does not explain it. Second, Experiment; which consists ' Handbook, vol. i. chap. ii. 2 On Induction and Deduction see the chapter on Thought, J3 OBSERVATIOX, 13 in the varying of the conditions under which the facts are observed. It leads to the discovery of essential reasons or causes. It proceeds by certain subordinate methods or canons of its own, called since Mill " canons of induction." The product of experimental research is the Hypothesis or Empirical Law : a more or less probable conjecture, based upon the results of experimentation, as to the true cause operating in the case in hand. This is, in so far, no longer a description merelj^, but an explanation. Third, Deduction / which is the final stage in scientific method. By it the general principle set forth in the hypothesis is made applicable to successive individual cases, and by a new appeal to experience the truth of this application is made sure. Each such successful application tends to establisli tlie hypothesis more firml}^ until it reaches the rank of a principle or Law of Nature. § 2. Application of Scientific Method to Psychology. The application to psychology of the principles of method just mentioned is, in the main, clear : yet many questions of lively debate arise in consistently carrying them out. The two great spheres of their operation are the two sources of psychological data, internal and external. Psychological Observation. I. Internal. As a means of access to the phenomena of mind we find available three distinct phases of inner observation. In the first place, the simple fact of Consciousness, that inner aspect which makes mental facts what they are, in its primitive form, is at once awareness of the states of self. However vague and in- definite this primitive awareness is at first, it is still a beginning. There is no experience in conscious life which leaves absolutely no trace of itself. Once it is an experience, a modification of subjectivity ; then it may become the object of the developed act of inner obser- vation. The first fleeting sensations of the child, when 14 PSYCHOLOGICAL METHOD. there is no subject or object, no store of memory images, no idea of self, exhibit in isolation the kind of primitive con- sciousness that lies at the basis of all knowledge of self. In adult life these experiences are assimilated to the developed forms of intellect and their separate meaning is lost. But in this category are included the vast number of first experi- ences as they pass steadily on in time, something every moment ; and all the information we glean from them before we recall, examine, and reflect upon them. Second, the state of mind called Primary -memory : the lingering in consciousness of an event just after the event itself is gone. The immediate past hangs around us as a line of trailing cloud on the horizon of consciousness. So speedy and involuntary^ is this presence of the shortly-past that it is sometimes considered the first stage of our inner observa- tion ; yet this cannot be held in the sense of denying the immediate awareness of the primitive consciousness. For example a loud noise, or a spoken word, may be unintelli- gible until its quick recall enables us to recognize it. We have had, in these cases, the " immediate awareness " of the first event, but the examination of the after-image which it leaves adds much to the scientific value of the experience. Third, we reach Reflection, or conscious observation. By reflection is meant the inspection of the events of the inner world as distinct objects of our knowledge. It is the highest form of internal observation. Thus, by reflection, inner happenings are built up into hypotheses concerning the nature and processes of the men- tal life. This constitutes the point of departure for the second stage in the finished scheme of method. II. External Observation. By the method of external observation we approach the various external sources of psychological data mentioned in the last chapter. The closed nature of the individual consciousness makes it im- possible that the consciousness of others should be reached except through the interpreted meaning of external signs. EXPERIMENT. 15 All the products of human genius and culture become thus the objects of observation, with a view to bringing the de- tached parts of truth thus discovered into liarmony with our individual experience. So, also, the observation of children and animals brings its rich contribution. By simple observation, however, in psychology, as is the case in the material sciences, we do not reach below the surface. Many claim that this is all that we can do, and that a description of mental facts is the true aim of the science. Yet, as rare as true description is in this field, and as broad a field for analysis as simple ob- servation affords, we find ourselves asking : Is there no means of breaking up the complex groups of mental states, of detaching individual mental movements from the enormous mass of interwoven threads which our adult thought presents? In short, is there no field for experi- ment, either internal or external, in psychology? We answer, as recent research is answering, that there is — but with important conditions and qualifications. § 3. Experiment ix Psychology. The need of experiment in psychology is exceedingly great. When we remember that, in the search for causes in the natural world, tlie difficulties are vastl}'- enhanced by the fact tliat single causes are never found at work alone, and tliat it is the function of experiment so to eliminate elements in a causal complex, that isolated agencies may be observed at work ; and when we further reflect that no single function of mind is ever found operating alone, but that all accompany and modify each — the inadequacy of simple observation in this field becomes apparent. A sense stimulation, for example, may arouse an intellectual train, an emotional outburst, a course of action ; are all these the effects of a single cause ? A course of action, conversely, may result from an emotion, a thought, a pjemory, an association, a sensation, an inspiration ; cau 16 PSYCHOLOGICAL METHOD. the simple description of the resulting action indicate which is its cause ? Antecedents and consequents are thrown into the mental life in inextricable confusion. Ex- ternal or bodily causes — ^an odor, a spoken word, a pain, an internal organic movement — may start a train. This train may be hindered or advanced by a thousand considerations or emotions ; other bodily or mental causes may modify it. And all together make up the cause or complex antecedent state ; while vague analogies of thought and feeling, such as temperament, heredity, education, make variations between individuals, and the present condition of the brain and nerve centers makes variations in the same in- dividual. How can we single out the cause, in this net- work, by observation ? It is as vain as to discover the cause of a conflagration from examining the blaze ; was it a match, lightning, friction, chemical composition ? Only one step can determine : the reconstruction, under artificial circumstances, of the conditions, and the endeavor to exhibit a single isolated cause. This is experiment. We may look at the case, as before, from the points of view of the internal and external approach to mind. I. Internal Experiment. The range of internal experi- ment is very contracted, from the fact that it is hard to induce artificial states of mind entirely from within. Yet we can often suggest things to ourselves that change the course of our thought and give us a plainly isolated effect. We can force ourselves into lines of thought or emotion by holding given images fixedly before the mind — such as a shocking murder or the death of a close friend — and watch the result in the flow of emotion. On a larger scale one can subject himself to a series of intellectual influences and note the change it works in his habits of thought and feeling. The actor has thus constantly to experiment with his emotional states, cultivating those which adequately portray the character he represents. All such intentional manipulation of consciousness, however, demands a high EX PER I ME XT. 17 degree of mental control and concentration, great delicacy of observation and fidelity of description, to be of use for the general science. Experiment of this kind, however, is more effective upon others than upon ourselves. Tiie whole possibility of sug- gestion to others is here open to our touch, and we may play upon their emotions, hopes, ambitions, plans, ideas, as upon the keyboard of an instrument. AVe are all more or less skilled in such experiment ; we suit our advice to the man — offering a money inducement to one, a posi- tion of honor to another. So educational methods proceed upon experimental know^ledge of others : the awarding of prizes, the use of object lessons, appeals to individual man- liness, corporeal punishment ; indeed all discrimination in the treatment of children proceeds upon such experimental knowledge. In the hypnotic state and in infant life ' an unlimited range of suggestion is open to the investigator, and in sleep the same kind of influence is possible though to a much more limited degree. II. External Experiment. The possibility of finding that a bodih^ or external cause has been the determining factor in a mental result, opens up to our view the sphere of external experiment. We are at once led to see that a series of experiments upon the body may be devised, and the results ascertained which follow in the conscious life ; that is, reversing the relation of cause and effect which ordinarily obtains, we may consider bodily modifica- tions cause and their accompanying mental modifications effects ; thus isolating mental facts through artificial and single physiological stimuli. That such a procedure is justified is seen from the fact that our daily lives are full of inferences of this kind. The connection between the physical and the mental is so close and unquestioned that we never fail to take it into ' See my article " Suggestion in Infancy," in Science, February 37, 1891. 18 PSYCHOLOGICAL METHOD. account. Many states of mind are treated as arising di- rectly from states of the body. The whole treatment of mental disease proceeds upon this basis ; and sensations, the material of knowledge, are known to arise from direct sense-stimulation. The effects of alcoholic stimulants upon the mind are plain. The elevation, however, of this rough sense of connection between mind and body into a law of scientific method is only now getting general recog- nition. Its results constitute what is called " physiologi- cal psychology." General Conclusion. We are thus led to the following general conclusion as to the nature and method of psycho- logical inquiry : There is, first of all, in consciousness a kind of activity which affords at once the necessity and the justification of a higher science, inductive, internal, descriptive, and analytic ; that its method is that of direct observation ; and that, inasmuch as the phenomena of which it is cognizant are purely mental, it must precede and embrace those branches of the science which deal wdth the phenomena of body. Second, these mental phenomena sustain an universal and uniform connection with the bodily organism through which physiological experiment becomes possible, carrying with it a twofold utility : the causal analysis of phenomena and the confirmation of their em- pirical generalizations. And third, the science can never reach completion, or its laws attain their widest generality, until all mental facts are interpreted in the light of this connection with body or shown to be independent of it. CHAPTER III. THE NERVOUS SYSTEM.^ § 1. Its Structure. The fact that body and mind are connected so closely, and that true psycliological method must proceed upon this connection, makes some preliminary knowledge neces- sary of the nervous system and its functions. Nerve-elements. As far as our knowledge goes, Ave are able to make a twofold distinction among the elements called nervous, nerve-fibers and nerve-cells. As to what these are, the general meaning ordinarily attached to the words expresses about the amount of knowledge physiol- ogists possess. That is, a nerve-fiber is a thread-like con- nection between different muscular and cellular masses. A greater or smaller number of these white thread-like fibers may unite together to constitute a " nerve," which connects an organ (muscle, gland, etc.) with a greater or smaller mass of cells. The cells, on the other hand, are micro- scopic elements shaped like a flask or long-necked squash. One of the necks — for there may be more than one — seems to be prolonged into the fiber, and is called the axis-cylia- der process of the cell. Both cells and nerves have nuclei, small dark points which are surrounded b}^ protoplasm. The nerves are also cut up at intervals by nodes resem- bling the divisions in a length of corn-stalk. See Figs. 1 and 2. Some cells, however, are found without such connections, as far as microscopic analysis is able to go. And in many cases no direct continuity of structure has been discovered ' Handbook, vol. ii. chap. i. 19 20 THE NERVOUS SYSTEM. between cells and fibers which are supposed to unite in a common function. In these cases the fiber divides into numerous ramifications, presenting the appearance of a tree with its top branches turned toward the cell. See Fig. 4. Fig. 1.— From apiece >f spinal cord. tI and5. gaiiglion-colls ; at Z>, axis-cylinder; j9, protoplasmic process ; C, neuroglia-cells. (After Raavier, from Edinger, Am. Ed.) The cells are largely gathered in masses or "centers," toward which fibers from different regions or organs con- verge and apparently lose themselves. What is usuall}'^ called the brain is a series of such centers, varying in size and complexity from the cerebral cortex or rind, down- wai'd into the sinnal cord. In the centers the cells are NERVE ELEMEXrs. 21 separated by a substance called neuroglia (see Fig. 1), wliicli may be simply a form of connective tissue not itself nervous — tjie opinion of the majority of neurologists — or a third nervous element whose func- tion is bound up with that of the cells — a view supported by some later research. Combination of Nerve-el6ments in a System. The elements spoken of some- what artificially as cells and fibers have no functional existence apart from each other and from the living organism as a whole. Viewed as a whole, as receiving, register- ing, and reacting upon stimuli, they con- stitute the nervous system. As a system, the nervous apparatus is essential to the life of a higher organism and partakes with it of a great differentiation of parts. Wliat we call organs or members of the body have a unity of their own struc- turally; but their functional activity is one witlr the general life-process of the whole. So the organs or members of the nervous system have a corresponding structural differentiation. Whether the three general functions of the system spoken of above, receiving, registering, and reacting upon stimuli, are in any way adequate as a functional conception or not, they will at any rate serve to guide us in describing the three great parts or divisions of the nerve-apparatus. We will accordingly say a word about these three divisions in order. The Receiving or Sensor Appara- tus. By this is meant that part of the Fig. 2.— Nerve fibers, (af rcr Schvvalbe). a. Axis cylinder ; $, slieathof Schwann ; n. nnciens ; p, pran- nlar substance atthe poles of thenucleus; r, Ranvicr's nodes, where the mednllary sheath is interrnpt- ed and the axis-cyl- inder appears. 22 THE XEBYOrS SYSTEM. nervous system which is normally concerned with- stim- uli from without. We say normally concerned, since there is reason to believe that all nerve-tissue has the receiving proj^erty. But we find a great sj'stem of fibrous pathways arranged for the evident purpose of propagat- ing disturbances from the periphery of the body, and from various organs, to the higher ceuters. Further, these fibrous pathways may have special receiving organs ex- posed to the peculiar stimulus which we call psychologi- cally the stimulus to a particular sensation ; such special organs being peculiar to the special senses, as the eye for sight, ear for hearing, etc. Accordingly, the receiving apparatus includes two distinct elements, the senso7' coiirse and the end-organ. The latter (say the eye) i-eceives some form of excitation (light), and the former (optic nerve) propagates it to the brain. The existence of sensor courses which have no end- organs is sufiicient to show that the latter is not a neces- sary part of the system, except when the sj^stem is highly differentiated. A sensor nerve may be stimulated mechan- ically by a blow, by a touch upon an exposed point, etc., even in the case of the nerves of special sense ; they then report the sensations ordinarily secured through their end- organs.^ The nerves of special sense show no structural peculiari- ties except the possession of the end-organ. By nerves of special sense are meant those which report sensations rec- ognized and classed as having distinct psychological qual- ity. Tliat is, we find special end -organs for each of the seven classes of sensations discussed below, the muscles being considered end-organs of the muscular sense. Besides these, there is a mass of nerve-courses which report less distinctly differentiated and localized stimuli, the purest and most general psychological condition that * For example, sparks of light which result from a blow on the optic nerve or from mechanical irritation of a blind eye. THE SENSOn APPAnATUS. 23 they induce being pleasure and pain. Tliese are called general as o23posed to the special courses, and constitute the physiological basis of the general sensihility. As to distribution, the sensor apparatus is coincident in extent with the body itself. The orgaws of general sen- FiG. 3.— The spinal cord and nerve-roote. A, a small portion of the cord seen from the ventral side ; B, the same seen laterally; C, a cross-section of the cord; D, the two roots of a spinal nerve; l,anterior(ventral) fissure: 2, posterior (dorsal) fissure; 3, surface groove along the line of attachment of the anterior nerve- roots: 4, line of origin of the posterior roots; 5, anterior root filament of a spinal nerve ; 6, posterior root filament; 6', ganglion of the posterior root; 7. 7, the first two divisions of the nerve-trunk after its formation by the union of the two roots. sibilitj'' are distributed throughout in the form of very fine fibrils ; these fibrils being gathered into l)undles and these again into larger bundles or nerves as they approach the central course, the spinal cord. AYith these are the nerves of touch and muscular movement, also of general distribu- tion, the whole being consolidated into two columns which form part of the white matter of the spinal cord. The pos- terior or dorsal portion of the cord (the portion farther hack — ?(/> in animals) is called the sensor portion (pos- 24 THE XEnrors SYSTEM. tero- median columns). After gathering up tlie representa- tive fibers from all the successive nerves of sense wliicli run into the spinal cord, these tracts terminate in the upper enlargement of the cord (medulla); but further pathways lead up to the highest center, the cortex of the brain — and this is the essential point. For the location of these tracts in the cord, see Fig. 3. Another tract (the cerebellar) is also supposed to carry incoming impulses upward ; it arises from cells distributed along the cord and passes continuously to the cerebellum (little brain). As the cerebellum is also in direct connection with the hemispheres, another upward path is thus estab- lished. Foster further suj^poses that incoming impulses may travel by the gray matter of the cord (see below), or by portions of the gray matter with the longitudinal fibers which connect different segments of the cord together.^ Upon the endings of the sensor courses recent research has thrown some light. Peripherally, the sensor fibers end in the tree-like ramifications spoken of above. Going inward, such a fiber reaches first a cell in the spinal gan- glion, then penetrates the posterior horn of the cord, and terminates in the gray matter of the cord in the " tree structure " again. Here its influence seems to be trans- mitted to a sensory cell from which a fiber proceeds up the posterior column to the cerebral cortex as described, end- ing as before in the " tree structure." See Fig. 4. The arrangemetit of the apparatus of the special senses is more special, indicating to a degree the order of devel- opment of their several functions. The muscular sense extends to all the muscles ; touch and temperature to the peripher}^, the end-organs residing largely in the skin."^ ^ Text-hook of Physiology , ^i\i ed., pt. lii. p. 1104. Cf. his whole discussion, ibid. § 9. '■^ And in the mucous membrane of the mouth and pharynx, which constitutes with the skin the derivatives of the epiblastic layer of the embryo. THE MOTOn APPARATCS. 25 Tbe other special senses, siglit, lieariiig, taste, and smell, have each a particular locality; but they are grouped together, and their nerves, by reason of their special and closer connection with the central ;iervous masses in the skull, are called cranial nerves. The Reacting or Motor Apparatus The analogy be- tween tlie receiving and the reacting apparatus is so close Fig. 4.— Transverse section of spinal cord, showing anterior (17) and posterior horn«, sense organ (skin, 2), muscle (23), brain cortex (12), and spinal ganglion, (3). Sensory path— 2. 5, 3, 4.6, 7, 8, 9, 9i, 10, 11, 12, 13, 14. Volnntary motor path— 15, 16. 17, 18, 19, 20, 21, 22, 23. Reflex path -2, 5, M, 4, 6, 7, 8, 9, 20, 21, 22. 23. Note the " tree-structure " nerve endings. (After Waldeyer.) tliat they may be taken up together ; more especially as the purest type of reaction, as will appear below, assumes that there is no break of continuity between them. The nature of the reaction itself is a point of function and is reserved ; the apparatus is what asks attention now. In the reaction we find another system of nerves, the motor courses^ quite indistinguishable from the sensor 26 THE KEnVOUS SYSTEM. courses, except in their localities and their endings. They are also alike among themselves as regards their end-organ, the muscles.^ They issue directly from the bodj^ of the muscles and converge to the spinal cord, of which they constitute roughly the anterior (front) or ventral portion — the so-called pyramidal tracts. The essential facts, again, are the continuity of structure throughout and the universal distribution of the motor courses to the muscular tissue. The distribution, however, does not secure equall}^ ready reaction of all the muscles ; indeed, some of the muscles are either entirely outside the range of voluntary control, or are brought within only by much exertion. As to their endings the motor courses exhibit more sim- plicity. They arise directly from cells in the cortex, and have their first ending in the *' tree-structure " in the ante- rior horns of the spinal gray matter. There the *' influence " is taken up by the spinal motor cell, and from it is trans- mitted direct to the muscle by means of a nerve with the "tree-structure" ending. See Fig. 4. At the upper end of the spinal cord there is an enlarge- ment, the medulla oblongata^ in which occurs a rearrange- ment of all the courses and their distribution to the various masses of the brain. Above the medulla again we find other white fibrous bodies — which need not be enumerated — serving two evident purposes ; ^. e.^ they gather together fibers which minister to the same function, and distribute these fibers to the cellular bodies at which such functions have their brain-seat. In these higher white masses, motor and sensor courses are inextricably interwoven ; and in only a few cases has research succeeded in establishing pathwa3^s up or down. Without giving details, we may say that the following points are quite definite : 1. Sensor tracts pass from all parts of the periphery of the body up through the dorsal column of the spinal cord, ' The secretive and vaso-motor connections are, for our present purpose, neglected. SEXSOR AXT) MOTOJl TRACTS. 27 cross (decussate) in part in the medulla, and reach the sur- face of the opposite hemisphere of the brain (largely the rear and nether portion). 2. Motor tracts pass from all parts of the periphery up through the ventral column of the spinal cord, cross in part Fig. 5.— Scheme of pyracnidal tracts, p^,])"^,])^. Periphery of body; n\n^,v^, spinal nuclei of oriijin ; Pi/S, lateral pyramidal tract; Pt/V. anterior pyrauiuhil tract ; ca, anterior commissure of spinal cord ; DP, decussation of pyramids ; F;/. pyramids; Pp, pes pedunculi cerebri ; Ci, internal capsule ; Po, pons : 7ifw, nuclei pontis ; cb, cerebellum; />•», periphery supplied by cranial nerves; n*, nucleus of origin of a cranial nerve ; C to 6'^, cortex cerebri. (Obersleiner.) in the medulla, and reach the opposite hemisphere in the motor zone (area on both sides the fissure* of Rolando, including the paracentral lobule *). Tliese courses are called the pyramidal tracts, from the pyramid form in * See below, § 4, I, and Frontispiece. 28 Tiihj xERVovs srsTEyf. wliicli they are buuclied on the ventral side of the medulla. See Figs. 5 and 6. 3. Association tracts develop, in the course of the life of the individual, to connect all parts of the cortex of the Cortex of the brain Fig. C— Diagram of innervation of a muscle. (After Edinger, Am. EdO brain with one another. They are almost, if not quite, absent at birth. In the words of Edinger : "They extend everyvvdiere from convolution to convolution, connecting parts which lie near eacli other as well as those which are w idely separated. They are developed when two different regions of tlie cortex are associated in a common action." * See Fig. 7. ' Stntctvre of the Central Nervous System, p. 69. ASSOCIATION r It ACTS. 29 Under the same head may be included also the fibers which connect the two hemispheres with each other, Fig. -Diagrammatic representation of a part of the association fibers of one hemisphere. (After Edinger, Am. Ed.^ making of them a single organ in relation to the lower parts of the system. Such connections are found in two great bundles called the corpus callosum, which is the floor Fig. 8,— Frontal section of tlie course of the corpus callosum and the anterior commissure, (After Edinger, Am. Ed.) 30 THE NERVOUS SYSTEM. of the great longitudinal fissure which separates the hemi- spheres from above; and in the anterior commissure below. Both are shown in the accompanying figure (8). The Registering Apparatus. Under this term we in- clude the more or less complex chain of cellular elements which constitutes/ the center receiving and reacting. The word registering emphasizes again the integration or development side of the nerve-process. In its most gen- eral or schematic outline, the system is made up of two similar nerve-courses brought into organic connection at their upper end by this cellular series. It may be repre- M_ \ s Fig. 9. sented to the eye in the following simple way : M being the motor course, S the sensor course, and C the central elements: the whole constitutes the elementary weryows arc (Fig. 9). Our knowledge of the central elements is exceedingly vague, both as regards structure and function. As to structure, the most exact thing that we can say is that the center is cellular and probably in all cases complex. Its complexity is indeed so striking and elaborate that it is this feature that tends to obscure all others and render re- search fruitless. A general distinction is made by physi- ologists between the simple arc and the complex mass of many arcs with their accompanying highly integrated center ; but the simple arc is a pure abstraction. Indeed its very conception is dependent upon the results of an analysis of the centers which has never been made. In reality it is probable that the simplest nerve-reaction of which we have any knowledge involves a cellular mass and a nunaber of ITS STRUCTURE. 31 I alternative motor and sensor tracts. Such a relatively simple system is found in the ascidians, which have only a single ganglion with sensor and motor filaments. See Fig. 10. In distribution, the central masses again illustrate the hierarchical arrangement due to development. The sim- plest of such arcs are at the points of union of nerve- courses, points where the motor and the sensor find an interchange of energies, or a distribution so uninvolved as to follow from the nature of the nervous integration it represents, without appeal to a higher and more complex center. Such comparatively simple points are called ganglia. For example, the nerves which enter the spinal cord on eitlier side at intervals throughout its wdiole extent divide a short distance from the cord, and send branches called motor and sensory roots, respec- tively, into the cord. Just above the point of division, on the sensory root, we find a sicelling or lump, a ganglion. thought, represents a junction, to use a railroad figure, for the transfer of passengers and the interchange of tele- graphic messages.^ See Fig. 3 above. The spinal cord is made up of a series of segments, to- gether forming a column in the center of which is a con- tinuous mass of gray (cellular) matter. This gray column gives off the spinal nerves from its two posterior and two anterior horns (see Fig. 3) ; the nerves thus given off, right aud left at the same level, meet just below tlie enlargement or ganglion outside the cord. Above the spinal cord the gray matter is enormously increased, as w-e should expect 1 On the fuuctions of the ganglia ami centers generally, see below, p. 3a f. Fig. 10.— Nervous eys- tem of an Aecidian (Carpenter), a, the mouth ; b, the vent ; c, the ganglion ; d, muscular sac. The ganglion, it is 32 THE NERVOUS SYSTEM. from the increase in the fibrous pathways ah-eady de- scribed. Thus a number of bodies are formed in three con- nected systems :^ first, the most central gray matter, serv- ing to connect the spinal column with the higlier centers, and giving the cells from which arise the cranial nerves ; second, the tegmental system, including all tlie masses which lie in the interior of tlie brain (the most important being the striate bodies and the optic thalan%i)\ and third, the surface masses, the cerebrum, which has its gray mat- ter arranged in layers, giving the cortex or rind, and the cerebellum ox little brain, a similar mass behind and beneath the cerebrum with a similar cortex of its own. For present purposes the essential points again to be noted in this connection are, first, what we have called the hierarchical cliaracter of the series, tlie unbroken advance in structural complexity ; and second, the continuity of connection and influence through it all. § 2. Flnctions op the Nervous System. Fundamental Properties of Nervous Tissue. Experi- mental research upon living nerve-tissue has issued in a conception of protoplasm which includes two functional elements. At the first glance, nerve substance exhibits the property called in general scientific nomenclature irritability. This property is by no means confined to developed nerve-elements ; it is exhibited by all living animal tissue, by forms of organism in which a nervous system is entirel}'' wanting. In some forms of vegetable life, as the sensitive plant, the same property is presented. In the case of nervous irritability, however, whenever the substance assumes the complexity of a system, we are led to view it under two distinct functional rubrics. Recalling a former division, we find the receiving and the reacting ^ Following Foster, Text-hook of Physiology, pt, ill. pp. 977-998. For details and diagrams see any of the Physiologies ; Ladd's small Outlines of Physiological Psychology is convenieut for reference. ITS FUNCTIONS. 33 apparatus to be appropriate to the same function, that of propagation, transmission, or conduction ; and the central arc, the registering apparatus, suggests a function of inte- gration. Assuming the results of later exposition, these two functions may be called, respectively, Neurility and Sentience. Let us consider, for example, the central arc A, of Fig. 9, above, to be the center or nucleus of a protoplasmic mass, and the two lines M and S to be two radii from the center to the outer surface. If, then, the mass be stimulated at the outer end of S, and this be followed by the withdrawal of the point stimulated, we have a phenomenon of irrita- bilit^^ But we may suppose S to be a line of conduction of the excitation to A, and M the line of reverse conduction or reaction which results in the contraction ; both of these fall under the conception of Neurility. The process by which they are held together at the exchange-bureau A, so to speak, is Sentience. This rough conception may be made more distinct as the two processes are taken up singly. 1. Neurility. Under the head of neurility we are intro- duced to a class of phenomena which have striking analo- gies in physical science. The conception or phenomenon of conduction is familiar in what we know of light, sound, and heat propagation ; but the special analogy which at once suggests itself is electric conduction along a metallic wire. Setting aside as a matter of speculation the hy- pothesis that neural force is identical with electricity, we may still find in the analogy much help to a clear con- ception of nervous conduction. Indeed the theory of nervous action most current among authorities — as w^ell as in the popular mind — finds its general exposition in terms of the analogy with electric action. On this theory, the nerve-courses are simply and only conductive tracts, as the electric wire in a telegraph system ; the centers, on the contrary, are the generators of 34 THE NERVOUS SYSTEM. "nervous force." At the center we have, therefore, a storage-battery from whicli force is drawn off along'^the motor courses upon the occasion of the arrival of a stimulus from the sensor course. The centers, on this theory, are the essential nervous agents, or producers, and the courses are brought into operation onl}^ as they are charged from the central battery or pile. Neurility, therefore, is simply the molecular state which constitutes a course a good nervous conductor. This theory is objected to both on theoretical grounds and from experiment. It makes the distinction between courses and centers too absolute and mechanical. Accord- ing to it, any distinct djmamic property is taken from the nerve-tracts ; while experiments show that the elementary portions of both sensor and motor nerves have a life and function of their own. The eye when removed from its socket, thus losing all connection with a center or ganglion, still shows sensitiveness to light, and has a motor reaction in the contraction or expansion of the iris. Pfliiger main- tains that there is an increase in intensity in the nervous dis- turbance as it traverses the motor nerve, and Richet thinks a similar increase in the sensor nerves probable. The ordi- nary phenomenon called knee-jerk is thought by some to take place without appeal to a nervous center. Accordingly, another theory is advanced which seems more philosophical to the present writer, so far as he ven- tures to have an opinion on a matter so purely physiological. This second conception of the nervous system makes it a living organism instinct with nervous force or neural prop- erties throughout. This system is in a state of unstable equilibrium and constant change, due to stimuli through sense-organs and to spontaneous central discharge. Dis- turbances tend to equalize themselves everywhere in the system by a species of centrifugal and centripetal tension, which, through its greater or less effectiveness in this direc- tion or that, upon this course or that, results in conduction - SENTIENCE. 