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A BEGINNER’S PSYCHOLOGY

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A BEGINNER’S PSYCHOLOGY

BY

EDWARD BRADFORD TITCHENER

New York

THE MACMILLAN COMPANY

1915

All rights reserved

Copyright, 1915,

By THE MACMILLAN COMPANY.

Set up and electrotyped. Published December, 1915.

Norwood Press

J. S. Cushing Co.—Berwick & Smith Co.
Norwood, Mass., U.S.A.

To

THE MEMORY OF

THOMAS HENRY HUXLEY

PREFACE

It is an acknowledged fact that we perceive errors in the work of others more readily than in our own.—Leonardo da Vinci

In this Beginner’s Psychology I have tried to write, as nearly as might be, the kind of book that I should have found useful when I was beginning my own study of psychology. That was nearly thirty years ago; and I read Bain, and the Mills, and Spencer, and Rabier, and as much of Wundt as a struggling acquaintance with German would allow. Curiously enough, it was a paragraph in James Mill, most unpsychological of psychologists, that set me on the introspective track,—though many years had to pass before I properly understood what had put him off it. A book like this would have saved me a great deal of labour and vexation of spirit. Nowadays, of course, there are many introductions to psychology, and the beginner has a whole library of text-books to choose from. Still, they are of varying merit; and, what is perhaps more important, their temperamental appeal is diverse.

I do not find it easy to relate this new book to the older Primer,—which will not be further revised. There is change all through; every paragraph has been rewritten. The greatest change is, however, a shift of attitude; I now lay less stress than I did upon knowledge and more upon point of view. The beginner in any science is oppressed and sometimes disheartened by the amount he has to learn; so many men have written, and so many are writing; the books say such different things, and the magazine articles are so upsetting! Enviable is the senior who can reply, when some scientific question is on the carpet,—There are three main views, A’s and B’s and C’s, and you will find them here and there and otherwhere! But as time goes by this erstwhile beginner comes to see that knowledge is, after all, a matter of time itself. If he keeps on working, knowledge is added unto him; and not only knowledge, but also what is just as valuable as knowledge, the power of expert assimilation; so that presently, when some special point is in debate, he is not ashamed of the plea of ignorance. He has learned that one man cannot compass the full range of a science, and he is assured that so-many hours of expert attention will make him master of the new matter. He comes in this way not, surely, to underestimate knowledge, but to be less anxious about it; and as that preoccupation goes, the point of view seems to be more and more important. Why is it that beginners in science are so often disjointed in their thinking, so often superficial, unable to correlate what they know, logically all at sea? There is no doubt that they are, whether they study physics or chemistry, biology or psychology. I think the main reason is that they have never got the scientific point of view; they are taught Physics or Biology, but not Science. Hence I have, in this book, written an inordinately long introduction, and have kept continually harping on the difference between fact and meaning. I try to make the reader see clearly what I take Science to be. It does not matter whether he agrees with me; that is a detail; I shall be fully satisfied if he learns to be clear and definite in his objections, realizes his own point of view, and sticks to it in working out later his own psychological system. Muddlement is the enemy; and there is a good deal of muddled thinking even in modern books.

Not that I offer this little essay as a model of clear thought! The ideas of current psychology and the words in which they find expression are still, in very large measure, an affair of tradition and compromise; and even if a writer has fought through to clarity,—past experience forbids me to hope that: but even if one had,—a book meant for beginners may not be too consistently radical; some touch must be maintained with the past, and some too with the multifarious trends of the present. There is something turbid in the very atmosphere of an elementary psychology (is the air much clearer elsewhere?), and it is difficult to see things in perspective. So the critic who will soon be saying that the ideal text-book of psychology has yet to be written will be heartily in the right, even if he is not particularly helpful. The present work has its due share of the mistakes and minor contradictions that are inevitable to a first writing; at many points it falls short of my intention,—l’œuvre qu’on porte en soi paraît toujours plus belle que celle qu’on a faite; and I daresay that the intention itself is not within measureable distance of the ideal. It is, nevertheless, the best I can do at the time; and it is also, I repeat, the kind of book that I should have liked to have when I began psychologising.

Psychological text-books usually contain a chapter on the physiology of the central nervous system. The reader will find no such chapter here; for I hold, and have always held, that the student should get his elementary knowledge of neurology, not at second hand from the psychologist, but at first hand from the physiologist. I have added to every chapter a list of Questions, looking partly to increase of knowledge, but especially to a test of the reader’s understanding of what he has just read. I have also added a list of References for further reading. It depends upon the maturity and general mental habit of the student whether these references—made as they are, in many cases, to authors who do not agree either with one another or with the text of the book—should be followed up at once, or only after the text itself has been digested. The decision must be left to the instructor. My own opinion is that beginners are best given one thing at a time, and that the knowledge-questions and the references should therefore, in the ordinary run of teaching, be postponed until some ‘feeling’ for psychology, some steadiness of psychological attitude, has become apparent.

I have avoided the term ‘consciousness.’ Experimental psychology made a serious effort to give it a scientific meaning; but the attempt has failed; the word is too slippery, and so is better discarded. The term ‘introspection’ is, I have no doubt, travelling the same road; and I could easily have avoided it, too; but the time is, perhaps, not quite ripe. I have said nothing of the ‘thought-element’, which seems to me to be a psychological pretender, supported only by the logicising tendencies of the day; and if I am wrong no great harm has been done, since a description of this alleged elementary process, by positive characters, is not yet forthcoming. My references are confined to works available in the English language; I think it unlikely that the students for whom this book is intended will have attained to any considerable knowledge of French or German. Lastly,—I believe that this is my last major omission,—I have referred only incidentally to the ‘application’ of psychology; for science is not technology, though history goes to show that any the least fact of science may, some day or other, find its sphere of practical usefulness.

Two of my illustrations are borrowed: the swallow-figure on p. 138 from Professor Ebbinghaus, and the cut on p. 282 from Dr. A. A. Grünbaum.

I am sorry to confess that a few of the quotations which head the chapters are mosaics, pieced together from different paragraphs of the original. Even great writers are, at times, more diffuse than one could wish; or perhaps it would be fairer to say that they did not write with a view to chapter-headings. I hope, in any case, that no injustice has been done.

It is a very pleasant duty to acknowledge the assistance that I have received from my Cornell colleagues, Prof. H. P. Weld and Drs. W. S. Foster and E. G. Boring, and from Dr. L. D. Boring of Wells College. I am indebted to all for many points of valid criticism, and I wish to express to all my sincere thanks for much self-sacrificing labour.

I have retained the late Professor Huxley’s name in the forefront of this new primer, partly as an act of homage to the master in Science,—the brilliant investigator, the fearless critic, the lucid expositor; and partly, also, as a personal tribute to the man it was my earlier privilege to know.

Cornell Heights, Ithaca, N.Y.

July, 1915.

CONTENTS

A BEGINNER’S PSYCHOLOGY

[A BEGINNER’S PSYCHOLOGY]

CHAPTER I

Psychology: What it Is and What it Does

It is well for a man, when he seeks a clear and unbiassed opinion upon some certain matter, to forget many things, and to begin to look at it as if he knew nothing at all before.—Li Hung Chang

§ 1. Common Sense and Science.—We live in a world of values. We have material standards of comfort, and moral standards of conduct; and we eat and drink, and dress, and house our families, and educate our children, and carry on our business in life, with these standards more or less definitely before us. We approve good manners; we avoid extravagance and display; we aim at efficiency; we try to be honest; we should like to be cultivated. Everywhere and always our ordinary living implies this reference to values, to better and worse, desirable and undesirable, vulgar and refined. And that is the same thing as saying that our ordinary living is not scientific. It is not either unscientific, in the regular meaning of that word; it has nothing to do with science; it is non-scientific or extra-scientific. For science deals, not with values, but with facts. There is no good or bad, sick or well, useful or useless, in science. When the results of science are taken over into everyday life, they are transformed into values; the telegraph becomes a business necessity, the telephone a household convenience, the motor-car a means of recreation; the physician works to cure, the educator to fit for citizenship, the social reformer to correct abuses. Science itself, however, works simply to ascertain the truth, to discover the fact. Mr. H. G. Wells complains in a recent novel that no sick soul could find help or relief in a modern text-book of psychology. Of course not! Psychology is the science of mind, not the source of mental comfort or improvement. A sick soul would not go, for that matter, to a text-book of theology; it would go to some proved and trusted friend, or to some wise and tender book written by one who had himself suffered. So a sick body would betake itself, not to the physiological laboratory, but to a physician’s consulting room or to a hospital.

We live, again, in a world whose centre is ourself. This does not necessarily mean that we are all selfish; a life may be very unselfish. But whether we are selfish or unselfish, we live in a universe which revolves about the Me. Our self spreads and expands, to embrace our clothes and house and books, our family and relations, our professional competence and connection, our political and religious beliefs; we find ourselves in all these things, and they become a part of us. A famine in India is a real event and takes its place in the world only if we are made uncomfortable when we read of it, or are stirred to send in a contribution, or suspect mismanagement somewhere and think we could have done better. And this, once more, is the same thing as saying that our ordinary living is not scientific. For science, which deals with facts, is on that account impersonal and disinterested. Men of science honour Darwin, because they are human beings and live, like everyone else, in a world of values; but these same men of science are ready at any moment to test and criticise Darwin’s work with the utmost rigour; while any parts of the work that are solidly established pass without name into the structure of the science to which they belong. A text-book of chemistry is about as impersonal as anything can be, despite the fact that every observation it describes and every law it lays down was once somebody’s personal observation or discovery, and so formed part of some self-centred universe. That personal interest is irrelevant to science. It is as irrelevant to psychology as to chemistry. The psychologist has a great deal to do with his own mind; but that is because his own mind is the most easily accessible part of his subject-matter; it is not in the least because the mind happens to be his own. He does not care as psychologist—though he may care very much as human being—whether his mind is superior and talented and broad and cultivated or is the reverse of all these things; for in the first place these adjectives are all adjectives of value, and he is in search of facts; and secondly they are words of personal or individual appraisement, and he is not concerned to praise or blame himself. Nor is he concerned to trace the motives or judge the character of other men. There is a common belief that the psychologist is an uncanny person to meet, because he is always studying human nature and is able to read thoughts. This belief belongs to the non-scientific world; those who hold it fear that the psychologist will detect in them some pettiness or meanness of human nature, or will lay his finger on some unfounded enthusiasm or some unreasoned detraction that they wish to conceal. As well might they think that the physicist whom they ask to dinner will be occupied with the surface-tension of his soup or the insulating properties of his mashed potato.

If we trace the history of human thought, we find that the scientific attitude, as we have here described it, has emerged very slowly from that mixed medley of superstition and knowledge and belief and practical interest for which we have no better name than common sense. How common sense has been constituted, and how science has gradually worked its way to an independent position,—these are interesting questions; but it is plain that we cannot enter upon them in a primer of one special science. Some references for further reading will be given at the end of the chapter. Meanwhile, the important thing is to understand clearly the aims and limitations of science. Science aims at truth; it deals with facts, with the nature of things given, not with values or meanings or uses; and it deals with these materials impersonally and disinterestedly. The student of science who fails to grasp the scientific point of view will fail also to get the perspective of a scientific text-book; he will not see the wood for the trees; and he will be disappointed with what science has to offer him; he will want to know the use of all this knowledge, while science has no regard for use. The laws of psychology may be put to very many uses, in business, in education, in legal procedure, in medicine, in the ministrations of religion; but such uses are, from the psychologist’s point of view, by-products of his science; just as the nautical almanac is a by-product of astronomy, or the safety-match a by-product of chemistry, or the stamping-out of malaria a by-product of biology. These practical results may be immensely important for everyday life; but science, in its impersonal and disinterested search for facts, makes no difference between one fact and another.

[§ 2]. The Subject-matter of Psychology.—Psychology is the science of mind. What, then, is mind? Everybody knows that, you will say, just as everybody knows what is matter. Everybody knows, yes, in terms of common sense; but we have seen that common sense is not science. Besides, common sense is not articulate; it cannot readily express itself; and it is a little afraid of plain statements. Close this book, now, and write down what you take mind to be; give yourself plenty of time; when you have finished, go over what you have written, and ask yourself if you really know what all the words and phrases mean, if you can define them or stand an examination on them; the exercise will be worth while.

Open the book again! The exercise was worth while; but it was not quite fair. For the fact is that these great comprehensive words that we all use and all understand cannot be rigorously defined; they are too old; they have lived through too many changes; they have gathered about them too many conflicting associations. They pass muster in our everyday discourse only because we take them for granted and do not scrutinise them too closely. The expert alone can say what common sense means by mind; and even the expert must speak in general terms, qualifying and with reservations.

It seems, however, that the prime factor in the common-sense notion of mind is the idea of activity. We ascribe to mind the same sort of voluntary and purposeful activity that we ascribe to our fellow-men; and we distinguish this activity from the blind necessity of cause and effect. We find ourselves, and those about us, deliberating, intending, resolving, planning, recalling, doubting; and we say that these and similar activities are activities of mind. We also find ourselves, and those about us, breathing, secreting, moving; but here we draw distinctions. Breathing, we say, is a physical affair, though we may hold the breath by an act of will. Secretion results from some physical or chemical cause; only if we cry for sorrow or sweat for fear is mind influencing body. Walking and blinking may be physical only; but if we turn our steps by intention into a certain path, or blink on purpose to clear our sight, the physical movements become subject to the action of mind.

So long as we stick to examples, all this seems straightforward; only it is not easy to decide whether mind is activity, or whether these various activities are activities of mind. On the whole, common sense leans to the latter view: the activities are manifestations of mind. Mind itself is then something immaterial, lying behind the manifestations. What sort of thing? Apparently, another human being, an inner man that dwells within the outer man, an insubstantial mannikin living inside the head. Does that sound absurd? But it did not seem absurd just now to read that we ascribe to mind the same sort of voluntary and purposeful activity that we ascribe to our fellow-men; and how could we do that unless mind were something like a human being? This inner man appears, in fact, to be the mind of common sense; the inner man thinks, reflects, remembers, desires; he is influenced by the outer man, becoming gloomy and morose when his host cannot digest; and he influences the outer man, who sheds tears when his inmate is grieved. A curious view, when we write it out and think of it in cold logic; but a view that we should understand if we traced the growth of common sense from its first beginnings; and a view of highly respectable antiquity. Very ancient superstitions are connected with the man who is seen in the eye; the Egyptian ka or spirit-double is a smaller copy of the outer man; Greek vase-paintings show the human soul as a tiny human being; primitive thought has from time immemorial explained, and the modern savage still explains, the life and motion of man, or his repose in sleep and death, by the presence or absence of the little creature normally at work within him.

