The stimulus that arouses this sort of behavior is something new and unfamiliar, or at least relatively so. When an object has been thoroughly examined, it is dropped for something else. It is when the cat has just been brought into a strange house that she rummages all over it from garret to cellar. A familiar object is "taken for granted", and arouses little exploratory response.

Quite a group of conscious impulses and emotions goes with exploratory behavior. The feeling or impulse of curiosity is something that everybody knows; like other impulses, it is most strongly felt when the end in view cannot be immediately reached. When you are prevented by considerations of propriety or politeness from satisfying your curiosity, then it is that curiosity is most "gnawing". A very definite emotion that occurs on encountering something extremely novel and strange is what we know as "surprise", and somewhat akin to this is "wonder".

Exploration, though fundamentally a form of playful activity, has great practical value in making the child acquainted with the world. It contains the germ of seeking for knowledge. We shall have to recur to this instinct more than once, under the head of "attention" and again under "reasoning".

{156}

Manipulation and exploration go hand in hand and might be considered as one tendency rather than two. The child wishes to get hold of an object, that arouses his curiosity, and he examines it while handling it. You cannot properly get acquainted with an object by simply looking at it, you need to manipulate it and make it perform; and you get little satisfaction from manipulating an object unless you can watch how it behaves.

Tendencies running counter to exploration and manipulation.

Just as playful activity in general is limited by the counter tendencies of fatigue and inertia, so the tendency to explore and handle the unfamiliar is held in check by counter tendencies which we may call "caution" and "contentment".

Watch an animal in the presence of a strange object. He looks at it, sniffs, and approaches it in a hesitating manner; suddenly he runs away for a short distance, then faces about and approaches again. You can see that he is almost evenly balanced between two contrary tendencies, one of which is curiosity, while the other is much like fear. It is not full-fledged fear, not so much a tendency to escape as an alertness to be ready to escape.

Watch a child just introduced to a strange person or an odd-looking toy. The child seems fascinated, and can scarcely take his eyes from the novel object, but at the same time he "feels strange", and cannot commit himself heartily to getting acquainted. There is quite a dose of caution in the child's make-up—more in some children than in others, to be sure—with the result that the child's curiosity gets him into much less trouble than might be expected. Whether caution is simply to be identified with fear or is a somewhat different native tendency, it is certainly a check upon curiosity.

By "contentment" we mean here a liking for the familiar, {157} which offsets to some extent the fascination of the novel. If you are perfectly contented, you are not inclined to go out exploring; and when you have had your fill of the new and strange, you like to get back to familiar surroundings, where you can rest in content. Just as playful behavior of all sorts decreases with increasing age, so the love for exploring decreases, and the elderly person clings to the familiar. But even children may insist in occupying their own particular chair, on eating from a particular plate, and on being sung to sleep always with the same old song. They are "little creatures of habit", not only in the sense that they readily form habits, but in the sense that they find satisfaction in familiar ways and things. Here we see the germ of a "conservative" tendency in human nature, which balances, to a greater or less extent, and may decidedly overbalance, the "radical" tendency of exploration.

Laughter.

We certainly must not omit this from our list of instincts, for, though it does not appear till some time after birth, it has all the earmarks of an instinctive response. If it were a learned movement, it could be made at will, whereas, as a matter of fact, few people are able to produce a convincing laugh except when genuinely amused, which means when the instinctive tendency to laugh is aroused by some appropriate stimulus. The emotion that goes with laughing may be called mirth or amusement, and it is a strongly impulsive state of mind, the impulse being simply to laugh, with no further end in view.