35 or iieurility. Differentiation, tlierefore, in tlie system, is primarily structural differentiation, due to tlie adaptation of the life-process to changing conditions in the environ- ment. The " dynamic" conception, as the latter may be called, is supported by a class of facts which show a ready and facile influence throughout the system, difficult to account for if the parts between whicii the transfer occurs are functionally distinct ; such general transfer affords the so- called law of diffusion. For example, a simple sensory stimulus may, Avhen intense, or when the system is excited from disease, lead to general irritation and diffusive dis- charge. On the other hand, a reflex having its center in a particular spinal ganglion may be partially stopped by a sensory excitation from another part of the body. Cases of association between sounds and colors,^ and phenomena of contrast* generally, show sucli dynamic connections be- tween disparate sense-regions. Urban tschitsch found that the perception of color was im[)roved when a tuning-fork was made to vibrate near tlie ear. However it may be explained, nervous conduction is of fundamental importance for the theory of sensibility. And for practical purposes the wave or current theory serves, as in electricity, all ordinary requirements. The nervous wave, therefore, is called centripetal or afferent when mov- ing toward the center, and centrifugal or efferent when moving toward the periphery. The rate of transmission differs somewhat in the two directions, being about 120 feet per second for sensor and 110 feet for motor impulses. Transmission through the spinal cord takes place consider- ably more slowly. 2. Sentience. From the interpretation of results, and from ph}''siological analogies, some general statements may be made concerning the processes at the centers, and these general statements are valuable for psycholog}^ ; but they ^ See below. ' Below, chap. viii. i^ o, 36 THE NERVOUS SYSTEM. do not pretend to throw any light upon the genesis or nature of nervous force. a. Integration. Of these general statements, the first concerns what has already been called the integrating function of nerve centers. By this is meant the building up of a center to greater complexity of structure through new stimulations. It takes place by reason of the ex- treme plasticity of the nervous elements in taking on ar- rangements suited to more habitual and, at the same time, more complex reactions. The center becomes the theater of multiple and conflicting stimulations ; its reaction is the outcome of a warfare of interests, and the pathway of dis- charge is a line of conduction most favorable to future sim- ilar outbursts. A center gains by such complex activities in two ways : first, its habitual reactions become a rock- bed or layer of elements, so to speak, of fixed function is- suing in established paths of least resistance ; and second, the center grows, gaining new and more mobile elements, and responding by more complex and difficult move- ments. For example, the center for the movements of the hands is educated, from the early painful lessons of the baby's finger movements to the delicate and rapid touch of the skillful musician. Not only has the center become fixed and automatic for movements at first painfully learned, but it lias become educated by learning, so that it acquires new combinations more easily. This twofold growth becomes the basis of the division of the sentient apparatus into centers and ganglia. The " rock-bed " elements, so- called, fall into fixed ganglionic connections, and the new and free cells take up the higher function, only in their turn to become " fixed " by habit and to give place to yat other and more complex combinations. This integrating process is what gives the hierarchical order to the system, and throws its law of development into fine relief. In- tegration, therefore, represents a structural change in the direction both of simplicity and of complexity : of siui- SENTIENCE. 37 plicity, because it gives ease and rapidity to habitual movements ; of complexity, because it brings into play new elements which must be assimilated to the unity of the center. h. Retention. The conception of integration necessarily includes that of the permanence of the modification on Avhich it depends. If reactions are integrated in such a way as to secure the upbuilding of the sjstem and its more perfect adaptation, then we must suppose that each reaction works a minute structural change in the organism. So much is included in the conception of integration. And from the ph^^siological side tiiis would seem to be suffi- cient. Retention, as a physiological principle, may, there- fore, be called growth in functional complexity ; while the term integration refers rather to growth in structural complexity. Accordingly, the conception of nervous retention runs somewhat like this : Nervous retention is a state of dynamic tension or tendency due to former nervous discharges in the same direction ; the two essential points, again, being the dynamic or tension aspect of nerve-action in general, and the particularization of this tension along a given path determined by previous like discharges. c. Selection. A third fact of sentience may be called selection. It denotes the undoubted property of the living nervous system of reacting within limits of greater or less adaptation. It shows p?*6/t?re/iC6 for certain stimuli above others, if the word preference can be shorn of all its refer- ence to conscious choice. A system will react on a stim- ulus at one time which it will refuse under other circum- stances ; or it will distinguish between stimuli exacth' alike, as far as human sensibility for differences can deter- mine. The brainless carp will distinguisli food with some degree of precision, and experiments by Pfluger and Goltz on brainless frogs show that they adapt their muscular reactions to varied positions of the limbs which could not S8 THE NERVOUS SYSTEM. have been experienced before in tlie life of the creatures. Schrader has also reported many similar cases of apparent preference and choice in brainless pigeons. Such instances seem to show a selective function in nerve- reactions of the purest type, i. e., those simply ganglionic, Avhere the effects of consciousness are either quite wanting or reduced to a minimum in intensit}^ The explanation is perhaps to be found in the peculiar delicacy of the receiv- ing apparatus. To say that a brainless animal selects when we are unable to point out differences, is only to say that more debased currency will pass for gold with us than with it. Instead of selecting between two stimuli, therefore, it has had only one, and has responded to it ; the other being mistakenly considered by us as fitted to excite it. Does the nervous S3^stem select from a multitude of similar touches ? The magnet selects from a multitude of similar filings ; and the explanation seems to be the same. Neither the touches nor the filings are similar, after all. Another explanation of selection must be mentioned, however, both because it is held and because it affords a philosophical and quite plausible hypothesis ; it is possible that our subsequent discussions will bring us into accord with it. It holds that sentience involves eonsciousness, that nervous action is always conscious (not self-conscious) action, and that a fundamental mark of consciousness is preferential selection or choice. On this theory, therefore, all such cases are instances of real selection, due to the presence of consciousness. The explanation given to nerv- ous selection has psj^chological significance, since, accord- ing as it is explained, it may or may not give us data for our theory of voluntary choice. Law of Nervous Dynamogenesis. Sentience, in view of what has been said, is a general word for the rise and distribution of nervous force. The receiving and reacting functions are both essential, the one necessarily giving rise to the other ; there is no incoming nervous process, there- A UTOMA TIC RE A CTIOK. 3 9 fore, that does not tend to liberate energy on the outgoing courses. Eoery stimulus has a ilynaniogenic or motor force — may accordingly pass as a statement of the law in its individual bearing, the only bearing which is available as having a psychological analogy. § 3. Kinds of Nervous Reaction. The twofold growth of the nervous system spoken of under integration gives us data for a distinction among different reactions. Integration involves, on one side, a downward or "ganglionic" growth, represented in func- tion by the more unconscious and unintended reactions of the muscular system ; aiid, on the other side, an upward or " central " growth, represented by the more difficult muscular performances, in which attention and effort are called out. These two laws of growth act together, and in the result, in our motor experience, we find every degree of nervous facility or the contrary. Three stages of such growth, from down up, so to speak, are usually distinguished. 1. Automatic Heaction.— By the automatic in nerve- function is meant tlieself acting, i. «., those reactions which find their stimulus in the living conditions of the physical organism itself. Certain organic processes are neces- sary^ to the life of the individual and the race — circula- tion, respiration, digestion, etc. The dependence of these essential functions upon external stimuli of time and place would give an accidental and varied character to these reactions which would subserve death rather than life. Accordingly^ the automatic centers represent the most consolidated and fixed portions of the nervous system, at the same time they are complex and elaborate. These functions may or may not be conscious, their most health- ful activitv beinof sfenerallv most free from conscious over- sight. AVith very rare exceptions, also, they cannot be modified by the will or brought under voluntaiy control. 40 THE NERVOUS SYSTEM. 2. Keflex Reactions. A iiervous circuit is reflex wlien its motor reaction upon a particular kind of stimulus is single, definite, constant, and does not involve volition in its execution. In more general terms, a reaction is reflex wlienever we are certain beforehand that it will take the form of a particular well-defined muscular movement, and will do its work without any interference or mandate from ourselves. We are disposed to stand apart and attribute the reaction to the organism or to the external stimulus. For example, if a ball suddenly approach my ej^e, incloses, or if it strike sharply upon my knee, my foot flies up ; we do not say I close my eye or raise my foot. Or we go further out still and say the man who threw the ball made my eye close or my foot fly up — so thoroughh^ do we dis- tinguish this class of reactions in consciousness from those which we attribute to our own agency. In its physiological character, this kind of reaction represents a less organized and consolidated system of elements than the automatic. A reflex reaction is gener- ally conscious in its operation, and always so in its com- pleted results. Its center, also, is not cut off functionally from the higher centers of the brain, which exercise a con- trolling influence. Yet we know that this connection is not an essential one to the reaction itself, since after the removal of the cerebrum and with it all active conscious- ness (certainly ; perhaps all consciousness), the reaction still takes place. Each of the segments of the spinal cord has its own reactions apart from its brain-connection. Indeed, reflex reactions are most perfect and pure when consciousness in the form of attention is not directed to the movements. These facts tend to throw reflexes rather on the side of the " downward " growth spoken of, and assimilate them to automatic reactions. The phe- nomena presented by the reactions of a brainless frog illustrate pure reflexes very clearly. The downward growth appears from the fact that many REFLEX RE AC ri OK. 41 of our reflexes are acquired from habit and repetition. Motor processes at first difficult and simple are welded to- getlier in complex masses, and the whole becomes spon- taneous and reflex. The case is cited of a musician who was seized witli an epileptic attack in the midst of an orchestral performance, and continued to play the measure quite correctly wdiile in a state of apparently complete un- consciousness. This is only an exaggerated case of our common experience in walking, writing, etc. Just as a number of single experiences of movement become merged in a single idea of the whole, and the impulse to begin the combination is sufficient to secure the performance of all the details, so single nervous reactions become integrated in a compound reflex. This consideration leads to a further distinction between more or less organized reflexes ; namely, between what are called secondary-automatic reactions and reflexes proper. In the case of our movements in walking, for example, the successive reactions are not sufficiently organized to belong properly to a single stimulus — sa}^ the original idea of our destination, or the sensation of our first footfall upon the pavement ; but the steps in succession are probably ex- cited by the successive afferent impressions of the steps accomplished. Each step stimulates the next, etc. That tliere is no voluntary stimulation after the first is seen in cases of reverie or absent-mindedness, when we go along accustomed paths and find ourselves where we least in- tended to " bring up." The distinction, therefore, is merely one in degree of integration. If the centers are sufficiently organized "downward" to carr}^ out the en- tire chain of movements when once begun, we have a pure reflex ; if new sensory stimulation is necessary at each stage in the series, the reaction is secondary-automatic. 3. Voluntary Reaction. A third great class of nervous reactions is called voluntary. By voluntary reactions are meant such motor effects as follow upon the conscious will 42 Tim NERVOUS SYSTEM. to move. Tiiey cover the whole class of intended move- ments and those brought about by greater or less effort. Voluntary movements show variation in several distinct particulars ; such as strength, continuance, rapidity, and direction. The voluntary reaction undoubtedly represents the highest stage of development of nerve-tissue as respects coraplexit}^, or the lowest stage as respects consolida- tion and fixedness. It is the polar opposite of the purely automatic function. The nervous elements are in a state of extreme mobility and instability. The connections through its mass are infinite in number and complexity, and numberless alternative courses are accordingly open to the motor outburst of a sense-stimulation. Considering the state of the cerebral center dynamically, we may say that its potential energy is constantly seeking discharge, and that this discharge in one course rather than another — the course pictured and designed in consciousness — repre- sents the line of tension which is chosen. The last expression, though ps3^chological, is necessary to express the physiological fact which distinguishes such reactions. The stimulus is in all voluntary reactions a central one, and a conscious pictured one ; this much at least. If we admit that no discharge from the centers can take place without a previous liberation of tension, then we may divide such liberations from tension into two classes : that which is brought about b}^ an incoming current, and that which is brouglit about by an earlier cerebral dis- charge. The former is a reflex reaction, the latter may be a voluntary reaction. One at least of the conditions of voluntary action is fulfilled, the physiological condition. Whether this is sufficient in all cases, or in any case, to ac. count for the action, it is our subsequent task to deter- mine. 4. Negative Reaction or Inhibition. Under the name of inhibition, or arrest, a class of phenomena is included INHIBITION. 43 which are, as far as our know ledge goes, peculiar to nervous activities. Every positive reaction is accompanied by a re- verse wave, an arrest, so to speak, of its full effects. It is analogous to a negative force acting to counteract and neu- tralize the outgoing discharge. It seems to take place in the center. The effective force of a reaction, therefore, is always less b}^ the amount of nervous arrest. This neutral- izing factor has been measured in certain conditions of nerve-reaction. The kind of reaction showing least arrest is the reflex ; and, in general, the more consolidated a nerve-track or center, the less exhibition do we discover of the reverse wave. On the other hand, inhibition is at its maximum in reactions which involve centers of most complex activity. The phenomena of voluntary control — inhibition by the Avill — are in evidence here, however w^e may construe the will. For it should be remembered that w^e must find a mechanical basis for muscular control, even though we advocate a directive and selective function of will. Hence we may say that inhibition is a concomitant of instability and complexity of nervous tissue ; and it be- longs on the side of the *' upw^ard " growth of the system. This general view is sustained by the fact now estab- lished that each segmental reflex in the spinal cord is sub- ject to inhibition from the higher segments, and in turn inhibits those lower down. The reflexes of a frog's legs immersed in dilute acid are more rapid and violent after the hemispheres have been removed — showing the normal inhibitive function of the cortex ; and the reflexes of a lizard's tail have been shown to increase in vigor as the seg- ments of the spinal cord are successivel}^ removed. The same lack of inhibition appears in the greater automatism, suggestibilit}^, and wayward impulsiveness of certain forms of insanit3^ The same truth is made plain from the fact that lesions of the motor zone of the cortex in man produce greater motor disturbances than in animals, and 44 THE NERVOUS SYSTEM. greater in the dog than in tlie rabbit ; the inference being that the snbcortical centers are more independent, less in- hibited, as we go lower down in the scale of animal organ- ization. § 4. Corollaries : So-called " Principles op Nervous Action." The foregoing discussion has brought us to a position from which to estimate the current " principles of nervous action." That they are corollaries deducible from the more particular truths already cited is in itself proof of the truth of the conception sketched in the foregoing pages. These " principles " may be spoken of in their logi- cal order. I. Principle of Specialization of Function. Accord- ing to this principle, different regions of the nervous sys- tem are concerned with different and exclusive functions. Most important consequences flow from this principle in the sphere of brain physiology and anatomy. And in the local divisions of the cerebral surface we find facts highly important to our own science. Pacts of Specialization. A general fact or two may be mentioned in view of subsequent points of discussion. In the two halves or hemispheres of the brain we are led to recognize a twofold or duplicate organ, analogous, to the doubleness of the eyes while performing together a single function. In regard to the function of the brain as a whole, we may say that in the main it is performed equally well by either hemisphere alone. If one hemisphere be entirely removed or destroyed, there is no perceptible impairment of the mind, at least in its great apperceptive activities. The hemispheres are moreover capable of separate activities at the same time ; the movements of organs on the right side of the body which are governed by the motor area in the left hemisphere, may be different from simultaneous movements on the left side governed by the motor area in SPECIA LIZA TIOK 45 the right heniispliere. Again, there are certain functions Avhich are presided over by one of the hemispheres exchi- sively, the other having no part in them : the motor speech- center is in the left hemisphere for right-lianded persons, and it is probable that there is a corresponding functional development for the delicate movements of one hand only, as in writing, etc. Accordingly, instead of considering the brain as two duplicate organs, either of which might be educated to perform all the cerebral offices, we have to con- sider it as a double organ whose functions are partly separate and partly conjoint. That is, the facts point to the con- clusion that {a) there is a class of functions over which the hemispheres have conjoint dominion : functions which they may perform together and which either may perform alone, and functions which the}' must perform together and can- not perform alone ; and {b) there are functions which are peculiar to each alone : which one must perform alone, and in which the other has no share. The great divisions of function may be stated in general terms under three heads in accordance with the facts now presented. 1. PureljM-eflex functions are presided over by the spinal cord and lower centers. 2. The automatic functions proceed out from the "central" and "tegmental" systems of centers. 3. Sensation and voluntary movement have their seat in man in the cortex of the brain. If 1 atid 2 be considered together as giving only one degree of complexity, and 3 be added as giving another decree, we may show their relation by Fig. 11, in which the circuit s, c, mt, represents all reactions not voluntary, and s, c, sp, mp^ e, mt, those which are voluntar3\ For convenience in later discussion, the higher reaction may be taken alone and simplified, as in Fig. 12, called the " motor square " ; in which we have the three elements jis before (.*?/>, mp, mt) with an added element (>/?<'), i. 6"., 46 THE NERVOUS SYSTEM. the consciousness of movement accomplished (represented by the dotted line mc in Fig. 11), the lower centers (c) being here left out of account. The degree to which the cortex serves the purposes of mind above the bare reception of present stimuli and mechanical reaction upon them, is seen in tlie behavior of animals deprived of the cortex. Frogs and pigeons have been fully tested in view of this question. It is found, in mjp sense organ mt muscla Fig. 11. Fig. 12. s, c, mt = Reflex circuit (1 and 2 of text). s, c, sp, mp, c, mt = Voluntary circuit (3 of text). brief, that the life and reactions of the creature are unim- paired as far as the immediate environment is concerned : it lives, breathes, flies, sees, eats, carries out reactions of response to direct stimulation. But it fails to respond to remote stimuli ; the reactions are for the most part unin- fluenced either by the past or the future. The creature lacks spontaneity. Memory has disappeared ; so have generalization and purpose. Tiie creature has sensations, but not jjerceptions, as far as a line can be drawn between tliese states. It fails to recognize and it fails to attend. It CEREBRAL LOCALIZATIOX. 47 is plain, then, that such a hemisphereless creature lacks largely the co-ordinating, retaining, relating, or, as it is called below, the apperceiving, function. It illustrates wluit, on Hume's theory of knowledge, ought to be the condition of us all. Tlie terras psycA/c-blindness, ^:>sycA/c'-deaf ness, etc., are given to this condition, in which there is no physical blindness, etc., but in which sensations have lost their mental meaning. As for particular reactions, however, the greatest differ- ence is found in different animals. In dogs and birds many functions are performed by tlie lower centers which are presided over by the hemispheres exclusively in monkeys and in man. This illustrates what has been observed above, i. e., that reactions at one time reasonable and intel- ligent may become nervous and mechanical : and this con- sideration, based upon extended experimental proof, leads us to recognize, below, the great elasticity of the system as regards specialization. When these maimed animals are kept alive, their condition improves, and they begin to get something of their intelligence back again. Cerebral Localization.* The question as to whether there are local areas in the cortex or gray matter of the brain which are especially active in the exercise of the sense and motor activities, is of great importance for general psj'^chology. Experiments have been very conflict- ing in their results, but it is now generally admitted that there are a limited number of w^ell ascertained areas. The motor functions are grouped around the fissure of Rolando, extending roughly from the vertex of the skull downward and forward in a line which passes slightly in front of the orifice of the ear. The centers for the leg, arm, and face are in the order named, proceeding downward. The special muscular groups involved in the finer movements of these organs are distributed on both sides of the Rolandic fissure. Movements of speech have their center for right-handed persons in the third frontal gyre of the left hemisphere, ' Cf . figures opposite the title-page, 48 THE NERVOUS SYSTEM. The sensory area comprehends the region lying back of and beneath the motor zone ; the fissure of Sylvius being a rough horizontal boundary between tlie motor and sensory areas. Of the special senses, sight is located in the occip- ital lobe, including the so-called angular gyre at the upper end of the Sylvian fissure. The centers for hearing, taste, and smell lie, less exactly, in the temporo-sphenoidal lobe, the horizontal area below the fissure of Sylvius. In man the destruction of the frontal lobes seems to bring about a higlier kind of " psj^chic blindness" : a loss of voluntary attention, co-ordination, and thought. The liypothesis is widely current that these lobes are the final center of convergence for the connections between the sensory and motor centers of the brain. Tlie loss of con- nection between this seat and any other area cuts the latter with its store of memories off from its full role in the mental life. For example, speech may be impaired by the loss of any one of three functions located in different areas, ^. e., word-seeing, word-hearing, and Avord-uttering. II. Principle of Indifference of Function. The prin- ciple of indifference includes the class of facts which show that the nerve-courses are not the agents of different or specific forces, but parts of a common svsteni and agents of a common life. As a matter of fact, we find that differ- ent courses can be made to perform each other's function. If a piece of sensor nerve be joined to a cut end of a motor nerve and grow in place, it will conduct the motor impulse continuously with the motor piece. Tlie contrary is also true. Tiie range of such experiments is very limited, since it is impossible to exchange the end-connections of nerves either centrally or peripherally ; but the facts at hand establish conclusively the princij)le of indifference as re- gards the sensor and motor nerve-tracts. In its applica- tion to the centers the same principle has a different name, since it takes a somewhat different form of manifestation, i, e.y the principle of subsfitntiofi. PRTNCIPLE OF SUBSTITUTIOX. 49 III. Principle of Substitution. The question here is tliis : Can the nerve-centers be made to take up each other's function ? Researclies in cerebral localization, chiefly upon animals, tend to show that such a substitution of function is possible, at least to a limited degree. The removal of a cortical center, which occasions loss of one of the special senses, say sight, or the loss of control over a certain muscular area, seems to be made good by the as- sumption of the deranged function by a contiguous, or, at least, a connected center. At any rate the animal recovers, if kept alive a sufticiently long period. The word " seems" is used advisedly, for it is still uncertain whether the loss of such a function is due to the destruction of the entire apparatus normally reacting to this function, or to its par- tial loss, the remaining elements being temporarily in- hibited by so-called " physiological shock," or, in the case of electrical stimulation, by diffusion of the current. The latter is known to be the case in many of the experiments on brain-tissue, especially when the surgical method is employed without the extremest care. This latter view is also supported by the remarkable fact that in the monkey and man these substitutions are exceedingly rare ; a result v:e would expect on the shock theory, considering the higher degree of delicacy and differentiation attained by the system in these higher organisms. Yet in the case of rabbits and dogs, such substitution of function, notably of the sight-function, is probably established on a firm basis. IV. Principle of Specific Connection. The limits which the growth of the organistn sets to the substitution of functions find their expression in what is called " specific connection" through the system. By this principle is meant, in general, two things : First, that nerve-courses are specific only according as they have certain well- defined connections at center or periphery. These con- nections keep the courses to an invariable function. The 50 THE NERVOUS SYSTEM. optic nerve has a specific connection with the retina and with the optic center in the brain ; the auditory nerve with the ear and the center for hearing ; and so on. In this case, it is the end-organ or the center which is specific, not the nerve- tract. And second, it means that nerve- centers are specific according as their connections necessi- tate their reacting to a specific stimulus. The optic center has specific connections with the retina through the optic nerve ; tlie center for sounds with the ear, through the auditory nerve, and so on. Now there are as many of these specific connections as there are kinds of stimuli issuing in motor reactions. Consequently, the only specific things after all are the stimulus and the movement. V. Principle of Summation of Stimuli. If the stimu- lus more than overcomes the arrest in a given case, there is loft over, so to speak, a surplus of positive energy, or posi- tive " molecular work." This positive molecular work is work of reaction, or exhaustion of the system ; negative work being inhibitory or conserving. This surplus repre- sents, therefore, a disposition favorable to a second stimu- lus of the same kind. We have, therefore, here a certain summation of stimuli in cases of recurring excitations of the same character. After moving the thumbs in a certain rotatory manner a certain number of times, we say they are " ready " for that movement ; they have taken on a disposition to react to the same stimulus again. This union of former stimuli with later in the nervous center, giving an easier and smoother reaction, is the phenomenon of sum- mation. Its most remarkable exhibition is seen in cases in which the earlier stimulus is not sufficient to overcome the arrest or inertia of the center, and does not give a re- action at all ; so a weak electrical stimulus : even here we find the center so " prepared " by this insufticient stimulus that it responds when that identical stimulus is repeated a sufficient number of times. The most favorable interval between such shocks is about .001 second. The successive HABIT AND ACCOMMODATION. 51 blows of a toothed wheel upon a metallic tongue give an audible sound when a single such blow is inaudible. The different senses vary very much in the interval of time between successive stimulations necessar\^ to prevent summation or fusion ; the finger discriminates 1000 touches per second ; an interval of .005 second is sufficient to keep sharp sounds apart ; electric shocks on the forehead fuse if more than 60 occur per second. With sensations of sight, the fusion occurs across a greater interval, say .05 second, by reason of the persistence of optical after-images. § 5. FiffAL Statement of Nervous Function. We are now in a position to give the general conception of nervous function in broadest statement ; a statement the accepted terms of which have great psychological signifi- cance. All the phenomena of consolidation or " down- ward growtli," on the one hand, illustrate what is known as the law of Habit; all the phenomena of specialization, or " upward growth," illustrate the law of Accommodation. Law of Habit. Ph\^siologically, habit means readiness for function, produced by previous exercise of the function. Anatomically, it means tiie arrangement of elements more suitably for a function, in consequence of former modifi- cations of arrangement through that function. Psycho- logically, it means loss of oversight, diffusion of attention, subsiding consciousness. Law of Accommodatioii. Physiologically and anatomi- cally, accommodation means the breaking up of a habit, the widening of the organic for the reception or accom- modation of a new condition. Psychologically, it means reviving consciousness, concentration of attention, volun- tary control — the mental state which has its most general expression in what we know as Interest.^ In habit and interest we find the psychological poles corresponding to the lowest and the highest in the activities t)l" the nervous system. ' See (lie discussion of " Interest " below, chap. xix. § 1 CHAPTER ly. CLASSIFICATION AND DIVISION. » § 1. Three Great Classes. Besides their common characteristic, consciousness, mental facts have special cliaracteristics which distinguish them from one another and by which they may be divided into great classes. The necessity of this classification is seen in the great multiplicity and variety of these facts. In the beginning of every science, the statement is neces- sary of the natural knowledge of resemblances and differ- ences, which we may use as a starting-point for investiga- tion. In this classification two great dangers are to be avoided. First, many psychologists, neglecting real re- semblances, have made too many divisions or faculties, in a measure dividing the mind into independent princi- palities and losing sight of the unity of nature which under- lies all phenomena of mind. Again, others go to the other extreme in excessive opposition to the " faculty theory," especially in recent years, and fail to recognize essential differences in mental states. In the main, however, it is agreed that there are three great classes of facts in the mental life, however strongly the attempt to reduce tliem further may be urged. These three classes express t'le residt of three distinct functions of the mind : Intellect^ Feelmg, and Will. They may be called : 1st, Presentative, or intellectual states ; 2d, Affect- ive, or states of feeling ; and 3d, Volitional, or states of will. These great departments of mental fact are shown ' llamlbook, vol. i. cliap. iii THREE (iUEAT CLASSES. 