Yet however natural a view like this may be, science can make nothing of it. For one thing, it merely pushes the problem a step further back. The inner man acts on the outer man and is acted on by him; but who or what gives the inner man, in his turn, the power to influence and to be influenced? We must suppose an endless nest of mannikins. That and other such arguments apart, however, the view is non-scientific because it offers an interpretation and not a description of mind. The mind with which psychology deals must be a mind that is describable in terms of observed fact; otherwise it cannot form the subject-matter of a science. So we must start afresh, and ask what mind is, when mind is looked at from the scientific point of view.

You will better understand the answer to this question when you have worked through the book. The answer will then have been given in the concrete and particular; now it can be given only in the abstract and general. Remember that it is given, nevertheless, in terms of work done and results obtained; it is not an answer that the psychologist makes up beforehand, but one that he himself has been led to in the course of his attempt to work scientifically upon mind. In brief it is this.

We find that the field of science has been surveyed from two different standpoints. Men of science have set out, on the one hand, to describe the world as it would be with man left out. The result is what we call physical science. The world of physics is colourless, toneless, neither cold nor warm; its spaces are always of the same extent, its times are always of the same duration, its mass is invariable; it would be just what it is now if mankind were swept from the face of the earth. For what is light in the text-books of physics?—a train of electromagnetic waves; and sound is a vibratory motion of air or water; and heat is a dance of molecules; and all these things are independent of man. But men of science have tried, on the other hand, to describe the world as it is in man’s experience, as it appears with man left in; and the result of this endeavour is psychology. The world of psychology contains looks and tones and feels; it is the world of dark and light, of noise and silence, of rough and smooth; its space is sometimes large and sometimes small, as everyone knows who in adult life has gone back to his childhood’s home; its time is sometimes short and sometimes long; it has no invariables. It contains also the thoughts, emotions, memories, imaginations, volitions that you naturally ascribe to mind; it contains, that is, so much of these things as belongs to the sphere of observable fact. It is obviously very different from the world of physics, though both worlds alike have been opened up to us by science, by the impersonal and disinterested search for facts.

So we have a world of matter and a world of mind. The physicist, however, describes and measures the various phases of energy, without assuming any material substance in the background, any matter of which this energy is the manifestation. Matter, if the word is to be used at all, is simply the inclusive name for all the forms of energy. And the psychologist, in the same way, describes and measures—so far as he is able to measure—the phenomena of his world, without assuming any active or perduring mind in the background; for him, mind is simply the inclusive name of all these phenomena. That is the first rough answer to our question. Much more must be said, if the answer is to be precise; but even as it is we have travelled a long way from the little man living inside the head!

[§ 3]. Mind and Body.—The first thing to get clear about is the nature of the man left in the world, the man whose presence is necessary for psychology and unnecessary for physics. Since we are talking science, this man will be man as science views him, and not the man of common sense; he will be, that is, the organism known to biology as homo sapiens, and not the self-centred person whom we meet in the everyday world of values. But the human organism owes its organic character, the organisation of its parts into a single whole, to its nervous system. All over the body and all through the body are dotted sense-organs, which take up physical and chemical impressions from their surroundings; these impressions are transmitted along nerve-fibres to the brain; in the brain they are grouped, arranged, supplemented, arrested, modified in all sorts of ways; and finally, it may be after radical transformation in the brain, they issue along other nerve-fibres to the muscles and glands. The nervous system thus receives, elaborates, and emits. Moreover, there is strong evidence to show that the world which psychology explores depends for its existence upon the functioning of the nervous system; or, if we prefer a stricter formula, that this world is correlated with the functioning of the nervous system. The man left in thus reduces to a nervous system; and that is the truth of the statement, often met with in popular scientific writing, that the brain is the organ of mind. There is no organ of mind; that phrase is an echo of the old-world search after the place of residence of the mannikin-mind, which was assigned variously to heart, liver, eye, brain, blood, or was supposed somehow to perfuse the whole body. The scientific fact is that, whenever we come upon mental phenomena, then we also find a functional nervous system; we know nothing of the former apart from the latter; the two orders are thus correlated.

The fact of this correlation has been established by two principal lines of evidence. In the first place, we find all through the animal kingdom that size of brain and complexity of nervous system are matched by range and complexity of mental phenomena. The brain of man is, by absolute measurement, an organ of great size; it is heavier than that of any other animal with the exception of a few of the very largest (such as the elephant); and in these cases the superior weight is due, not to superior development of the elaborating part of the brain, but to the bulk of the receiving and emitting portions, which are of a size to correspond with the bulk of the body. The brain of man is also relatively, as compared with the weight of the whole body, heavier than the brain of any other animal with the exception of a few of the most highly developed small mammals (such as certain monkeys); and in these cases again the superiority depends on the bulk of the receiving and emitting portions of the brain, which reflect the keen sensitivity and muscular agility of the animal. We know, on the other side, that the mental life of man is richer than that of any other creature. Secondly, we find that disturbance of certain parts of the brain indicates a certain form of mental disturbance; and, conversely, that particular forms of mental disturbance indicate disturbance of particular parts of the brain. One may become blind from injury to the brain as well as from such defect of the eye as prevents optical impressions from reaching the brain.

These are the two lines of evidence. How, though, you may now ask, do we know anything about the distribution of mental phenomena in the animal kingdom? How do we know that the lower animals live in mental worlds? and still more how can we say anything as to the nature of the phenomena that make up those worlds?

Consider first the case of your fellow-men. You do not doubt that they have experiences like your own; you take them for granted, accept them instinctively as your kin, and are able—the better as you know them better—to put yourself in their place. If, however, you had to argue the matter with a sceptic, you would point to the facts of our common life. Man’s family life, social life, civic life, national life, is based on the assumption that human experience is alike for everyone, and would be impossible if the assumption were falsified by the facts. All these forms of life, for instance, presuppose language and laws; and language and laws necessarily imply a community of experience. You would point, also, to likeness of physical organisation, likeness of sense-organs and nervous system; and you would point, lastly, to conduct or behaviour. When you feel in a certain way, you act in a certain way; your behaviour expresses your feeling; and when, under the same circumstances, a creature of like organisation regularly acts in the same way, you have a right to infer that this creature has a like feeling.

Now consider the higher animals. They possess a physical organisation closely resembling that of man. They also behave in ways that appear to express feeling. If you were familiar only with their structure, with their sense-organs and nervous system, you would be ready to endow them with mind; if you knew them only by their behaviour, you would reach the same conclusion; since you may know both, and may therefore correlate physical structure with conduct, you are able to form a fairly accurate idea of their mental world. But as you go down the scale of life, difficulties arise. The nervous system changes its type, and presently disappears; and behaviour becomes equivocal, so that students of behaviour dispute whether it is still expressive or is purely mechanical. The controversy is even carried over from the animals to the plants; there are psychologists who seriously attribute a mental life to plants. Be that as it may, the important point for us is that, as the nervous system simplifies, so does all available evidence indicate that the world of mind simplifies with it; and if mind extends further down the line of life than the nervous system, we have merely to change the wording of our general statement; we must expand it, and say that, throughout the realm of life, size and complexity of the nervous system, or of that vital mechanism which precedes the nervous system and anticipates its functions, are matched by range and complexity of mental phenomena.

The nature of these phenomena cannot be set forth with any assurance. It is difficult enough to psychologise the life of the Australian Arunta, who is our fellow-man, or of the dog who has been our companion for half-a-dozen years. What shall we say of the spider, or the amœba, or of sundew and eelgrass? All that we can do is to follow back the history of the sense-organs, from complex to simple, comparing as we go; and to observe how the organism behaves under given circumstances, comparing this behaviour with that of other organisms higher and lower in the scale, and bringing our comparison back again and again to its final term in our own experience. We lose a great deal when we lose the nervous system; but life, after all, is a continuous development; and the disappearance of this special structure, though it may mean that our statements become vaguer and less definite, need not make our general quest hopeless. Honesty of purpose, and a passion for knowledge, and sound scientific training will carry a man further, even in this dark continent, than the casual enquirer would deem possible.

[§ 4]. The Problem of Psychology.—The subject-matter of psychology, as we saw on p. 9, is the whole world as it shows itself to a scientific scrutiny with man left in. Or, to put the same thing in another way, psychology gives a scientific description of the whole range of human experience correlated with the function of the human nervous system. We have just learned, however, that there is a psychology of the lower animals, possibly even of plants; and we must therefore say that we were speaking in § 2 of the subject-matter of human psychology. This is the psychology that will occupy us in the present book. Let us now see what our actual task is. What have we to do, in order to get a scientific description of mind?

We must do what everybody does who begins to describe; we must take things piecemeal. When you are away at the seaside, and are describing your room in a letter home, you tell of exposure and windows and carpets and furniture and pictures; you break up the room into parts, and list them one by one; but you do not list at haphazard; you bring your items into such connection as will make it easy for your readers to reconstruct the room. The man of science does the same sort of thing; he analyses, and all the while he is analysing he has his eyes open for relations, for putting his elements together again as they belong. The chemist analyses water into oxygen and hydrogen, and acetic acid into carbon, oxygen, and hydrogen; and you see at once that this analysis is the first step toward a scientific description; for it reduces the compounds to their elementary components, and it shows that the two compounds have certain elements in common. But the chemist, almost in the same breath, is putting together again. The ordinary formulas for water and acetic acid, H₂O and C₂H₄O₂, indicate that; for they show the number of atoms of the various elements that are held in the compound. Chemistry also has graphic formulas, of a kind that look complicated to the outsider but that are really more instructive than the others,—formulas which show in what manner, under what laws, the atoms are bound together. Any good encyclopædia will give you samples.

The psychologist, now, stands before a like problem. The mental world, no less than the material, comes to us in the gross; mental phenomena are complex, often highly complex; we must reduce them to their elements, we must keep analysing till we can analyse no further, if we are to describe them in a scientific way. And here too synthesis goes hand in hand with analysis. Psychology, to be sure, does not write graphic formulas; but psychology has to show how its elements go together, to discover the laws of their connection; we shall find that tones and colours go together in very different ways. All the while that we are tearing a bit of our world apart, and finding its elements, we are trying to put those elements back again in their places and to reconstruct the original experience.

Synthesis, unfortunately, is often very difficult; and you must notice that a failure to reconstruct does not necessarily mean that the preceding analysis was wrong. A chemist may analyse a given substance into a certain number of elements, each one represented by a certain number of atoms; yet if he puts these elements together again, in the right proportions, he may—perhaps because he is now working at a different temperature—come out with another substance of different properties. His analysis was not therefore wrong; but his attempt at synthesis is a failure because he has not taken account of all the relevant circumstances. It may happen similarly in psychology that we do not know all the relevant circumstances; or it may happen that we know them but cannot control them; in such cases we cannot reconstruct. The only thing to do is then to make analysis its own test; we analyse again and again; and if the result is always the same, we are satisfied to let it stand. Children who do not know how to prove an example in arithmetic follow the same plan; if they get the same answer several times over, and if their schoolmate gets that answer too, they are satisfied; and when the work has been honestly done, the agreement is pretty good evidence that they are right.

Notice one other point: that if you sit down to describe, there is simply no escape from analysis. To begin a description is to be analysing. Well-meaning people sometimes shake their heads at scientific psychology; all this dissecting work, they say, misses the real issue; it kills mind; it destroys the living, breathing reality of experience, and offers in its place a catalogue of dead facts. The mannikin again! Of course, if mind is a little man inside you, you must kill him to dissect him,—though he nevertheless crops up again, alive and well, after the autopsy. The mannikin, as we have seen, cannot face cold logic. No, the task of science is to describe; if you are to describe you must analyse; and the results are every bit as real as the unanalysed experience. Dead facts? But a fact is the most live thing possible; it will survive any number of theories, and will still give birth to more.

Lastly, since mental phenomena are correlated with the function of the nervous system, the psychologist’s task is not complete until he has acquainted himself with the physiology of that system, and has worked out the correlation as accurately as is possible. Here, again, is something that you will better understand when you have read further in the book. For the present we will notice two points. First, the psychologist can gain access to a large part of his world only by way of the organs of sense; and it is therefore important that he know the structure and functions of these organs and their relation to the brain. Secondly, a train of mental phenomena may be guided and directed by events, occurring within the nervous system, which themselves have no counterpart in the world of mind; for, while all mental phenomena are correlated with processes in the nervous system, not all processes in the nervous system have mental phenomena to correspond with them. Unless, then, the psychologist knows the nature of these guiding events, he will be like the chemist who failed to take account of temperature; he will lack knowledge of relevant circumstances. Special books upon the nervous system have been written, giving in outline what the student of psychology needs to know; some of them are referred to at the end of the chapter; but it is an advantage to have taken a practical course in the physiology of the nervous system, and to be able to think in terms of neural processes. If you have had no such opportunity you can still learn a good deal from diagrams and verbal accounts; and you may find comfort in the assurance that there have been eminent psychologists who knew very little about the brain.

In fine, then, the problem of human psychology is threefold: to analyse mental phenomena into their elements, to discover the laws of mental connection, and to work out in detail and under all its phases the correlation of mind with nervous system.

[§ 5]. The Method of Psychology.—Having learned what we have to do, let us ask what method we are to follow in doing it. So far as the nervous system is concerned, it is evident that the psychologist must take his cue from the physiologist; indeed, this part of his problem makes him, for the time being, a physiologist, only that his real interest remains centred in mind. But how is it when he is attacking the other parts of the problem? Is there a special psychological method, a peculiar way of working, that he must adopt in his study of mental phenomena? The answer is No: his method is that of science in general.

This method may be summed up in a single word as observation. All scientific description, all description that reflects a disinterested and impersonal search for fact, is got by way of observation. And observation implies three things: a certain attitude towards phenomena, a vivid experience of the particular phenomenon which is the object of observation, and an adequate report of this experience in words. The relation of these three things will be clear if we write a formula for observation, thus:

psychological (vivid experience → full report).

The adjective outside the bracket shows that we take up a psychological attitude to the world; in other words, that the world which we are exploring is (to use our catch-phrase again) the world with man left in. The adjective applies to the whole contents of the bracket; the experience which we are to have is mental experience, and our account of it is to be couched in psychological language. We are, then, ready for the experience; it comes, and we give it our best attention; we then express it in words; and we try to express it fully and adequately, in the words that it itself points to and requires. When the account has been written down, and so made available for other students, we have completed a psychological observation. When a number of such observations have been taken, we have the materials for a scientific description.