The most difficult question about laughter is to tell in general psychological terms what is the stimulus that arouses it. We have several ingenious theories of humor, which purport to tell; but they are based on adult humor, and we have as yet no comprehensive genetic study of laughter, tracing it up from its beginnings in the child. Laughing certainly belongs with the play instincts, and possibly the {158} stimulus is no more definite, at first, than that which arouses other playful activity. The baby seems to smile, at first, just from good spirits (euphoria). The stimuli that, a little later, arouse a burst of laughter have an element of what we may call "expected surprise" (as dropping a rattle and exploding with laughter when it bangs on the floor, and keeping this up time after time), and this element can still be detected in various forms of joke that are effective mirth-provokers in the adult. But why the child should laugh when tickled, at the same time trying to escape, is a poser. Many students of humor have subscribed to the theory that what makes us laugh is a sudden sense of our own superiority, thus attaching laughter to the self-assertive instinct, soon to be discussed. The laugh of victory, the laugh of defiance, the laugh of mockery, the sly or malicious laugh, support this theory, but can it be stretched to cover the laugh of good humor, the tickle laugh, or the baby's laugh in general? That seems very doubtful, and we must admit that we do not know the essential element in a laughter stimulus. One thing is fairly certain: that, while laughing is a native response, we learn what to laugh at, for the most part, just as we learn what to fear.

Fighting.

Hold the new-born infant's arms tightly against its sides, and you witness a very peculiar reaction: the body stiffens, the breath may be held till the face is "red with anger"; the child begins to cry and then to scream; the legs are moved up and down, and the arms, if they can be got free, make striking or slashing movements. In somewhat older children, any sort of restraint or interference with free movement may give a similar picture, except that the motor response is more efficient, consisting in struggling, striking, kicking, and biting. It is not so much pain as interference that gives this reaction. You get it if you take away a toy the child is playing with, or if you forbid {159} the child to do something he is bent on doing. In animals, the fighting response is made to restraint, to being attacked, or to being interfered with in the course of feeding, or mating, or in the instinctive care of the young. The mother lioness, or dog or cat or hen, is proverbially dangerous; any interference with the young leads to an attack by the mother. The human mother is no exception to this rule. In human adults, the tendency to fight is awakened by any interference with one's enterprises, by being insulted or got the better of or in any way set down in one's self-esteem.

In general, the stimulus to fighting is restraint or interference. Let any reaction-tendency be first aroused and then interfered with, and pugnacious behavior is the instinctive result.

The stimulus may be an inanimate object. You may see a child kick the door viciously when unable to open it; and grown-ups will sometimes tear, break or throw down angrily any article which they cannot make do as they wish. A bad workman quarrels with his tools. Undoubtedly, however, interference from other persons is the most effective stimulus.

The impulse so aroused is directed primarily towards getting rid of the restraint or interference, but also towards inflicting damage on the opponent; and with this impulse often goes the stirred-up organic and emotional state of anger. As brought out in the chapter on emotion, the organic state in anger is nearly or quite identical with that in fear of the active type; and the two states of the individual differ in respect to impulse rather than in respect to emotion. In fear, the impulse is to get away from the adversary, in anger to get at him. The emotion of anger is not always aroused in fighting, for sometimes there is a cold-blooded desire to damage the adversary.

The motor response, instinctively consisting of struggling, kicking, etc., as already described, becomes modified {160} by learning, and may take the form of scientific fistwork, or the form of angry talk, favored by adults. Or, the adversary may be damaged in his business, in his possessions, in his reputation, or in other indirect ways. The fighting spirit, the most stimulating of the emotions, gives energy to many human enterprises, good as well as bad. The successful reformer must needs be something of a fighter.

Thus far we have said nothing to justify our placing fighting here among the play instincts. Fighting against attack has survival value, fighting to protect the young has survival value, and, in general, the defensive sort of fighting has survival value, even though interference with play activity is just as apt to give this response as interference with more serious activities.

But there is more than this to the fighting instinct. The stimulus of interference is not always required. Consider dogs. The mere presence of another dog is often enough to start a scrap, and a good fighting dog will sally forth in search of a fight, and return considerably mauled up, which does not improve his chances for survival, to say the least. Fighting of this aggressive sort is a luxury rather than a necessity. It has play value rather than survival value. There can be no manner of doubt that pugnacious individuals, dogs or men, get more solid satisfaction from a good fight than from any other amusement. You see people "itching for a fight", and actually "trying to pick a quarrel", by provoking some other person who is strictly minding his own business and not interfering in the least. A battle of words usually starts in some such way, with no real reason, and a battle of words often develops into a battle of tooth and nail. Two women were brought before the judge for fighting, and the judge asked Mrs. Smith to tell how it started. "Well, it was this way, your honor. I met Mrs. Brown carrying a basket on her arm, and I says {161} to her, 'What have ye got in that basket?' says I. 'Eggs', says she. 'No!' says I. 'Yes!' says she. 'Ye lie!' says I. 'Ye lie!' says she. And a 'Whoop!' says I, and a 'Whoop!' says she; and that's the way it began, sir."