53 in the very distinct propositions, "I feel somehow," "I know somethinor " " I do soniethino-." ^ The grounds of this classification are found m immediate consciousness, and it can find its justification only in an appeal to direct experience. The presentative states have as their common characteristic their reference to a t/iinr/ or object. Knowledge is a function of mind only as there is something to be known, and in the higher forms of its operation its states are taken to re-present or signify ob- jects. In its earliest beginnings also, in sensation, the objective bearing of knowledge, as affording us a reference away from ourselves to a something which is presented to consciousness, 'is its distinguislung feature. The affective states, on the contrary, as states of feeling, lack this element of objectivity ; that is, they are states in which consciousness is itself affected primarily (pain, fear). They may be entirely lacking in the presentative or knowledge element, or the two may be combined in any degree of connection. They extend from the simplest bodily feelings to the highest emotions, and include impulses, temperaments, and i>ersonal tendencies of all kinds. In strong contrast to these well-marked divisions the third class, volitional states, stand out in consciousness distinguished by a characteristic foreign to the other two, the sense of effort or c.vertion. It takes the forms of mental attention, choice, and resolution. The other orders of mental facts may or may not exhibit this will-element. I ma}^ be passively affected by pain or emotion, or I may be conscious of a free pla}^ of presenta- tions with no effort of nw own to control or direct them. This last phase, therefore, may be set apart as a third class, and as representing a third function. MVard, Eiicyc. Britannica, art. "Psychology." 54 CLASSIFICATION AND DIVISION. § 2. tJxiTY OF THE Three Classes in COXSCIOUSXESS. With tlie distinction of the three classes of mental fact and the three functions they represent clearly brouglit out, it must still b^ remembered that the latter are merely functions. They are not three psychological lives which lie parallel with one another. They are a single life. Their unity in a single principle may be seen under several aspects. I. T/iey have unity of end. They are functions of a common mental organism and minister to its development. The unity of the body is realized in the unity of the func- tions of the different organs. The end of all is the con- servation and development of the whole. So the intel- lectual functions are one, in their tendency to preserve the independence of the self and accomplish its destiny. "By intelligence we conceive the end of conduct, b}'' sensibility we are excited to produce it, and by will we govern these impulses in the light of reason and assure the victory of the best. Without intelligence, man is blind ; without feeling, he is inert ; without will, he is a slave." ^ II. 2'hey are one in their collective activity. Each seems to depend on the others in an essential way. At- tention is necessary to all thought, and feeling is often necessarj'^ to direct or is effectual in preventing the direc- tion of the attention. In its reflex activity, attention seems to be a representative or relating function, but it has the fundamental quality of will in its active exercise as mental effort. A volition, as has been said, proceeds upon ideas and appetences to such an extent that one school of psj^chologists reduce will to the conflict of ideas and another make it a conflict of feelings. Feeling also involves images or ideas, through memory or imagination, or arises from association, and all of these are representa- ' Rabier, loc. cit., Compare throughout this section. DIVISION. 56 tive. And it seems possible, sometimes, to originate the train from whicli feeling arises by a powerful act of will. III. They find their formal unity in consciousness. The completed view of the mind ends, as it began, with con- sciousness, a^ the necessary background and formal unity of the whole. Consciousness bespeaks the unit being, the subject of this threefold activity, and in its healthfulness or derangement, under normal stimulation of this threefold order, the proper balance and end of the whole is accom- plished. § 3. Division of the Subject. In view of the above classification, the subject-matter of psychology falls into convenient parts for treatment. In addition to the three great classes of facts spoken of, the form or mark which is common to them all, consciousness, must be considered. There are, accordingly, the following four great divisions : Part I. General Characteristics of Mind. Part II. Intellect. Part III. Feeling. Part IV. Will. PART I. GENERAL CHARACTERISTICS OF MIND, CHAPTER y. CONSCIOUSNESS.' In the foregoing chapters the term consciousness has been used without explanation. Familiarity with it in the gen- eral significance it bears in ordinary discourse has been assumed. It is necessar^^, however, at the outset, to inquire more fully into its nature and position in the science. § 1. Nature of Consciousness. Definition. Disregarding less important varieties, we may say that two general views of the nature of conscious- ness prevail among psychologists. On the one liand, it is held that consciousness is itself a capacity, function, or faculty of mind, an inner sense for the perception of the mind and its states, as sight and hearing are outer senses for the perception of body. This view rests upon the fact of reflection, the developed means of observation of inner states, which has, in common with sense-perception, the relation of subject and object within itself ; but not upon the original awareness which we have of our first experi- ences. This latter bears no analogy whatever to external perception; This doctrine of consciousness makes it not essential, but accidental, to mind, an added thing, whii-.h may be wanting, as external senses, memor}?-, imagination, may be wanting ; and admits the supposition of uncon- scious mind. ^Handbook, vol. i. chap, iv, and vol. ii. chap. ii. 5C ITS AUEA. 57 The opposing view is this, that consciousness is the com- mon and necessary form of all mental states ; without it mind is not and cannot be. It is the point of division and differentiation between mind and not-mind. From the empirical point of view we may make the fol- lowing observations : 1. Consciousness is not a power or energy of mind. It does not involve the conscious effort of attention. In a state of reminiscence, of reverie, the states of mind are un- controlled, and come and go with no let or hindrance from the mind. We are then fully conscious of this play of states, but of no exercise of mental effort accompan^^ing it. 2. Consciousness is not an organ of the mind, to be used b}^ the inner subject in perceiving his states. It is not an inner sense, since it accompanies tliC exercise of all the senses and is necessary to tlieir function. The senses have specific physical basis also, wliile consciousness depends upon the liealth}^ and normal activity of the sensorium as a whole. Consciousness is, therefore, the 0)ie conditioii and abiding characteristic of mental states} § 2. Area of Coxsciousxess. The area of consciousness is the sum of the presentations at any time in consciousness, whether tliey be distinct or vague. Experiments show tliat twelve to fifteen strokes of a pendulum can be held in consciousness at once Avithout counting or grouping. If they be grouped by fives, as mau}^ as forty ma}^ be retained. The most favorable inter- val between them is .2 to .3 second. Consciousness may be likened to the visual field in which objects are scattered, those being most clearly seen which are in the line of direct vision or center of the field, and those which lie near the circumference most indistinct. Between these limits there are all degrees of distinctness. So ideas are distinct or 'On the theory of ''Unconscious Mind" see my Handbook of Psycliology , vol. i. chap. iv. § 3. ^8 CONSCIOnSNESS. vague in consciousness according as they are in the line of mental vision, or attention. The idea attended to is most distinct, those connected closel}^ with it in any way less so, and those which are accidentally present and quite unob- served actively, least so. According as they lie in one or other locality of this general distribution, consciousness of them is said to have different degrees or forms. Degrees of Consciousness. These may be illustrated by an example. As I write, the noise of my pen is almost unnoticed. If continued some time, it is no longer noticed and is said to be subconscious. If the pen is a poor one, and scratches more as used, I continue to write, though 1. The Unconscious (physiological). 2. The Subconscious. ) 3. Diffused Consciousness. ) '^^^^^^* f Reactive Con- 4. Active Consciousness ! sciousness. or Attention. j Voluntary Con- [ sciousness. 5. Apperception. Fig. 13.— Graphic Representation of Area of Consciousness, after Analogy with Vision. conscious of the disturbing noise, but give it no attention. It is then said to be in a state of diffused consciousness. Thus a thousand things around us — the table, chair, books — are present to our minds, but we are passive in regard to them. If now my attention is drawn involuntarily to mj^ pen we have reactive consciousness, or reflex attention,' and if I voluntarily examine the point in order to remedy it, there is an active puiting forth of myself mentally; there arises active consciousness or voluntary attention. Tlie state of things in which the attention is concentrated upon an image is apperception. Further, all the lower condi- tions, in which there is no attention, either voluntary or involuntary, may be designated in common as passive con- sciousness. See Fig. 13. APPERCEPTION. 59 It is well to note the play of ideas through all these forms of transition, from the dark region of subconscious- ness to the brilliant focus of attention. Images pass both ways constantl}^, acting varyingly upon one another and making up the w^onderful kaleidoscope of the inner life. Apperception. Apperception characterizes the changes which take place in active consciousness. By it is meant the synthesis in consciousness by which mental data of any kind (sensations^ percepts, concepts^ are constructed into higher forms of relation and the perception of things which are related becomes the perception of the relation of things. ' " Tlie two presentations a and ^," says Lotze/ " constitute siniplj- occasions Avhereby the reaction of a spiritual activity is aroused, through which new presenta- tions — such as similarity, identity, contrast, arise — presen- tations which w^ould not be possible without the exercise of this new spiritual activity." The relation of percepts is not the same as the perception of relation. Apperception is the comprehensive "power of discovering relations"; but is not limited to the operations of reasoning. It is the essential fact, as shall appear in all the stages of mental generalization. This use of the word apperception to express the broadest act of mental relation is of great importance and value. The treatment of the very distinct and familiar act of mind in attention, of grasping details and relating them to one another in a new mental product, has heretofore been confined to its special operations — as perception, concep- tion, judgment — to each of which a different name was given. The term apperception singles out that act of mind which is common to them all — the relating activity of attention — and thus, by its general application, em- phasizes the unity of the intellectual function as a whole. In general, we may say, whenever by an act of attention ' Outline of Psychology, § 23. 60 C0X8CI0 U8NE88. mental data are unified into a related whote, this is an act of apperception. § 3. Development of Coxsciousxess. The beginnings of consciousness are enveloped in great obscurity. Shortly after birth a child begins to show signs of memory and of the power of connecting impres- sions. But both the memor^^ and power of association are very weak and depend upon intense degrees of excita- tion, as a very bright light or a very loud noise. Wlien the child is several months old, a familiar person is for- gotten after a week's absence. Gradually attention is dis- covered, at first vague and discontinuous, and after a few weeks becoming more persistent and intelligent. This is shown earliest for sight and touch, the two senses which discover space relations. It is probable that the earliest consciousness is a mass of touch and muscular sensations experienced in part before birth, and that it is only as the special senses become adapted to their living environment and sensitive to their peculiar forms of excitation, that the general organic condition is broken up and the kinds of sensation differentiated. This process of differentiation of the sensations of touch and muscular sense gives us very early the form of our own body and the locality of its l^arts, and this serves as point of departure for the placing of external objects. The movements of the body contrib- ute largely to the apprehension of the dimensions, forms and areas of things in space. The movements of the body are at first random and without control, arising from nervous discharge under conditions of physical discomfort. The child then passes through a stage of development in which its movements are largely adaptations of the organ- ism to outside stimulations. After the sixth or seventh month imitation of others' movements becomes its prevailing reaction. In "persistent imitation" — the trj^-try- again, experience — we have the first voluntary efforts of the ITS DEVELOPMENT. 61 child.' These effort-movements gradually take on a positive character, but even after two or three years it is difficult for the child to execute any given combination of movements. This fact of control of the bod}^ seems to be the first be- ginning of the exercise of will. It involves a subjective reference more distinct and peculiar to itself than any of the purely affective sensations, and leads on to the notion of the Zand so to 56{/*-consciousness. The development of consciousness is largely dependent upon the development of the physical organism. The senses must be awake to their functions before the mind can exhibit its functions. Not till the eyes are open and in proper movement can the impressions of that sense be- gin to play their very great role in the forms of external perception. So also must the centers become accustomed to their reactions. If we liken the elective activities of the developed nervous system to lines of least resistance, we may say that, for the very young child, such organic pathways are largely wanting and they must be established and maintained by actual exercise. These early physical modifications becoming more and more definite and multi- plied, the more complex forms of mental function are made possible. Like other organs of the body, also, the brain grows in size and complexity. It attains its largest size probably much before the maturity of manhood ; but its structural development, which consists in the differentia- tion of parts for special functions and the establishment of various connections throughout its bulk, is then but well begun. The basal ganglia seem to develop their activities earlier than the cerebral hemispheres. This is to be ex- pected, since they are connected with the organic and essential processes of the body. • On the development of the child's active life see my articles, "Sug- gestion in Infancy," " Infants' Movements," " Origin of Volition in Childhood," in Science, February 27, 1891, Januarys, 1892, and No- vcniber 18, 1892. 62 CONSCIOUSNESS. The relative value of different images in the early stages of mental growth is illustrated by the following experi- ment ^ made by the writer upon a girl six and one-half months old. The child's nurse, who had been with her for five months, was absent for three weeks, and on her re- turn was not recognized by her face alone, nor by her voice 'alone (spoken words), but was fully recognized by sight (face) and sound (nursery rhyme) images together. § 4. Nervous Conditions of Consciousness. General Conditions. There are two great theories of the physical basis of consciousness : the first, represented by Mr. Lewes,'* holds that the nerve-process, considered in its most general form as irritability, is everywhere con- scious. On this view, each nervous center, each so-called arc, has its own consciousness, and the ordinary conscious- ness of the individual is only the outcome of many lower consciousnesses that we all possess. The brain-conscious- ness is the only one we are conscious of, so to speak ; but there is consciousness in the spinal cord and in ganglia wherever we find them. The other theory, or class of theories, holds that a given degree of development is necessary before consciousness is found at all. In the development of the system, therefore, consciousness appears only at a certain stage of integration or " upw^ard growth." This theory is generally accepted, though for purposes of division rather than from positive argument. In the nature of the case, it is impossible to disprove con- sciousness in lower centers. It also seems true that our personal consciousness repre- sents a condition of slow, difficult, and impeded — conse- quently of highly developed and well balanced — integra- tion. The smoothest reflexes are not conscious ; the hard- 1 See Science, May 2, 1890. *Hekl also by Bain {Emotions and Will, Appendix A), and in a inodKk'd form by Wundt. ITS CONDITIOXS. 63 fought decisions are most conscious. It seems likely, therefore, that some degree of inhibition is necessary in the nervous basis — at any rate for vivid consciousness. On the other hand, there are considerations which are giving more prominence to the view of Mr. Lewes at pres- ent. They tend to show that our distinctions are arbitrar^'^, and open the door at least for presumptive evidence that consciousness is coextensive with nervous reactions. Among these considerations are recent proofs of so- called multiple personalities which may be induced in the same nervous organism in the hypnotic state.* The explanation is at least a tempting one, that, the higher centers being inhibited, their conscious content is wanting, and the lower centers supply experience which was before outside the conscious area. Again, in the scale of animal organisms, it is difficult to draw a line denoting the point of nervous complexity below which there is no conscious- ness. The fact of a possible substitution of function be- tween the brain and spinal ganglia spoken of above, would indicate a possible common element of consciousness. Particular Conditions. A further question arises as to the immediate conditions of consciousness in the nervous centers. Given a nervous organism capable of conscious- ness, on what particular state or aspect of it does the con- tinuous presence of consciousness depend ? Here, again, recent views are little more than guesses. The view supported by Herzen seems to have most evidence, i. e., that consciousness arises from the breaking down or ex- penditure of tlie cellular structure in the centers. This is concluded from the fact that the attention, a state of concentration and expenditure, is the state of most vivid consciousness ; that consciousness is most vague and indis- tinct wlien no brain-work is being done, as in cases of dolcefar niente or diffused attention ; that unconsciousness is most nearly reached in sleep and analogous states when ' Pierre Janet, A"f"i/o/fisiue Psychologique. 64 ., CONSCIOUSJVESS. the brain processes have largely subsided from the lack of sensory stimuli or motor impulses. The chemical re- sults of active thought, increased heat, and organic waste deposits in the brain would indicate chemical work and disintegration. It is also true tliat consciousness depends upon the nor- mal condition of the mechanism as a whole. Any failure in the blood supply (anaemia) leads to faintness and faint- ing, and the same result often follow^s from congestion of blood in the brain (hyperaemia). In general we may say that the healthful activity of the brain, in its normal physiological relations, gives clear consciousness. It should be borne in mind, also, that all hypotheses as to the condi- tions in which it arises shed no light on w^hat conscious- ness is. On this point even the biologist Schneider is clear. § 5. Sentience and Sensibility. It has become apparent that nervous activity, considered for itself alone, does not bring us into the range of psj^cho- logical science. However we may decide the inquiry as to whether such activity is ever entirely free from con- sciousness, it is yet true that it may be quite outside of what is called the individual's consciousness. IVie man is not conscious after the guillotine has done its work, however active the nervous reflexes of his limbs may be, and how- ever firmly wc may believe that his spinal ganglia have an " inner aspect." In other words, the greater part of our ordinary nervous reactions are not above the threshold of our conscious lives. So we reach a distinction between sentience as a nervous property and sentience as a con- scious phenomenon, between sentience and sensibility.^ Sensibility is synonymous with the usual consciousness of ' Lewes uses the two terms io senses precisely the reverse of this, Physiml Basis of iUnd, p. 323 ; i. e., to him sensibility is the ner- vous property everywhere ; so also Sergi, PsycJiologie PhysioUh (jiquc, p. 13. KFXnS OF COJYSCIOUSWESS. 65 the individual's experience, and sentience is tlie nervous function which, as far as we know, may yet be accompanied by consciousness or inner aspect in general. For a working test of the limits of sensibility we may say that there is no sensibility (1) where there is no brain ; (2) where there is no trace left in memory ; (3) whore there is no expressive or adaptive motor reaction. Yet in all of tliesy cases sentience ma}^ be present, as the sensitive plant seems clearly to show. The transition from simple sentience to the full con- sciousness is through subconscious modifications. On the side of the nervous system they indicate a stimulus and reac- tion too faint to reach into the sensibility. Yet they in- fluence the conscious life and give it direction and inten- sity ; a fact seen again on the physical side under the principle of summation of stimuli. § 6. Kinds of Consciousxess as Dependent on Xervous Complexity. 1. Passive Consciousness. Subconscious sensibility tends to secure recognition in the mental life as what is called jyassive consciousness, to distinguish it from the active forms which involve more or less attention. The writer often finds that he can start counting the strokes of a clock after the clock has struck several times, naming the correct number of each stroke to the end, although he was not aware of the strokes before he began to count. This illustrates the subconscious. In most cases passive consciousness is, by its very nature, undetected, and it ex- ists as a normal state apart from active consciousness only in lower forms of organic life or in very young children. In adult life we catch it most nearly when just beginning to recover from a swoon ; the sounds around us are heard, but have no meaning, relation, or escort. Of this state abstracted from the condition of our usual self-conscious- pess, we may make the following remarks : 1. It is a state QQ CONSCIOUSNESS. of pure sensibilit}^ or simple awareness. 2. It carries no reference to an external object or to the body, that is, no such reference inside the inner aspect. 3. It has no refer- ence to self as an object of inner apprehension, no volun- tary effort known as " my effort." 4. It has no relational or apperceptive quality. It is not knowledge, but pure feeling. It is the hypothetical affective state in all its purity. The possibility of turning attention to a dim presenta- tion and making it vivid, shows that the cerebral basis of these lower forms of human consciousness is not one of separateness from the highest centers, but of community with them ; indeed a nervous discharge already in volun- tary operation may be diverted into a subconscious reac- tion without the attention. The physiological basis of passive consciousness, then, is a state of temporary loss of tension in a brain-area which shares in the highest integra- tion and instability. 2. Reactive Consciousness. By reactive consciousness is meant tlie state commonly designated as involuntary attention. In passive consciousness only the reception of stimuli is a matter of sensibility ; here consciousness seems to attach also to the responsive member of the nervous arc. There is as truly a reaction in consciousness as there is in the nervous system. We may accordingly analyze this form of consciousness for purposes of treatment into three elements, corresponding to the three elements of the nerv- ous arc. First, the receiving consciousness, the stimulus — say a loud, unexpected sound ; second, the attention invol- untarily drawn, the registering element, as appears below ; and third, the muscular reaction following upon the sound — say flight from fancied danger. The analogy, accord- ingly, between the typical brain process and the typical mental process finds here its most general force and de- mands the most careful treatment. Questions of the most radical philosophical importance begin here, REACTIVE CONSCIOUSNESS. 67 Characteristics of the Reactive Consciousness. In gen- eral, this form of consciousness is distinguished by a feel- ing of expenditure. Attention alwaj^s means expenditure even when quite invohmtary. Any further designation would onl}^ becloud a sensation which everyone can point out clearly enough in his own experience — the sense of being caught and carried away mentally. Again, the reactive consciousness has an additional ele- ment which we call the sensation oi fatifjue.^ This sensa- tion is distinct from that of expenditure, and arises only after prolonged attention or in conditions of antecedent nervous exhaustion. As to what this feeling is, again no further descrij^tion is necessary now. Moreover, on the muscular side we find two different classes of effects : the reactive effects peculiar to the par- ticular stimulus, and besides these the peculiar muscular accompaniments of attention itself. The latter are con- stant, and the former vary with the stimulus. For ex- ample, a student hears his name called suddenly and loudly. The particular reaction habitual to such a stimulus is a speech reaction — the response. Hullo ! or Yes ! But, before speaking, he finds he has turned his attention — probably his head — to the source of the sound, and by so doing has brought into play a different set of nerves and muscles. Now, of these two reactions it is the speech- reaction which answers in consciousness to the motor side of the nervous arc, stimulated by the sound, and it is only this that we can say follows the attention without finding ourselves on debatable ground. The attentive movements seem to belong peculiarly to the attention itself, and so fall under the central element in the typical reaction. Consequently, in the motor phenomena of the reactive consciousness, there are two very distinct elements which subsequent discussion must not confuse : the motor effects of the stimulus which is attended to, and the motor accoiij- ' piscussed below, cliaj). xxiii. § 4, 68 CONSCIOUSNESS. paiiiraents of the attention itself. This may be seen in Fig. 14, in which a new^ element (cc = co-ordinating center) is added as the central process of attention. A new motor process {mp') is stimulated, and this produces new- muscular movements {mt'). The ordinary reaction also takes place (mp, mt ; in this case, speech) following from the ordinary stimulus (sp ; in this case, sound). The > w/j Fig. 14. Fig. 15. sp, mp, mt = Motor reaction. sp, cc, mj/, mt' = Motor accompaniments of the attention. matter is again simplified in the " motor square " diagram. Fig. 15. 3. Voluntary Consciousness. Voluntary consciousness may be characterized b}^ several new affective elements — new modifications of sensibility. Without anticipating later analysis, we may say that it exhibits, first, deliberation. By this is meant, in general, a doubleness of sensibility, a consciousness of being drawn apart, or of inward conflict — to limit the case to the feeling aspect, apart from the play of ideas involved. This feeling of deliberation leads on to another element of sensibility, namely, the feeling of ' Cf. Fii?s. 11 and 12, above. VOLXTNTARY COXSCIOU^^XESS. 60 decision or consent ; in wliicli the doubleness spoken of is resolved in a pleasant unity of consciousness again. And further, we find another possible element, apparently distinct from the preceding, the feeling of effort. In this sensation there is an active identification of ourselves with the reac- tion decided upon ; a conscious putting forth of ourselves to reinforce our decision. An^^ analysis of volition must, at least, take account of these three distinguishable aspects of sensibilit3\^ Xow it is in the selective and inhibitive functions of the nervous system that the physical basis of the voluntary consciousness is to be found. As far as such selection and inhibition are conscious at all, they have probably the nervous essentials of volition. Of the three sensible ele- ments involved, the first and second have clear physiologi- cal analogies. Deliberation in consciousness is analogous to dynamic complexity and instability in the brain-centers ; there is such a thing as temporary balance in the nervous S3^stem, and it suggests itself at once as the physical counter- 2)art of mental hesitation. Inhibition also, as far as our physiological knowledge goes, seems to have full conscious value here. Decision, as following upon deliberation, is again analogous to the state of central readiness for the discharge of nervous force, when the equilibrium is destroyed and the motor outburst only waits for the requisite stimulus to take its outward course. With effort, however, the case is on the surface different. There is no evident nervous function corresponding to this state of sensibility ; that is, no function not already sup- plied with its conscious analog3^ The question of such an analogy or ph^^sical basis of effort, therefore, comes finally to wait upon ^ more thoroughgoing mental analysis of this sensation. If effort be reduced to expenditure, and expendi- ture to incoming sensations from the muscles, then there is ^ For detailed consideration of these three features of voluntary con- sciousness, see below, chap, xxvi, and xxvii. § 1. 10 C0NSGl0TfSmS8. no need for such an analogy ; but if effort resist further anal}^sis, then physiology is as yet at fault. Fundamental Properties of Consciousness. The gen- eral fact is evident, in view of all that has been said, that different events in consciousness are of different value, come in with a different introduction, have different qualities wliich mark each as itself and not another ; in short, that consciousness has a fundamental property of discrhnination : and further, it is clear that under these differences in its events consciousuess acts differentl}^ courting some changes and avoiding others, reacting so on one stimulus and thus on another — the further funda- mental property of selection. We have found, also, that consciousness has degrees of excitement,^ intensity, coloring, of its own according as this event happens in it or that. These properties are evidently tl)e basis of the threefold division of conscious states already pointed out : Intellect (discrimination), feeling (degree of excitement) and will (selection). § 7. The Nervous System and the Unity of Consciousness. The functional unity of the nervous system has already received sufficient emphasis. The conception advocated in the preceding pages is a dynamic conception. The parts of the system have meaning only as they are related to each other in a system whose activity as a whole gives value to the activity of the parts in the general life-process. We have not many nervous systems, but one ; the laws of its growth are not many, but one ; its function is one, its teleological end is one. So consciousness has not many forms, pfssive, reactive, sensory, motor, voluntary, inhibitive. These are all partial aspects of a single unitary presence. There is no sensor ' On the relation of this property to pleasure and pain, see chap. xvi. nNlTT OF CONSCIOUSNESS. Tl plienomenon but lias its dj^namic or reactive side. There is no motor phenomenon in consciousness, but it springs from antecedents of sensibility. There is no voluntary phenomenon, but it rests on both. Consciousness, there- fore, is one as the nervous process is one.* ' See a statement and criticism of the theory which accounts for mental unity by the organic unity of the nervous system, in my Handbook of Psychology , vol, ii. chap. ii. § 6. CHAPTER VI. ATTENTION.! § 1. Definition of Attention. In the consideration of consciousness, a difference was found in its general aspect according as a number of pres- entations were loosely scattered about its field or as some one held the mind directed to itself. Consciousness is thus passive or active. Active consciousness is in general atten- tion. It is the focusing of the mind upon a presenta- tion. It is in all cases a conscious act. What goes on in the relating of this presentation to others, in their combi- nation, dissolution, arrangement, is due to the activity of apperception, which is, in a large measure, subconscious ; but the attention which makes the activity of appei-ception possible is a matter of immediate consciousness. Reflex or Involuntary Attention.