Observation is by no means easy; “there is not one person in a hundred,” said Huxley, “who can describe the commonest occurrence with even an approach to accuracy.” The reasons are partly of a technical nature; the use of scientific method is a bit of skilled labour, and skilled labour presupposes training; at first we are likely to be careless and clumsy; we do not see the need of scrupulous care, just because we do not know exactly what it is that we are doing. The great reason lies, however, in that difference between science and common sense to which we have already adverted; common sense interprets, and science describes. Malobservation is due, in the great majority of cases, to the ingrained tendency of the onlooker to interpret, to explain, what he observes. How many educated men and women to-day believe that the full moon dissipates the clouds? and how many more believe that changes of the moon coincide in some way with changes of the weather?

These remarks apply very definitely to psychology. The psychological observer needs technical training, first and foremost, because mental phenomena never stand still to be observed; mind is always in course, always going on; he must learn either to take rapid notes as the experience is passing, while he still remains alert to the new phases as they come, or he must register the experience phase by phase in memory, and reproduce it in words after it has passed. Nothing could well be more misleading, as a name for mental phenomena, than the familiar phrase ‘states of consciousness’; for a state is something relatively stable and permanent. Mental experiences are moving, proceeding, ongoing experiences; we might make up one of Lewis Carroll’s portmanteau-words, and say that their essence is a processence. We shall henceforth speak of them as mental processes; only remember that they are not processes of something or in something, like the processes of decomposition and fermentation; they are experiences whose very nature is a proceeding, a course in time.

Secondly, the psychological observer is badly handicapped by common sense, which has long drawn a distinction between the method of psychology and the method of physics. Psychology is supposed to look within, to turn its eyes inward; physics is supposed to look out upon the objective world, and to keep its eyes in their normal position. The method of psychology is then an introspection or self-contemplation, a looking-in; and the method of the physical sciences is an inspection, a looking-at. The self which is thus introspected is, of course, judged and valued and approved and blamed; we know the ear-marks of common sense. So we find that the hero of yesterday’s novel “was not given to introspection. His external interests in life were too engrossing for him to think deeply or continuously about himself. Such a habit of mind he used vehemently to deprecate as morbid, egotistical. But now”—now the fateful girl is on the scene; the hero begins to think about himself; and flatters himself, poor man, that he is turning psychologist.

Unfortunately, neither a keen appreciation of his own virtue nor a rooted distrust of his own powers makes a man into a psychologist. Science turns its back upon the world of values. If, then, we are to keep the word introspection for the method of psychology, we must write the equations:

where the adjectives outside the brackets mean simply what we have already stated them to mean. When once the initial attitude has been taken, and the world to be explored has thus been determined, the methods are the same. The beginner in psychology will however find, again and again, that his common-sense self stands in the way of disinterested observation; and as the word introspection contains a reference to this self, he may prefer to drop it altogether.

So much for observation in general! When we come to particulars, we find that science, wherever possible, has recourse to experiment. This does not mean that science renounces observation. For an experiment, if we push our definition back to fundamentals, is simply an observation that may be repeated, that may be isolated, and that may be varied. See the advantages! Repetition gives us plenty of time for observation; we need not mind overlooking something now, since we shall have the opportunity of picking it up later; and we can go on, observing and observing, until our description of the phenomenon is as complete as it can be made. Isolation makes our task easier; disturbing influences are ruled out; our attention is not distracted; we can give ourselves wholly to the matter in hand. Variation—the substituting of one factor for another in successive observations, or the emphasising in one observation of a factor that was obscure in another—helps us to clear up doubtful points; to distinguish what is universal from what is only accidental in the phenomenon we are observing; and to bring this phenomenon into relation with kindred phenomena. Repetition saves hurry and worry; isolation prevents distraction; variation keeps us from jumping at conclusions. These are the advantages of experiment; and all experiments, in physics, in chemistry, in biology, everywhere, fall under this definition.

Psychology needs the experimental method for both the reasons noted above: because the observed phenomena are elusive and slippery processes, and because the observer is warped and biassed by common sense. We may therefore show by an example how psychological experiment is possible. Suppose that we wish to find out how a printed word is perceived,—whether we read it letter by letter, or take in its form as a whole, or take in certain letters clearly and the general form vaguely. We first prepare our material. We print upon cards, or photograph upon lantern slides, a large number of words. We employ different printing types; different groups of letters; different lengths of words; single words and groups of words; words properly spelled, and words altered by mutilation or omission of particular letters at different parts of the word. Every one of these classes of stimuli, as the words may be technically called, is represented by a number of cards or slides. The stimuli are mixed in haphazard order, and are thrown upon the screen by a reflectoscope or projection lantern in an otherwise dark room; a pneumatic shutter before the lantern makes it possible to show them for a brief time, say, a fifth of a second. All this apparatus is put in the charge of an experimenter. When the material is ready, and the whole arrangement works properly, an observer is called in. He works for a limited time, at the same hour every day, and only after a certain time has been allowed for his eyes to accustom themselves to the dark. The stimuli are presented at regular intervals. The observer reports what he perceives at every exposure of a stimulus, and the experimenter writes down what he says.

It is plain, now, that these observations may be repeated. For one thing, there is a group of like cards in every class; and for another thing, the observer himself (since he works every day at the same time and under the same circumstances) is a fairly constant quantity. Besides, the observations may also be made by other observers, in other laboratories, under precisely the same circumstances; they may be repeated in just the same sense that a physical observation may be repeated. Secondly, the observations are isolated; they are made in a dark and quiet room, free from outside disturbance. No doubt, the observer’s thoughts may wander in the intervals between observations. For this reason, the experimenter gives a preconcerted signal, or calls out Now, a second or two before a word is shown; this signal warns the observer to pull himself together and to free himself from any such distractions. Thirdly, the observations are varied; for we employ all sorts of words, both normally printed and variously changed; and the stimuli may be presented for various lengths of time. Here, then, is a true psychological experiment; and if many observers, after many observations, give the same account of their perceptive experience, that account may stand as established psychological fact.

Not all mental phenomena can be subjected to experiment so neatly as this particular perception; and the psychologist must still fall back, more often than he likes, upon casual observation or imperfect experiments. The reason is that psychology has only recently become an experimental science. Common-sense psychology is very old: we have a complete treatise in Greek from the hand of Aristotle, and a text-book in Pali compiled by some Buddhist sage, both dating from the fourth century B.C. But while it is in the sixteenth century of our era that the physicist abandons scholastic speculation and begins to study nature by experiment, it is not till the last quarter of the nineteenth that the psychologist follows suit. In or about the year 1875 the late Professor James, then instructor in anatomy and physiology at Harvard, had a single room devoted to psychological apparatus and experiments; and in 1879 Professor Wundt opened at the University of Leipsic, in a very modest way, the laboratory which has since become the most famous in the world. It is true that experiments in psychology had been made by individuals long before laboratories were thought of; but the same thing is true of physics and chemistry; and we may remember, when we come to the weak places of psychological exposition, that laboratory research and instruction are not yet fifty years old.

[§ 6]. Process and Meaning.—Science, we said on p. 4, does not deal with values or meanings or uses, but only with facts; and we have just seen how words, which in everyday life are practically all meaning, may be made the objects of psychological experiment. Still, in their case, after all, we were simply ignoring meaning; so far as the observer was able to read words at all from the stimuli flashed on the screen, he read words which had a meaning, and a meaning that the experimenter might have discovered if he had been interested in it. We have not offered any evidence that mental processes are not intrinsically meaningful, that meaning is not an essential aspect of their nature; we have just assumed that they may be treated, scientifically, as bare facts. Let us now see whether meaning is essential to them or not. There are several heads of evidence.

First, meaning may be stripped from the mental process to which it normally belongs. Repeat aloud some word—the first that occurs to you; house, for instance—over and over again; presently the sound of the word becomes meaningless and blank; you are puzzled and a morsel frightened as you hear it. The same loss of meaning is observed in pathological cases; there are patients who can hear and see words as plainly as you can, but who are unable to understand what they hear and see; the bare perception is there, but it is bereft of its meaning.

Secondly, a meaningless experience may take on a meaning. A friend shows you a card, upon which is scrawled a tangle of lines; you cannot make head or tail of it. He tells you to look at the back; you see the date there written; you think at once of a great earthquake; you realise that the scrawl is a seismographic record. Meaning has thus been attached or added to a bare perception. Similarly, in learning a new script or a new language, you attach meaning to what was at first meaningless. The first experiments in the teaching of the blind deaf-mute Laura Bridgman “were made by pasting upon several common articles, such as keys, spoon, knives, and the like, little paper labels on which the name of the article had been printed in raised letters.” These meaningless feels, as they were at the outset, came presently to mean the objects with which the teacher had connected them.

Thirdly, an experience and its meaning may be disjoined in time. We often ask, in conversation, to have a remark repeated; we have heard without understanding; but before the speaker has time to repeat, we ourselves begin to reply; the meaning has come, but comes after an appreciable interval. So we may have to wait a little while before we can recall the meaning of some foreign word that nevertheless, as we say, we know perfectly well. This disjunction is also found in pathological cases. A patient “with slight stupor could not answer questions except very slowly. She was constantly saying: ‘I see everything, but I don’t know anything.’ It took her five minutes to tell the time when she was shown a clock.”

Here the experience comes first, and the meaning follows after. This order may, however, be reversed. You want to know the German of the proverb ‘Out of the frying pan into the fire’; you have the meaning, but you cannot think of the words; and presently the words leap to mind, aus dem Regen in die Traufe, out of the rain into the roof-drip. Or you know what you want to say, but you cannot get this meaning into words. An author who is very definitely aware of the meaning he wishes to convey to his reader may nevertheless have to write a paragraph ten or twenty times over before the sight and sound of his own words give back that meaning to himself. Or again, you may anticipate, in listening to a lecture, the meaning of what the lecturer is going to say, and yet you may be surprised at the words which he actually uses.

Fourthly, one and the same experience may have several meanings. Any dictionary is a proof of that! A lecturer may demonstrate the fact to a class by drawing on the blackboard, line by line, the figure of some such thing as, for instance, a desk-telephone. As the drawing proceeds, the lines may mean a pump, or a student lamp, or an electric portable, or a railway semaphore, or a jack, or various other things. In this case, to be sure, a single meaning is given when the drawing is complete; but there are plenty of experiences—a bit of bad handwriting, a distant object, an obscure patch in a painting—that leave us permanently unable to decide among several meanings. How often do we worry over a chance remark: it seemed to mean this, but could it have meant that, or is it possible that it really meant the other?

Fifthly, one and the same meaning may attach to several experiences. You walk into a room, and there see a table; you go into the same room in the dark and hurt yourself, and you complain that you ran against the table; you hear a noise overhead, and wish that the maid would not drag that table about. Here the meaning of a particular table is carried by three modes of perceptive experience. In certain forms of mental disorder one obsessing meaning colours all the experiences of the daily life. The patient “scents poison and treachery on all sides. He has slowly convinced himself by numerous tests in little things that he is no longer liked. The workmen are refractory and disobedient with him more than with anyone else. His chiefs and his fellows play malicious tricks upon him. His food tastes differently, and does not agree with him. When he goes to another town, it is plain that his enemies have anticipated him by writing letters to his injury.” Every experience that this man has means persecution.

Sixthly, meaning and mental process are not covariants. Richness and fullness of experience do not necessarily correspond with wealth of meaning; you may, in fact, be bewildered, and fail to find a meaning just because there is so much material to take in; your first hearing of a Wagner opera gave you, probably, more sound than sense. Conversely, poverty of experience does not necessarily mean loss or reduction of meaning; if that were the case, we could not pack so much meaning into such little things as words.

All this evidence would be greatly strengthened if we went beyond the limits of individual experience, and compared man with man, profession with profession, race with race, age with age. What is meaningless to me might be full of meaning to you; the same landscape yields different meanings to the geologist and the farmer; a protruded tongue means insult here, but politeness in Thibet; the art of the telegrapher would have spelled black magic a few centuries ago. Enough has perhaps been said to give plausibility, at any rate, to the statement that mental processes do not intrinsically mean, that meaning is not a constituent part of their nature; and that may suffice for the present; we shall come back again to meaning later. Value and use need hardly be discussed; they are, far more clearly than meaning, additional to (and detachable from) experience. If, however, the reader thinks that the point should be worked out in their case also, he may put them through the same sort of examination as that to which we have just subjected meaning; evidence will at once be forthcoming.

[§ 7]. The Scope of Psychology.—Science, like the Elephant’s Child in the story, is full of an insatiable curiosity. Just as the physicist reaches out, analysing and measuring, to the farthest limits of the stellar universe, so does the psychologist seek to explore every nook and corner of the world of mind; nay more, he will follow after a mere suspicion of mind; we have seen him trying to psychologise the plants. The result is a vast number of books and monographs and articles on psychology, written by men and women of very different interests, knowledge and training; for science does not advance on an ordered front, but still depends largely on individual initiative. A high authority on the Middle Ages has said that one mortal life would hardly suffice for the reading of a moderate part of mediæval Latin; and the psychologist must recognise, whether with pride or with despair, that one life-time is hardly enough for the mastery of even a single limited field of psychology. The student has to get clear on general principles, and then to resign himself to work intensively upon some special aspect of the subject-matter,—keeping as closely as he may in touch with his fellow-workers, and aiming to see his own labours in a just perspective, but realising that psychology as a whole is beyond his individual compass.

Does that sound exaggerated? Let us then attempt a rough classification! We begin with the psychology of the normal mind. Under this heading we have to distinguish (1) human psychology. Human psychology may be general, the psychology of the adult civilised man, which forms the principal topic of the text-books of psychology; special, the psychology of the human mind at some other stage of individual development: infancy, childhood, adolescence, senility; differential, the study of the differences between individual minds; or genetic, the study of the development of mind from childhood to manhood, and its gradual decay in old age. (2) Animal psychology may be subdivided, in the same way, into general, special, differential and genetic psychology. (3) Plant psychology is still in its first beginnings; but many students are taking the subject seriously. (4) Comparative psychology is the comparative study, either of various types of animal mind, or of the minds of plants, animals and man. It, again, may be general, special or genetic.

All these psychologies deal with the individual mind. There is also a collective psychology; and, though its divisions are not yet sharply marked off from one another, we may distinguish (5) social psychology, which includes the study of what is called the social consciousness, and also the scientific study of the products of the collective mind: language, law and custom, myth and religion; (6) ethnic psychology, the differential psychology of nations or races; and (7) class psychology, the differential psychology of classes or professions.