We have, then, to recognize aggressive fighting, in addition to defensive, and the aggressive sort certainly belongs among the play instincts.

The instincts that by acting counter to fighting hold it in check are several: laughter—a good laugh together allays hostility; or the parental instinct—a parent will stand treatment from his child that he would quickly resent from any one else; or self-assertion—"Too proud to fight!" But the most direct checks are afforded by inertia—"What's the use?"—and especially by fear and caution.

Fighting, both defensive and aggressive, has so close a connection with the more generalized self-assertive tendency that it might be included under that instinct. It may be regarded as a special form of self-assertive behavior, often complicated with the emotion of anger.

Self-assertion.

What then is this wonderful instinct of self-assertion, to which fighting and much of laughing are subordinate? "Assertiveness", "masterfulness", and the "mastery impulse" are alternative names. Of all the native tendencies, this is the one most frequently aroused, since there is scarcely a moment of waking (or dreaming) life when it is not more or less in action. It is so much a matter of course that we do not notice it in ourselves, and often not in other persons; and even clever psychological observers have seemed entirely blind to it, and given it no place in their list of instincts.

Self-assertion, like fighting, has two forms, the defensive and the aggressive, and in either case it may be a response to either people or things. That gives four varieties of self-assertive behavior, which may be labeled as follows:

{162}

1. Defensive reaction to things, overcoming obstruction, putting through what has been undertaken—the success motive.

2. Defensive reaction to persons, resisting domination by them—the independence motive.

3. Aggressive reaction to things—seeking for power.

4. Aggressive reaction to persons—seeking to dominate. We will take these up in order, beginning with the most elemental.

1. Overcoming obstruction. The stimulus here is much the same as that which induces fighting, but the response is simpler, without anger and without the impulse to do damage. Take hold of a baby's foot and move it this way or that, and you will find that the muscles of the leg are offering resistance to this extraneous movement. Obstruct a movement that the baby is making, and additional force is put into the movement to overcome the obstruction. An adult behaves in a similar way. Let him be pushing a lawn-mower and encounter unexpected resistance from a stretch of tough grass; involuntarily he pushes harder and keeps on going—unless the obstruction is too great. Let him start to lift something that is heavier than he thinks; involuntarily he "strains" at the weight, which means that a complex instinctive response occurs, involving a rigid setting of the chest with holding of the breath, and increased muscular effort. This instinctive reaction may be powerful enough to cause rupture.

Other than purely physical resistance is overcome by other self-assertive responses. When the child's toy will not do what he wants it to do, he does not give up at once, but tries again and puts more effort into his manipulation. When, in school, he is learning to write, and finds difficulty in producing the desired marks, he bends over the desk, twists his foot round the leg of his chair, screws up his face, {163} and in other ways reveals the great effort he is making. An adult, engaged in some piece of mental work, and encountering a distraction, such as the sound of the phonograph downstairs, may, of course, give up and listen to the music, but, if he is very intent on what he is doing, he puts more energy into his work and overcomes the distraction. When he encounters a baffling problem of any sort, he does not like to give it up, even if it is as unimportant as a conundrum, but cudgels his brains for the solution. As a general proposition, and one of the most general propositions that psychology has to present, we may say that obstruction of any sort, encountered in carrying out any intention whatever, acts as a stimulus to the putting of additional energy into the action.

Anger is often aroused by obstruction, but anger does not develop a tenth as often, in the course of the day, as the plain overcoming reaction. The impulse is not to do damage, but to overcome the obstruction and do what we have set out to do. The emotional state might sometimes be called "determination", sometimes "zeal"; but the most elementary state belonging here is effort. The feeling of effort is, partly at least, a sensation complex resulting from stiffening the trunk and neck, knitting the brows, and other muscular strains that have practical utility in overcoming physical resistance and that are carried over to the overcoming of other sorts of resistance, where they have no obvious utility. Effort is a simpler emotion than anger, and occurs much more frequently.