^ Upon observation of ourselves, we find that attention may be stimulated either from some foreign and unexpected source or from the will. A loud noise, a violent contact, a disagreeable odor, at once attract the attention without our volition or even against it. This is reflex or involuntary attention. In the normal state of the consciousness, attention is con- stantly open to appeals of this kind. Minds with little power of will live under control of such external excita- tion. The attention is drawn hither and thither in rapid transition with no fixed concentration upon any sensation or idea. In such minds, as we shall see later, the functions of apperception are disturbed, and its products instable. ^ Handbook, vol. 1. chap. v. '•^ On involuntary attention considered as reactive consciousness, see above, chap. v. § 6. 73 REFLEX ATTENTION. ^3 This state of inability to liokl tlie attention against otlier solicitations is called distraction : the attention is, as it were, drawn apart in its efforts at adaptation to different conditions. A case of what may be called chronic involuntary atten- tion is found in the insistent idea. It very frequently occurs in normal life that a single idea, either by reason of a strong association or of a feeling, or because of previous attention, or even in consequence of the very effort of the will to banish it from consciousness, remains before the mind and holds the attention. This is called an insistent or, in its more intense forms, fixed idea. It is generally removed by a change of scene, companions, and surround- ings, the old association being broken or new ideas claiming the attention. As an idea becomes fixed or imperative, it gathers round it other ideas in growing associations and connections, which soon give a morbid tone to the entire mental life. This is the beginning frequently of mono- manias and permanent delusions,' which become chronic in insanity. Frequently also, it is supposed, the primary tendency to some form of nerve disturbance or brain dis- ease, due to heredity, gives occasion and strength to such derangement.^ The mechanical nature of involuntary attention and its intimate relation to all phj^sical and mental states is seen in the acts of a patient in a state of hypnotic hallucina- tion. Here it seems that the element of will is entirelj^ eliminated. The patient has apparently no control over either body or mind, and many suggestions either physi- cal or mental from the hypnotizer are immediately realized in action. It seems only necessary'- that the attention should be secured, to start the entire train of apperceptive processes Avith the physical changes which are associated ' See case described by Cowles, Amer. Jour, of Psycli., February, 1888. ' See further statement below, chap. xiv. 74 ATTENTION. with them ; or a physical attitude or movement may be forced upon the patient, only to be followed by all the emotional and intellectual states it suggests. In these states the intellectual life seems quite normal and the emo- tions are very excitable and facile in their play ; but all in- ner control is lost. Action results with complete necessity. The important fact in this form of hypnotism then seems to be the fixing of an idea till it becomes imperative, with the general subjective state unchanged by the substitution of ideas which it brings about. Voluntary Attention.^ In strong opposition to this is voluntary attention or attention proper. It may be de- iined as a state of active co7isciousness due to voluntary inental exertion or effort. Here a distinctly new element enters into consciousness, mental effort. In voluntary at- tention we find the first exhibition of will. It is the be- ginning of all control over the mental life. A thousand things may appeal to me for consideration and I may re- fuse them my attention. I may give myself to a train of thought and be substantially unconscious of sounds, sights, contacts which would ordinarily excite my attention. It is thus in the familiar condition of abstraction or ahsent- mindedness. This peculiar outgoing of the self is the something we call consent, in the mental life. From it we largely arrive at consciousness of self, by a reference of what we do, to ourselves as doing it. The frequent or prolonged exercise of attention to the same presentation or idea tends to bring It involuntarily before the mind. Its repetition in varied circumstances establishes various associations by which it may be revived. Insistent and fixed ideas usually become so from volun- tary thought upon them — from what we call "brood- ing " over a subject. Thus the line between reflex and voluntary attention is changed and much that was before a matter of choice becomes automatic and necessary. ' See also the discussion below, chap, xxvii. BEAmXGS OF ATTEXTIOX 75 § 2. Bearings of Attention in the Mental Life. In its relation to the great classes of mental facts, the at- tention is of the first importance. In general it may l)e said that attentw?i intensifies a me?ital state. It may be considered more particularly and in detail. I. Relation of Attention to Sensation. There is a twofold or reactive relation between attention and sensa- tion. On the one hand, increased hitensity of sensation draios the attention. The change in intensity of the sensa- tion is a direct stimulus to the attention, and the attention in this case is reflex. On the other hand, attention directed to a se)isatio?i increases its intensity. We have already seen that many sensations may lie in consciousness almost unfelt, while the attention is otherwise occupied. It is only necessary to direct the attention to them to give them their full force. But more than this, the attention may give them increased and very acute intensity. By fixing the attention upon bruises and burns, we increase the pain they give us. Hence the efforts we make to divert a sick man's attention from the seat of his disease, hy fixing his attention on some new artificial sensation, or by interest- ing him in another topic of conversation. Hot cloths relieve headache, by producing a counter-irritation. This effect of the attention is especially great in nervous dis- eases. Paralj^sis has been cured or driven from limb to limb in hj^pnotic patients by a mere suggestion, which so completely occupied the attention as to induce belief in the effect. So insomnia and sometimes dyspepsia and other diseases xn^j be cured. Attention has an influence also upon the time occupied by a sensation. Experiments show tliat a certain time is necessary for tlie feeling of an excitation from any of the sense organs and the reaction in the movement of the organ. This time is greatly reduced when the excitation is expected.' ^ For details, see section on Psychometry, chap. viii. § 7. 76 ATTENTION. A certain time seems to be necessary for the adjustment of the attention to the nature and source of tiie stimuhis, and this is reduced wlien tlie idea is j^resent beforehand and the attention is already partially adjusted. II. Relation of Attention to Movement. The move- ment of the members of the body is very closely con- nected with corresponding ideas. No voluntary movement takes place without its idea in the mind : and often the idea produces the movement without any voluntary im- pulse or even contrary to it.' The imitative faculty of children shows this tendency to carry out all movements thought of. We often find ourselves following the move- ments of the hands or lips of a speaker with slight move- ments of our own. It is probable that no word comes into tlie mind without its partial formation by the vocal organs, as is seen in the movements of the lips b}^ many in reading to themselves and in our thinking aloud. No doubt the pliysical association involved plays a great role in all such cases. The thought of a movement has preceded and led to the movement so often, that there is a positive tendency, at the nervous centers, to the discharge of the energy necessary to the accomplisliment of the act, along the proper courses. An interesting illustration has recently come to light in the cases of loss of the power of speech simply from brain injury in the centers for writing the words. This tendency to movement is greatly increased by the exercise of attention. The attention tends to bring the idea more distinctly before the mind and thus removes all competing ideas which should incite to different move- ments. This is especially the case when the attention dwells upon the organ or on the thought of movement. There is then a twofold effect due to the attention. It ^ Fere claims that every sensory excitation at first induces an aug- mentation of motive force which is measurable on the dynamometer : see law of " mental dj^namogenesis " below, chap, xxiii. § 1. ATTENTIOX AXD MOVEMEyr. 11 tends to develop latent sensations, as we saw above, in the organ, and these sensations lead to movement for their relief or continuance ; or it produces movement by the distinct purpose to perfonn an act thought of. For example, if the picture is vividh^ presented of a workman who has his thumb crushed by a hammer, we make instinc- tive movements to protect the thumbs, b}" folding them in the hands. The facts of hypnotic suggestion already spoken of show the automatic connection between an idea strongly attended to and its physical performance. The absence of will does not interfere with the performance of the action, but only with the power to prevent or direct it. The con- sciousness is so contracted in this state that each idea in turn is held in the focus of attention. III. Relation of Attention to the Intellect. Attention, either voluntary or reflex, is directly involved in the opera- tions of the intellectual function. In general, it may be said that attention increases the vividness of presentative states and thus renders more definite and lasting the apper- ceptive activities of synthesis, aualj'sis, relation, as seen in niemor}^, association, judgment, and reasoning. It is necessary, first, to tlie retention of images. The capacity to retain mental pictures depends upon the intensity of the original presentation, and the clearness of its relations ; and this intensity and clearness are enhanced by the atten- tion. The supply of materials which we have for use in the higher forms of thought depends at once upon our attentiveness to what passes before us in our everyday life. When we w ish to retain any event, we press it upon the attention and note its surroundings. Second, attention increases the intensity of the reproduced image in the same way. If w^e recall the face of a friend, it is, at first, dim and indistinct, but by holding it closely before us and scrutiniz- ing it, we can bring it clearly out in more detail. Tlie attention shifts rapidly from point to point upon the 78 ATTENTION. image. Third, the duration or time of all mental states, as of simple sensation, is made shorter by attention, as is seen in experiments on the association of ideas and estimation of differences. IV. Relation of Attention to Peeling. Attention lias the same intensifying influence upon the affective states in general as upon sensation. Emotion is heightened when the attention is directed to it. Hope, joy, fear, anger, grow very greatly in intensity when thought of, and as quickly die down when dismissed from the attention. With tlie higher emotions it is very difficult to control tlie attention, so tlioroughly do they usurp the field of consciousness. So, also, pleasure and pain, called the hedonic tone of feeling, are increased by being attended to and diminished when the attention is withdrawn. The especial relation existing between the attention and the feeling of interest^ has often been remarked by psychol- ogists. This feeling of interest is often akin to that of personal advantage or individual preference, which we find playing an important part in the flow of our associated ideas. It gives a spontaneousness and ease to the attention which renders the latter more effective and less wearisome to the inner life. Attention to that whicli interests us does not demand the same outgo of mental effort. V. Relation of Attention to the Bodily Functions. Attention long directed tends to derange the automatic functions of the body. The automatic functions are those which go on unconsciously to ourselves. The action of the heart is accelerated by being closely attended to. The digestive apparatus may be deranged by being watched, and so also may the breatliing process. Atten- tion is also accompanied by certain attitudes of the body, such as turning the head or eye in a given direction, bend- ing forward, frowning, and other muscular contractions. A feeling of tension is felt also in the end organ. This *Se^ discussion of "Interest," below, chap. xix. ^1. ATTENTION IN EDUCATION. 79 tends to show that it is the motor elements of the brain which are involved in attention, while the effect it works upon sensation shows a sensory modification following upon the other. § 3. Educational Bearings of the Doctrine of Attention/ Training of the Attention. The considerations already advanced tend to show the importance of the attention in education. The secret of the case rests upon making attention completely voluntary. Strength of thought depends very largely upon the voluntary control or concentration of attention, in such a way as to prevent distraction from accidental and unexpected influences. This training of the attention should begin at the earliest possible period. The child should be taught to observe continuously some thing that interests him, and encour- aged to ask questions about objects and their relations. In very early life these things should be left to his own selection, until the laws of apperceptive synthesis are developed, that is, until he learns somewhat to connect things and events and see their bearings. Otherwise the forcing of the will may interfere with the development of the emotions, which are then the controlling factor. But as soon as practicable, the teacher should attract and hold the child's attention, at first to pleasant things and after- ward to indifferent things. Great care should be exercised in the general surroundings. All distractions, such as open windows, pet animals, pla3^things, should be guarded against : they practically call upon the child to attend to several things at once. Care should be taken also not to fatigue the attention. The periods of study had better be too short than too long ; for if the child growls tired, the effort becomes painful and the subject distasteful. Fre- quent recesses should be given and recitations should not 'See also Sully, Outlines of PsycJtology, p. 103. 80 ATTENTION. be longer than fifteen to twenty mimites, for children under twelve to fourteen j^ears of age. The child's inter- est should never be allowed to flag. Habits of Attention. In this way regular habits of at- tention may be formed very early, which have the same force in life as all other habits. Attention tlius becomes application^ which is voluntary and agreeable : and with this basis the student has no trouble in devoting himself to subjects of thought for longer periods. A caution is perhaj^s in order, as to sameness in the kinds of instruction given in early life. It is not Avell that the same general cast of thought should engage too much of the early attention of the student. It gives a bent to all his subsequent development. John Stuart Mill is a good example of this. It is especially dangerous when it involves the emotional side of our nature. Reli- gious teachers use this fact not only properly to instruct in morality and religion, but also to excite early prejudices and repulsions which can never be shaken off. Nurses often give children associations of fear which persist through life. This is the origin, frequently, of the insist- ent ideas spoken of, which intrude themselves upon us and make many of us to a degree hobbyists and mono- maniacs. Attention Necessary to Apperception. As will appear later, it is only in and through the attention that the apperceptive function of mind comes into play. In its discriminating, selecting, and relating results, the concen- trated attention is called apperception ; but the active process which produces these results is the attention. At- tention and apperception seem to be the subjective and presentational sides respectively of the same mental fact. PART IL INTELLECT. CHAPTER Aai. DIVISION OF THE INTELLECTUAL FUNCTION.i The Intellect is the instrument of knowledge. Using the word " function " simply to mean " aspect," or " ex- hibition," we may say that Intellect has two functions : I. The Apperceptive Function, which in turn com- prises : 1. Presentation or Acquisitio?i, being a. Sensation ; b. Perception. 2. liejwesentation, being a. Conservation or Memory ; b. Combination ; c. Elaboration. II. The Rational Function. • § 1. Demarkatiox of the Functions. I. The Apperceptive Function. Under this function are included all those changes in the presented content of consciousness which take place under the form of apper- ception ; those which owe their product to the concentra- tion "^ of attention. The function of Presentation or Acquisition is that by which the material of knowledge is gained. It covers the ' Handbook, vol. i. chap. vi. * See the defiuition of apperception, above p. 59. 81 82 DIVISION OF INTELLECT. two sources of our knowledge in experience, Sense-percep- tion and Self -consciousness. The function of Representation, as the word implies, is that by which the material acquired in presentation is re- tained, reproduced, and intelligently used in the processes of mind. Its operations are considered under three great heads : a. Conservation or Memory, w^hich includes the Retention, Reproduction, Recognition, and liocalization in time, of Representations ; h. Combination, which is the disposition of reproduced states in the new forms of the Imagination, the law of its disposition being Association ; c. Elaboration, which is tbe function of intellect proper, constituting the operations of Thought. Under it we find again three mental stages. Conception, Judgment, Reason- ing. II. The Rational Function. In this aspect we view consciousness not as content, but as form or mold for the material of knowledge. All the foregoing operations, both presentative and representative, are subject to a law of universal validity, the law of Identity or Non-contradiction. And the intelligence w^hen exercised upon things in general is governed by tlie principle of Sufficient Reason. As judgments these principles are also synthetic, but they seem to carry their own universal validity as matters of self-veflection, and not to be given in the content of apperception. These with other principles of the same nature, as causation, right and wrong, run through all knowledge and constitute the Reason. THE APPERCEPTIVE FUNCTION. PRESENT A TION. CHAPTER VIII. SENSATION. > § 1. General Nature of Sensation. Sensations are the primary eveuts of the mental life. The\^ are so called because they arise through the senses. AYe use the word in its usual sense, as meaning the great body of ps^'chological phenomena, both affective and presentative, which result witldn the mind immediately from impressions upon the senses. The experiences of moisture and resistance which follow from contact with a piece of iron, and the pain felt in case it is hot, are equally sensations. Distinction between Sensation and Impression. Sen- sation being thus defined, it must be carefully distinguished from the physical phenomenon which precedes or accom- panies it. The impression is the modification of the organ, especially of the nerves and nervous centers, which arises from an external stimulus ; as the vibration of ether or air. The nature of the different sense impressions is not well understood ; but in each case they are some form of move- ment. They have all the characteristics of physical phe- nomena : they can be located, measured, apprehended by the senses. Sensations, on the other hand, cannot be com- pared M'ith movement of any kind. The difference between ' lliti,,Vi,H,k of Pfz?^c any ])articular one remaining intact when that one and those named before it are destroyed — namely, delicacy or co-ordination of movement, delicacy of touch, pain, voluntary movement, electric feelings, muscular irri- tability. From this general survey of sensation, in respect to quality, the distinction between affective and presentative elements in sensation is more clear. In each sense when the affective element is strong the presentative is faint. When a very bright light strikes the eye it produces a strong affective sensation, but vision is indistinct. On the contrary, when we read printed words they represent thought, but are onh^ slightly affective. The case is the same with sound and touch. § 6. Quantity of Sensation : Psychophysics. Weber's Law. By quantity is meant intensity or mass. Until quite recently it was considered impossible to meas- ure intensities in sensation, from the fact that they are subjective entirely and we have no abiding internal meas- ure to which to refer them. Tliis difficulty has been par- tially overcome b}'^ establishing an external unit of meas- urement, and comparing sensations through it with one another. A relative measurement is in this way attained. Tliis external standard is the quantity of stimulus agreed upon as producing a unit of sensation. The external ex- citation thus becomes the means of approach to the measurement of the internal fact. For example, if the sensation given by the weight of one gram on the back of the hand be taken as the unit of sensation for pressure, other sensations can be compared with it, in relation to ' The student may profitably consult Ribot's exposition of this topic, German Psycliology of To-day, p. 134 ff. 104 SE]\^SATTO]\''. their respective excitations, Tliis procedure has actually been carried out in those of tlie senses most accessible to experiment and the following law formulated, known as Weber's laio : In order that any sensatio?i may increase hy quantities always equal, the excitation must be increased by a constant fraction of the excitation itself ; or, the ex- citation must groio in geometrical jjrogression (1, 2, 4, 8) in order that the sensation grow in arithmetical progres- sion (1, 2, 3, 4)/ or yet again, the sensation varies as tlie logarithm of the excitation.^ Besides its application to the regular sense perceptions, Weber's law applies, with the same limitations, to the esti- mation of linear distance and to the judgment of the flight of small portions of time. In order that I may judge a line twice as long as another it must be really more than twice ' Fechner. In arriving at this law it was necessary to show that the sinallest perceptible difference between two sensations of the same sense requires a constant fractional increase of the smaller excitation. This has been shown with reasonable exactness for moderate degrees of in- tensity of sensations of sight (ylff), touch (i), and sound 0. In deal- ing with high intensities the proper working of the organ is deranged and the results vitiated ; as with very bright lights. In the case of taste and smell the difficulties of isolating the sensation and measuring the amount of the stimulus have been almost insurmountable. Three distinct methods of arriving at the smallest perceptible difference of sensation are employed, all of which depend upon the subjective estimate of the person experimented with as to the equality of two stimuli, such as weights or lights. (See Ladd, loc. cit., p. 364.) The scale of sensation values has its zero or vanishing point at the smallest perceptible sensation for each of the senses. Hence the neces- sity of instituting another series of experiments on all the senses to discover this value. The point at which a growing excitation first begins to be felt as a sensation is called the threshold value of the excitation and the sensation is said to be at the threshold. This point varies very greatly according to the conditions of the senses as to exhaustion, and the state of the mind, as preoccupied or attentive. Upon these two classes of data, smallest perceptible difference of sansations and smallest perceptible sensation, the logarithmic law of r EXTEKSITT OF SENSATION. 105 as long ; and in estimating five seconds I make the time too sliort by about one-fourth/ The interpretation of Weber's law has occasioned much discussion. How are we to construe the fact that the sen- sation, which must be considered as effect, does not increase proportionally to the stimulus, which is cause ? The answer probably is that the disproportion is due to the loss of excitation energy in the phj'siological processes involved, the processes of transmission by the nerves and of central stimulation. This makes the central process the cause of the sensation, instead of the peripheral process, and the law of causation liolds. Extensive or Massive Sensations. The quantity of sensation, considered as intensity or ititensive masSy is to be distinguished from its quantity considered as extensity or extensive massive^iess. If I paste one postage stamp on my hand and then another beside it, tlie sensation is increased in the second case in extensive massiveness, but not in intensity. This distinction in quantity is possible only when there are coexistent sensations of the same sense wliicli do not coalesce to produce a higlier intensity. It seems to depend upon an extensive organ of stimulation, skin, retina, which is stimulated over a more or less ex- tended area. It is experienced in putting the hand in Fechner is based. Assuming that the differences of sensation to he barely perceived are infinitesimal quantities, and that the difference in the excitation is also Infinitely small, as compared with the whole stimulus, we ma}\ by the calculus, equate differentials and write (making ds Increment of sensation, de increment of excitation, and k the proportional constant) d8 = k^, e whence, by integration, 8 = k log e ; or, the sensation varies as the logarithm of the excitation. The threshold value then being given, the scale is built up. ' This can be readily shown by counting seconds with the eyes on the second-hand of a watch, and then attempting to repeat it with the eyes closed. Below one second the time is judged too long. 106 SENSAriOK. water, or in hearing, at the same time, a continued musical note and a harsh noise. The difference between the two kinds of increase in sensation is distinct enough to require separate mention. That it is found equally in connection with some of the non-spatial senses,^ however, seems to be sufficient proof that it is not an immediate datum of space- knowledge, rs some would have it. It is probable that distinctions of extensity are as fundamental as those of intensity, and that they represent one of tlie first reactions of consciousness upon a nervous arrangement which has been perfected through former race development and in- heritance. § 7. Duration of Sensation and Thought : psyciiometry. Since the discoveries of Helmholtz and others, as to the velocity of nerve transmission, it has become possible to arrive at a determination of the time necessary for differ- ent sensations and for some of the simpler apperceptive processes. I. Beginning with simple sensation the case is briefly this : let the skin of a man in normal conditions be pricked and let him speak as soon as the pain is felt, or let a word be spoken and let the subject press a button as soon as he hears it. The period that elapses between the two events, in any such experiment arranged for two senses, is called the simple reaction time and varies from i to ^ second, ac- cording to the individual and according to the conditions of the experiment. Upon consideration, it is readily seen that thi« period may be divided into three parts : first, the stimulation of the sense organ and sensor nerve transmission to the brain center ; second, the mental process of sensation, discrimi- nation, and volition, etc. ; and third, motor transmission and stimulation of the organ moved. Now since the veloc- ' Stumpf finds original exteusity in sound-tones. ITS DURATION. 107 ity in both the motor and sensor nerves is known, we reach by subtraction the time of tlie mental act. Instruments are used by means of which differences to the ten-thou- sandth of a second are noted. By this analysis of the simple reaction time we arrive at two general principles : a. The simplest mental act occupies an appreciable period of time. h. The purely physiological or transmission time is less than half of the entire reaction.^ Consequently the time taken up by the sensation and motor impulse varies slightly either way from ^^ second. Tliis cannot be called purely mental time, however, for the central physical change goes on at the same time. An easy way to get an approximate value for the simple reaction is to request a class of students to stand in line, each grasping hands in turn with his neighbor. When the Hue is complete let an outsider give a signal "now" at a given position of the second-hand of his watch. At the signal the student first in line presses the hand of the next, and so on, as rapidly as possible, down the line, the last stu- dent calling " now " the instant his hand is pressed. At this second " now " the outsider again notes his watch. Now if the entire number of seconds elapsed be divided by the number in line plus two (the outsider reacts twice), the re- sult will be the reaction time for one student. II. Passing from sensation to the reproduction of ideas as memory pictures, it is concluded from experiments con- ducted similarly : a. The time occupied in the reproduction of a state of consciousness is longer than the time of its production. b. The time of reproduction depends inversely upon tlie degree of attention given (l) to the original sensation, (2) to the reproduction. ^ This was conjectured by Darwin from the fact that we wink the eyes without having a change of sensation from light to darkness — Zodnomia. 1. p. 24. 108 sensation: III. A tliird operation on wliich many experiments have been made is that of distinction or discrimination. To ex- periment upon sigljt, let two colored lights be shown, the subject understanding that he is to react by speaking or pressing a button only when he sees the color agreed upon beforehand. This involves first a comparison and then a judgment, with volition. The entire time is found to be about i to J second. Bj^ an easy process the purely physio- logical time is eliminated, and the duration of the mental act is found to be -^^ second (Kries) to J^- second (Wundt). The discrimination is easier when the sensation is of hio^li intensity ; and since, in all reactions, the signal must be discriminated from other sensations in consciousness, we have the principle that loithin certain limits the duration varies iiwersely as the strength of the stimulus. IV. Experiment has rendered service, also, in defining and confirming the laws of association. The time of a simple association is found to be f second to -| second. Repetition greatly shortens the time by strengthening the association. V. A fifth class of experiments relates to the logical judgment of subordination, ^. e.,from genus to species. It is found that the time is longest when the subject is abstract and the predicate a more general notion (man is intelli- gent), shortest when the subject is concrete and the predi- cate a less general notion (the house is red). The average of a great number of experiments gives the time about one second Thic is important as illustrating the growth of the general and abstract notion from the concrete, and indicates that the order of instruction of children should be the same. It should be said that these results, which are not in- tended here to be exhaustive, are true only in an average sense and under normal conditions ; and further, that they represent only a single tj^pe of our everyday mental processes, that of more or less concentrated at- tention and expectation. The fact that the subject of the EFFECTS OF ATTENTION. 109 experiment must take part in tlie arrangements and concert his actions with those of others makes it impossible to obtain results without the attention. In life, however, most of our actions are not foreseen, and our attention is drawn to sen- sations by their occurrence, not beforehand. The degree of attention, however, may be somewhat varied and the results noted. The boilily states also greatly influence the duration of mental acts. Fatigue and other unusual physical con- ditions tend to lengthen the reaction time. The senses with which the most exact results have been obtained are sight, hearing, and touch, the most presentative senses : with taste and smell the mechanical difficulties are very great. In dreams, the ascertained durations do not seem to hold, since the flow of presentations then takes on, in many cases, enormous rapidity.' Effect of Attention upon the Duration and Quantity of Sensation. We have already noted the general law that attention increases the intensity of sensations. It is at once seen that this principle interferes with the application of Weber's law, since a given stimulus is felt more strongly if attended to than otherwise : so that in comparing sensa- tions by their excitations it is necessary to keep the atten- tion constant in the two cases. The effects of attention upon the duration of sensations is even more marked. In general, attention dlmuiishes the time necessary for the re- action. The shortest times are obtained by concentrating the attention. To such an extent may this give rise to ex- pectation of the excitation that it is sometimes anticipated, the reaction of the hand, for example, being given before the signal is made. In the hypnotic state, where the at- tention is strongly fixed, the time is shortened. This con- ' For attempts to determine the perception, apperception, and will time separately, see references given by Ladd, Elements of Physi- ological Psychology, chap. viii. Otlier accessible resumes are Ribot, German Psyclwlogy of To-day, p. 250 ff., and Jastrow, Time Relations of Mental PJienomena. 110 SENSATION. centration is especially necessary at first, before the mus- cular reaction becomes automatic, for practice shortens the reaction time. Further, according as the attention is given to the ex- pected stimulus (touch, sound, etc.) or to the reacting organ (finger, in pressing a button, etc.), we have important vari- ations in the time. In the former case the reaction is called sensory, in the latter case motor. In the " sensory " form of reaction the time is about one-half longer than in the "motor" form. Effect of Duration upon the Intensity of Sensation. Within short periods the intensity of a sensation is di- minished if its stimulus be continued. This arises from the accommodation of the organ to the stimulus. It ap- plies especially to slight pleasurable or painful stimuli. Long continued stimulation, however, from exhaustion of the organ, becomes increasingly intense and painful ; and sensations at first pleasurable become painful under this condition. § 8. Tone of Sexsatiox. By the " hedonic tone " of sensation is meant the feeling of pleasure or pain w^hich accompanies it. It represents somewhat in all sensations, and in the higher senses almost entirely, the affective element. Pleasure and pain are only and wholly affective. Our whole sensational experience is accompanied by pleasure and pain and so has tone.