Turn now to the psychology of the abnormal mind. Here we find, under the heading of individual psychology, (8) the psychology of deficient and exceptional minds; of blind deaf-mutism, of genius, of the subnormal and the supernormal child; (9) the psychology of temporary mental derangement; of dream, of hypnosis, of intoxications, of occasional hallucination and illusion; and (10) the psychology of permanent mental disorder, of the chronic derangements of insanity. We may also study (11) the psychology of temporary derangement of the collective mind, that is, of the manias or mental epidemics that sometimes sweep society: the mediæval dance-manias, unmotived panics, outbursts of superstition, of religious persecution.

If we proceed further, from psychology proper to psychotechnics, or to what is ordinarily termed applied psychology, we have the great departments of (12) educational psychology, (13) medical psychology or psychotherapeutics, (14) juristic psychology, or the psychology of evidence and testimony, and (15) economic psychology, which includes such things as vocational psychology and the psychology of advertising.

You need not ascribe any special importance to this classification; still less need you memorise it. The various topics might very likely be better arranged, and the list is by no means complete. Realise, however, that every term in the list has its text-books and treatises, its manuals and monographs, and very likely its magazine or magazines; realise again that, although the emphasis varies in the different countries, the list might be filled out not alone in English, but in all the chief European tongues; and remember, lastly, that some of the headings have a very long history, and a correspondingly long series of printed works over and above those that represent current knowledge. You then get a glimmering of the range and scope of psychology. It is true, of course, that much of what has been printed is out of date, or inaccurate, or superficial, or prejudiced, and for these or like reasons may safely be scrapped. Yet it all has to be sifted.

The mere bulk of psychological material would be less formidable if every writer adopted the same principles and wrote from the same point of view; but that is hardly to be expected. Psychology has always been exposed to the infection of common sense; it has only recently turned to scientific methods; and when the time came for it to take its place among the sciences, there was naturally difference of opinion regarding the standpoint it should assume, the procedure it should follow, the model it should seek to copy. Where such differences of opinion obtain, the best way to begin your study is to master one system thoroughly; your ideas are thus made consistent and your knowledge receives an orderly arrangement; then, as you read further, you can use this system as a touch-stone whereby to test new ideas and to arrange new knowledge; and if the new ideas seem preferable to the old, or if the old framework breaks down under the new knowledge, you can alter your own system accordingly. If you begin, on the contrary, by studying a number of works abreast, you are liable to become confused. And it is better to be wrong than to be muddled; for truth, as Bacon said, emerges more quickly from error than from confusion.

[§ 8]. A Personal Word to the Reader.—These introductory sections are not easy. The only way to make them easy would be, as an Irishman might say, to leave the difficult things out; but then you would come to the later chapters, where we study mental phenomena in the concrete, with all sorts of prepossessions and misunderstandings; psychology would be one long difficulty instead of being, as it henceforth ought to be, a bit of straight sailing.

So you must face the initial difficulty and overcome it. Indeed, you must do more than merely understand. The author’s undergraduates who break down in a preliminary examination always explain that they followed the lectures perfectly, and thought they understood the text-book, but that they were somehow unable to put things properly in their own words. The author’s small daughter who comes home with an elaborate example in compound interest explains, in the same manner, that she thoroughly understood the rule when She explained it, but that she can’t now see just how to go to work for herself. It may be that these excuses are not wholly reliable; they bear, at any rate, upon the present point. You must not only understand what you read as you read it; you must exercise your thought upon what you have read; you must be able to explain the paragraphs, in your own words, to others; you must find instances and illustrations for yourself; you must make the substance of the paragraphs a part of your habitual mental furniture; you must note how the old ways of thinking crop up to mislead you, and must correct and criticise the natural man. In a word, just as you practise your way into a language by reading, translating, writing, speaking; or just as you practise your way into algebra by doing exercise after exercise until the rule seems to be part of you and applies itself of its own accord; so must you keep practising your psychology until it becomes instinctive. You will gain some help by answering the appended questions; but after the book has done all that it can for you, the real induction into psychology remains to do for yourself.

Some of the questions are concerned with forms of expression; and you should take these very seriously, since language will be one of your greatest stumbling-blocks. Language is older than science, and has developed under pressure of practical needs. Hence the phrases that come most naturally to your lips may embody a view of the world, or an attitude toward experience, that is totally foreign to the scientific context. If a visitor from Mars heard us all talking about the sunset, what would he think of our knowledge of the heavenly bodies? Yet we cannot escape from language; and if Newton could express his ideas in Latin, we ought to be able to express ours in English. It is a good plan, at the start, to have your technical definitions always at hand, and to try the effect of substituting these definitions for the words that you have been using; if the resulting clumsiness makes sense, you may let your first expressions pass; but if not, you should try again.

You will notice, as you read on in the book, that back references become numerous. Be advised to look these references up! They send you, in every case, to a particular page, so that their finding is easy, and you can refresh your memory without any great loss of time; though, for that matter, it will do no harm to glance over the section in which they occur. If you, on your part, want to refer to some past discussion, consult the index; it has been made fairly full, and is meant to be used.

[Questions and Exercises]

Many of the books to which you will be referred, now and later, have appeared in numerous editions, library and popular, English and American. The references are made so complete that you will easily find the corresponding passages in editions other than those used by the author.

(1) Discuss the following definitions of science. If you have access to the books, read the passages in which the definitions occur; if not, do the best you can with your present knowledge. Try to see a reason even for the definitions that you cannot accept.

(a) Science is perfected common sense (Huxley). The definition accords with the view of Spencer that science and ordinary knowledge are allied in nature, and that the one is but a perfected and extended form of the other. What is there in the common interests of these two men, or in the period in which they lived, to account for such a definition?

(b) Reduced to its lowest terms, science is the observation of phenomena and the colligation of the results of observation into groups (Hill).

(c) When may any subject be said to enter the scientific stage? I suppose when the facts of it begin to resolve themselves into groups; when phenomena are no longer isolated experiences, but appear in connection and order; when, after certain antecedents, certain consequents are uniformly seen to follow; when facts enough have been collected to furnish a basis for conjectural explanation, and when conjectures have so far ceased to be utterly vague, that it is possible in some degree to foresee the future by the help of them (Froude).

(d) Mechanics is the science of motion; and its problem is to describe the motions that occur in nature completely and in the simplest way (Kirchhoff). Can this definition of mechanics be generalised, so that it applies to science at large?

T. H. Huxley, Science Primers: Introductory, 1880, 18 f.; H. Spencer, The Genesis of Science, in Essays, ii., 1891, 8; A. Hill, Introduction to Science, 1900, 3; J. A. Froude, The Science of History, in Short Studies on Great Subjects, First Series, i., 1901, 13 f.; G. R. Kirchhoff, Vorlesungen über mathematische Physik: Mechanik, 1883, 1.

(2) Helmholtz tells us that whoever, in the pursuit of science, seeks after immediately practical utility, may generally rest assured that he will seek in vain; and Clifford asserts that the most useful parts of science have been investigated for the sake of truth, and not for their usefulness. Yet Pearson holds that one of the claims of science to our support is the increased comfort that it adds to practical life. How do you reconcile these statements?

H. von Helmholtz, On the Relation of Natural Science to General Science, in Popular Lectures on Scientific Subjects, i., 1904, 25; W. K. Clifford, On Some of the Conditions of Mental Development, in Lectures and Essays, i., 1879, 104; K. Pearson, The Grammar of Science, ch. i., 1900, 29 f., 37.

(3) Discuss the following definitions of psychology:

(a) The science which describes and explains the phenomena of consciousness, as such (Ladd).

(b) The science of behaviour (Pillsbury).

(c) The science of individual experience (Ward).

(d) The positive science of mental process (Stout).

G. T. Ladd, Psychology, Descriptive and Explanatory, 1894, 1; W. B. Pillsbury, The Essentials of Psychology, 1911, 5; J. Ward, Psychology, in Encyclopædia Britannica, xxii., 1911, 548; G. F. Stout, Analytic Psychology, i., 1896, 1.

(4) Can you bring the following series of statements into relation, and show that they illustrate natural (even necessary) stages in the history of human thought? (Note the phrasing in every case!)

(a) The savage thinker seems to have taken for granted, as a matter of course, the ordinary operations of his own mind. It hardly occurred to him to think about the machinery of thinking (Tylor).

(b) The modern mind is, what the ancient mind was not, brooding and self-conscious; and its meditative self-consciousness has discovered depths in the human soul which the Greeks and Romans did not dream of, and would not have understood (Mill).

(c) When to save his own soul became man’s first business, he must needs know that soul, must study, must examine it. Prescribed as a duty, introspection became at once a main characteristic of religious life (Burr).

(d) There is nothing more interesting to the ordinary individual than the workings of his own mind. This interest alone would justify the existence of the science [of psychology] (Pillsbury).

(e) If we could say in English ‘it thinks’, as we say ‘it rains’ or ‘it blows’, we should be stating the fact most simply and with the minimum of assumption (James).

E. B. Tylor, Animism, in Primitive Culture, i., 1891, 497; W. Knight, Rectorial Addresses delivered at the University of St. Andrews, 1863-1893; J. S. Mill, 1894, 38; A. R. Burr, Religious Confession and Confessants, 1914, 86; W. B. Pillsbury, op. cit., 5; W. James, The Principles of Psychology, i., 1890, 224 f.

(5) What is the earliest notion of your own mind that you can recall?

(6) Four newspapers describe the same gown as gold brocade, white silk, light mauve, and sea-green with cream or ivory sheen on it. How could this difference of report have arisen?

(7) Newton is said to have discovered the law of gravitation by observing the fall of an apple from a bough. Was this a simple observation, or could it be said to have anything of the experiment about it?

(8) What are the characteristics of a good observer? of a good experimenter?

(9) The older psychologies speak, in technical terms, not of mental processes but of powers, faculties, capacities of the mind. What view of mind do these expressions imply?

(10) Rousseau remarked that definitions would be all very well if we did not use words to make them; les définitions pourraient être bonnes si l’on n’employait pas des mots pour les faire (Œuvres complètes de J. J. Rousseau: Émile, tome i., 1823, livre ii., 160). Illustrate this remark by reference to psychology.

(11) Try to describe your experience on some occasion which leads you to say: (a) I have made up my mind; (b) I have half a mind to do so-and-so; (c) That puts me in mind of so-and-so. Try to get down to the bare facts; it will be difficult; but try again and again, and do not be satisfied to report meanings.

(12) Describe your fountain-pen from the points of view of common sense, of physics, and of psychology. Do not attempt too much detail, but get the differences in point of view clearly on paper.

References for Further Reading

§ 1. Some general references have already been given; add W. Whewell, History of the Inductive Sciences, 3d ed., 1857. The book is out of date, but still useful. For science in the Middle Ages, see H. O. Taylor, The Mediæval Mind, 2d ed., 1914 (references in index). For the genesis of science, consult Tylor, as cited above; J. G. Frazer, Balder the Beautiful, 1913, 304 ff.; all the volumes of The Golden Bough are instructive. For an object-lesson in scientific thinking take H. Spencer, The Study of Sociology, 9th ed., 1880 (also no. 5 of International Scientific Series).

§ 2. Tylor, as above; J. G. Frazer, Taboo and the Perils of the Soul, 1911, 26 ff.; E. B. Titchener, Psychology: Science or Technology? in Popular Science Monthly, lxxxiv., 1914, 39 ff.; J. Ward, Psychology, in Encyclopædia Britannica, xxii., 1911, 547 f.

§ 3. W. McDougall, Physiological Psychology, 1905; W. Wundt, Principles of Physiological Psychology, i., 1904, 1 ff., 27 ff., 280 ff.; R. M. Yerkes, Animal Psychology and Criteria of the Psychic, in Journal of Philosophy, Psychology, and Scientific Methods, ii., 1905, 141 ff.; M. F. Washburn, The Animal Mind, 1908; A. W. Yerkes, Mind in Plants, in The Atlantic Monthly, Novr. 1914, 634 ff.; J. B. Watson, Behaviour, An Introduction to Comparative Psychology, 1914.

§ 4. O. Kuelpe, Introduction to Philosophy, 1897, 55 ff.; Wundt, as above; G. T. Ladd and R. S. Woodworth, Elements of Physiological Psychology, 1911; E. W. Fiske, An Elementary Study of the Brain, 1913; K. Dunlap, An Outline of Psychobiology, 1914.

§ 5. W. S. Jevons, The Principles of Science, 1900, bk. iv., chs. xviii., xix.; E. B. Titchener, Prolegomena to a Study of Introspection, in American Journal of Psychology, xxiii., 1912, 427 ff.; O. Kuelpe, Outlines of Psychology, 1909, § 2; W. A. Hammond, Aristotle’s Psychology, 1902; C. A. F. Rhys Davids, A Buddhist Manual of Psychological Ethics, 1900.

§ 6. M. Howe and F. H. Hall, Laura Bridgman, 1903, 49 f.; G. Stoerring, Mental Pathology in its Relation to Normal Psychology, 1907 (the quotations from this work are sometimes condensed in the text); S. I. Franz, Handbook of Mental Examination Methods, 1912, 68, 80.

§ 7. Add, as typical, to works already cited: W. Preyer, The Mind of the Child, 1888-9 (human special); J. M. Baldwin, Mental Development in the Child and the Race, 1906 (human genetic); id., Social and Ethical Interpretations in Mental Development, 1906 (social); G. Le Bon, The Psychology of Peoples, 1898 (ethnic); A. Moll, Hypnotism, 1891 (derangement); G. Le Bon, The Crowd, 1910; J. Jastrow, Fact and Fable in Psychology, 1900 (collective derangement); E. L. Thorndike, The Principles of Teaching Based on Psychology, 1906; H. Münsterberg, Psychology, General and Applied, 1914. For the history of psychology, see O. Klemm, A History of Psychology, 1914; M. Dessoir, Outlines of the History of Psychology, 1912.

[CHAPTER II]

Sensation

Now that these points have been determined, let us proceed to a general discussion of the whole subject of Sensation.—Aristotle

§ 9. Sensations from the Skin.—The skin is part of our organic birthright. One of the great differences between the living and the not-living lies in the possession of a skin; stone and iron weather and rust, but even the naked amœba has its ectosarc, and flowers of tan their plasmoderm. The skin is also the oldest of the sense-organs, and the mother of all the rest; how old, we dare hardly guess; but we know that the chemical elements which make up living tissue took form early in the history of our planet, earlier than the heavy metals. So it is natural to begin our survey of sensations by questioning the skin.