2. Resisting domination by other persons. The child shows from an early age that he "has a will of his own", and "wants his own way" in opposition to the commands of other persons. There is an independent spirit in man that is native rather than acquired. The strength of this impulse differs, to be sure, in different individuals, some {164} children being more "contrary" and others more docile; but there probably never was a child without a good dose of disobedience in his make-up. In order to have a nice, obedient child, you have to "break" him like a colt, though you can use reason as well as force in breaking a child. This process of "breaking" gives a habit of obedience to certain persons and along certain lines; but, outside of these limits, the child's independence is still there and ready to be awakened by any attempt to dominate him. In youth, with the sense of power that comes from attaining adult stature and muscular strength, the independent spirit is strengthened, with the result that you seldom see a youth, or an adult, who can take orders without at least some inner opposition and resentment.

3. Seeking for power over things. The self-assertive response to things is not limited to overcoming the obstructions offered by things to the accomplishment of our purposes; but we derive so much positive satisfaction from overcoming obstruction and mastering things that we go out in search of things to master. The child's manipulation has an element of masterfulness in it, for he not only likes to see things perform, but he likes to be the one that makes them perform. If he has a horn, he is not satisfied till he can sound it himself. The man with his automobile is in the same case. When it balks, he is stimulated to overcome it; but when it runs smoothly for him, he has a sense of mastery and power that is highly gratifying. Chopping down a big tree, or moving a big rock with a crowbar, affords the same kind of gratification; and so does cutting with a sharp knife, or shooting with a good bow or gun, or operating any tool or machine that increases one's power. Quite apart from the utility of the result accomplished, any big achievement is a source of satisfaction to the one who has done it, because it gives play to aggressive self-assertion. Many {165} great achievements are motived as much by the zest for achievement as by calculation of the advantages to be secured.

4. Seeking to dominate other people. The individual not simply resists domination by other people, but he seeks to dominate them himself. Even the baby gives orders and demands obedience. Get a number of children together, and you will see more than one of them attempt to be the leader in their play. Some must necessarily be followers just now, but they will attempt to take the lead on another occasion. The "born leader" is perhaps one who has an exceptionally strong dose of masterfulness in his make-up, but he is, still more, one who has abilities, physical or mental, that give him the advantage in the universal struggle for leadership.

Besides giving orders and taking the lead, there are other ways in which the child finds satisfaction for his instinct to dominate. Showing off is one, bragging is one, doing all the talking is one; and, though in growing older and mixing with people the child becomes less naive in his manner of bragging and showing off, he continues even as an adult to reach the same end in more subtle ways. Going about to win applause or social recognition is a seeking for domination. Anything in which one can surpass another becomes a means of self-assertion. One may demonstrate his superiority in size, strength, beauty, skill, cleverness, virtue, good humor, cooeperativeness, or even humility, and derive satisfaction from any such demonstration. The impulse to dominate assumes literally a thousand disguises, more rather than less.

Rivalry and emulation, sometimes accorded a separate place in a list of the instincts, seem well enough provided for under the general head of self-assertion. They belong on the social side of assertive behavior, i.e., they are responses to other people and aim at the domination of other {166} people or against being dominated by them. But the struggle for mastery, in rivalry, does not take the form of a direct personal encounter. Compare wrestling with a contest in throwing the hammer. In wrestling the mastery impulse finds a direct outlet in subduing the opponent, while in throwing the hammer each contestant tries to beat the other indirectly, by surpassing him in a certain performance. This you would call rivalry, but wrestling is scarcely rivalry, because the struggle for mastery is so direct. Rivalry may seek to demonstrate superiority in some performance, or to win the favor of some person or social group, as in the case of rivals in love.

When we speak of "emulation", we have in mind the sort of behavior observed when one child says, "See what I can do!" and the other counters with, "Pooh! I can do that, too". Or, the first child wins applause by some performance, and we then notice the second child attempting the same. It is a case of resisting the indirect domination of another, by not letting him surpass us in performance or in social recognition.