* * For detailed treatment see below, chap. xvii. CHAPTER IX. PERCEPTION. § 1. Definition of Perception. The theory of perception is perhaps the most important as well as the most difficult problem of psychology. The interpretation of the higher processes of mind rests upon it and it underlies the body of our general philosophy. The great philosophies of the world take their rise from initial differences in the method of construing perception. Leav- ing the general problems of the theory of knowledge to metaphysics, we have to do only with the process of percep- tion, considered as an operation of mind in attaining knowl- edge of the external world. That is, we have to answer the simple question, " How do we arrive at the knowledge of individual objects localized in space and time ? " In view of the terms of this question and of the analysis which follows, we may define perception in a general way. Perception is the apperceptive or synthetic process of mind ichereby the data of sensation take on the forms of represen- tation in space and time : or, considered more with reference to things external to us, it is the process of the construction of our representation of the external world. § 2. Analysis of Perception. A little reflection leads to the conclusion that our percep- tion of the external world is a matter of mental construc- tion. All advance into the region of mind must be through mental states. The characteristic of mind is consciousness, and nothing can enter the domain of mind except through the mediation of consciousness. This is seen in the fact that our images play in consciousness in such a way as 111 112 PERCEPTION. sometimes to deceive us in regard to the external world. When the eye is deranged the mind is deceived in regard to colors and distances. When we have a cold our taste is impaired. When the hand is amputated irritation of the nerve ends is still localized in the hand. This amounts to saying that the mental picture which in every case is nec- essary to tlie perception of the object, is impaired or dissi- pated. The nervous system also intervenes between the mind and the world, and the proper activity of mind in representation depends upon the normal functioning of this system. This fact, that the mind deals with its images primarily and with external realities only through these images, is best seen when we consider that all mental states are modifications of consciousness itself, and that the per- ception of the external world, however real that world be, with its conditions of space and time, is possible only by some process of mind whereby these conditions can be mentally reconstructed and the intensive data of experience cast in the forms of this reconstruction. It is the business of a theory of perception also to tell how we come to have the presentative or knowledge ele- ment pointed out in sensation. Space, time, force, etc., were recognized as such elements ; in perception we find the process by which sensations come to take on these forms. The construction of the representation of the external world has three stages which we may call, respectively, Differentiation, Localization, and Sense- Intuition. § 3. Differentiation. The beginning of all life experience is probably, as has been already said, a state of general undifferentiated feel- ing. This state of things has been described briefly in the section on the growth of consciousness. There are, at this beginning of sensation, no distinct forms for the different senses, no notion of externality, no perception either of one's own body or of tilings. It is easy to imagine one's LOCALIZATION. 113 self in that condition. All plu^sical feeling is then vague, like the internal sensations which we cannot localize nor trace to their causes. It is probable that the muscular sense, with touch, constitutes almost the whole of this experience. The earliest transition from this state of general sensation is also probably due to touch and the muscular sense, tlirough differences of intensity in feelings of resistance, and through the sense of locality in the body. The special oi-gans of the other senses are more complex and must, be adapted to their function of reporting impressions from without. Yet no step toward a real differentiation of sensa- tions can take place till a reaction of consciousness is possible in the shape of attention. As has been seen, definite sensa- tions as such are not distinguished without attention. At first this attention is reflex. But by it the unordered and chaotic mass of sensation, which is thrown ujjon the helpless individual, is divided, and distinguished. As this differentiation proceeds, each sense becomes a distinct source of affective experience, somewhat in the following order of development : muscular sense, touch, temperature, light, sound, taste, smell, color. The mere fact of differen- tiation, however, can gi\ e us no sense of difference between our own body and a foreign body. This distinction can arise only after we begin to localize our states ; and even then all these states are located first in the bodily organs. § 4. Localization. Another aspect of the synthesis w^hich is called perception is localization. By this is meant the mental reference of sensations to a locality in space. " Things," as we perceive them, are always in space. Here is a new idea or form, of w^hich, in the purely intensive character that sensation at first presents, we find no intimation. Whence does it arise, and to what factor in the perceiving process is it due ? This is the question of the origin of the idea of space : one of the problems most discussed in general philosophy, 114 PERCEPTION. and one to which contemporary psychology is full}^ alive. With the farther metaphysical question, What is space ? we are not concerned. The Perception of Space. It is generally agreed by psychologists that our first experiences of space are con- nected with the muscular and touch sensations of our own body. As has been said, the sensory content, before all differentiation, is largely muscular. The beginnings of differentiation seem at once to implicate the extensive or massive quality of sensation. There is a vague feeling of whereness in this early muscular sensation, and it becomes more definite as the extensive or spread-out sensations from the skin become broken up in localities. But at this begin- ning of space experience the question confronts us : How can excitations of the skin and muscles, which are trans- mitted in the form of molecular action through the nerve substance, and which have thereby lost their local coloring, report their locality to the subject ? and further, how, if they preserve this local coloring in such a way as to present specific differences of motion at tlie central bureau, can these differences be reported to the mind, which is a con- scious presence, not itself spread out in space ? Tliere is only one answer wliich does not either beg the question at issue or overlook some one of its essential con- ditions ; ^. e.. The mind has a native and original capacity of reacting, when certain physiological data are present , in such a way that the objects which serve to stimulate it appear under the form of space. Data for the Perception of Space. In the perception of space relations by the muscular sense, touch, and sight, the three senses through wliich it is accomplished, two classes of data seem to be involved. Tiiese data are of a ph^^sical kind and serve as basis for the mental reaction just spoken of. They are muscular movements and local signs. I. Muscular Movement, Under the discussion of the IDEA OF SPACE, 115 muscular sense, the twofold nature of the sensations in- volved was spoken of. Sensations of " effort " were dis- tinguished from sensations of " resistance." Both of these seem necessary to the finished feeling of movement, though feelings of resistance play a predominating role. We learn from pathological cases that if the feeling of resistance be destroyed, a limb may be moved voluntarily, but there may be no knowledge of the actual movement and, consequently, no indication of space position. But, on the other hand, the movement of a limb mechanically is felt as movement when there is no voluntary motor discharge. Hence, whether we hold that space is a succession of resistances? or that space is an original element in the muscular experi- ence, we still find the element of muscular resistance in our first sensations of locality. AVe see below that movement enters in the perception both of tactual and of visual space. Inasmuch as feelings of resistance involve touch as well as pure muscular experience, the second of our data, the local sUjn, is brought into play. II. Local Sign. By local signs are meant specific local differences in the arrangement (Lotze) or structure (Wundt) of the elements in the skin. By reason of these differences localities partake in perception of the position they occupy in space. I refer an excitation to my hand or foot ; why do I give it such a specific reference ? Why do I locate a pain in my right hand rather than in my left ? Simultaneous sensations of a purely intensive nature, as tastes, sounds, are fused together ; but simultaneous sensations from neighboring points of the skin and retina preserve their peculiar character and relation to one another, and we dis- tinguish different localities because the sensations from them are really different. As has been said, the first idea of our own body results from muscular sensations w^hich arise from early movements, and these sensations are vague and confused ; yet even here the feeling of extension is present, also vague and confused. Whence comes it ? It 116 PERCEPTION. can only come from initial differences of some kind which are perpetuated through transmission to the brain. These differ- ences, probably in the skin or sensor nerves, and possibly a matter largely of association, afford a second datum for the localization of sensations in different portions of the body. The theory of local signs was first propounded by Lotze, who, however, varied it in its application to different orders of sensation. For sight he made the local sign consist in the fixed amount of muscular movement which any retinal point must undergo to be brought into the line of clearest vision. Tliis is a different and definite quantity for every point in the retina. In the skin the local sign, for Lotze, was the combination of light accessory sensations which are provoked in immediate connection with the point of contact. There would be a varying amount of radiation of stimulus in the skin according to the varjdng structural consistency of the parts over which the skin is stretched, as bone, nmscle, ligament. This hypothesis found devel- opment in the more natural position that the local sign was an implanted peculiarity in the structure of the skin itself. A further theory, very w^idely adopted, and sug- gested by Czermak, makes the local distinctions in the skin due to the ramifications of the spread-out nerve fibrils, each such nerve end reacting for its own position and being thus a local sign. This position is most probable. It is supported by the fact already cited, that the sensibility of the skin to local differences varies greatly in different parts of the body, and may be increased by the fixing of the attention, by exercise, and in the hypnotic state. These latter condi- tions tend to bring into play finer elements of the ramify- ing nerve, and thus to diminish the distance between the sensitive points. And the same facts tend to refute the theory that the units of tactual feeling are found in Weber's " circles of sensation." ' • On the genercal theory of local signs see liibot, German Psychol, of/y of To-day, chaps, iii. und iv. IDEA OF fiPACE. Ill iJusidc'S the i^eneral coiisideratioii that some SJicli liypoth- esis as that of local signs is necessaiy to the case, there is direct evidence of the existence of these signs. Tlie fact of varying local discrimination in the skin has been men- tioned ; it is also true of the retina. The relative discrim- ination of localities grows less delicate as we proceed fi*om the center to the edge of the retina. The quality of massiveness or extensity of sensations of touch and sight depends upon the simultaneous independent excitation of units of sensation, and can be accounted for only on the assumption of some characteristic by which these units are kept distinct. If the skin of the forehead be bent down upon the nose and grow there, its irritation is felt still at the foreliead. Tlie same is seen in the retina in certain pathological affections, in whicli the retinal elements are displaced : the irritating points of light falling upon these elements are localized where they would be seen by the healthy eye. Synthesis of Data. But the fact of local signs, taken in connection with muscular sensations, is not sufficient to account for the perception of space. Wliatever these signs be, the local color or tone they give is a modification in quality alone, or an intensive change in the sensation in question, and there still remains the necessity for a mental reaction whereby this intensive sensation, modification, or sign is construed in extensive form. How can we infer differences of external position from differences in our feelings ? Let a sensation of red be modified in any wa}'' whatever as to its redness, and we are still absolutely in the dark as to its location on the right hand or the left. Nor would any number of partial sensations which I dis- criminate in it, nor the order of these partial sensations in coming to me, tell me that the colored object was " round like an orange or a ball." Admitting the concomitant sen- sations of Lotze, one of two things must be true : either these concomitant sensations co-ordinate themselves in space 118 PERCEPTION. ill virtue of their own quality or they do not. If they do thus co-ordinate themselves, why could not the original sensations co-ordinate themselves? If they do not thus co-ordinate themselves, what help are they to us in this co-ordination ? They must be only data by which the co-ordinating activity of mind proceeds in the matter of space perception. Tactual Perception of Space. Upon this basis the mental reconstruction of spatial position proceeds in the case of touch. Locality in the skin being tlius given, its definition becomes very exact in experience. Feelings at first vaguely localized are given precise spatial position. This is rendered easy by the exploring power of active touch. If left to passive touch from external objects it is unlikely that we would ever arrive at a clear conception of the extent and form of our own bodies. But by free movement of the hands, with active touch, the relative parts are explored. This is evident from the fact that localization is most exact in the parts of the body most open to active toucli and freest in movement, as tlie hand, arm, tongue, as contrasted with the back and cheeks. This process is also aided by our larger movements and their reversal, and takes place with rapid advance in early childhood. Visual Perception of Space. As has been already in- timated, the same data enter into the visual perception of space, muscular movement, and local sign. The evi- dence of the presence of local signs in the retina has also been adduced. Ever since the time of Berkeley^ it has been generally admitted that the original perception of the eye is of a colored surface only: that is, that the eye has no immediate perception of depth or distance. This is shown most decisively by cases in which sight has been restored to those who were born blind. About a dozen cases of the removal of congenital cataract from the eyes ^ Berkeley, TJceory of Vision. VISUAL SPACE!, 119 of persons of some age are on record, the oldest and most famous being the Cheselden case/ In each of these cases the evidence is very clear. When sight is restored the patient sees everything in the same plane : there is no dis- tance, no relief, nothing but a colored surface, and this surface seems to be near the globe of the eye. The blind man on whom Clieselden operated said that objects touched his eye. Home's patient said the same of the sun and of the head of the physician. The patients of Xunnely and Franz had the same experience. The muscular movements of the eye are of extreme delicacy and variety. Tliere is for every point of the retina a fixed amount and direction of movement necessary to substitute for It tlie center of clearest vision ; and when such a point, right, left, above, below, is excited there is at once a tendenc}' to revolve the ball of the eye in such a way as to bring the center of vision to this point. This represents a given degree of central nervous discharge to bring about the muscular strain. Since movement of tlie eyes precedes vision, there are no means whereby such movement can be ruled out ; and further, the influence it exerts in localization is seen in the fact that if one of the muscles of the eye be destroj^ed, so that no movement fol- lows its stimulation, objects are localized as if this move- ment had taken place." The necessity for a reaction of consciousness upon these data is the same as in the case of touch. Sensations from ' See details of Cheselden and other cases in McCosh's PsycJiology, vol. 1. p. 45. ^ See references given by Wundt, Phys. Psych., 2d ed.,ii. p. 91, and i. p. 375 : " For instance, one suffering from paresis of the right external muscle of the eye, so that the muscle is able by the utmost effort to effect a lateral movement of 20°, locates an object which in reality is only 20^ distant from the median plane, at a point as far outward as corresponds to the utmost outward movement of the normal eye, and when asked to touch the object places his finger far beyond it to the right." 120 PERGUPTtOn. the extended surface of tlie retina and from its movements over the visual field can be only intensive and qualitative modifications of consciousness, which are appreliended under space-form by the mind's own reconstruction. The process in this case is the same as in touch with tlie muscular sense. Spatial perception by touch and the muscular sense pre- cedes spatial perception by siglit. The idea, as a mental acquisition, is probably gained rouglily before we see at all. But this does not impair the fact of spatial perception by sight. Having the idea of space, why do we clotlie the data of sight with this form, and why do we not thus clothe the sensations to which we do not assign a spatial arrangement ? Evidently because sight offers also the data which are necessary for the mental reconstruction of space. Perception of Foreign Body. The distinction between our own and a foreign body arises very early in child life and is not subsequent to 1?iie completed idea of our own body. As we have seen, the perception of our own bod}^ as extended involves both distance or movement, and resistance. In the primary feeling of resistance we have the beginning of the perception of foreign body. The amount of movement or distance, measured in muscular sensation, indicates roughly, at first, but with great pre- cision later, the localities of objects around us in reference to our own body. This is greatly aided by active touch and by sight. We feel round a bod3^ and give it the third dimension, which we have already found to be an attribute of our own body. The distinction between our own members and other objects is further assisted by the phenomenon of double touch ; that is, the two sensations of touchinor and beinor touched, when we come in contact with our own skin. In paralysis our own limbs are to us as foreign bodies, inasmuch as the sensation of active touch is present alone. Another important series of double sensa- tions arises when the child sees and also feels his own move- ments. Another important fact is that we both see and feel our own movements, while we only see other movements. PEnCEPTTOX OF DTSTAXfE. \2\ Visual Perception of Distance. The visual percep- tion of distance or deptli proceeds upon the tactual and muscular perception of distance. It consists in the ac- quired interpretation of light and color differences in terms of distance already given by the skin and muscles. The original colored surface presented in vision is pro- jected more or less distantly, according as its lights and shades are associated with a greater or less muscular or tactual coefficient. This is seen in the fact that the original errors of sight, in respect to distance, are rectified by touch and muscular movement. In the Trinchinetti case tlie patient at first '* attempted to grasp an orange with her hand very near the eye ; then, perceiving her error, stretched out her forefinger and pushed it in a straight line slowly until she reached her object." Other patients have done the same, when first restored to sight. This interpretation in terms of muscular and tactual feeling becomes, in later experience, a matter of the sensitiveness of the eye itself. Its own mechanism of movement and retinal reaction gives data by association for the percep- tion of depth. A number of factors enter in the mechanical adjustment of the eye to sight at different distances. Among them we may mention : a. A muscular strain when the object is near, due to the slight contraction of the pupil and the swelling of the anterior surface of the crystalline lens. This is called the sensation of accommodation, b. Differ- ence in an object when seen near or far whh both ej^es. The difference in the angle of vision of the two e3'es enables us to see parts of the sides and thickness of the object gazed at, and this datum of depth varies with the distance, c. Strain arising from the varying angle made by the lines of vision of the two eyes. When the object is near the eyes turn toward each other ; this is known as the sensation of convergence, d. Dimness of outline of a distant object, or poor light, the retinal elements being but 122 PERCEPTIOy. feebly excited, e. Dirninislied size, fewer of the elements being excited, f. In addition there are more general con- siderations which aid our estimation of distance, such as tlie number of intervening objects, the known size of the object, and others. The finer estimation of distance is a matter of cultiva- tion and practice. Indications entirely lost to the ordi- nary observer are unconsciously taken into account by the sailor and artist ; such as tlie length of shadows, the air perspective, and delicate discrimination of colors. All this is clearly a matter of acquired judgment, which may be improved to an endless degree almost by the exercise of trained attention and study. In pictorial art the process is reversed, the task of the artist being to interpret back upon a plane surface those data of the perception of depth which we all unconsciously proceed upon. So fixed do the associations of distance become that, while our own sense experiences were sufticient to convert our primitive sensa- tions of color into a complex of objects about us, we need a teacher of the elements of perspective to enable us to revert again to the conditions of our original perception. Localization of Sounds in Space. The position of sounding objects in space is roughly indicated by the ear, but this rough localization proceeds upon the previous per- ception of objects by touch and sight. It is only after the surrounding world is tolerably familiar and its sounds al- ready associated with known objects, that the sensations of hearing are definitely placed. This localization by the ear involves distance and direction. The distance of sounding bodies is judged from the intensity of the sound, especially when the normal sound is well known. When the hearing is impaired sounds are located farther away. The sense of direction seems to arise from several causes, the principal of which is the relative strength of the sound in the two ears. The sounding body is located on the side on which the ear receives more sound waves. If a sound be made on SENSE-TNTUITIOX. 123 the median vertical line through the head — say above — it is not localized, but a slight variation on either side the line is at once detected. Consequently, we locate sounds as right and left, before and behind, much better than up and down. Again, there is a tendency to locate loud sounds in front, from the fact that more sound waves from that di- rection are collected by the external ear. Delicate sensa- tions of touch and muscular movement also in the ear aid us in localizing sounds, though to a much less degree than in tlie hearing of some animals wliose ear muscles are largely developed. Feeling of Equilibrium from the Ear. Recent in- vestigations have shown that the feeling of equilibrium of tlie body in space is due in part, at least, to combined muscular and auricular sensations. The feeling of erect- ness arises from muscular strain in the limbs and trunk. The feeling of direction involves also the muscles of the eye. Feelings of the rotation and general position of the head in respect to the body are given by the semicircular canals of the ear. These canals are projected in the three dimensions of space to which they seem to have, respectively, a determinate relation. Ideal Product of Localization : Idea of Space. The idea of space, as thus treated, is acquired in concrete per- ception. Space, so far, has meant extension, considered as an attribute of objects extended. The finished idea of space, as a great void, is derived only b}^ a process of ab- straction to be considered later. From the perception of a body extended we pass to the conception of an extension or space which this body fills : we abstract the body and leave the space.* § 5. Sexse-Intuitiox. The third and last stage in the process of the perception of the external world may be called Sense-Intuition. In 1 On theories of space-perception see my Handbook of Psychology, vol. i. chap. viii. § 4. 124 PEnCEPTIOK. the first of tlie three stages under wliicli we found this process naturally taking place, i. e., Differentiation, we saw the breaking up of the general and vague sensory content of the infant's consciousness into the discriminated sensa- tions of the different senses; in the second, i. e., Localization, these sensations have taken position in space ; in the third, i. e., Sense- Intuition, sensations are gathered together in the permanent units or wholes which we call " things" in our ordinary dealings with the w^orld. As illustrating the incompleteness of the perceptive proc- ess at the stage to which we have now advanced, we may imagine a consciousness holding a given number of well dif- ferentiated and localized sensations ; say, a taste, a smell, etc., as in "psychic blindness," These have no connection among themselves at their first experience, although they are given the same locality and occur at about the same time. There is no reason that they should be thought of to- gether, or that one should suggest the other. That is, there is no reason that the intuition ^^Tp/e should emerge. There is a furtlier process by which this important lack is supplied, and sensations, until now isolated and disconnected, are thrown into permanent complexes or groups. In this further advance several necessary steps are apparent. I. Attention. However sensations may be grouped in the passing panorama of consciousness, they have no last- ing connection unless their coexistence is attended to. And not only so, but it is doubtful whether simple reflex at- tention would be sufficient for the grouping of sensations in a complex whole. It may at least be safely said that the arranging and co-ordinating power of voluntary at- tention greatly facilitates our earliest intuition of things. It is here that the relating or apperceiving function of active attention is most apparent. It will be seen in treat- ing of memory that the degree and intensity of the power of retaining and reproducing presentations depends upon the degree of attention given to the original experience. SEKSE-IXTCITIOX. 125 This is especially true of the relations in wliicli these original presentations stand to one another. The touch, taste, color, smell, or any two or three of the qualities of the apple are experienced, for the first time, in immediate conjunction and, while merely a colligation of sensations, are attended to as such, and their coexistence pictured. At first the muscular and touch sensations, as localized, precede, and upon these the sensations of other senses are gradually linked. II. Association: a principle by which presentations once experienced together tend to come up in memory in the same order and connection. By this principle the revival of one of the former sensations tends to arouse the others with which it was before experienced. In tlie further extension of our experience additional sensations are added to the associated group, as when we learn that an apple before known as si)herical and red is also sweet and fragrant. Like asso- ciations in general, this grouping of sensations becomes fixed onh^ by much repetition and with the help of many bodily movements. Thus the object in perception becomes clearly defined and distinguished from others, and the ex- ternal world takes on its permanent foi-m, as a whole of various "things" existing in relation to one another. An additional fact, important to the permanent fixing and discrimination of percepts, is this, that we learn very early to name objects as we perceive them. This is a mental function to be considered later, and it need be noticed here only to remark that it is a great auxiliary to the lasting quality of our sense-intuitions. In the ordinary education of children, when their knowledge of language goes ahead of their experience of things, the names are ready beforehand and are applied, under instruction, to objects presented to them, with a number of qualities clearly pointed out. Thus the process of growth in the combination of qualities is greatly abbreviated. Teaching by object lessons is therefore justified psychologically as a 126 PERCEPTION. method, in that it leads tlie child to attach the right name to the right object, in the first place, and thus to avoid all tentative and mistaken efforts at discrimination. Motor Intuition.^ Muscular sensations gradually be- come grouped or integrated in a similar way. With wider use, a larger number of muscles are associated in the per- formance of a common movement. These motor intuitions take the form of ideal or pictured co-ordinations of move- ment, which become more and more sure and automatic as the muscles are exercised in groups after repeated effort. The early random movements of the child are thus worked up into the systematic co-ordinated muscular groups of the adult life, by gradual adaptation to the environment : for example, walking, piano pla^nng. § 6. Reflection or Self-consciousness. The highest form of consciousness is 5e{/*-consciousness. The notion of self, like other notions, is a gradual growth. Tiie vague feeling of the ego which the first affective ex- periences afford, the feeling of modification in the con- sciousness as the background or theater of presentation, and the recurrence of this feeling again and again in con- nection with objects new and old — and added to this the mass of more constant organic and vital sensation — all this is the beginning of the sense of personality or self. Its at- tributes of permanence, identity, and activity become more prominent with the development of will in connection with muscular effort, and with the establishment of the relation of subject and object which is finally a fundamental fact. By reflection is meant the turning in of the mind to itself as its own object. By the result of reflection is meant, therefore, the knowledge which the mind has of its own operations, recognized as its own. It is an advance on the simple awareness of consciousness, in which there is ^Compare Maudsley's discussiou, P/ii/siologt/ and Pathology of the Mind, Americnn edition, chap. viii. IDEA OF SELF. 127 no reference to self as different from its object. In reflec- tion, this reference has distinct place, and the self is dis- covered through the act of attentive inspection, as having and exercising the characteristics of mind. Ideal Product of Reflection: Idea of Self Through reflection, therefore, the idea of self is attained and assumes its important place in the mental world. Round the self as a center the intellectual life plays. To it all possible forms of experience are referred. It brings coherence into the circuit of consciousness, by giving it a center of refer- ence and a circumference of limitation to the individual. EEPEESENTATIOK MEMORY. CHAPTER X. RETENTION AND REPRODUCTION. ^ Our states of consciousness, as a general fact, are all lia- ble to reproduction, recall, or revival. The original states of consciousness are designated Presentations, or primary states ; and the corresponding revived states, to which they give rise, Representations, or secoyidary states. § 1. General Nature of Memory. The capacity to be revived on suitable conditions ex- tends to all states of consciousness. This revival is most vivid and facile for sensations of sight, touch, and sound, from the fact already noticed that these sensations are mostly presentative, having the forms of space and time. Objects seen are readily pictured when the eyes are closed, and sounds of tunes, and more especially of words, are re- produced with great ease. In reading a page we recall the sounds of the spoken words involuntarily ; and, if it be a page of poetry, the rhythm and rhyme are caught by the quick revival of the words and measures in succession. Other sensations, as tastes and odors, are also capable of reproduction. The fact that we distinguish and classify them is sufficient proof of tliis. Their reproduction is more obscure from the fact that, being more affective, they caunot be pictured under the presentative forms of time ' Qi. my Handbook of Psychology, vol. i. chap. ix. 138 j^ATUBE OF MEMORY. 