The skin is a shifty witness; and to get positive answers, we must literally cross-examine it; we must go over its surface point by point and line by line, with all sorts of mechanical and thermal and electrical and chemical stimuli. The outcome is a little surprising; we find only four sensations, pressure, cold, warmth and pain. The organs of these sensations are dotted in a sort of irregular mosaic all over the skin, and the intervening spaces are insensitive. The organs of pressure, distributed over about 95% of the bodily surface, are nerve-skeins twined about the roots of the hairs; on the hairless areas of the body, we find the nerve-skein by itself. The organ of pain is probably a little brush-like bunch of nerve-fibrils just below the epidermis. The organs of warmth and cold are certainly distinct; the sensations are not degrees of one sensation, as the thermometer might lead us to suppose; but the precise nature of their nerve-endings has not yet been made out.

You may easily find pressure spots by fastening a short horsehair with sealing-wax at right angles to the end of a match, and applying the horsehair point to the back of the hand above a hair-bulb, that is, just to windward of the issuing hair; dot the horsehair about, here and there, till the sensation flashes up. You may find cold spots by passing the blunt point of a lead pencil slowly across the closed eyelid. Warm spots are more difficult to demonstrate. For pain, take the shaft of a pin loosely between finger and thumb of the right hand, and bring the point down sharply on the back of the left hand; you get two sensations; the first is a pressure, the second—which pricks or stings—is a pain.

As a rule, these organs are not stimulated separately but in groups. Itch, for instance, is due to the light stimulation of a field of pain-endings, and superficial tickle to that of a field of pressure-organs. The experience of heat, curiously enough, is a blend of warmth and cold; there are no heat spots. It may be observed in this way: if you apply a surface of increasing warmth to a region of the skin which has both cold and warm spots, you feel for some time only the warmth; but when the stimulus has reached a certain temperature, the cold spots, suddenly and paradoxically, flash out their sensations of cold; and the blend of warmth and of paradoxical cold is felt as heat. Cement a smooth copper coin to a handle, and apply it at gradually increasing temperature to the middle of the forehead just under the hair; you will presently find the heat. Or if you cannot do that, note the shiver of cold when you next step into an overhot bath.

When we compare these results with the show that the skin makes as a sense-organ in everyday life, we can hardly help bringing against it the charge of dishonesty. The pressure spots give us tickle, contact or light pressure, and pressure proper; the pain spots, itch, prick or sting, and pain proper. The cold spots give cold and cool, the warm spots lukewarm and warm; cold and warm spots together give heat; cold and pain give biting cold; cold and warm and pain give burning or scalding heat; and that is all. Yet the skin pretends to tell us of hard and soft, wet and dry, light and heavy, rough and smooth, yielding and resistant, sharp and blunt, clammy and greasy, oily and sticky, stiff and elastic, and so on. Where do we get all these experiences?

[§ 10]. Kinæsthetic Sensations.—We get them, for the most part, from the cooperation with the skin of certain deeper-lying tissues. Psychologists have long suspected the existence of a muscle sense. We now know that sensations are derived, not only from the muscles, but also from the tendons and the capsules of the joints. These tissues are, of course, closely bound together, and are all alike affected by movement of a limb or of the body. Their disentanglement, from the point of view of sensation, has been a slow and difficult matter. Psychology has here been greatly aided by pathology; for there are diseases in which the skin alone is insensitive, in which skin and muscles alone are insensitive, and in which the whole limb is insensitive; so that a first rough differentiation is made for us by nature herself. It is also possible artificially to anæsthetise muscle and joint; and psychologists have devised various forms of experiment whereby some single tissue is thrown into relief above the others.

Not only, however, are the sensations of these tissues aroused by movement; they also form the sensory basis of our perception of the movement of body and limbs. For this reason they have been named kinæsthetic, or movement-perceiving. They are of the following kinds.

First, we have from the muscles the sensation of physical fatigue. If the skin over a muscle is rendered anæsthetic, and the muscle is thrown into forced contraction by an electric current, we have, to begin with, a dull dead pressure; as time goes on, or if the strength of the current is increased, this pressure becomes dragging, the sensation of fatigue; and finally it becomes sore and achy, and passes over into dull pain. From the tendons we get a sensation which, when we are actively pushing or pulling, we call effort, and when we are passively holding or resisting we call strain; it, too, passes over into pain. Lastly, from the joints we have a pressure: something like the pressure you feel if you smear the right forefinger with vaseline, and turn it in the loosely closed left hand. Take a piece of elastic between the forefingers and thumbs; pull it out, and then relax it; at the moment of relaxation there is a pressure in the finger-joints, which is the specific joint-sensation.

Muscle and joint, then, yield sensations which are like those of pressure on the skin; and muscle and tendon yield sensations which are like those of pain from the skin; it is small wonder that the skin, the only portion of this whole sensory apparatus that is open to view, should ordinarily be credited with the entire number. In point of fact, there are very few of the experiences listed on p. 45 that do not imply the cooperation of some or all of the deeper-lying organs, the nerve-spindles of muscle and tendon and the nerve-corpuscles of the joints. Those that really belong to the skin owe their specific character to the context in which they are set; they change their meaning as a particular word changes its meaning from one sentence to another; think of the horribly clammy feel of a bit of cold boiled potato as you set your finger on it in the dark, and of its totally different feel when you have turned the light on and see what it is you are touching! Wetness, for instance, proves on analysis to be a complex of pressure and temperature; it is possible, when the observer does not know the nature of the stimulus, to arouse the feel of wet from perfectly dry things, such as powder, or cotton wool, or bits of metal; and it is possible to wet the observer’s hand with water and yet to arouse the feel only of a dry pressure or a dry warmth or cold.

So our very first adventure in psychology brings out, as clearly as we need wish, the difference between science and common sense. The skin is really living upon borrowed capital; it has added to its own sensations those derived from the subjacent tissues; but common sense, blind to what it cannot see, ascribes to it a ‘sense of touch’ that includes everything and examines nothing. More than this, common sense fails to draw the distinction between process and meaning which we discussed in § 6, and therefore ascribes to the sense of touch a variety of sensory experience that far outruns the facts. Hardness and softness and stickiness and oiliness and the rest are, no doubt, separate and distinct as meanings; but when we analyse the corresponding experiences, we find only the half-dozen sensations mentioned above.

[§ 11]. Taste and Smell.—The great physiologist Carl Ludwig once remarked that smell is the most unselfish of all the senses; it gives up everything it has to taste, and asks nothing in return. Taste is, indeed, an inveterate borrower; it borrows from smell and from touch, very much as the skin borrows from the underlying organs. When we have a cold in the head, we say that we cannot taste; but how is taste affected? The truth is that our nose is stopped, and we cannot smell.

If the surface of the tongue is explored with various sorts of stimuli, and the nose is kept out of function by plugging of the nostrils, we find four sensations: sweet, bitter, sour, and salt. Think, then, how much ‘taste’ there would be in the meats and vegetables that deck our tables, if the nose were closed and condiments were not added! The sensation of sweet is strongest at the tip of the tongue; bitter at the root; sour along the sides; salt is fairly evenly distributed over all three areas; the middle region of the tongue is insensitive to taste. The sensory cells are grouped in flask-shaped structures, the taste-buds or taste-beakers, which are again gathered together in or about the papillæ of the tongue’s surface; some of these you can see, as red specks upon the dull pink mucous membrane, if you look at the tip of your tongue in a glass. There is only one instance of a blend of tastes; if sweet and salt are mixed, there appears a new taste, flat or vapid in character. Apart from these five things—sweet, bitter, sour, salt, vapid,—we ‘taste’ entirely by smell or touch.

Smell, on the other hand, has more sensations than we can count or name; more sensations, probably, than all the rest of our senses put together. We can make out certain great groups of odours: flower, fruit, spicy, musky, leek, burned, rank, foul, nauseous; we may take as examples vanilla, orange, cinnamon, sandalwood, onion, toast, cheese, opium, garbage. Realise that the flower odours comprise the scents of all the flowers, as well as those of vanilla, tea, hay, and suchlike things; or that the spicy odours comprise the scents of all the spices, as well as those of thyme, geranium, bergamot, cedarwood, and suchlike things; and you will get some idea of the variety of the world of smell. When we add that odours freely blend or combine to give new scents, you will understand that the number of smell sensations is enormous.

The sensory cells are found in two patches of mucous membrane, each about as big as the little-finger nail, which lie saddle-wise across the blind top of the nasal cavities. They cannot be stimulated directly; but particles carried into the outer nostrils by the breath-stream, or into the inner nostrils by the air-stream thrown back in the act of swallowing, eddy upward to them and thus arouse sensation. The second mode of stimulation plays, of course, into the hands of taste; we think we taste when we swallow; we forget that we have inner nostrils, though we know very well that we can sniff up a lotion and bring it down into the back of the mouth. But though the stimulation is thus indirect, the cells are extraordinarily sensitive; a mere trace of odorous substance will set up a sensation; and the nose is also keenly discriminative.

Yet in spite of the tens of thousands of sensations, and in spite of the extraordinary sensitivity of the cells, we often read that in man the sense of smell is degenerating! Of this there is not one particle of evidence. We could not, truly, live by smell, as dogs do; but then men have never been dogs; and even so there are cases on record—among the Botocudos of Brazil and the aboriginal tribes of the Malay peninsula—of savage hunters who track their game by scent. There is no atom of evidence that, since man was man, his sense of smell has degenerated. It is true, on the other hand, that the sense of smell has fallen into disuse. The reason is that smell is essentially a ground sense, as you may convince yourself any summer day that you lie out on the grass, or any time that you are willing to spend a few minutes on a dining-room floor; birds in general have a very obtuse sense of smell, and many of them perhaps lack sensations of smell altogether. When, then, mankind assumed the upright position, and the nostrils were lifted several feet above the surface of the ground, the sense was removed from its normal environment, and fell into disuse; sight and hearing took its place. But it may still be used. The late Sir Francis Galton, a cousin of Darwin’s, once made an essay, for instance, at an arithmetic by smell; peppermint stood for one, camphor for two, carbolic acid for three, and so on. “There was not the slightest difficulty in banishing all visual and auditory images from the mind, leaving nothing in consciousness besides real or imaginary scents. In this way I convinced myself of the possibility of doing sums in simple addition with considerable speed and accuracy solely by means of imaginary scents. Subtraction succeeded as well as addition.” Needless to say, it is not worth our while to do this sort of work; the very fact that odours have no settled system of names, like cold or pain, red or blue, shows that they have not been utilized in human life. It is fair to add, also, that sight and hearing are better suited than smell to our everyday needs; for smells very soon fade out and disappear; indeed, if they did not, the work of garbage collectors or of medical students in the dissecting room would be permanently disagreeable.

[§ 12]. Sensations from the Ear.—Sensations of hearing fall into two great groups, tones and noises. When we are speaking of tones, we naturally think of the keyboard of a piano. The piano tones are, in reality, not simple tones or sensations but compound tones; and we are able, after a little practice, to break up a compound tone into its simple constituents. You may get a fair notion of a really simple tone by blowing gently across the mouth of an empty bottle. The tone is dull and hollow, as compared with the bright solidity of a piano tone, but it has also a pleasant mellowness. With these two aids, the bottle tone and the piano keyboard, we may approach our study of tonal sensations.

Tones have, first of all, the character that we call pitch; they lie, that is, up or down in the scale; they belong to the bass or the treble or to a middle region. The word ‘pitch’ means height; it is a term borrowed from perceptions of sight; and we cannot yet say certainly how it came to be applied to tones. Secondly, tones have the character of volume,—another borrowed word! The highest note on the piano seems shrunken, narrowed, pointed, as compared with the deepest note in the bass; and the difference comes out even more clearly with bottle tones. Thirdly, tones show a sort of recurrence. If you run your finger-nail quickly up the keyboard in a glissando, you perceive a change only of pitch and volume; but if you play the notes c, d, e in one octave and then in another and then in a third, you realise that all the sequences are alike; we talk, indeed, of playing the same notes in different octaves. This recurring character of tones is called tonality.

It has recently been stated that tones have a further character, that of vocality. Consider the series of vowels, U, O, A, E, I (voiced approximately as in the words moot, moat, mart, mate, meet); there is no doubt that U suggests a low bottle tone, and I a high whistle tone. Experiments seem to show that, as we go up the scale, the tones say M-M, U, O, A, E, I, S-S, F-F, CH (the sound in the Scotch loch); and, curiously enough, that they say these things at intervals of an octave; so that, when we have found a pure O, we find the pure A just an octave higher, and the tones that lie between give Oa, OA, oA, according to their position. The question is still in debate; for these experiments are opposed by others, and the whole subject of the nature of vowel-sounds is very thorny. It is quite clear that high and low tones sound definitely like U and I; but some of the other vowels are far less distinct; and the point of change from vowel to vowel does not appear to be as sharp and precise as the first experiments indicated. On the whole, we shall do best to suspend judgement.

There are some ten thousand simple tones in the complete tonal scale; but the compound tones employed by music are only about a hundred in number, and are selected from a middle range of hearing. The compound tone, as we have said, breaks up on analysis into simple partial tones; the lowest is called the fundamental, the others the overtones. It is a remarkable fact that the overtones always stand in a definite relation to the fundamental. The various musical instruments do not, however, sound all the overtones alike; their construction favours some, and weakens or destroys others; and that is the main reason why we can tell a harp-tone, for instance, from a tone of the same pitch played on oboe or trumpet. The compound tones thus owe their colour or timbre, in the first instance, to the number and relative loudness of the overtones which accompany the fundamental. Timbre has other factors; but this is the primary source of difference.

Overtones may readily be heard. Strike a c, very lightly, on the piano. When it has ceased to sound, strike loudly the c next below; you can probably, even at the first trial, hear the higher c in the lower. Now strike very lightly the g next above your higher c, and then the lower c again loudly; you will probably hear the g. Helmholtz, working with thin strings, was able to hear no less than fifteen overtones with the fundamental.

This blending of the partial tones in a compound tone, to give a single and unitary impression, is an example of what is called tonal fusion. The best fusion is that of two tones which constitute an octave; here, indeed, the blend is so close that it is often confused with unison; a soprano and a bass singer, told to sing in unison, will start off without hesitation an octave apart. Next after the octave stands the fifth (c and g); boys who think they are whistling the same notes often whistle, in fact, a fifth apart. Other pairs of tones give lesser degrees of fusion.