Thwarted self-assertion deserves special mention, as the basis for quite a number of queer emotional states. Shame, sulkiness, sullenness, peevishness, stubbornness, defiance, all go with wounded self-assertion under different conditions. Envy and jealousy belong here, too. Shyness and embarrassment go with self-assertion that is doubtful of winning recognition. Opposed to all these are self-confidence, the cheerful state of mind of one who seeks to master some person or thing and fully expects to do so, and elation, the joyful state of one who has mastered.

Submission.

Is there any counter-tendency that limits self-assertion and holds it in check? Inertia and fear of course have this effect, but is there any specific instinct precisely opposite to self-assertion? A difficult question, not {167} yet to be answered with any assurance; but there is some evidence of a native submissive or yielding tendency. Two forms may be distinguished: yielding to obstruction, and yielding to the domination of other persons.

Giving up, in the face of obstacles, is certainly common enough, but at first thought we should say that the individual was passive in the matter, and simply forced to yield, as a stone is brought to a stop when it strikes a wall. In reality, giving up is not quite so passive as this. There is no external force that can absolutely force us to give up, unless by clubbing us on the head or somehow putting our reactive mechanism out of commission. As long as our brain, nerves and muscles are able to act, no external force can absolutely compel us to cease struggling. Since, then, we do cease struggling before we are absolutely out of commission, our giving up is not a purely passive affair, but our own act, a kind of reaction; and no doubt a native reaction. Further, when struggling against a stubborn obstacle, we sometimes feel an impulse to give up, and giving up brings relief.

The ability to give up is not a mere element of weakness in our nature, but is a valuable asset in adapting ourselves to the environment. Adaptation is called for when the reaction first and most naturally made to a given situation does not meet the requirements of the situation. A too stubborn assertiveness means persistence in this unsuitable reaction, and no progress towards a successful issue; whereas giving up the first plan of attack, and trying something else instead, is the way towards success. Some people are too stubborn to be adaptable.

The docility of the child, who believes whatever is told him, has in it an element of submissiveness. There is submissiveness also in the receptive attitude appropriate in observation and forming opinions—the attitude of looking for the facts and accepting them as they are rather than seeking {168} to confirm one's own prepossessions. Bias is self-assertive, impartiality is submissive to some degree.

Yielding to the domination of other persons often occurs unwillingly, and then comes under the head of "thwarted self-assertion"; but the question is whether it ever occurs willingly and affords satisfaction to the individual who yields. We certainly yield with good grace to one who so far outclasses us that competition with him is unthinkable. An adult may arouse the submissive response in a child; and the social group, by virtue of its superior power and permanence, may arouse it in the individual adult. Hero worship seems a good example of willing submission, agreeable to the one who submits. There are persons who are "lost" without a hero, without some one to lean on, some one to tell them what to do and even what to believe. This looks much like the "filial" or "infantile" instinct that was mentioned before as a possibility, and the dependent spirit in an adult possibly represents a continuation of the infantile attitude into adult life.

Some behavior that looks submissive is really self-assertion in disguise. There are two forms of self-assertion that are specially likely to be taken for submission. Wounded or thwarted self-assertion is one. Shame and envy are like submission in this respect, that they involve an absence of self-confidence or self-assurance, but they do not afford the satisfaction of willing submission, nor the relief of giving up the struggle against obstacles. So far from being genuinely submissive, they are states in which the self is making a violent and insistent demand for justification or social recognition. The other form of self-assertion which looks like submission occurs when a person identifies himself with a superior individual or with a social group. He will then boast of the prowess of his hero or of the prestige of his group, whether it be his family, his school, {169} his town or his country. Now, boasting cannot by any stretch of the imagination be regarded as a sign of submissiveness; it is a sign of assertiveness, and nothing else. What has happened here is that the individual, having identified himself with his hero or his group, finds in their greatness a means of asserting himself as against other individuals who have not the good fortune to be so identified. This transferred self-assertion is a strong element in loyalty and public spirit, and plays a large and useful part in public affairs.

{170}

EXERCISES

1. Make an outline of the chapter, in the form of a table, which shall show for each instinct: (a) the natural stimulus, (b) the native motor response, (c) the end-result that the instinct tends towards, in its adult as well as its native condition, and (d) the emotion, if any, that goes with the activity of the instinct.