129 and space. But that these forms, and consequently memory pictures in general, are not essential to memory, is seen in the fact that pains and pleasures, and tlie emo- tions, which are purely affective states, are remembered with great distinctness ; these states afford no data for our picturing faculty. According to Epicurus, the memory of past pleasure and the imagination of future pleasure are the principal source of our happiness. Sympathy depends upon the revival of our own pains and pleasures ; for we cannot sympathize strongly in cases which our own experi- ence does not cover. And finally, the acts of will are pres- ent in memory, giving, according to their nature, moral satisfaction or regret. Strictly speaking, a distinction is to be drawn between states which are revii^ed after having once disappeared from consciousness, and those which persist in consciousness a short period after the external stimulus has ceased to act. The latter is a mental after-image, somewhat like the physical after-image on the retina, alread}^ mentioned. Every percept clearly distinguished leaves its outline in consciousness for a very small period, and then fades rapidly away. In the case of a rapid succession of presen- tations there is a coexistence of elements and not a revival. This is the case, probably, with written and spoken words, tunes, rapid rhythm. Proof that Presentation and Representation differ only in Degree or Intensity.^ Several kinds of evidence ma}^ be adduced in support of the claim that presentation and representation are one and the same process. I. From Conscious7iess. We are aware in consciousness of no peculiar marks of revived states by which to distin- guish them from percepts, except that they are prevail- ingly of less intensity. In the conscious reproduction the conditions of the presentation are vaguely reproduced. The representation of a name, sound, the tic-tac of the 'Cf. Rubier, Psychologic, pp. 153-157. 130 BETENTIOJ^ AND REPRODUCTION. pendulum, is referred to the ear. The image of an extended object is formed as extended in the fiekl of vision. If we try to recall the taste of an orange we seem to have a kind of after-taste on the tongue. In recalling emotion the general conditions of our first experience of it are found with it in memory by the law of association. There is this difference between the train of presentations and that of representations, that the latter is accompanied by a feel- ing of familiarity and anticipation. But it is doubtful whether this feeling is present at the reproduction, unless it involve a measure of comj^lexity which was also present in the original. This feeling is present in the perception, also, when by repetition an element of represen- tation is involved in it. In the case of voluntary reproduc- tion, it is true, there is the addition of an exercise of will, which is of great importance in affording us a means of dis- tinguishing between the percept and its image ; but this is not necessary to the reproduction more than to the original perception, since most of our memory pictures arise involun- tarily.* It has its counterpart also in certain voluntary efforts of perception ; as when we explore an unknown scene with the eye or feel over an unknown surface. II. Presentations and Representations have the same Physiological Antecedents and Effects, The physiological antecedents of both primary and secondary mental states are spoken of later under the physical conditions of mem- ory. It is sufficient to say, here, that the immediate ante- cedents, the brain processes, are the same in both cases. The remote antecedents of the percept — presence of an object, and stimulus of the sense — are w'anting in the case of the revived image ; but it is the immediate antecedent upon which the representation depends. The physical consequences or effects are also the same. Mtiller says that the simple idea of a nauseous taste is some- ' This relation to will is given due recognition in a later connection, Tjelow, chap. xix. § 5. PllESEXTATIOJS' AND BEPRESENTATION. 131 times sufficient to produce sickness, the natural effect of tlie real sensation. The visual picture of a person who has once provoked our anger serves to produce it again with the same physical expression. Intense mental picturing of a primary color may so exliaust the retinal elements that the compleraentar}" color is seen when the eyes are opened. It is hard to think upon an energetic action without imitating it, just as in the original attention to the perform- ance of it by others we had such "a bodily tendency ; and to have a word in mind is usually to form it with the organs of speech. Further, the simple thought of great cold makes one shiver. The thought of the drawing of a sharp knife over glass sets one's teeth on edge, as Darwin says. Anyone who has attended a clinical operation knows how acute the suggested sensations of cutting are at first. in. Frequent Confusion between Presentation and He- presentation. The strongest, indeed the decisive, proof that psychologically these two classes of states are really one is this : we frequently mistake one for the other. " The proof," said Reid, " that there is an essential differ- ence of nature between these states is that we never con- found a sensation, however feeble, with an image, or the contrary." This is simply an error of observation. We do often confound them, and several different cases of this confusion may be pointed out. 1. Whe7i the intensity of the image is very great. This is the case in hallucinations and insanity. " Patients con- tinually hear voices speaking to them, or about them, reply- ing to their most secret thoughts, suggesting to them pro- fane and obscene ideas, and advising and threatening them." * In these cases abnormal brain action gives the image the verisimilitude of a sensation and the distinction is completely lost. The same result may arise in normal life from simple force of imagination. Newton could bring before him, when in the dark, an image of the sun, with all the characteristics of reality, and Goethe coulc^ ' Maudsle^y, loc. cit. 132 RETENTION AND REPRODUCTION evoke an object and cause it to pass through a series of transformations. Further, there are cases of regular mistake in our per- ceptions, in which an image passes for tlie real object. In reading rapidly we do not see all the letters individualh^, but pass over them with a supply of appropriate images. Proof readers know this from sad experience. It is proba- ble that we see the first letters of the words and the last, slurring over the middle characters and supplying them from our knowledge and from the connection. Yet we think that each letter has been seen in order. Tlie blind spot in the field of vision is filled in by the one-eyed man and th« field seems to present an unbroken continuity. And our acquired perceptions are often imaged additions to our presentations and interpretations of them. In all these cases the image is of such intensity as to seem homo- geneous with the presentational field which it supple- ments. 2. When the actual sensation is very feeble. The same result is found when the sensation is reduced in intensity to the similitude of the image. For example, when a sound dies out little by little the time comes when one is uncer- tain whether he still hears it or only remembers it. If the two experiences were distinct in nature the line between them would be very plain. Patients often cannot tell whether they feel a pain or only imagine it. This is especially the case in states of hypnotic hallu- cination. Here a mere suggestion of the presence of an object suffices to place its image in the conscious field of the patient with a persistence and perceptive consistency which nothing but a counter-suggestion can remove. The image becomes for the patient an actual object for all the senses, the ordinary tests of illusion* fail, and there is absolutely no distinction to the subject between the image and the reality. In all cases in which there is no actual perceptive ex|)eri- ' See chap. xiv. § 4. DEFIXITIOX OF MEMORY. 133 eiice to correct the force of images, we are liable to illusion, and lience the mere absence of percepts is often sufficient to cause the errors attributed above to the strens^theninor or weakening of sensation. This is the case in dreaming. The dream world is the only world then in consciousness, and though its intensity is probably feeble, as is seen in the fact that dreams do not linger generally in conscious- ness, it is taken for real, simply from the absence of any- thing more real wherewith to contrast it. Definition of Memory. In considering the entire mental function which we call memory, we find that it involves several factors or stages, which are sometimes treated as distinct operations, but may more properly be considered, as we find them, together. Together they constitute a chain of events whereby the mental life of the past is retained and utilized in the present. First, there is the permanent possibility of the revival of a past experience wlien its first circumstances are repeated ; this is called Retention. Kext, there is the actual return of the image to consciousness : Reproduction. Third, this image is known as having already been presented in our past expe- rience : Recognition. And finally, there is, in most cases, an immediate reference to the exact past time of its first experience : Localization in time. These, taken to- gether, constitut'e a finished act of memor}^ and will be considered in the order of their actual rise in conscious- ness. Accordingly, memory may be defined as a mental revival of conscious experience: in which the word experience refers to the past and suggests Retention ; the term revival answers to Reproduction ; and the word mental makes the whole a conscious feat of Recognition. This definition puts the case in the broadest light and admits any interpretation of the subordinate operations which may be consistent with fact. 134 llETBNTION AND REPRODUCTION. § 2. Retention. It is seen, in the above analysis, tliat an act of memory touches consciousness at two points : at the beginning, i. 6., at the time of the original presentation, and at the end, ^. e., in the act of conscious revival. We remember nothing of which we were not conscious at the time of its occurrence, nor do we remember anything when we are in a state of unconsciousness. These two points of contact conceded, the question at once arises : what of the inter- vening period ? I saw, for example, a house yesterday or last year ; I was conscious of the presentation. I recall the image of the house to-day, or a year hence ; I am con- scious of the representation. But where has it been in the mean time, while I was not conscious of it? Several answers to tliis question have been proposed. Theories of Retention. I. linages, ice are told by the metaphysicians,^ are stored avmyin the mind, in the pigeon- holes of the soul, to be brought out for use when the proc- esses of mind require them. This view, it is needless to say, is not now advocated in this language. The mind has no pigeon holes ; it is not a storehouse of images. But it is maintained in more discriminating form by others who, very commendably, wish to maintain the continuity of mind over the chasm of forgetfulness which divides these two points of conscious life. Yet it seems sufficient answer to this to say that, if the image has left consciousness it has left the mind, as far as we know. It is only by con- sciousness that we can discover the image at all. This has greater force in view of tlie complete fulfillment of all the requirements of the case which we find in the theory advocated below. II. Rete7ition is due to a psychological habit. This the- ory refers retention to habit, and conceives of habit as a permanent disposition of the mind to do again, whenever * See Hamilton on "Latent Images," Metaphysics, lect. xxx. THEORIES OF RETEXTIOX. 135 circumstances permit, what it has once clone — to think again what it has once thought. As a description of the actual fact this is true. Tliere is such a tendency, to a very marked degree ; but it is merely an observed aspect of memory, and, in noting it, we do not at all explain the ac- tivity of memory. When we have called it a habit, a dis- position, a permanent tendency of mind, what more can we say? The questions arise : Is it based on psychological grounds, or will physiological facts explain it? Is it an ultimate law, or can it be reduced to simpler principles ? Habits are not facts of consciousness, and we have no ex- perience of them except by observation of the states which are supposed to exemplify them ; so that they elude our observation. If it is submitted, therefore, as an explana- tion of retention that the mind becomes accustomed to acting in certain waj^s, and so repeats itself, the ground of this mental custom must be again referred to that chasm of the unconscious which affords so ready a repository for the outcasts of our ignorance. AsVolkmann remarks, moreover, inasmuch as the repres- entations are not essences, but functions, the dispositions or habits of mind must be functional dispositions. Now a functional disposition can only consist in a slight persist- ence of the function, which, in turn, can only mean a con- tinuation or persistence of the representation in complete unconsciousness. By physical disposition or tendency we may mean combination or arrangement ; a readiness of parts for a given result. But in speaking of presentations, as functions, we cannot employ such a meaning. Wundt himself remarks : "If we carry the view (of dispositions of mind) over from the physical to the mental, only conscious presentations can be considered real presentations, while those that are driven out of consciousness may be consid- ered as mental dispositions of an iinhmmn hind io^Y2iV^. re- vival." And he goes on to say : " The essential difference between the spheres of the physical and mental consists in 136 RETENTION AND nEPRODVCTION. this, that in the former case we may hope to learn more of the changes which we call dispositions, while on the mental side this hope is forever forbidden, inasmuch as the limits of consciousness are at the same time the limits of our inner experience." * III. The linage is suhco7iscious. The school of Herbart support tlie theory that every image which is capable of being revived in consciousness exists in a state of dimin- islied intensity, having fallen below the " tliresliold " of con- sciousness, to rise again when, for any reason, its intensity J is heightened. This may mean that the representation is vaguely or dimly conscious, lying in a state of diffused attention, but still entering as a factor in the complex whole of our present state ; in which case the theory is true, as far as those images are concerned which can be found, however dimly, in consciousness. But it then over- looks the great mass of newly recalled facts ; facts which are in no sense even in subconsciousness, as my memory of a date in history when I am thinking of something to which it is quite foreign. As for these entii'ely unconscious states, the Herbartians have no alternative but to hold that they lie, with minimum intensitj'^, in the depths of the psychic life. This is the old metaphysical theory in more modern guise. The phrase " unconscious presentation " may be more scientific and less material than " latent im- ages" or " stored-up ideas," but it is equally obscure — and less picturesque. Another pertinent objection to this theory is that it sup- poses a degree of separateness or individuality in these supposed unconscious states, which in real mental life is impossible. If representations coexist, with slight inten- sities, in unconscious mind, why do not those of the same quality coalesce, as in real presentation ? I have a dis- tinct memory of two notes, say c and c' : if they are both present in subconsciousness, differing only in intensity from ' Phys. Psych., 2d ed., ii. p. 205. " THEORIES OF HETENTIOX 137 the real sensations, why do they not coalesce in a single sound as real sounds do ? So generally with tliese states : there is no interference or mutual hindrance, as in real ex- perience. General Criticism. As a general criticism of the pre- ceding theories of retention, the following consideration is of great importance. They agree, especially the first and third, in regarding tlie representation or image as a thing of itself, a something which exists, and whose pres- ence somewhere else must be supposed, when it is not pres- ent in consciousness. We are told the percept of the house was in consciousness yesterday and the representation will be again to-morrow ; the image of the house must be some- where to-day. And tliese theories attempt to conjecture the whereabouts of this image. Very slight consideration leads us to see that this manner of thought is quite mis- taken. The image is not a thing at all, to be stored away or sunk in subconsciousness like a stone in a lake ; it is a state, a mental product, dependent upon a process, and in the absence of this process it simply ceases to exist. The true answer to the question, as to where the presentation is in the time between percept and memory, is JVowhere. Its reinstatement is simply the reinstitution of the process which at first gave it rise. Its recall is a recreation, really a new presentation, not the old image. AVe never have the same representation twice. We are thus led to another theorj^ IV. Physiological Theory of Retention. Disregarding the fact of actual reproduction, which is considered below, and looking only to the permanent possibility of such re- production, that is, to the set of conditions of such a kind as to make the revival of mental states at any time real, we are led to the view that retention is physical, a matter of the modification of brain and nerve structure or function, such modification persisting and giving rise to a phj'siological habit or tendency. Before proceeding 138 BETEKTION AND REPRODUCTION. farther to explain and defend this view some general ob- jections may be met. 1. It is objected that physiological modifications coukl not last as retention does, even admitting the general prin. ciple tliat every organic modification must leave some trace behind it. Here the question is simply as to the length of an admitted process of obliteration. It is not held that these modifications do not fade away and finally disappear, as far as memory is concerned. The fact of forgetfulness, seemingly absolute, establishes the tendency of these traces to disappear. Therefore we only have to ask, liow long, relatively, might thej^ last ? Admitting this point, we still find it possible to hold that these nervous modifications l^ersist indefiniteh'-, as memory sometimes appears to.^ There are analogous cases of long persistence of physical modification. If a key be laid upon a white paper, and ex- posed to the sun, and the paper be then preserved in dark- ness, the image of the key is visible for some years. Even in case of organic modification where the physical elements are undergoing perpetual renewal, the form persists. An insignificant scar on the skin remains through life. The virus of smallpox, or the presence once of an infectious disease, leaves marks sometimes, throughout the elements of the body, which are never erased. Muscular fiber is permanently modified by exercise. We have a further analogy in the permanent disposition Avhich the motor centers assume for the co-ordination of movements. At first complex movements are performed with great difficulty, the central nervous disposition being wanting ; but after some practice these dispositions become established and the co-ordinated movements become semi-automatic. Of the ' See Ribot, Leg Maladies de la Memoire, chap. iv. , and Taine, In- telligence, 11. chap. 11., for remarkable cases of such memory. An ignorant girl, during a severe illness In her twenty-fifth year, recited long pieces of Greek, Latin, and Hebrew, which she had heard her uncle repeat when she was nine years old. TBEOnY OF BETESTIOK 139 superior centers tlie same, in all probability, may be said. Furtliermore, liypnotic experiments show beyond question that experiences absolutely beyond recall in the normal life may come readily back to the hypnotic somnambulist. 2. It is further objected that the brain does not afford sufficient substance or accommodation for so many co- existing memories, supposing them to be permanent traces, either in the organism or its functions. But this difficulty, although frequently urged, does not deserve serious thought. According to the most moderate estimate, the large brain contains about 600,000,000 cells and even a larger number of fibers. And we are not at all obliged to think of these elements as having a single function only. They are known, on the contrary, to act together in specific con- nections, and the varieties of connections of so many ele- ments is simply infinite. Further, we have here, also, analogous cases which settle the question without further consideration : the coexistence of innumerable functional dispositions in the motor arrangement of the nerves and muscles of a single organ of the body ; the marvelous fact of the life development of an organism incased in a single germ, at first microscopic — a germ which possesses, in dis- position or tendenc}^, all the organic characteristics of the parents to the most minute detail, as the color of hair, shape of face, and those indescribable similarities of feature which constitute family resemblance, or the disposition to peculiar motor habits.' If a single germ cell may possess such inexplicable power of preserving differences of form and function, what limit can we set to the similar power of the brain ? 3. It is again objected that the reduction of retention to a physical tendency and modification interferes with men- tal continuity and destroys the unity of mind. This, how- ever, is seen not to be the case, when we remember that we ' See the case of three generations having the habit of striking the nose with the fist while asleep, Paulhau, Physiologie de V Esprit, p. 164. 140 RETENTION AND UEPRODUCTION are dealing with tlio retention of individual states or pres- entations, Avliose lapse from consciousness does not affect the unity and continued persistence of consciousness itself. If a presentation be quite out of consciousness it is lost to the mental life, whatever be our theor}^ of its fate — wliether it be in unconsciousness, weak consciousness, or in physical disposition. The unity of consciousness, the conscious active unity of apperception, remains present throughout all the come and go of states, some other presentation taking the place of that which is lapsed ; or, in other words, another content occupying the active process. The unity of the mental life consists, not in the persistence of single states, buf: in the conscious oneness of the ego as voluntary activit3\^ Physical Basis of Memory. As to the nature of the physical basis, which constitutes the primary condition of retention, we may speak in general outline. In the case of any sensation and its reaction in movement, two classes of physical data are involved : sensor and motor. The sensa- tion has its seat in the gray matter of the brain, from which, by a fibrous connection, and through certain motor elements in the brain or spinal cord, communication is established with the muscular tissue. Each such sj^stem of connected or associated elements is called a sensori-motor circuit. Now every sensation, say that arising from a bell, gives two kinds of modifications in the nervous system : first, it works an unknown change in the sensor cells, and second, it tends to establish motor connections. Accepting this as the simplest type of such action, we can conceive of innumerable modifications and complications of it. Numer- ous motor connections may be possible from a single seat of sensor change. For example, upon feeling a painful con- tact with the body, we have numerous alternative move- ments to relieve it. When a limb is fatigued we may move ' See the section on ' ' Mental Unity " in my Handbook of Psychology, vol. ii. chap. 11. § 6, THEORY OF llETENTION. 141 it into various positions of change. When we hear a word we liave a tendency both to speak and to write it, involving different motor connections, or we may make a gesture ex- pressive of its meaning. In the same way, different sensory centers become connected with one another by their fre- quent association together : as the taste and color of an apple. Now every time the sense in question is excited by the same stimulus, the same course of transmission, by the law of least resistance, is liable to be called into pla}" ; and there is a tendency to confirm both the sensor modifi- cation and the sensori-motor circuit. Thus greater facility and rapidity are given to the process, and there arises in the nervous organism a readiness or disposition to repeat its own acts under similar circumstances. Now in the case of reproduction, or memor}^, the same nerve elements are affected, and in the same manner ; ex- cept that the sensor centers are excited from within instead of from without : from some other center instead of from the end organ. For example, if instead of hearing the striking of the bell I am thinking of architecture, then of the cathedral at Thun, the bells of Thun arise to mind, and I have a memory of the sound of a bell. This, by an estab- lished association, excites, entirely from within, the center of vision, giving a visual image of a bell ; this excites the motor-connection with the organs of speech, and I pro- nounce the Avord bell. Thus the same elements are brought into play as in the actual presentations by the senses in- volved — the bell itself being absent. This is the physical basis of a memory. The organism is disposed toward the revival of the state of consciousness of the original per- ception. The execution of movements, at first difficult, be- comes easy, then semi-automatic, and often irresistible, and nothing remains to make the physical retention real repro- duction, save the mental conditions Avhich inaugurate its movement. In memory, the connection is ideo-tnotor. Mental Conditions of Retention. The mental condi- 142 RETENTION AND REPRODUCTION tions of re.tention are the essential thing — not the reten- tion itself, which we have found to be a matter of the physical organism. First we note the intensity of the sen- sation. Sensations or perceptions of slight intensity are not remembered ; this is because they do not reach the relating and fixing activity of apperception. It is proba- ble that they are retained as bodily modifications and have their influence upon the general cast of our memory, as is shown in their possible recall in the hypnotic state. But, not having been given a place and connection in the mental life, they have no associations of sufficient strength to accomplish their recall. Intense sensations, on the other hand, draw the attention to themselves and are remem- bered. Another condition, or facilitating circumstance, is repetition of the first sense-experience. Repetition tends to bring a presentation before the attention from the very fact that it is the same experience we have before met. A presentation which is at first too slight for notice and so escapes attention, at another time, and under different con- ditions, is apperceived and fixed in an escort of conscious states. In many cases, also, the very fact of repetition serves to add actual strength to the presentation, proceed- ing upon the nervous modification or tendency begotten of its earlier occurrence. Tlie most important of these conditions, however, and that to which those mentioned may be subordinated, is the attention. The attention considered in its entire function as the apperceptive agent of our mental life is, as shall be seen later, the one essential mental condition of memor}^ Here we deal only with its bearing on retention. It is a universal principle that things attended to are remembered, and things not attended to are forgotten. This arises from a twofold effect of attention : first, as was seen in the chapter on attention, it increases the intensity of presenta- tions, and so gives them a greater strength and nearness in the flow of niental states ; and, second, it gives them a CONDITIONS OF REPRODUCTION. 143 related position, as of contiguity, resemblance, cause, in reference to other states with which or near which thej'' occur. We shall see, in studying association,^ that our mental experiences are never isolated. They are always bound together by relations which the mind discerns in apperception. The more closely and definitely they are bound together the more permanent are our acquisitions ; and the more loosely bound, the more easily dropped out and lost. Now apperception is this binding. When we say we experience a sight and attend to it we mean that we bring out its details in relation to one another and in relation to our earlier and later experience, giving them a place in the permanent texture of our memory. § 3. Reproduction. s Primary Condition. The first condition of the reproduction of an image is the ph3^siological disposition which appears to constitute retention. Assuming reten- tion, therefore, we inquire into the further elements of reproduction. It is easy to see that this purely physical modification does not account for the revival of an image in consciousness. The essential element of memory is lacking. The simple fact that matter modified as you please does not remember serves to refute the theory of " organic memory." We might, with as much reason, say that the post remembers the nail which was driven into it, because it retains a permanent modification in the arrange- ment of its elements, or that the seasoned meerschaum pipe remembers by virtue of the molecular changes which its frequent use has wrought, as that the brain remembers because of its molecular dispositions. Of the physical process we may say : a. That it is the necessary basis of memory, as far as our experience goes. h. That it accounts for retention, c. That it gives direction to the flow of our memories, by the determination of one of many alternative nervous courses. But it is no more an approach ' Chap. xii. 144 RETENTION AND REPRODUCTION. to an explanation of tlie revival in consciousness of an image than of the first perception itself. The pliysical process determines vjhat I shall remember : the mental process, that I shall remember it. The primary condition, therefore, of reproduction is the reinstatement of the original presentation by a new apperceptive construction. Supplementary Condition. It lias already been made more or less clear that a reproduction is a recreation, a new product, which is due to the same conditions as the orig- inal perception, with the lack of the external stimulus. This lack is, however, seeming rather than real, since the central stimulus is as really supplied from within as though the object were present. Admitting, then, the physiolog- ical disposition of the organism, due to former experience, we find the further supplementary condition of reproduc- tion to be a neio stimulus of the centers, arising generally from, an inner or mental source. This new stimulus, how- ever, is not always mental, since there is a vast range of bodily conditions from which the centers may be excited, stimuli which may be called intra-organic in distinction both from the excitations of the external world and from those of the world of conscious states. Any stimulus which fulfills the one condition of reproducing the physical func- tion, as it operated in perception — the mental conditions being again also present — suftices for the revival of a pres- entation. This theory of reproduction explains many mysterious facts which are inexplicable on the theory of mental habit or of unconscious memory. The whole field of unconscious trains of ideas is covered by the consideration of an organic process. We are often surprised at the sudden ap- pearance in consciousness of a representation which has no apparent connection with our train of thought.^ Yet, by close attention, we can often find some dim association ' Cf. Hamilton, Led. on Metaphysics, iv. cand Mill, Examination of JIamiUou, chap. xv. AIDS TO REPRODUCTION. 145 with an earlier state. In consciousness we have forgotten tiie connection, but an organic disposition asserts itself through all the links of our earlier presentation, and the unexpected idea is the consequence. This is supported by the fact drawn from ps\'chometry, tliat in nmny reactions tlie physiological process seems to take less time tlian the mental/ It is quite conceivable, therefore, that when a SLM'ies of nervous modifications follow one another very quickly, sufficient time is not afforded between them for the conscious presentation. Often, also, after vain efforts to remember a date or name, we give it up, but when think- ing of other things it suddenly pops up, so to speak, in consciousness. It is possible that in our casting about for the desired memory we have started a train of association which has run its course in the organic dispositions, and terminated successfully. These cases will be again re- ferred to in the consideration of the association of ideas. This explanation seems much more natural than the mys- terious hypothesis of unconscious mind. The principle that the same physical process is involved in the reproduction as in the presentation is confirmed by the distinction above noted between a persistent presenta- tion and its revived image. The persistent presentation is seen, at once, to depend upon the same excitation and nerve process which gave the percept ; yet it remains when the object is withdrawn. Hence we have every reason to be- lieve that the revived image is due to the same nerve process, since it differs from the persistent presentation only in its separation from the external stimulus by a very brief period of time. One is a prolongation of the primary state, the other a restoration of it ; the former is the con- tinuous effect of a continuous cause, the other the inter- mittent effect of an intermittent cause. Secondary Aids to Reproduction. There are certain secondary conditions which tend to the most ready repro- ' See chap. viii. § 7. 