Tones generate as well as blend. If you sound together two high tones, such as you get from a double bicycle whistle, or from small bottles of different sizes, you hear, besides these tones themselves, a third tone, very much deeper, larger, more booming; this differential tone is easy to find and, once heard, cannot be mistaken. Only, the two tones must not be too nearly alike in pitch; for, if they are, you hear, instead of a differential tone, slow surges or quick rattlings of sound. Take two bottles of the same size, and mistune one of them by pouring in small amounts of water; have them blown steadily together; the course of the beats, as they are called, from a slow surge through a rattle to a harsh blur, may thus be followed.

Noises, which form a class of sensations distinct from tones, are nevertheless aroused by the same sort of stimuli. If a tonal stimulus is sounded for a very brief time, we hear a dry knock; if a large number of tonal stimuli are sounded all at once, we hear a buzz or crash. Noises have pitch; the spit of a pistol is higher than the crack of a rifle, and the sizzle of frying fat is higher than the murmur of falling rain; but no one has yet established a complete scale of noise.

The sensory cells are found in the inner ear, a tiny structure with an extremely complicated mechanism. Many different views of its action have been put forward. That which is most generally accepted was proposed by the German physicist H. von Helmholtz. The ear contains a narrow triangular membrane which carries many thousands of stiffish cross-fibres; and the theory is that the air-waves which impinge on the outer ear play, selectively, upon these fibres; every air-wave throws into vibration the fibre which is tuned to respond to it. A compound tonal stimulus is thus analysed by the membrane into a number of simple tonal stimuli, and every simple stimulus excites the nerve-fibril attached to its particular cross-fibre. This theory explains our ability to analyse compound tones into their simple components.

The ear is, however, more than an organ of hearing. It includes organs, of a very ancient type, which help to regulate our balance in walking, our precision in turning corners or avoiding obstacles, and so on. Each ear, for instance, has three little organs that resemble minute spirit-levels, set in the three planes of space, and that give us the sensation of ‘swimming’ when the head is sharply jerked, and the sensation of dizziness when we twirl on our heels. For the most part these organs act reflexly, without furnishing sensations; or at any rate furnish sensations of little strength, and of a pressure-like kind that blends indistinguishably with the kinæsthetic sensations from the tissues beneath the skin; but in the cases mentioned the swimmy, dizzy sensation may be noticed.

[§ 13]. Sensations from the Eye.—You may study tones by help of the piano and a few medicine bottles; but for the study of lights and colours you must go beyond household appliances, and secure a fairly large set of coloured and grey papers; sample-books may be obtained, very cheaply, from the manufacturers. You will notice, first of all, that as the world of sounds divides into tones and noises, so does the world of looks divide into what we have just called colours and lights. The colourless looks or lights may be arranged in a single straight line that passes from purest white through the greys to deepest black; they are, as sensations, older than colours, just as noise is older than tone. Colours are more varied. Consider, to begin with, the character of colour proper or hue, that is, the differences of colour that show in the rainbow. Hues may be arranged, not in one straight line, but in a square. Setting out, say, from red, you pass through red-yellow or orange to yellow; that is one straight line; setting out again from yellow, you pass through yellow-green to green; from green you pass through green-blue to blue; and finally from blue you come back, by way of blue-red (violet and purple), to the original red. Colours have, besides, two further characters, that bring them into relation with lights. They differ in tint, that is, in darkness or lightness; brown is darker than yellow, sky-blue is lighter than navy-blue. They differ also in saturation or chroma, that is, in poorness or richness of hue; pinks and yellows look faded and washed-out as compared with rich reds and blues. Tint brings colours into relation with lights, because, if we can say that a colour is darker or lighter than a particular grey, we can also find some grey that matches it in darkness or lightness; and chroma brings colours into relation with lights, in the sense that the better chroma is farther off from colourlessness (that is, from grey) than the poorer chroma of the same hue and tint.

All lights and colours are psychologically simple. Paints may be mixed on a palette, and colour-stimuli may be mixed in all sorts of ways; we learn in physics that white daylight is a mixture of all the rays that are seen separately in the rainbow. Yet a white, considered just as a look, is perfectly simple; and the looks of orange and yellow-green and green-blue are equally simple. There are no compound colours, to correspond with compound tones. Hence the number of light and colour sensations is very large, at least ten times as large as the number of simple tones.

The organ of vision is the eye; and the eye is a little photographic camera, with shutter, iris-diaphragm, self-adjusting lens, dark chamber, and self-renewing sensitive film. We are concerned only with the film, that is, with the retina or nervous network that lines the posterior half of the eyeball. It seems that the retina is really made up of three interfused films; for simplicity’s sake you may consider them as lying upon one another, just as three saucers might do if you piled them together. The oldest and largest film, the bottom saucer, gives us the sensations of black and white; the middlemost, somewhat smaller, gives us blue and yellow; and the topmost and smallest gives us a purplish-red and a bluish-green. The existence and size of the three films can be shown by experiment; for we are all totally colour-blind at the edge of the field of vision, and are blind to reds and greens for some distance further in toward the centre. There are also cases of inherited colour-blindness, in which the eye is blind either for all colours (total colour-blindness) or for red and green alone (partial colour-blindness); the latter form is fairly common, as is natural,—for the red-green film, being the last to come, might be expected to be the first to go. Partial colour-blindness was first brought to scientific notice by the English chemist John Dalton in 1798. Dalton was a Quaker, but made no objection to wearing the scarlet gown of a doctor of laws, because, as he said, “to me its colour is that of nature—the colour of those green leaves”; it is needless to remark that he did not see green either! The defect is practically important for pilots and signalmen, who have to distinguish red and green lights.

From these three films we get all the lights and colours that we see in the daytime, with the single exception of neutral grey; and this appears to come, not from the eye at all, but from the brain. It may be seen even when the retina is quite blind, provided that the rest of the nervous apparatus is in working order; and it may be seen by night as well as by day; it is mixed, physiologically, with all our sensations of light and colour, though we cannot by psychological analysis pick it out from the lights and colours. Strange enough! but we shall understand better as we go on. The German physiologist Ewald Hering has shown that the processes which take place in the films are, in all probability, chemical processes of an antagonistic or reversible kind; that is why we never see a bluish-yellow, or a greenish-red; if we throw on the same part of the retina, at the same time, equal amounts of black and white, or of blue and yellow, or of purplish-red and bluish-green, the chemical processes go on in opposite directions and cancel each other, with the result that we see just nothing. This antagonism can be proved, under the right experimental conditions, for blue-yellow and for red-green; if these pairs are fittingly thrown together on the retina we see, in fact, only neutral grey; so that our seeing of the same grey, when black and white stimuli are acting together, does not necessarily mean that grey is a retinal mixture of black and white; the black and white may also cancel each other, and leave only the brain-grey to be seen.

We have, then, the three films in each eyeball, and we have the brain-grey behind them. More than this: we have a night or twilight eye. When colours fade out, as twilight deepens, another retinal film comes into play; the lights that we still see come, not from the black-white film, but from a fourth film, of the same size, whose only sensation is a slightly bluish-white. Of course, this white is always mixed, physiologically, with the brain-grey; we never see it by itself; but we owe to it, among other things, the silvery look of blues in the twilight. The very centre of the twilight eye is totally blind; if on a moonless night you want to see a faint star or a distant street-lamp you must not look directly at it, but just to one side of it. Children’s fear of the dark is partly due to the fact that they cannot see what they turn their gaze upon; there had seemed to be something there, but when they looked at it, it eluded them; and if they think they see it again, and look in the new direction, again it is gone.

Now suppose that you are looking out, in daylight, over a variegated landscape. Somewhere or other you see a patch of light grey. You get this sensation from the black-white film and the brain-grey; the white-process is stronger than the black-process in the film, and the excess of white, added physiologically to the brain-grey, shows as light grey. Or again, you see a patch of dark purple. This sensation comes from the red-green film (excess of red); from the blue-yellow film (excess of blue); from the black-white film (excess of black); and from the brain-grey. All the lights and colours of the landscape can be accounted for in the same way.

Not quite correctly, however!—there are still other factors at work. The film-processes are antagonistic, for instance, even when they go on in different parts of a film; lights and colours contrast with one another; if you lay a strip of grey paper on red, it looks greenish; on blue, yellowish; on white, blackish; make the trial with your own papers. So all the various lights and colours of the landscape stand out, by contrast, against one another; the eye makes their differences greater than they ought physically, from the nature of the stimuli, to appear. Black, indeed, is wholly a contrast-sensation; it has no physical stimulus; and you see deep black only in strong illumination.

Contrast is effective at once, the moment you cast your eyes on the landscape. As time goes on, however, the opposed film-processes tend to settle down into a state of balance or equilibrium; so that actually, if you stared at the landscape long enough, without moving your eyes, you would finally see nothing but the brain-grey. This levelling down of all lights and all colours toward neutral grey is called adaptation. Stand up two strips of black and white paper, side by side, and stare at their line of junction for a minute or two; even in that short time you will find that they tend toward a uniform grey. If, now, a stimulus to which you are wholly or partly adapted is suddenly removed, the antagonism of the film-processes shows itself once more; you see an after-image. Lay a disc of red on grey; stare at it for half a minute; flick it away, keeping the eyes steady, and look at the grey background; you see a corresponding disc of green. White leaves a black after-image, black a white; blue a yellow after-image, and yellow a blue.

It is clear, then, that the lights and colours of the landscape depend on many things beside the stimuli there presented; they depend on contrast, on the previous adaptation of the eye, on the presence or absence of after-images. The main reason that we do not notice all these influences is that we ordinarily view the landscape, not for itself, but for what it means; it shows us the familiar trees and stream and houses, and we take their stability for granted. That is the main reason; it is not the only one. We have said, for instance, that the normal retina is totally colour-blind along its outer edge, and partially colour-blind for some distance in toward the centre; the edge of the landscape ought therefore to be colourless, and a certain outlying portion of it ought to appear simply as blue and yellow. There is no hint of these differences; and the explanation is that we are accustomed to turn our eyes directly towards what we want to see, and therefore to view it with all three of the daylight films; head and eyes move so easily, and we see so much better with the centre of the retina, that we totally disregard the altered look of things seen ‘out of the corner of the eye.’ Even if we do not, we are likely to remember how the things appear in direct vision; we paint them over, so to speak, with memory-colours, colours that represent their natural or average appearance at the centre of the visual field; indeed, we may paint these colours over the whole landscape, and in that way correct the changes due to contrast or adaptation. We always talk of a certain book as brown; we recognise it in all lights, and in all states of the eye, by its brown colour; we see it, in memory-colour, as brown; whereas, if that same brown were shown us in all the different circumstances without our knowing it to be the same, it might give us sensations of yellow, of pale brown, of deep brown, of black. These two factors, movement of the eyes and memory-colour, lead us to overlook, in great part, the actual variation of lights and colours in the landscape.

A final word may be added regarding the likeness of sight and smell. Odours and colours fade out by adaptation; odours, like lights and colours, contrast, and even cancel one another; and smell-stimuli as well as sight-stimuli mix to produce new and simple sensations. It is highly probable that the sensory cells of smell are the seat of only a few chemical processes, by whose combination all the wealth of odours is created, just as the cone-cells of the retina are the seat of those three reversible processes (black-white, blue-yellow, red-green) whose combination endows us with the variety of daylight vision. We have as yet, however, no such definite grounds for hypothesis as we have in the case of sight; we cannot even guess what these processes are, or how many of them are taking place in the smell-membrane.

[§ 14]. Organic Sensations.—There are still other sensations, coming to us from the internal bodily organs; from various parts of the alimentary canal, from the organs of sex, from heart and blood-vessels, from the lungs, from the sheathing membrane of the bones; but it is doubtful if they are of new kinds; probably they consist simply of pressure, cold, warmth, and pain. The dull deep-seated pains that we call aches are, perhaps, different from the bright pains of the skin; but most of the differences among pains, differences that we express by the terms lancing, throbbing, piercing, stabbing, thrilling, gnawing, boring, shooting, racking, and so on, are either differences of time (steady, intermittent) or space (localised, diffused) or degree (moderate, acute), or else are differences due to the blending of pain with various other sensations.

The organic sensations, like the kinæsthetic, tend thus to occur in groups or complexes, and we have as yet no very sure means of disentangling them. It is, nevertheless, quite clear that in their case, as in that of the touch-blends, we have to distinguish between experience and meaning. Hunger and nausea seem, for example, to be very different; yet the core of both turns out on analysis to be the same dull pain; and we know that the onset of a bilious attack is often heralded by an unusually keen appetite, so that the beginnings of nausea are in fact confused with a growing hunger. The difference between hunger and nausea is due partly to a difference in the processes which ordinarily accompany the central pain,—motor restlessness or lassitude in the case of hunger, and dizziness in that of nausea; but more especially to a difference of meaning or interpretation; hunger stands for want of food, and nausea for indigestion.

We shall see later that organic sensations play a large part in emotion, as kinæsthetic sensations do in perception. Plato set the ‘spirited’ or ‘passionate’ part of the soul in the breast; the Psalms abound in phrases that suggest the same idea; we speak to-day of the heart coming up to the mouth, or dropping to the boots. So we read in the Old Testament that Joseph’s bowels yearned upon his brother, and in the New Testament of bowels of compassion; and the inner stir that the writers have in mind is familiar to everybody.

[§ 15]. Sensation and Attribute.—We have been talking all this while about sensations, but we have not yet said what sensations are. They make up, as you will have guessed, one class of the mental elements, the elementary mental processes of § 4, that we reach by analysis of our complex experiences. They are therefore simple and irreducible items of the mental world. How shall we define them?

We can define them, in strictness, only by writing down a complete list of what we have called their characters. Every sensation shows itself to us under various aspects, or, as we are accustomed to say, possesses a number of attributes. We have been dealing, so far, with the qualitative aspect of sensations. This may itself be single; the quality of lights is just their lightness or darkness; or it may be manifold; the quality of colours can be properly described only if we take account of hue, tint, and chroma; that of tones only if we take account of pitch, volume, and tonality, perhaps also of vocality. Quality is the natural thing to start out from, because it is what interests us most in everyday life, and has therefore been named; so that, when we speak of sensations, we speak of them by their qualities. There are, however, several other attributes; sensations possess intensity, and vividness, and duration, and some of them possess extension. We shall discuss these aspects later on.

Does it seem strange, now, that an elementary hit of experience should turn so many sides to the observer? Think then of chemistry, and of the chemical elements. Sodium is a chemical element; but it has many aspects or properties; physically regarded, it is soft, it is fusible, it volatilises at high temperatures; chemically, it combines with oxygen, it decomposes water, it is univalent, it has a low atomic weight, it is electropositive, and so forth. Sodium cannot be reduced, chemically, to anything simpler than itself, but it is nevertheless many-sided. The same thing is true of sensations.