2. An adult tendency or propensity may be simply an unmodified instinct, or it may be derived from instincts by combination, etc. Try to identify each of the following as an instinct, or to analyze it into two or more instincts:

(a) Love for adventure. (b) Patriotism. (c) A father's pride in his children. (d) Love for travel. (e) Insubordination. (f) Love for dancing.

3. Which of the instincts are most concerned in making people work?

4. Show how self-assertion finds gratification in the life-work of

an actor. a physician. a housekeeper. a teacher. a railroad engineer.

5. Arrange the following impulses and emotions in the order of the frequency of their occurrence in your ordinary day's work and play:

(a) Fear. (b) Anger. (c) Disgust (d) Curiosity. (e) Self-assertion. (f) Submission. (g) The tendency to protect or "mother" another.

6. How do "practical jokes" lend support to the view that laughter is primarily aroused by a sense of one's own superiority?

7. Get together a dozen jokes or funny stories, and see how many of them can be placed with the practical jokes in this respect.

8. Mention some laughter-stimuli that do not lend support to the theory mentioned in Exercise 6.

9. What instincts find outlet in (a) dress, (b) automobiling, (c) athletics, (d) social conversation?



{171}



REFERENCES

McDougall's Social Psychology gives, in Chapters III and IV, an inventory of the instinctive equipment of mankind, and in Chapter V attempts to analyze many complex human emotions and propensities into their native elements.

Thorndike, in his Educational Psychology, Briefer Course, 1914, Chapters, II-V, attempts a more precise analysis of stimulus and response.

Watson's Psychology from the Standpoint of a Behaviorist, 1919, attempts in Chapter VI to show that there are only three primary emotions, fear, rage and love; and in Chapter VII gives a critical review of the work on human instincts.

H. C. Warren, in Chapter VI of his Human Psychology, 1919, gives a brief survey of the reflexes and instincts.

{172}

CHAPTER IX

THE FEELINGS

PLEASANTNESS AND UNPLEASANTNESS, AND OTHER STATES OF FEELINGS AND THEIR INFLUENCE UPON BEHAVIOR

Feeling is subjective and unanalyzed. It is conscious, and an "unconscious feeling" would be a contradiction in terms. But, while conscious, it is not cognitive; it is not "knowing something", even about your subjective condition; it is simply "the way you feel". As soon as you begin to analyze it, and say, "I feel badly here or there, in this way or in that", you know something about your subjective condition, but the feeling has evaporated for the instant. In passing over into definite knowledge of facts, it has ceased to be feeling.

Feeling is an undercurrent of consciousness, or we might call it a background. The foreground consists of what you are taking notice of or thinking about, or of what you are intending to do; that is to say, the foreground is cognitive or impulsive, or it may be both at once, as when we are intent on throwing this stone and hitting that tree. In the background lies the conscious subjective condition. Behind facts observed and acts intended lies the state of the individual's feeling, sometimes calm, sometimes excited, sometimes expectant, sometimes gloomy, sometimes buoyant.

The number of different ways of feeling must be very great, and it would be no great task to find a hundred different words, some of them no doubt partly synonymous, to complete the sentence, "I feel ". All the {173} emotions, as "stirred-up states of mind", belong under the general head of the feelings.

But when the psychologist speaks of the feelings, he usually means the elementary feelings. An emotion is far from elementary. If you accept the James-Lange theory, you think of an emotion as a blend of organic sensations; and if you reject that theory, you would still probably agree that such an emotion as anger or fear seems a big, complex state of feeling. It seems more complex than such a sensation as red, warm, or bitter, which are called elementary sensations because no one has ever succeeded in decomposing them into simpler sensations. Now, the question is whether any feelings can be indicated that are as elementary as these simple sensations.

Pleasantness and Unpleasantness Are Simple Feelings

No one has ever been able to break up the feelings of pleasantness and unpleasantness into anything simpler. "Pleasure" and "displeasure" are not always so simple; they are names for whole states of mind which may be very complex, including sensations and thoughts in addition to the feelings of pleasantness and unpleasantness. "Pain" does not make a satisfactory substitute for the long word "unpleasantness", because "pain", as we shall see in the next chapter, is properly the name of a certain sensation, and feelings are to be distinguished from sensations. Red, warm and bitter, along with many others, are sensations, but pleasantness and unpleasantness are not sensations.