146 BETENTION AND REPRODUCTION. duction of mental pictures. In tlieir general nature thej are almost identical with the auxiliary conditions of the actual perception of objects, and so add new evidence of the identity of the two classes of facts. Among them we may notice : a. Intensity of the nervous stimulation. All direct excitants of our nerve tissue, as coffee, opium, hash- eesh, stimulate the reproduction of images and thus aid the memory temporarily. So also any occurrence that excites the nervous system as a whole, as a blow on the head, great danger, a threat of death/ b. The absence or feeble iiiten- sity of present states of consciousness. This tends to throw the attention upon the revived image, which is ordinarily feebler than the present presentation. For this reason we close our eyes when trying to remember something, c. As before, in the case of retention, the attention is the princi- pal aid to reproduction. Representations must be attended to, to be apprehended at all, and after this, attention makes them still more distinct. Indirectly also, attention may be used to call up representations. We think of an object or event in some known relation to the one we wish to re- member, and set a train of association going which secures to us the desired image. Often, however, the fixing of the attention may hinder the memory seriously, from the fact that it tends to hold an image before the mind to the ex- clusion of others and so impedes the flow of association. d. By association, finally, as is seen later,^ the function of reproduction is given consistency and unity, and made available for the higher uses of mind. Power of Imaging. Tlie power of recalling mental pic- tures varies greatly with individuals and at different periods of life. Images of sight are most distinct and last- ing and become our type of memory pictures in general ; ' Hepce, probably, the frequent, but not universal, experience of mi- nute memory of past events when one is in danger, as of drowning ; generally it is greatly overstated. ^ Chap, xii, MENTAL GROWTH. U7 they arise also and become fixed very earlj^ in child life. Persons who have this power to a marked degree are known as having good imaginations, though simple revival of images is tlie most rudimentary form of imagination. It may be a bane to the mental life ratlier than an advantage, as in the case of insistent and fixed ideas. In accordance with the principle of attention already noticed, the images of childhood are strongest in our memory. The attention at that period is not burdened with details, and trivial things are of great interest and importance : such images are also recalled so often in after years that repetition gives them great vividness and numberless associations. Many old people are constantly led back in conversation to their childhood, even when memory of middle life is fail- ing. Galton has found the farther remarkable fact that a small proportion of persons have a peculiar mental scheme or diagram in consciousness in which they arrange num- bers, colors, etc., when imaging them. " Number forms " and other such peculiarities seem to be innate and heredi- tary. Cases have long been known of individuals who at- tach particular colors to particular sounds, such as green, blue, etc., to certain letters of the alphabet. Griiber has recently reported "disparate associations" of this kind be- tween sight and taste, sight and smell, sound and taste, etc. He even finds in one subject certain tastes accompanying degrees of muscular exertion, and colors attaching to tem- perature sensations.' Retention and Reproduction as Mental Growth. The growth of the mind through accumulated experience is a matter of individual appreciation. There is a constant enlargement of view and strength of purpose due to 'For a typical "Number Form" see my Handbook of Psyclwl- ogy, vol. ii. appendix C ; also a variety of them in Galton 's Inqui ri(S into Human Faculty. On the other peculiar facts mentioned see x\\>o his discussious on " Mental Imagery " and " Color Associations " \\\ the same hook. 148 RETENTION AND REPRODUCTION exercise. Every mental experience leaves tlie mind dif- ferent, as every physical change leaves the body different. Tliere is a progressive develojiment of self -hood — a realiza- tion of mental possibility in the form of actual life, which gives individuality to the man and colors his disposition. In this sense all experience is retained mentall}^, retained in the altered possibilities which it opens up. Proceeding we shall find that mental habits appear stronger, perhaps, than physical, and such habits, dispositions, vague feelings of intellectual preference and aversion are the sum of all the elements, however minute, of our past. CHAPTER XL RECOGNITIOX AND LOCALIZATION.* § 1. Recognition. Recognition is the tliird stage reached in the develop- ment of memory. Granted an image reproduced, a re- presentation, it is then recognized. Representations are " accompanied," says Locke, " with an additional perception (feeling) indicating that they are not new, that they liave been before experienced. This is ordinarily csiWedrecogni- tion^ This additional fact of recognition, however, does not always accompany revived images, and by the study of the cases in which it is absent we are able to learn wliat recoG^nition is. Feeling of Familiarity. In a general view of recogni- tion from the standpoint of common consciousness it con- sists in the feeling of familiarity with which an imageor object affects us. We say feeling, since the recognition, in itself, accompanies the act of knowledge in which the object or image is again presented ; that is, repro- duction is assumed in recognition. This feeling of famil- iarity is vague and often misplaced, and ordinarily goes unanalyzed. Distinction between Recognition of an Object and of an Image. The means by which recognition arises vary as the recognition is of an object or of an image. In the case of the second perception of an object its recognition is probably accomplished by means of an image which is already recognized. We have a comparison between the percept and the image, and feel them the same or ' Cf. Diy Handbook of Psychology , vol. 1. chap. x. 149 150 RECOGNITION AND LOCALIZATION. similar. This is seen to be the case in frequent instances in everyday life. If we are asked whether an object is the same as one seen before, we often say we do not know, for we do not remember how tlie former object looked ; which means that we are unable to call up and recognize any image with which the object present may be compared. In the case of the recognition of an image such a procedure is impossible. It would presuppose another image still, and so on indefinitely. The question, therefore, is nar- rowed down to the means by which we recognize a repro- duced image.* The recognition of an image depends upon the degree in vjhich its apperceptive relatio7is are re-established. It has already been seen that the reproduction of an image con- sists in the reinstatement of the conditions, physical or mental, of the original perception. Such a reinstatement of the conditions suffices to bring an image back into con- sciousness ; but it is not then necessarily recognized. It is only when some of the mental connections — the relations established among the perceptual elements by apperceptive attention — are again more or less consciously presented that the sense of familiarity is felt. It is necessary that there be some accompanying conscious elements to which the recognized elements are related. Often when an image arises in consciousness we do not recognize it till we bring back some association with it. Often, also, we see a face and in so far recognize it as to feel vaguelj^ familiar with it ; while we strive to bring up more of its apperceptive connections in order fully to identify it. This first vague recognition is probably due to the felt beginnings of the revival of the spatial proportions of the face. This is further proved by the fact that percepts which are not related in the first presentation — for example single isolated sensations, as the stroke of a bell — are not recog- ' On theories of recognition see my Handbook of Psycliology, vol. i. chap. X. § 1. THEORY OF ilECOGNlTtOX. 151 nizetl in the representation. We say of such presentations that tliere is notliing distinguishing or characteristic about thera whereby tliey should be recognized. But this is only to say that tliere were no specific points of connection between this image and others, or between the parts which are separately apperceived. As soon as some sign is made of a peculiar kind in connection with the image it is recog- nized. Recent experiments by Lehmann on the recogni- tion of differences of color strikingly confirm this view. Different shades of gray, which could not be recognized Avhen seen quite alone, were recognized when they were given names beforehand, or when a number was attached to each in the first perception. Of nine shades without names or numbers, only forty-six per cent, gave true recognitions ; while the same shades, with numbers, gave seventy-five per cent, of correct identifications. Here the introduction of a simple local relation in the perception gave the necessary clew. The same appears in the experi- ment noted above ; ^ my infant recognized her nurse after her absence only when several senses re-enforced one another. And further support is derived from the phe- nomenon of so-called psychic blindness, deafness, etc., i. e., recognition is absent in animals deprived of the higher co-ordinating brain centers. This view of the case also enables us to take account of the subjective element of recognition, which is overlooked in other theories. There is more in recognition than the sense of familiarity with an image. There is the feeling of ourselves as in familiar circumstances. It is one's self who has been in this state before. Tids feeling of self develops largely, as we have seen, in connection with active attention. But attention is the organ of the process of apperception. Consequently when by reinstatement of this process the fact of recognition is experienced, it carries with it essentially the feeling of an emphasized self : the self of the first apperception is again evident in the self ' Above, chap, v, § 3. 152 RECOGNITION AND LOCALIZATION of the reapperceptioii, and the sense of sameness of the ap- perceptive content really arises with the sense of the same- ness of the individual who has it. Recognition of the image, therefore, and sense of personal identity, both rest ultimately in differences in the amount^ ease, facility^ good adjustment of the attention.^ § 2. Ideal Pkoduct of Recognition : Personal Identity. In the foregoing discussion the origin of the idea of identity, in general, and the identity of self, becomes clear. In our feeling of personal identity it is not self apart from the events in consciousness of which we are conscious as persisting : it is the consciousness of something which abides in the midst of these events which constitutes tliis feeling. It rests, first, upon reproduction, since a sirigle present experience does not afford the duration or time through which we feel ourselves to be the same. There must be reproduced images with which our present ex- perience is compared. But further, these images must be recognized, and must carry with them that feeling of familiarity which is afforded in the reinstatement of the apperceptive process of attention. This activity is felt to be my activity in the second experience as in the first, and the recognition of the I takes place in virtue of this re- peated activity. § 3. Localization in Time. The question as to the origin of the idea of time must be approached, as in the similar problem of space, from the standpoint of concrete perception of filled time. Time in the abstract we do not know. We experience time only as we experience events, definite and individual, in time. We sometimes seem to apprehend the flow of pure time, as in the night we lie awake in silence, conscious of the vacancy of our minds ; but even then this flow of time is ' Cf. below, chap. xix. § 5. IDEA OF TIME. 153 marked off by distinct events — tlie beating of the heart, the direction of attention to fragmentary sentences or words which flit over our consciousness and are looked at only to be dismissed. The inquiry then seems to be as to the localization of events in time, as we have already considered the local- ization of things in space. There are two general char- acters of our notion of time which are ordinarily used in attempting to define the notion ; w^m^Xy, duration and suc- cession. These correspond in the case of time, respectively, to length and position in the case of space. The terms of the problem of localization in time are analogous to those of localization in space. Why is it that tlie experiences or events of our inner life are arranged in time order, as before and after? It is quite possible that it sliould be otherwise. Suppose a being with no memoiy whatever ; to him each event would be now. There would l)e no past or future ; every mental fact would be w^orth its face value in the present, with no relation to other mental facts. And again, granting the fact of memory, why is it that each event takes its proper place in the line of time — the place it occupied in the original experience and no other ? And further, even though retained and reproduced in con- sciousness as a present state, why does it not simply remain a factor in the complex make-up of our present experience ? In more general terms, how are states of consciousness of a purely intensive and qualitative nature projected and localized in time form ? The answer, as before for space perception, is this : By a mental reconstruction of time, loherehy conscious data are interpreted in terms of succession. Data for the Reconstruction of Time. The data upon ■which the mental reconstruction of time proceeds are ex- ceedingly obscure ; the more so because of the differences between this process and that in the case of space, to which it is supposed to be analogous. In case of space we have 1 5 4 RE GO GNtTIOK AND LOCA LIZA TtON. iioii-spatiul senses to compare with spatial senses. But with time there is no sucli resource, and we are unable to iix upon facts as absolutely necessary to the idea of time, as shown by the absence of that idea in their absence. There are one or two kinds of data, however, so consciously involved in our localization of objects in time that they may be safely indicated. I. Intensity as an Indication of Time. Upon con- sideration, the most evident characteristic of our past ex- periences is their progressive fading, as they grow more remote. In general, the last hour is more distinct than its predecessor, and yesterday than the day before. It maj^ therefore be stated as a general rule that the intensity of a representation is a sign of its locality in time, in reference to other representations brought with it into consciousness. This rests upon the principle of memory, that — with cer- tain exceptions, to be instanced later — the power of repro- duction and the intensity of the reproduced image vary inversely as the time elapsed since the original perception. Presentations, therefore, experienced in the order a, b, c, dy w^ould be reproduced in an order of intensity d, c, b, a ; and this inverse intensive order serves as a sign for their mental interpretation in the original time order «, b, c, d. This is further supported by the fact that mistakes as to the rela- tive time of events are occasioned by simple differences in the intensity of their reproduction. Things which im- pressed us stronglj^ linger in our memory and seem to be recent, while later events are dim or forgotten. More intense images also serve as rallying points or dates in the past, around which other events are grouped. We date many subsequent events from the death of a friend, the burning of a house, or some other great occurrence. The fact of the interpretation of intensities cannot be deemed sufficient in itself, however, for time localization. If uncorrected, the tendency to mistakes spoken of would be a source of continual illusion. Of two successive pres- IDEA OF TIME. 155 entations the stronger would always be located last, what- ever might be their real order. Hence we cannot stop here with some, who call these differences of intensive coloring the "temporal sign "; but must seek some further point of reference in the mental life for these, as yet, confused representations. II. Movements of Attention as Indicating Position in Time. Although not as clearly of simple import as the fact of intensity, in its relation to localization in time, the act of attention has an undoubted influence. From one aspect, it assists and re-enforces the indication given by intensive coloring. Attention pursues, in the main, a regular rhythmical course and so brings out clearly the in- tensive relations of successive mental facts. On the other hand, it tends to subvert these indications, since strong attention placed upon one presentation or a series in- creases its intensity relatively to adjacent states of mind. The former are thus thrown out of their true time order. As further evidence that the primary movement of the attention is of extreme import in the genesis of the idea of time, the following facts may be spoken of. a. The flow of time seems accelerated when the attention is agreeably occupied. This is most true when the occupation is varied in easy stages, and the active efforts of mind are not strongly taxed, h. The flow of time is, on the other hand, impeded when the attention is kept in a strained or con- centrated condition : this is due to weariness in the mental life, which seems to have an immediate influence upon our time intuition, c. Time flows slowly when exciting im- pressions follow in such rapid succession as to leave the attention in a state of confusion. Here there is not suflicient time for the adjustment of the attention to the successive excitations, and the perception of the lapse of time is, as a consequence, confused, d. Time flows slowly when the mind is unoccupied. There are no outstanding ideas upon 156 llECOGNITION AND LOCALIZATION. which the grasping and relating power of attention ma}'" seize, e. After a given movement of attention, a future movement over the same series is easy, while the rearrange- ment of tlie series is difficult ; thus tlie absence of mental effort is a sign of temporal order, f. In dreams, where the force of attention is greatly diminished, the sense of time is confused and mistaken. The least inference which can be drawn from such facts is this : that the varying states of our attentive mental life are, in some way, signs employed in the mental reconstruc- tion of time, i. e., temporal signs. These signs coexist with those derived from our passive sense experiences, and to- gether constitute a general class of data. The intensit}^- phases of reproduced presentations, on the one hand, seem to bear especially upon the succession of events in the past : we think of succession by the number of things in time. The phases of the attention bear especially upon the feeling of duration in the present : we measure duration in terms of our own attentive adjustment, as having experienced and expecting to experience. Duration is the feeling of the interval between things in time.^ Mental Synthesis, 'i'he difference between the data and their finished time form is sinipl}^ the difference between the succession of ideas and the idea of succession. This difference is very great. As Bradley puts it : " Suppose there is a series of facts outside the mind, the question re- mains. How can they get in ? "^ In oi'der to the succession of ideas, only one need be present at a time, and they need have no constant connection. But for the idea of succession there must be at least two ideas before the mind, the pre- ceding and the succeeding. This involves the bringing up of past states to the level of the present. Now the mind sees all its states in this way — brought up to the plane of ^This distinction is due to Dr. Ward, "Psychology" in Encyc. Brit., 9th ed. '^ Principles of Logic, p. 74. umrs OF BUB A now. 157 the present. I think of four events which happened in four successive days. They are all now present to my conscious- ness, and it is only my present state of which I am conscious. Of this state «, ^, c, d are factors. How is it that these present intensive, qualitative states are projected in an order of time, the same as their original occurrence ? How is it, to use Ward's figure, that certain states are thrown back in a line at right angles to this plane of the present ? " We may, if we represent succession as a line, represent simulta- neity as a second line at right angles to the first. Xow it is with the former line that we have to do in treating of time as it is, and with the latter in treating of our intuition of time. . . In a succession of events, say of sense impres- sions «, h, c, f7, 6, . . . the presence of h means the absence of a and c, but the presentation of this succession involves the simultaneous presence, in some mode or other, of tw^o or more of the presentations a, 6, c, c^." * This is analogous, as the same writer says, to the projection of the simultaneously perceived points of the visual field in a line of spatial suc- cession, representing distance. It is seen at once that whatever be the qualitative color- ing attaching to these simultaneous states, it can serve only as datum for their temporal discrimination. If a is located as before ^, and h as before c, it can only be through the mental interpretation of some accompaniment of a, 5, and c, respectively, by which their temporal position is deter- mined. This interpretation or synthesis is called the inen- tal reconstruction of time. Units of Duration. If it be true that the sense of the lapse of time depends intimately upon the rhythmical phases of the attention, we would expect to find units of duration in the flow of time which would correspond with these phases. Experiments in determining the area of con- sciousness show such units, in the maximal length of filled time which we are able to compass with a single imme- diate intuition. It was stated, in speaking of the area of ' Loc. cit. 158 RECOGNITION AND LOCALIZATION^. consciousness, that about twelve distinct impressions of sound, succeeding one another at intervals of .2 to .3 second, could be held in consciousness together. Multiplying this interval by the number of ijupressions, we have 2.4 to 3.6 seconds as approximately the extent of our distinct unit consciousness of filled time. The maximal extent of our intuition of empty time or pure duration is probably consid- erably shorter, as is shown by experiments as to the cor- rectness of our estimate of small periods of time. It is found that we estimate correctly an empty period of .7 to .8 second, shorter periods being overestimated and longer periods made too short. The images given in this "unit" constitute, in contrast with ordinary representations, our so-called "primary memory." It is through this unit consciousness of time that all time distance is estimated. The representations that it includes constitute the plane of the immediate present, which we may consider, in reference to time, as a circle, the earlier impressions in it passing out at one side and the later coming in, as a constant stream. Time, as we know it, is not a single line of succession, but numerous lines giving a certain number of coexistences in the present. It is out of this circle of the present that the past is projected in lines at right angles to its plane, like distance from the field of vision. This is but a figure to aid our conception, but so natural and convenient a figure that we employ it even in unreflective thinking : as when we say, an event is "so far back," or that tw^o events happened " side by side." And there is no reason, in the nature of the case, that intensive data should be spoken of in terms of tirrie, rather than in terms of space. ^ Perception of Time by the Ear. Of the special senses the ear is most acute in the appreciation and measurement of time. Single sound stimuli are discriminated with great ' On theories of time perception see my Handbook of Psychology, vol. i, chap. X. 1 3, KiynS OF MEMORY. 159 delicacy and exactness, both of interval and of duration. For this reason hearing is called the sense for the per- ception of time. Its function, in this respect, is similar to that of sight for space. It makes more exact and definite the vague time series reported first, probably, by the mus- cular sense and later by the other senses. This delicacy" of time perception underlies the pauses of speech, the quan- tity of vowel sounds, the metric flow of poetry, and, more than all, the rhythm and technical "time" of music. § 4. Ideal Product of Temporal Localization : Idea OF Time. From the conception of co-ordinated events in the form of past time we pass by abstraction to the idea of time: that is, we pass from filled to empty time. The point of immediate experience is called the present, in relation to the past, and the whole possibility of additional experience is called the future. The future, therefore, is not time at all, as the past is not : it is simply the anticipation of more experience like that already placed in the past. The finished product, the idea of time, is of late growth in the mental life of the child. § 5. Kinds of Memory : Local, Logical. We have found memory, viewed entirely from the sub- jective side, to be the revival of an image in its network of relations w4th other images. Things are remembered in groups, as they were at first perceived. This involves the variety of relations which are possible in apperception. The kinds of relations thus reproduced serve to aid us in distinguishing between different kinds of memory. For example, an image may carry with it the local connections of its first perception ; that is, its locality was the promi- nent feature of its apperception. Such memory is called local memory. It is in this way that we memorize long Sentences by the positioj:t on a printed or written page, qv 160 RECOGNITIOy AND LOCALIZATION. the parts and ornaments of a room. These memories are fleeting and temporary, generally, from the fact that local relations are accidental, and do not belong necessarih' to the objects remembered. It is only as long as we can re- produce the whole page that we oan recall the part desired. The same also is true of temporal memories. Bej^ond these extrinsic or accidental relations we find others which are essential. Cause and effect, substance and property, whole and parts, are such relations. Memory by means of these is called logical memory. It is more permanent and valu- able than local memory, from the fact that these relations always subsist, and the related image is always suggested, when that to which it is related is capable of being pre- sented. It is seen at once that logical memories should be cultivated rather than local, and that the latter, except when only temporary acquisition is desired, should be avoided. COMBINATION. CHAPTER XII. ASSOCIATION.! § 1. General Nature of Association. Definition of Association. In the foregoing chapters reference has been repeatedly made to tlie principle of "association of ideas"; indeed some knowledge of such a principle is so generally implied in the affairs of life that its familiarity has been assumed. Tlie truth that things owe their cliaracter to their associations, that men are in- fluenced, by their associates, is only a broader application of the law which takes its rise in the mental life. The conditions under wliich the revival of mental im- ages in general is possible have been stated. It proceeds upon a renewal of the nervous action which accompanied the first perception, and the reinstatement of the original apperceptive act with a sufficient intensity and duration. This, however, does not suffice to infor?n us what it is that gives specific direction to the flow of reproduced states. Why is it that among an infinite number of possible repro- ductions a particular representation rather than others is revived? This question indicates the tiwe function of associ- ation, which is the progressive revinal of particular mental states. Tlie/«e^ of association may also be defined as the relation hetxceen revived states of consciousness, icherehy con- tinuity of successive representation is secured in the form of neio integrated states. This we must fully explain. ' Cf. my Handbook of Psych)lofjy, vol. i. chap, xi. 161 162 ASSOCIATION. Ground or Reason of Association : the Preceding Idea. If we thus conceive of association, as the law of the con- nection of rej)resentations in consciousness, and picture the series of such representations, the nature of the connection in each case is seen to lie in the character of the antecedent image. For example, I am thinking at this instant of the rain ; and why ? Because I have seen the heavens covered with clouds. I have an idea of thunder because I have just seen a flash of lightning. I think of Napoleon because I have already thought of Caesar or Alexander. In each such case the idea at present before me is determined b}^ the idea which immediately preceded it. If the antecedent idea had been different, so would also the subsequent idea. If, for example, I had thought of Socrates instead of Alex- ander, it is altogether improbable that Napoleon would have come to mind. There are no states of mind which can be com^jletely isolated from this chain of connected links. Our whole mental life is a progressive series of integrations of ideas. Physiological Basis of Association. In speaking of the pliysiological habits which lie at the basis of retention we had occasion to point out the complex nature of the dispo- sitions or tendencies in the mental life to which they give rise. We may suppose both associative connections be- tween localities or elements in the cerebral cortex,' and the multiplication of these connections, in an intricate network of fibrous and cellular tissue. Considering these connec- tions as constituting the organic counterpart of tlie asso- ciated mental life, we see at once the wide capacity it affords for varied and related representation. The stimulus of a single element in the network arouses many connec- tions: first those best established and oftenest repeated, then others in varying degrees of strength of revival. For example, we may suppose the memories involved in the sight, touch, sound, written signs, and spoken word of a bell to be thus connected. The presentation of a bell to * Above, chap. iii. LAWS OF ASSOCIATION. 163 view revives at once no less than five different memories : the muscular memories involved in speaking the word bell, the word as heard when spoken and seen when written, the sound of the striking of the bell, and its hard, smooth touch. These come up in varying degrees of readiness, according as we are accustomed to exercise them respect- ively in our experience with bells. Other more indistinct memories, such as the church spire, dining rooms, crowd in upon us, each having its correlative accompaniment in the brain activities. The basis, therefore, of association is the same as that of retention, and admits of the same physiological explanation; that is to say, the mere possi- bility of association in revived states is provided for in the physiological retention of the related molecular changes occasioned at their first experience. The actual revival, however, as remembered states, is mental, as reproduction and recognition are mental. For this reason the laws of association are unconscious until critical examination of the nature of associated states reveals them. § 2. Laws of Association. I. Particular or Secondary Laws. " When we seek," says Aristotle, " after an idea which is not immediately before us, we reach it through the mediation of another idea, either by resemblance, or contrast, or contiguity.^'' ^ Modern psychologists generally follow Aristotle in this enumeration of the principles of association, at least as respects resemblance and contiguity. Deferring the dis- cussion of contrast, we may state two great laws of asso- ciation, depending upon the two classes into which, in introspection, the facts of the case seem to fall. In the first place images are associated. That is, one of two or more states, all of which are reproductions, pre- cedes and brings up the others. The face of a friend, whom I recall, recalls the place and time of our last meet- ' Quoted by Rabier, P»ychologie, p. 184. 164 ASSOCIATION. ing. On the other hand, a new experience, a presentation, may bring up images of the past. My new acquaintance recalls some one of my old friends. These two classes of facts exhaust the range of association. In the first of the two cases the images which come up together have been together in the mind before ; this is contiguity. Whatever their former relation to each other may liave been, when we experienced them, whether cause and effect, whole and parts, or any other of the relations the mind discovers, it matters not ; it is sufficient that they have been present before in consciousness, as contiguous in time. In tlie second case the presentation which tends to recall the image is always seen to be like the latter in some respect ; this is resemblance. Resemblance to an image — again dis- regarding contrast — is the only characteristic of a presenta- tion, which serves as ground for the immediate revival of that image. The two particular or secondary laws of association may, in accordance with the preceding, be formulated somewhat as follows : 1. Contiguity : Ideas which have been apperceived together are reproduced under the same apperceptive relations. 2. Resemblance: A presentation which in any way resembles an image tends to cause the reproduction of that image, with its related images. It should be noted that it is only a new presentation to which the law of resemblance can be said to apply as tend- ing to revive past images. As soon as the presentation is repeated its resemblance to the revived image is not emphasized in the reproduction, but the fact that the image which its former perception has left behind has once coexisted with the image suggested at that time, makes it a case of contiguity. For example, I meet a man B, and I think of my friend A, whom he resembles. After that |,l:e two images are associated together b^y reason of the LAWS OF ASSOCIATION. 165 contiguity tlius established ; so that when I see B again tlie resemblance is not necessary to the suggestion, tliough it still strikes rae, and is known to be the cause of the first association. In this case the repeated perception adds vividness and strength to the association, since the reality of the object passes over in a measurQ to the image which it calls up. Tliis reduction of a large class of cases of seeming resem- blance to contiguity is a step toward the elimination of resemblance altogether, as an ultimate ground of associa- tion. Further, while we hold that, from an empirical stand- point, resemblance is an evident and real reason for the connection between ideas, and must be recognized as such, still, on reflection, we find it possible to reduce all cases of resemblance, in their ultimate nature, to contiguity. In every case of resemblance between a presentation and the image it suggests, there may be said to be elements com- mon to the two : elements in the present presentation which affect us in an identical way with elements in the image which it resembles. In a strange portrait, which we say resembles a friend, there are certain points of feature or expression, few or many, which are identical with our friend's : these points coexist with others in the image of our friend, and the whole image is brought up by this co- existence or contiguity. In the presentation there are, say, elements a, h, c, etc., and in the image, elements A, J, C ; the common element b makes the presence of both neces- sary. Taine formulates a law to express this process of association: lVhe?i jjart of an idea appears in conscious- ness the lohole appears. It may be added that the common emotion accompanying a presentation and a memory may supply the point of identity between them. The great importance of the law of contiguity in oppo- sition to resemblance is further emphasized by the experi- ments of Lehmann already spoken of above.