So a complete list of the aspects or attributes of sensation is as near as we can come to a definition. But since that sort of statement is clumsy; since we cannot make it complete till we have observed the sensations under all their possible aspects; and since we know that mental processes are correlated with processes in the nervous system; we may adopt another plan, and define sensation by reference to the special bodily organ with which it is connected. Sensations are then elementary mental processes that come to us by way of skin, muscle, ear, and the rest of the sense-organs.

[§ 16]. The Intensity of Sensation.—A sensation may remain the same in quality, and yet vary in strength or intensity. A pressure may be the pressure of an ounce or of half-a-pound; it is always pressure, the same quality, but its intensity differs. The tone you get by blowing across the mouth of a bottle may be loud or faint, though it is still the same pitch, the same tone. The weight you carry may strain the arm very little or a great deal; the sensation of strain from the tendons is the same in both cases, but its intensity is different.

The study of this attribute of sensations has led to the discovery of a psychological law, which has much practical importance. Suppose that we are working with intensities of noise, the noise made by the drop of an ivory ball upon an ebony block. Suppose that, by varying the height from which the ball falls, we have found a series of intensities of sensation a, b, c, d, e, which may be represented by the numbers 1, 2, 3, 4, 5; a series, that is, in which the difference between the two noises a and b is equal in sensation to the difference between b and c, or between c and d, or between d and e. That sounds a little difficult; but the series may really be established without much trouble. Now, what about the stimuli, the heights of fall? Must the ball drop twice as far for b as for a, three times as far for c as for a, and so on? No: equal differences in intensity of sensation do not correspond with equal differences in intensity of stimulus. Equal differences in intensity of sensation correspond rather with relatively equal difference in the intensity of stimulus. In other words,

the sensation-series 1 2 3 4 5 corresponds with
a stimulus-series of the type 1 2 4 8 16;

or, mathematically expressed, an arithmetical series of intensities of sensation is correlated with a geometrical series of intensities of stimulus. In the instance given, the exponent of the geometrical series is 2; but that is only an imaginary instance; in the case of noise the actual exponent is 4/3, so that

the sensation-series 1 2 3 4 5 corresponds with
the stimulus series 1 ⁴/₃ ¹⁶/₉ ⁶⁴/₂₇ ²⁵⁶/₈₁;

or, if we take units of some sort, such as millimetres of height of fall,

the sensation-series 1 2 3 4 5 corresponds with
the stimulus-series 81 108 144 192 256.

This law of correlation was first formulated by the German physiologist E. H. Weber in 1834 as follows: “in comparing objects and observing the distinction between them, we perceive, not the difference between the objects, but the ratio of this difference to the magnitude of the objects compared.” Weber speaks of objects, because he was thinking of experiments that he had made with weights; he should have said sensations. His law holds, over a middle range of intensities of sensation, for lights, sounds, pressures, various kinæsthetic complexes, and odours. Its validity in the fields of taste and temperature is doubtful.

It is because of Weber’s law that we are able to ignore the manifold changes of illumination to which we are exposed in the course of the daylight hours; that the painter, who cannot at all reproduce by his pigments the absolute intensities of light in nature, can nevertheless give us a recognisably true copy of any natural scene; and that a large block of seats in the concert-room, at a moderate distance from the stage, can all be sold at the same price and all have equal advantages for hearing. You will readily find other instances of its working, if you are clear as regards the principle involved; namely, that the less you have of anything, the less need be added, and the more you have, the more must be added, to make an appreciable difference; or, on the negative side, that you are not likely to notice any difference in your surroundings, so long as the relations of the stimuli remain unchanged. So Weber’s law furnishes yet another reason for the apparent stability of the landscape that we discussed on p. 63.

Questions and Exercises

(1) Mark out, by indelible ink, a sq. cm. upon the outer surface of the forearm. Make upon transparent paper three maps of the area, marking hairs, veins, etc. Work over the area (a) with the horsehair, for pressure spots; (b) with a warmed carpenter’s spike, for warm spots; and (c) with a cooled spike, for cold spots. Enter the spots, as you find them, on the maps; remember to dot the hair down for pressure, but to draw the spike slowly and evenly along the skin for temperature. Lay the three maps together, and note the distribution and the relative number of the spots.

(2) After shampooing, the scalp is sensitive and irritable under the brush. Why?

(3) When you are writing with a pencil, or prodding in a pool with a stick, the sensations seem to come from the end of the pencil or stick. What organs are involved? And why should the sensations be localised as they are? Try to think out some experimental means of attacking this question.

(4) What sensations do you get in the act of yawning? What in that of swallowing? What unusual sensations do you have, from the face, after you have been running hard?

(5) How do sour and sweet in the mouth affect the sense of touch? Make solutions, in varying strengths, of sugar and of the juice of some very sour fruit; leave plenty of time between observations.

(6) Prepare some bits of apple, onion, and raw potato. Close your eyes and hold your nose; then pick up these morsels at random, and chew them. Can you tell the difference? How?

(7) Is there any evidence of taste contrast?

(8) Secure adaptation to the scent of camphor; breathe regularly, and note the length of time necessary for the odour to disappear. Now smell at vanilla, heliotrope, absolute alcohol. Do you smell them? Try to account for the result, arguing by analogy from what you know of colours.

(9) The next time that you listen to an orchestra, pick out the tones of the various instruments, and try to describe their timbre; do not be afraid to string adjectives together, but be sure that you hear what you put down. Later, look up in a reference-book the composition of these various compound tones, and see if there is any correlation between your description and the number and loudness of the overtones.

(10) If you drop a block of wood on a desk, the sound is simply noisy. If the same block forms part of a xylophone scale, and is struck with the wooden hammer, it gives a tone. How is this?

(11) When you next go to a reception, stand outside the main rooms for a minute, and try to determine the pitch of the buzz of voices; try to sing the pitch yourself. Is the buzz tonal or merely noisy?

(12) When you are listening to beats, do you hear one beating tone, or both the primary tones beating? If one tone only, is it identical with either of the primaries?

(13) Test the law of visual antagonism by getting the after-images of a number of colours.

(14) To prove normal colour-blindness, get a small square of red glass; stand before a window, with your left eye closed and your right eye fixed upon some distant point; bring the red glass slowly into the field, with the left hand, and note its changes.

(15) Can you suggest experiments for working out in detail the laws of visual contrast? Try to think what sort of things would be likely to enhance or to reduce the contrast-effect.

(16) Could a man go through life, and take an ordinary place in society, without knowing that he was colour-blind? Give your reasons.

(17) Blue and yellow are antagonistic; yet blue and yellow paints, mixed on the palette, give green. How is this?

(18) Dalton says: “In lecturing on optics I got six ribands,—blue, pink, lilac,—and red, green, and brown,—which matched very well, and told the curious audience so. One gentleman came up immediately afterwards and told me he perfectly agreed with me; he had not remarked the difference by candlelight.” How could these triads have been confused? and would the candlelight make any difference?

References

A more detailed treatment of sensation is given in the author’s Text-book of Psychology, 1910, 46 ff., 201 ff. The reader may further consult: J. H. Parsons, An Introduction to the Study of Colour Vision, 1915; H. L. F. von Helmholtz, On the Sensations of Tone as a Physiological Basis for the Theory of Music, translated by A. J. Ellis, 1895; C. S. Myers, A Text-book of Experimental Psychology, pt. i., 1911, chs. 2-8, 18, 19; G. T. Ladd and R. S. Woodworth, Elements of Physiological Psychology, 1911, pt. ii., chs. 1-3; W. Wundt, Lectures on Human and Animal Psychology, 1896, Lects. 2-7; various articles in Dictionary of Philosophy and Psychology, ed. by J. M. Baldwin, vols. i., ii., 1901-2; the chapters on sensation in E. A. Schäfer, Text-book of Physiology, ii., 1900, and W. H. Howell, A Text-book of Physiology, 1908; E. Mach, Contributions to the Analysis of the Sensations, trs. by C. M. Williams, 1910; E. B. Titchener, Experimental Psychology, II., ii., 1905, Introduction.

The special references to smell will be found in E. B. Tylor, Anthropology, 1881, ch. ix., 207; W. W. Skeat and C. O. Blagden, Pagan Races of the Malay Peninsula, i., 1906, 200; F. Galton, Psychological Review, i., 1894, 61 ff.; and those to Dalton in W. C. Henry, Memoirs of the Life and Scientific Researches of John Dalton, 1854, 24, 49, 172, 187. For the term kinæsthesis see H. C. Bastian, The Brain as an Organ of Mind, 1885, 543.

[CHAPTER III]

Simple Image and Feeling

Conceptions and apparitions [sensations and images] are nothing really but motion in some internal substance of the head; which motion not stopping there, but proceeding to the heart, of necessity must there either help or hinder the motion which is called vital; when it helpeth, it is called pleasure; but when such motion weakeneth or hindereth the vital motion, then it is called pain.—Thomas Hobbes

§ 17. Simple Images.—Common sense draws a sharp distinction between our present perception of an object or event, and our later revival of it in memory; and psychologists have been accustomed, in the same way, to distinguish the simple sensation, the elementary process in perception, from the simple image, the elementary process in memory. In fact, however, it is very doubtful if there is any real psychological difference between sensation and image. The statement is often made that the image is weaker, fainter, more fleeting than the corresponding sensation. Thus, the great philosopher David Hume (1711-1776) wrote: “All the perceptions of the human mind resolve themselves into two distinct kinds, which I shall call impressions and ideas. [Hume’s terminology is different from ours.] The difference between these consists in the degrees of force and liveliness, with which they strike upon the mind.” Hume himself admits that “in sleep, in a fever, in madness, or in any very violent emotions of soul, our ideas may approach to our impressions; as on the other hand it sometimes happens that our impressions are so faint and low, that we cannot distinguish them from our ideas.” It is certain that sensation and image are often confused; and some writers have accordingly proposed to drop the term ‘image’ and to replace it by ‘secondary sensation.’ Let us look at the facts.

There is no department of sense in which sensation stops entirely when its stimulus is removed; in all cases, even in that of sound, the sensation is prolonged, for a longer or shorter time, and either after an interval or without interruption, in what is called the positive after-image. Blow out a match in the dark, and wave the glowing stem about; you see complete circles or figures of eight; the sensation persists, although the stimulus has passed from one part of the retina to another. In some departments, the positive is followed by a negative after-image; we have already mentioned the antagonistic after-images of sight. So the removal of a continued warm stimulus leaves a sensation of coolness; and the swimming in the head that you feel while twirling round is followed, when you come to rest, by a swimming in the opposite direction. Lastly, the name of memory after-image has been given to an experience which is most familiar, perhaps, in the taking of dictation; as you write the words last spoken, the speaker’s voice still rings in your ears; the sound hangs for a few seconds, as if arrested, and your pen is guided by the mental echo. Similarly, an attentive glance at an object may set up a sort of photographic image that remains distinct for several seconds.

All the after-images are sensory in character. So too are the memory colours that we habitually lay over familiar objects (p. 63), and that make us see snow as white and gold as yellow and coal as black, just because they are ordinarily or typically white and yellow and black. So also are the recurrent images, those troublesome and haunting images to which most of us are subject at times: the tunes that run in our head and that we cannot get rid of, the rows of figures that obsess us after a long morning of calculation, the bright disc that keeps cropping up after we have spent several hours at the microscope. So, again, are the images that serve to complete and round out an imperfect perception. A favourite device of modern advertising is to outline the human figure only in part and to leave the remainder to the imagination; and you will perhaps notice, if you look attentively at such a figure, that the outline, so far as the suggestion of the neighbouring lines is unambiguous, is indeed completed in image, black on white or colour on colour; only where the completion is uncertain do the images fail. These tied images, so called because they are unequivocally bound up with the sensory portion of the perception, occur also in the sphere of sound; a missing orchestral part, if it is familiar, may be clearly heard by the conductor.

Not everyone has recurrent images; and perhaps only a large minority have tied images. The image—even if we decide that it is only a secondary sensation, psychologically indistinguishable from sensation—nevertheless represents a later stage of biological development than the sensation proper, and our equipment of images is correspondingly variable; your own experience may be richly imaginal, while your friend, under the same conditions, has hardly a trace of imagery. Those who do possess recurrent and tied images agree that they are distinguished from sensations rather by their context, by the presence or absence of certain other processes, than by any difference of nature. The same thing holds of those abnormal phenomena to which Hume referred. Hallucinatory images are by no means uncommon in the drowsy period that precedes sleep; we hear the telephone bell, or we hear our name called; some of us—there are, again, great differences in individuals—have hallucinations of sight. Dream images also differ markedly from individual to individual; but the dream is nearly always accepted as a real event. One of the most puzzling facts in this connection is the occurrence of concomitant or synæsthetic images. In the commonest case, that of coloured hearing, any auditory stimulus arouses, along with the appropriate sensation of hearing, whether tone or noise, a visual image of light or colour. The sound of the word Tuesday, for instance, may be seen as a light grey-green followed by a yellow! We might suppose, at first thought, that coloured hearing is due to association, to a connection between sight and hearing set up in childhood and continued into adult life; but the evidence points to some inborn connection in the nervous system; coloured hearing tends strongly to run in families. Moreover, we know of no natural or normal association of colours with tones, although the attempt has often been made to illustrate music by colours; the recent colour-scoring of the Russian composer Scriabin is, for instance, nothing more than an idiosyncrasy, and will make no general or permanent appeal to the musical public. There are many other kinds of synæsthesia, besides this connection of sight and sound; and we have no reason to think that every instance is to be explained in just the same way; in all cases, however, we have a particular sensation uniformly accompanied by another, which we may call either a secondary sensation or an image of sensory character.

Coming back to the normal life, we have next to note the part played in certain minds by habitual images. Just as, in Wagner’s operas, the performer comes upon the stage to the accompaniment of some characteristic musical phrase, some ‘motive,’ as it is called, which recurs again and again as he enters and reenters to take his share of the action, so in minds of the imaginal type such general notions as ‘virtue’ and ‘commerce’ and ‘summer’ may regularly call up mental pictures, little groups of images, which illustrate or characterise the notions: thus, virtue may be pictured mentally by the flash of a human figure, standing very upright. These pictures are usually incomplete, mere impressionist sketches; but they may remain unchanged for years.

Finally, we come to the images which enter into our ideas of memory and of imagination. We discuss these ideas later; here we need only say that the psychological distinction between sensation and image, if it is to be drawn at all, must be drawn between sensation and the free images of memory and imagination, and cannot be drawn earlier. Some psychologists believe that a memory-image can always be distinguished from a sensation, that the two processes differ in their intrinsic nature. It is difficult to put the question to the test of experiment; but what evidence we have seems to look the other way. We shall do best to suspend judgement.

The word ‘image’ is unfortunately used, as the foregoing paragraphs have shown, both for the simple image and for groups or clusters of images; thus, the recurrent image and the habitual image are always complex. Summing up our results, with this warning in mind, we may say that positive and negative after-images, memory colours, and synæsthetic images are definitely sensory in character; that the simple images which make up memory after-images, recurrent and tied and habitual images, hallucinations and dreams, appear to be of the same kind; and that the simple images which compose our ideas of memory and imagination may or may not be intrinsically different from sensations. The simple image may therefore be defined as an elementary mental process, akin to sensation and perhaps indistinguishable from it, which persists when the sensory stimulus is withdrawn or appears when the sensory stimulus is absent. We may say further that, while every normal person has very much the same equipment of sensations, there are great individual differences in the matter of secondary sensations or images; in some cases they are interwoven into the whole tissue of experience, in others they are infrequent or even lacking; we shall see presently how they may be replaced. In general, images of sight and sound are common; then come images of touch and temperature, and then again images of taste and smell, which are uncommon; organic images are very rare. Kinæsthetic images undoubtedly occur, and probably occur frequently; but they are likely to blend with kinæsthetic sensations, and so to escape notice.

[§ 18]. Simple Feelings and Sense-Feelings.—Many of our experiences are indifferent; but many of them, again, are pleasant or unpleasant. These two words, pleasant and unpleasant, denote elementary mental processes of a different sort from sensations and images; they are known as simple feelings. The term ‘feeling’ is itself even more ambiguous than the term ‘image’; it is natural to speak of ‘feeling’ a strain or effort, a warmth or cold; but we shall henceforth use it only in its technical meaning, to indicate the way in which stimuli affect us, pleasantly or unpleasantly. We must discard altogether the words pleasure and pain, although they have long been current as the names of the simple feelings, and although they are much less clumsy than pleasant and unpleasant. We discard them because pain is a sensation (p. 43); and pains, while usually unpleasant, may at times be pleasant; the scratching that relieves an itch and the nip of the wind on a brisk winter’s day are both pains, but they are also both pleasant.

The main difference between sensation and simple feeling is that a feeling cannot be made the object of direct attention. Try to attend to the pleasantness or unpleasantness of an experience, and the feeling evaporates, eludes you; it is like clutching a ghost; you find yourself beyond the feeling, so to speak, and face to face with some obtrusive sensation or image that you had no wish to meet. This peculiarity of feeling must, of course, be taken account of in our conduct of the psychological method of observation. The formula of observation (p. 19) was:

psychological (vivid experience → full report).

In the case of sensation, the observer is set or disposed, beforehand, to attend to sensation and to report upon sensation; the sensation comes, and is attended to; and the report which follows is determined, under the influence of the preliminary set or disposition, by the nature of the sensation. In the case of feeling, the observer is set to attend to sensation, but to report upon the feeling which accompanies the sensation; the sensation comes and is attended to; and the report then describes, under the influence of the preliminary set, the feeling which accompanied the sensation. That sounds a little paradoxical; but the method is not difficult in practice; and it has the advantage that we can use all manner of sensory stimuli (colours, tones, everything) in our study of feeling.

We find, first of all, that pleasant and unpleasant are really opposites; the colour or tone that is most often reported as pleasant is least often reported as unpleasant, and conversely. An obvious result? Not at all; for what is obvious to common sense demands very careful consideration at the hands of science; and the fact that, in this instance, common sense turns out to be right does not at all mean that we should have been justified in taking it for granted. We find, secondly, that intensity of feeling behaves like intensity of sensation (p. 67); the more pleasant or unpleasant an experience is, the more must the stimulus be changed if we are to feel a difference; and the less pleasant or unpleasant it is, the less change need be made to produce a change of feeling.

There is no convincing evidence of any qualities of feeling other than pleasant and unpleasant. There is evidence, on the other hand, that the simple feelings form intimate and characteristic blends with sensations, and especially with kinæsthetic and organic sensations; we may call such blends sense-feelings. Every sensory stimulus, even so local and trifling a thing as a tone of moderate intensity, sets up a widespread organic disturbance: a result that is natural, perhaps, in view of the manifold interconnections within the nervous system, but that we are nevertheless likely to overlook. This organic stir brings out kinæsthetic and organic sensations which may form the body of a sense-feeling, developed round about the disturbing tone, and giving it a peculiar tinge of feeling that it would not otherwise possess. The same thing holds of other stimuli. We can distinguish six types or classes of these sense-feelings: the agreeable and disagreeable, the exciting and subduing, and the straining and relaxing. Tastes and smells are preeminently agreeable or disagreeable. Deep tones are solemn and serious, that is, subduing; high tones are cheerful and playful, that is, exciting. The painter’s ‘warm’ colours, red and yellow, are exciting; his ‘cold’ blues are subduing; the gloom of a darkened room is positively depressing. Warmth and cold are themselves exciting and subduing. The straining and relaxing feelings are dependent upon the temporal course and succession of sensations; the interminable pedal-point in E♭ with which Wagner begins the Ring sets up a feeling of tension which is relaxed when the B♭ is added, only to grow again, and again relax when new tones are introduced; and if you follow the strokes of a slow-beating metronome you get a similar alternation of the two sense-feelings. Notice that the six names are all alike class-names; the sense-feelings themselves appear in numberless variety; but any particular sense-feeling may be referred to one or more of the classes. Notice also that the paired names are all opposites: a sense-feeling may be agreeably exciting, or agreeably subduing, but it cannot be excitingly subduing; and so on with the rest. Remember finally that the simple feeling taken alone, and not blended with sensory qualities into a sense-feeling, is always a bare pleasant or unpleasant.

We must next discuss the organic disturbances that accompany feeling itself. We know that feelings ‘express’ themselves in various ways; we blush for shame and pale from fear; we shake with rage, and our ‘heart beats high’ with hope. Now it is possible to measure all these organic changes; to record the rate and height of pulse, for instance, or the variation in the volume of a limb according as blood flows into it or is withdrawn from it; physiology puts the necessary instruments at our disposal. The observer may therefore be harnessed to some such system of recording apparatus, and may be subjected to some pleasant or unpleasant stimulus; he reports what he feels, and the experimenter is able to compare the report with the record from the instrument. The results of work of this sort are summed up in the following table; where a + stands for an increase, and a-for a decrease, of rate or height or volume, as the case may be.

The table asserts that, during a pleasant experience, our pulse is slowed and heightened; blood flows from the trunk into the extremities; and our breathing quickens and, perhaps, grows more shallow. During an unpleasant experience, the reverse of all these things takes place.

The pleasant and unpleasant experiences here referred to are, of course, agreeable and disagreeable sense-feelings; and we have the right to correlate the organic changes with pleasant and unpleasant feeling only because they remain the same so long as feeling remains the same, whatever may be the character of the sensory stimulus. There can be no doubt that similar tables may presently be made out for the other sense-feelings; indeed, that must be the case, in so far as the sense-feelings are stable blends of simple feeling with sensations. But it is not easy, in the case of the other pairs, to secure a stable blend, to keep the nature of the ‘excitement’ or the ‘relaxation’ just the same from experiment to experiment; and we shall therefore make no attempt here to list their bodily expressions. We come back to the general subject of expression when we deal with emotion (§ 51).

Can we now say anything definite about the nervous correlate of the simple feelings? Can we say what is going on in the nervous system when we feel pleasantly or unpleasantly? Unfortunately no: we have many theories, but no positive knowledge. There is, however, one view of feeling which has persisted from Aristotle to the present day; and we must say a word about it, if only because you cannot read far in psychology without running against some form of it, and you should not blindly accept it. We may call it the biological theory of feeling. Aristotle said that pleasure (we must now use the old-fashioned terms) accompanies the unimpeded exercise of any faculty, that is, the healthy exercise of any mental faculty upon its appropriate object; and that pain accompanies impeded activity. In more modern language, pleasure is for Aristotle a matter of efficiency. Herbert Spencer puts the same idea into evolutionary language; “pains are the correlatives of actions injurious to the organism, while pleasures are the correlatives of actions conducive to its welfare.” Does this statement really mean, though, that a man’s personal pleasures are always good for him and his personal pains bad for him?—because, if that is meant, it is not difficult to think of any number of cases to the contrary. No, not quite that; Spencer would qualify by saying that nature can only strike an average for the species; she cannot attend in detail to the individual; the sentence means that on the whole, in the long run, pleasures are good and pains are bad for us. We might reply that it is rather a poor average that makes the tearing off of a finger nail so exquisitely painful, though the loss hardly matters, and that allows the ravages of pulmonary tuberculosis to run so long a course before warning is given to the suffering organism. But let us offer a definite objection: a surgical operation is not pleasant; yet it may be the one thing necessary to save life. Spencer has his answer: “special and proximate pleasures and pains must be disregarded out of consideration for remote and diffused pleasures and pains.” In that case, however,—if the feelings are merely witnesses to the state of affairs at the moment, and not prophets of the future,—the correlation does not help us very much; nature’s achievement is less important, even for the species, than it seemed at first. Or take another objection: I am overheated, and I sit in a cooling draught; the result is catarrh or pneumonia; yet the coolness was pleasant. To be sure, says the biologist; and the local effect was good for you; the testimony of the feelings is limited in space as I have just acknowledged it to be limited in time. Again, however, we must rejoin that, in that event, the correlation is of less importance to the race than it was asserted to be; if things that are ‘sweet in the mouth’ are going to be ‘bitter in the belly’ we want to know it; it is small comfort to be told that the organ of taste is benefited by the pleasant sweetness. And so the argument might go on.

There is yet another difficulty. “Every pleasure,” says Spencer, “increases vitality; every pain decreases vitality. Every pleasure raises the tide of life; every pain lowers the tide of life.” Yet we read elsewhere that “pleasures are the incentives to life-supporting acts, and pains the deterrents from life-destroying acts.” Pain, then, is thoroughly bad for us, because it is detrimental to life; but pain at the same time is thoroughly good for us, because it prevents our doing what is detrimental to life. Pain as detrimental ought to have been eliminated by natural selection; pain as warning of what is detrimental has been conserved by natural selection. Can the two points of view be reconciled?

It would be foolish and overhasty to reject outright the biological view of feeling; the very fact that it has lasted through so many centuries and, in some form or other, has appealed to so many psychologists—the quotation which heads this chapter is a case in point!—raises a presumption in its favour. Our conclusion must rather be this: that general formulas, which need to be qualified almost as soon as they are phrased, and which lay themselves open to all kinds of specific objections, cannot help us to a psychology of feeling—or of anything else. When we have found out, by detailed experimental work, what the nervous correlate of simple feeling really is, then we may perhaps advance to some general biological view; but the detailed work must come first.

Questions and Exercises

(1) Answer the questions printed on pp. 255, 256 of F. Galton’s Inquiries into Human Faculty and Its Development (Everyman’s Library, E. P. Dutton & Co., New York; price 35 cents). When you have answered them, read Galton’s discussion of mental imagery, pp. 57 ff. (You will find many other interesting things in the book; for instance, the discussion of synæsthesia, pp. 105 ff.)

(2) Try to secure a memory after-image, (a) by glancing attentively at a lamplit study-table, and then closing the eyes; and (b) by listening attentively to a short musical phrase or to a dictated sentence. How do you distinguish this image from a positive after-image?

(3) Describe the tied images that you find in the following figure.

(4) How is it that very great differences in mental imagery may go undetected in everyday life?

(5) Try to give instances, from your own experience, (a) of the confusion of sensation and image, (b) of memory-colours, and (c) of the alteration of a perception by an image-complex. (An instance under (c) would be, for example, your failure to find something that you had lost, although it lay in plain sight, because you had a mental picture of it, different from its actual look in perception.)

(6) The following have been given, by various psychologists, as differences between sensation and simple feeling. What have you to say about them? (a) Sensation depends upon a present stimulus; feeling depends not only upon stimulus, but upon the whole state of the individual at the moment. (b) Sensations range between maximal differences; feelings between maximal opposites. (c) All sensations have corresponding images; there is no image of pleasantness or unpleasantness. (d) Sensations may be localised; feelings are not localisable.

(7) Professor Wundt, who first distinguished the groups of agreeable and disagreeable, exciting and subduing, straining and relaxing feelings, thinks that these experiences are not sense-feelings, but are all simple feelings; so that there are three dimensions of simple feeling, the pleasant-unpleasant, the exciting-subduing, and the straining-relaxing, corresponding in a way with the three dimensions of space. What criticism have you to offer? And how would you test Wundt’s theory?

(8) Do you think that a mixed feeling, a feeling which is at the same moment pleasant and unpleasant, is a possible experience? Give your reasons, and support them by observations. Can you remember any references, that bear on the question, in poetry or fiction?

(9) Analyse the sense-feelings of smarting pain, of health, of hunger, of oppressive heat.

(10) Can you give, from your own experience, any evidence for the belief that Weber’s law holds for intensity of feeling?

(11) The chapter teaches that the pleasantness of a perfume, of a word of praise, and of a kindly action is, as simple feeling, identical; there are no qualitative differences in the pleasant. To many persons this teaching is repugnant. Why? and how should their objections be answered?

(12) Define (without looking at the book!) sensation, simple image, simple feeling.

[References]

On images: Galton, as above; D. Hume, A Treatise of Human Nature, 1739, bk. i., pt. i., § 1; J. E. Downey, An Experiment on Getting an After-image from a Mental Image, in Psychological Review, viii., 1901, 42; E. B. Titchener, Lectures on the Experimental Psychology of the Thought-processes, 1909, Lect. 1; Text-book of Psychology, 1910, 194 ff.

On feeling: H. Spencer, The Principles of Psychology, i., 1881, ch. ix.; The Data of Ethics, 1887, chs. vi., vii.; J. M. Baldwin, Mental Development in the Child and the Race: Methods and Processes, 1906, ch. xvi., § 3; W. Wundt, Outlines of Psychology, trs. C. H. Judd, 1907, §§ 7, 12; E. B. Titchener, Lectures on the Elementary Psychology of Feeling and Attention, 1908, Lects. 2-4; Text-book of Psychology, 1910, 225 ff. For experimental methods: Titchener, Experimental Psychology, I., i., 1901, ch. vii.; ii., 1901, ch. vii.; C. S. Myers, A Text-book of Experimental Psychology, i., 1911, ch. xxiv.

[CHAPTER IV]

Attention