* The simple addition of a mark, number, or name to the several shades * See p. 151. 16G ASSOCIATION. of worsted aided the memory by contiguity, when the resemblances of the pieces to one another were too great for distinction. From all the variations in his experiments lie draws the conclusion that " the law that best explains the facts is the lavr of adjacency, in opposition to the law of similarity." Association by Contrast. Since Aristotle various thinkers have cited contrast as a distinct principle of association. It seems warranted at first sight by a variety of well-marked experiences. The sight of a dwarf brings up a giant, a bright color recalls strongly contrasted'colors, sour makes one think of sweet. There can be no doubt, in such cases of contrast, of the reality of the association ; but are there not other reasons than that of contrast to which it may be referred ? There are such reasons, it seems, in all cases, and we are led to reduce these associa- tions to resemblance, and ultimately to contiguity. 1. In most cases of contrast there is a standard of refer- ence to which both the presentation and the revived image are referred : this standard constitutes a point com- mon to both ideas, a point of resemblance. For example, the short man suggests the tall, since both are, at once, thought of in comparison with an average man. The one is short only as he is shorter than usual, and the other is tall only as he is taller than usual. Thus in the very concep- tion of the contrasted images a common element enters. This common element is the b of our earlier illustration, and secures the association by contiguity. . This variation from a normal standard accounts also for the association of emotional and volitional states, as great misery with great happiness, great effort with complete inertness. v 2. Many instances of contrast arise from the early charac- ter of our knowledge acquisitions. The beginnings of knowledge involve, as has been seen, a process of distin- guishing or differentiation : things are fixed and defined in relation to other things. This tends to fix in CjHX minds UNIVERSAL OR PRIMARY LAW. 167 many instances of contrast. In early education tlie child is taught to appreciate qualities in some objects by having pointed out to him the conspicuous absence of these quali- ties in other objects, until it becomes a mental habit. All such primary connecting of contrasted things takes place among contiguous states, and frequent repetition confirms the association. If we had only seen regular oval leaves they would have no contrasted associations ; but having once been led to observe leaves which are very indentate, the contrast at once presents itself afterward ; but the association is due primarily to the contiguity thus estab- lished. 3. It is also true that there is an emotional coloring in cases of contrast, as in resemblance, which supplies a con- necting point of similarity. Vague analogies which are stronger by reason of inherent contrasts, and contrasts which are brought out by an underlying analogy, occasion a repetition of an affective state, which ties together the members of the relation. For example, a three-handed monstrosity brings to mind a one-handed monstrosity, and all the circus oddities we have ever heard of come to mind ; simply because they are all monstrosities, they excite in us a common feeling of repulsion. They resemble one another in the fact of variation from normal nature, and in the common emotion this variation excites. The same may be said of states which involve similar volitional accom- paniments. It seems true, therefore, that all cases of association by contrast may be accounted for as either variations from a mental standard, contiguities observed and established in the process of the acquisitioji of knowledge, or emotional and volitional resemblances. II. Universal or Primary Law. One great principle of associative reproduction has been found in contiguity by succession, its special forms being simple contiguity, resemblance, and contrast. The tendency to association 168 ASSOCIATION. by this law is greatly strengthened by other factors, whose consideration leads to the underlying principle of all asso- ciation. If such contiguity were the whole case only the physical side of memory, that is, retention, would be opera- tive in the reproduction ; and our memories would present the uniform sequences and regular fadings which physical dispositions undergo. The peculiarities of personal men- tal life, the characteristics of individuals, which are so striking in the varieties of form and content of memory, would be greatly reduced. • But such a supposition is im- possible, since memory is mainly mental, as perception is. It is an active synthetic process of constructing relations. Apperception, therefore, is the power which gives defini- tive cast to our associations, and supplies the lack we liave spoken of. The relations discovered in apperception in their variety, and in their intensive phases, give char- acter and deeper meaning to contiguous experiences. Law of Correlation : Every association of mental states is an integration, clue to the previous correlation of these states in apperception. The relations which we discover among the objects of our perception are very varied, and many attempts have been made to classify tliem. Besides the relations of time and resemblance which have already found their place in association by contiguitj^, the principal connections which the intelligence finds among its objects are suhordination, causation, and design. The relation of subordination has various applications, as whole and parts, substance and accident, and underlies, as will be seen, the use of the notions of genus and species in the operations of reasoning. The real logical import of this relation is onlj^ apprehended after the formation of general notions and the growth of mind on its logical side. In early childhood it is simply apperceived as contiguity. Causation also, in its completed form, involves the ideas of necessity and potency, which give it the form of a univer^ sal relation between given data, while in child life it is nmVERSAL OR PnlMARY LAW. 169 simply successions of efforts and resistances. Design arises, even later in life, since it involves more seldom the simple fact of contiguity, and requires a larger stretch of expe- rience for its generalization. The very great value of correlations in our past expe- rience is apparent without amplification. Mere contiguity in time may fade and disappear, when a relation remains intact. For example, all the circumstances surrounding the first perception of a match, the time, persons, manner of striking, material lighted, are long since forgotten ; but the effect, a blaze of fire, is remembered. The elements of potency and necessitj^, peculiar to causation and foreign to mere contiguity, are in this case the means of memory. Correlation is, for the mental life, the essential thing. This has already been pointed out in the section on " kinds of memory";^ and the reason for it is that contiguity, which is merely the mental correlative of the physical proc- ess, is supplemented by movements of the attention w^hich give to our successive states an essential inner connec- tion, corresponding to the relations of external things. Examples readil}^ suggest themselves of memories which show this difference. We remember a string of foreign meaningless words only as long as the actual sounds persist in consciousness. But if we detect, in the sounds, simi- larities to words in our own tongue, they remain longer in memory through this relation. But as before, it is only after the words assume meaning and sense to us that they become permanent acquisitions. McCosh tells the story of a clergyman who asked a sailor boy to box the compass backward, which he readily did from the correlations of the points of direction with one another — they had the same meaning both wa3'S ; but when the boy retorted by asking the clergyman to repeat the Lord's Prayer back- ward the clergyman was defeated. In the latter case the words had no correlations or meaning, and tlfeir simple contiguity was not sufficient for menlor^^ ' See p. 159. 170 ASSOCIATION. Interest^ as Influencing Association. Aiiotlitr factor which influences greatly the direction and character of our associations is found in individual interests and talents. As a general thing our preferences take the direction of our talents. Individuals diifer notably in the manner in which tlie same experiences impress them, and in the re- lations they discover under the same external conditions. An artist sees the red evening sk}^ with feelings only of beauty and pleasure, while the farmer discovers in it prob- abilities of ruin to his crops. The student of a practical and utilitarian cast of mind cherishes his books only as a means of increasing his chances of success or usefulness in life, while his more ideal neighbor studies to secure a broader mental range or an acquaintance wath deeper truths for their own sake. In this there is an immediate intrusion of the prevailing temperament into the web of daily ex- perience, carrying the attention and effort over upon specific relations of things ; which tends in its turn to fix these correlations in mind and thus to heighten the dispo- sition in its peculiarity. Interest gives direction to asso- ciations, and associations becoming fixed give permanence to interest. In general it may be said tliat mental work is most successful when done along the line of inclination. It may be well to point out the danger arising from the free play of this law of association. Free exercise in the line of inclination, to tlie exclusion of other well-directed mental exertion, tends to develop great disproportion in the growth of mind, especially in childhood. Children sliould not be allowed to choose their mental pursuits. The disciplinary value of compulsory application to things which are distasteful is readily seen in the increased flexi- bility of the attention, greater voluntary control of the intellectual impulses, and the broadening of the mental horizon. It is only after these qualities and capabilities have been already attained by a well-balanced course of * On the general psycliology of interest see below, chap. xix. § 1. Fonm OF ASSOCIATION'. 171 compulsory training tliat the student should be allowed to devote himself to a more contracted circle of studies. § 3. Forms of Associatiox. Association by contiguity takes two great forms when regarded in reference to the objects or events from which our mental states arise. These events or objects may co- exist in time or space, or they may be successive in time. Thus distinguished we have association by Coexistence and by Succession. When we come, however, to consider that it is not objects which are associated, but our mental states, and that, in reproduction, these states must be projected in a time series whose form is always suc- cession, w^e find that coexistence of objects gives rise to succession of ideas. That this is true is seen from an ex- amination of the two possible kinds of coexistence in space and time. Objects which coexist in space, as has been already seen, are apperceived by a rapid shifting of the at- tention, the maximal unit of immediate apprehension, for sounding bodies, being about twelve distinct stimuli, each of which may be itself separately apperceived, and for sight about five to seven, which are given as one. For the other senses this range is still more contracted. Each such apper- ceptive unit constitutes a single presentation, capable of reproduction only as a whole, as one image, and not as a number of coexisting images : consequently the next image brouglit up is that to which the attention was next shifted, and the representation of all sensation arising from external stimuli must be in the form of succession. For example, after looking at, say, twenty crosses on a black- board, I reproduce them as four successive representations of five crosses each, or in a longer series of smaller units, the single crosses in each unit being reproduced not as co- existent images, but as components of the unit image of five. If they are reproduced as single crosses it is in suc- cession, arising either from the apperception of each cross 172 ASSOCIATION separately, or from the information that the crosses are all alike, which information takes the place of our own ex- ploration. So, however rejDroducecl, the representation arises from succession. Passing to coexistence in time the same is found to be true. Experiences which happen contemporaneously are reproduced in a single complex, as one image, and not as a plurality of images present together. For example, a musical chord is reproduced in its effect, as one thing, the whole giving a single modification. It is true we may analyze this complex into its elements, but such an analysis proceeds upon a previous anal^^sis of the actual presentation; so that the factors comprised have really been presented in succession. Suppose upon hearing the chord at first I distinguished in the whole effect four tones ; the act of distinguishing or relating these tones depends upon succes- sive acts of attention. And in so doing, the separate tone stimuli remain no longer coexistent, but are successive. Thus we hold that the one form of contiguous reproduc- tion is Succession. This we would expect from what has already been found to be the plij^sical basis of memor3\ Mental reproduction was seen to depend upon the persist- ence of physical changes in tlie form of pln'siological tendencies toward a series of successive brain changes; these have their mental accompaniment in the succession of conscious states under the law of association. By the law of cause and effect these brain changes are a series in time, the terms being sometimes complex physically; but giving a result in consciousness which is a single mental state, and not a coexisting pluralit}" of states. If consciousness be one, and liave but one center, these changes can only constitute for consciousness one modification at a time, the result being a single pres- entation. The presentations thus arising are thrown into successive form by the rhythmic activity of attention, under the limitation fixed by our units of duration.' If ' See p. 157. COMPLEX ASSOCIATIONS. 1*73 these units of duration were longer or shorter the succes- sion of our ideas would be slower or faster. . Complex Associations. The complex character of the physical tendencies which underlie associations has already been remarked. It is impossible to isolate a single track of nervous connection from the general network of elements which constitute the ground of all mental reaction : and the difficulty is almost as great in regard to mental phe- nomena. The idea which we find associated with a preceding state is only one, in most cases, of a great number of lines of mental direction which are open for our pursuit. And this complexity is enhanced when we remember that the first idea is itself only one of the numerous associative progeny of other states antecedent to it. These so-called lines of direction — pursuing the figure of a field of con- sciousness to which these lines would be perpendicular — all tend outward from a given point. For example, the year 1492 suggests the discovery of America, the great events of tiie Italian Renaissance, the Humanistic move- ment, and the Exodus of the children of Israel, together with any or many individual associations which may have been formed with it, such as the dates of other great geographical discoveries. Now in the revival of this net- work of relations the richness of its associations may serve as a help or as a hindrance to memory, according as the order of the revival be a converging or a diverging associa- tion. I. Converging Associations. In the converging associa- tion the mind enters upon one of many paths, all of wiiich lead to the same result. This is the great resource of memory in cases of voluntary recollection. "We cast about in consciousness for some idea related to the image we wish to call up, and the probability of our finding such a path- way to the goal depends upon the number of mental rela- tions which have been formed around it. In case I wish to ;-ecall the date 1492 J have only to think of anv one of th^ 1V4 ASSOCIATION. events mentioned which are associated with it, since they all converge in their lines of suggestion to the one result. II. Dwerging Associations. In this case the process is reversed and the me;nory is hindered and embarrassed by its possible alternatives. If I wish to remember the date of the invention of gunpowder, and can only do so through its association with the date 1492, I am liable, in the absence of all other means of help, to go after it in con- nection with the Exodus, or au}^ other of the divergent lines of association, and can perhaps only reach the true result, after liaving exhausted these possibilities by return- ing again and again to the central idea. § 4. Force of Association. From the preceding remarks the influences which tend to give force and permanence to an association are readily seen. On the one hand, the physiological dispositions which render reproduction possible, are made strong and lasting in the nervous structui-e by frequent repetition of the stimulus. Just to the degree of the repetition, as we should expect, is tlie association strengthened and made facile. This repetition, we may suppose, often takes place in dreams. After seeing an object two or three times the danger of again failing to recognize it is greatly reduced. Yet the ph^^siological dependence is the least important influence in the strengthening of association, since con- tiguity, though more universal, is less important than cor- relation in its establishment. The attention, which estab- lishes the observed relations in association, is the most important means of strengthening them. Strong attention to a single chain of events is often sufticient to lix it permanently in mind ; and we are generally able, when troubled with forgetfulness in a particular connection, to relate the desired event to some remembered fact, and thus to hold it iu the memorv train. CHAPTER XIII. IMAGINATION. » § ]. Passive Imagixatiox. The crowning phase of the imaging power of mind is the imagination. It may be understood in tw^o senses. First, imagination is often used to denote the general representa- tive function of mind, the power of representing b}^ images, thus inchiding memory and association, as well as the con- structive working up of images. Second, the word is often more properly restricted to this last process, that whereby the material of representation at the disposal of the mind is combined in forms of ideal construction, which are inde- pendent, in a measure, of the arrangements of external objects. While the latter is more properly the function which now claims explanation, it is not well to disregard the more general phases w^hich the broader definition has in view. Material of the Imagination. The material of the imag- ination, as of the representative function generally, is sup- plied entirely by the earlier function of presentation. The imagination never creates. It serves only to give form to ideas revived. The data of sense perception and self-con- sciousness supply all its content. And further, its material is alwa^^s capable of being represented in the form of mem- ory pictures. Proceeding, therefore, to consider the broad character- istics of the imaging power, and disregarding the more par- ticular processes which memory and association comprise, we find that general imagination is Passive and Active, ^ Cf. my Handbook of PsycJiology, vol. i. chap, xii, 176 IMAGINATION. Passive Imagination. By passive imagination is meant tlie spontaneous uncontrolled play of images in conscious- ness, from whatever cause they spring, and in whatever arrangement they take form. It finds its simplest type in the incoherent forms of dream consciousness. Here there is no mental supervision of the flow of ideas, no true appre- ciation of their relative value for the mental life, no exer- cise of will in selecting or combining them. The physical and intellectual causes of their production are free to work their own effects, and the result is the storming of con- sciousness, in its helpless state, with all the missiles of sense. Presuppositions : Memory and Association. It is read- ily seen that the free play of images proceeds upon the revival and association of images. The method of this revival is both physical and mental, and consists only in the wider range of the disjDOsitions of brain and mind which have been seen to lie at the basis of memory and association. 1. The physical basis here presents its most complex and intricate activity, as is seen in the boundless combinations presented. Indeed, this infinite complexity and irregularity have led many to deny the dependence of imagination upon the laws which ordinarily govern reproduction. But we have only to consider the real nature of the inter-connected chains of cerebral association to see that the truth is what the principle of association would lead us to believe. Let us consider the prevailing cast of a subject's consciousness to be determined by a great mass of systemic, emo- tional, and presentative groups. These cover the entire liistory of the past, and although their elements may be in subconsciousness, they are yet each capable, upon the rein- statement of the conditions of its first production, of assert- ing itself, in whole or in part, above the level of the general product. The result will not be the reproduction of long connected series of states. From the nature of the brain, the nerve elements which represent unessential or accidental MEMORY AXD ASSOCIATIOX. 177 mental modifications are also readily excited. As mental states, they are outside the chain of ideas, and seem quite detached and irrelevant ; but in their physical basis they are reasonable effects. And this result is indefinitely added to by the interplay of different cerebral trains. The entire brain vibrates with its single members, and sur- charged parts are thus excited by connections perhaps so delicate and fine that there are no elements in conscious- ness corresponding to them. Thus images far removed in thought from one another and never consciously connected are thrown toijether in imaQ:ination. This state of complete confusion in consciousness rarely extends over its whole area, however ; for while we are con- scious at all there is a greater or less degree of mental supervision. Even in dreams there is a glamour of logical or aesthetic consistency throw^n over the most inconsistent elements. AVe think we are making convincing arguments or reciting delicious stanzas, when, awaking, we find it the most meaningless jargon. And in states of light dreaming, when the picture as a whole is coherent, new excitations of the senses are accommodated to it. As lias been said, dreams are the most evident type of the free play of this physical causation. When we are asleep, the active, distinguishing, correlating, and arrang- ing function of mind is at rest ; some of the senses are freely open to excitation from without, and the mechanical element of our personality is predominant. Moreover, the withdrawal of the blood supply from the brain, which is the usual accompaniment of a reduced consciousness, tends to alter the relative potential of its parts. It facilitates the discharge of isolated regions, or exposes elements whose ordinary activity is covered by larger or more recent connections. As would be expected, very young children dream very little. They have not formed the physical habits which give to the reactive consciousness such complexity. 178 IMAGINATION. In our waking states, also, we often indulge in the state of uncontrolled representation, wliicb passive imagination presents. When we relax all mental exertion, and fall into reverie or day-dreams, this spontaneous flow of images is realized. Yet the play of representations is never in our waking states as detached and incoherent as in dreams. We can usually detect, even in our states of completest intellectual abandon, the successive connections in trains of ideas, governed by the principles of regular association. 2. The subjective aspect of passive imagination is of more importance and of greater obscurity than its physical basis. And yet its phenomena are in the main of the same nature. We would expect from the intricacy and confusion of this physical network of connections that the mental facts would present the same general appearance ; and that, on the other hand, while, in the midst of this intricacy, the laws of physics hold, so in the mental phenomena, the laws of association must hold, through all the appearance of lawless flow. The first part of this expectation, that the images of imagination will show detached and inco- herent form, is certainly realized in fact. The most strik- ing characteristic of imagination is the strange and wanton nature of its combinations. Detached parts of former images are combined in unexpected and ridiculous forms. Monsters before unknown are. put together from earlier creatures of thought. Situations are devised which involve persons and places impossible to be reached or associated in real life. And all that we know of the case leads us to the opinion that tlie second of our expectations also holds good, and that no stretch in the current of the life of fancy escapes the principles of association. § 2. Modes of Passive Imagination. Imagination, in its passive form, takes on two general modes; we first find a breaking up of the complexes of MODES OF PASSIVE LMAGIXATIOX. 179 experience into tlieir elements, small or great, and second, we find that these elements take on new shapes. These two modes may be called, respectively, Dissociation and Composition. I. Dissociation. From what has been said, the part played by dissociation is evident. If there were no such breaking up of representations imagination would be simply memory. The same forms of mental process would be indefinitely repeated. Our mental life would be wearisome in its sameness, except as we widened the range of our actual sense experience. As a process, disso- ciation may be more or less prominent, and its thorough- ness, or the contrary, indicates the degree of imaginative power possessed by individuals, since construction or recombination must be limited to the elements at hand. In the process ab-eady described the ground or reason of this dissociation may be seen. 1. It is often due to the breaking up of physical connec- tions in the brain. The fact of forgetf ulness or fading of memory is largely to be explained by the separation and dissolution of brain circuits. The command of a lan- guage, for example, may be lost from injury to the brain leading to the loss of verbal memories or to the impaii- ment of the movements of pronunciation. But single words or letters, parts of former groups, may remain clearly before us. By the dropping away of certain ele- ments of a complex whole the others become more vivid and the result is a more or less complete analysis. 2. The same is true of the mental side of our memory. By the principle already mentioned mental groups are acted upon variously by the attention, and attain different degrees of permanence in memory; so parts or elements of these groups may also be affected. Of a long argument I may remember, without effort, only a single step. Of a face only the nose, perhaps, or the chin, is clear in mem- ory. The whole of a word or sentence is often brought up ISO IMAGINATION. in memory from the persistence of a single letter or com- bination which before attracted the attention. Conse- quently, in the progressive fading which all representation undergoes, parts of groups, or elements of single images, fall away, while other parts or elements stand out alone. This, as before, constitutes a more or less complete analysis of former complexes. In associations by resemblance, as we have seen, points common to the two resembling presenta- tions get similar emphasis. 3. Further than this, we will find in active imagination a positive conscious separation of the parts of images. We are conscious of a tendency toward the reduction of com- plex products to their elements. We note irregularities in outline, protuberances, inconsistencies, and thus isolate portions of our representations. This is seen particularly where the association is not a necessary one, and the parts dissociated have a completeness and unity of their own : as the wings, legs, head of a bird, considered each for itself, or the subject, predicate, and copula of a jjropo- sition. II. Composition : Fancy. These detached data do not remain without form in consciousness, but are built up into new combinations. The forms of these combinations are, as has been said, apparently capricious and without law where there is no selection exercised in their arrano^e- ment. The combining function of passive imagination, viewed in its product, is called ,/h?icy. Fancy is the familiar deck- ing out of commonplace experience with images brought from distant and unexpected regions. Incongruous ele- ments are placed in juxtaposition, grotesque forms grow up from most familiar elements, the most extravagant antith- eses, and even contradictions, are allowed indulgence in this delightful license of thought. It brings freshness into the midst of tedious processes, and, in its subtle refinements, appeals directly to the emotional and aesthetic nature. The BELATIOX OF FAKCT TO REALITY. ISl passive automatic play of fancy is to be enipliasizecl in contrast with the more purposive construction of active imagination, which remains to be considered. The student should notice also the erdai'ijlnrj and dimin- ishimj functions of fancy. It brings about unexpected and grotesque alterations in the size of things. Pygmies and giants are ordinary acquaintances of our fancy. Tilings which we fear or dread are apt to be very large, and things which we ridicule or despise very small. It is probable that this, as many other aspects of the imagination, is due laro^elv to the emotional coloring of the time. The ordi- nary cori-ectives of reality and thought being wanting, the presentalive life is at the mercy of the emotional. The idea which calls the emotion forth accommodates itself to the emotion, by way of justification for it. Relation of Fancy to Reality. Passive imagination is characterized throughout by the absence of reference to the real world. In it the mind frees itself, as it were, from its accustomed bondage to external things, and makes its universe entirely within. The truthful images of memory are torn asunder and built up into forms never realized in nature or in sober thouglit. Animals are given voices, inanimate objects legs, and the world is peopled with beings as strange as rare. Yet this is true only in the nature of imagination, not in its actual results; for in its active forms, as we sliall see, it maintains a constant though covert reference to reality ; and even in the most automatic play which is ever realized there is slight supervision and correction from the underlying sense of consistency, beauty, and truth. Tlie vague feeling of satisfaction or dissatisfaction which we experience in connection with our fancies is due to the habit of comparing our mental, states with reality, and even in dreams, where all such reference to the external world is impossible, we make objects of our visions as truly as in the exj^erience of our wakinor life. 182 IMAGmATTOK. § 3. Active or Construotia^e Imagination. Definition. In addition to the processes described in tlie foregoing, the active imagination involves the exercise of will in some of its forms, whether it be the positive attempt to control the images of fancy, or tlie merest supervision and direction of their pla^^ This distinction is alreadv^ made familiar in the cases of attention and memory. Attention was found to be passive or reflex, and active or voluntary, and memory takes two forms, reminiscence and recollection, according as it is passive or active. The distinction, however, in this case is not an absolute one. The beginnings of mental supervision, or at least the feeling of such supervision, is found in the most mechanical play of images. Yet we shall find it valuable for purposes of analysis, as the foregoing sections on passive imagination seem to assure us. This phase of imaging is further called constructive, from the nature of its product. In it is emphasized again the intentional nature of the compound state which is built up. Passive combination or fancy is a kind of construc- tion ; but here we deal with the purposive putting together of elements for the attainment of an end of use or beauty. This is the process of artistic and scientific construction. § 4. Analysis of Constructive Imagination. In analyzing the process of construction by the imagina- tion we proceed upon the account already given of the passive play of images. That is, the dissociation of the elements of former ideal complexes is assumed, and their readiness to be recombined under the guidance of an idea or " plan." We may distinguish four factors or moments in the process of construction : Natural Imjyulse or Appe- tence, Intention, Selective Attention, and Feeling of Fitness. These may be considered in this order: I. Natural Impulse or Appetence. It is readily seen AITALTSTS OF COSSTnnCTIVE IMAGIXATIOX. 183 that if tlie automatic flo\v of images in imagination is to be intentionally modified, there must be some imi)ulsion, motiv^e, or desire whicli leads to it. An accidental modifi- cation would be self-defeating, and would secure no sys- tematic construction whatever. There must be some end in view, however vague, and a natural tendency toward it, an attraction or tlie contrary.' In a later chapter certain tendencies of ours toward or from certain ends or actions will become apparent. Leaving till then all further dis- cussion of their nature, we simply note here that all exer- cise of will springs from these "appetences," and that the intelligent exercise of will always has in view, as its end, objects Avhich arouse them. Among these " springs of action" may be mentioned love of pleasure and aversion to pain, the natural affections, love of the beautiful and the right : principles which are common to all men in some degree, but wliicli vary in force within very wide limits in individuals. Any or all of such principles, which are strong enough in the individual to lea