How, then, do the elementary feelings differ from sensations? In the first place, sensations submit readily to being picked out and observed, and in fact become more vivid when they are brought into the "foreground", while feelings grow vague and lose their character when thus singled {174} out for examination. Attend to the noises in the street and they stand out clearly, attend to the internal sensation of breathing and it stands out clearly, but attend to your pleasant state of feeling and it retreats out of sight.

In the second place, sensations are "localized"; you can tell pretty well where they seem to come from. Sensations of light, sound and smell are localized outside the body, sensations of touch are localized on the skin (or sometimes outside), taste sensations are localized in the mouth, organic and muscular sensations in some part of the body. On the other hand, pleasantness and unpleasantness are much less definitely localized; they seem to be "in us", without being in any special part of us.

In the third place, feelings differ from sensations in having no known sense organs. There is no special sense organ or set of sense organs for the feeling of pleasantness or unpleasantness, as there is for warmth or cold. Some sensations are pleasant, to be sure, and some unpleasant; but there is no one kind of sense organ that has the monopoly of either sort of feeling.

Feeling-Tone of Sensations

The pleasantness or unpleasantness characteristic of many sensations is called their "feeling-tone", and sensations that are markedly pleasant or unpleasant are said to have a strong or pronounced feeling-tone. Bitter is intrinsically unpleasant, sweet pleasant, the salty taste, when not too strong, neither one nor the other, so that it has no definite feeling-tone. Odors, as well as tastes, usually have a rather definite feeling-tone. Of sounds, smooth tones are pleasant, grating noises unpleasant. Bright colors are pleasant, while dull shades are sometimes unpleasant, sometimes merely indifferent or lacking in feeling-tone. Pain is usually unpleasant, moderate warmth and cold pleasant, simple touch {175} indifferent. Very intense sensations of any kind are likely to be unpleasant.

The statements made above as to the subjectivity and non-localization of feeling do not apply altogether to the feeling-tone of sensations. The pleasantness or unpleasantness of a sensation is localized with the sensation and seems to belong to the object rather than to ourselves. The unpleasantness of a toothache seems to be in the tooth rather than simply "in us". The pleasantness of a sweet taste is localized in the mouth, and we even think of the sweet substance as being objectively pleasant. We say that it is a "pleasant day", and that there is a "pleasant tang in the air", as if the pleasantness were an objective fact.

By arguing with a person, however, you can get him to admit that, while the day is pleasant to him, and the tang in the air pleasant to him, they may be unpleasant to another person; and he will admit that a sweet substance, ordinarily pleasant, is unpleasant when he has had too much of sweet things to eat. So you can make him realize that pleasantness and unpleasantness depend on the individual and his condition, and are subjective rather than objective. Show a group of people a bit of color, and you will find them agreeing much better as to what color that is than as to how pleasant it is. Feeling-tone is subjective in the sense that people disagree about it.

Theories of Feelings

1. Pleasantness might represent a general organic state, and unpleasantness the contrary state, each state being an internal bodily response to pleasant or unpleasant stimuli, and making itself felt as an unanalyzable compound of vague internal sensations.

This theory of feeling is certainly attractive, and it would {176} account very well for all the facts so far stated, for the subjectivity of feeling, for its lack of localization, and for the absence of specific sense organs for the feelings. It would bring the feelings into line with the emotions. But the real test of the theory lies just here: can we discover radically different organic states for the two opposite feelings?

Numerous experiments have been conducted in the search for such radically different organic states, but thus far the search has been rather disappointing. Arrange to record the subject's breathing and heart beat, apply pleasant and unpleasant stimuli to him, and see whether there is any characteristic organic change that goes with pleasant stimuli, and an opposite change with unpleasant stimuli. You should also obtain an introspective report from your subject, so as to be sure that the "pleasant stimuli" actually gave a feeling of pleasantness, etc. Certain experiments of this sort have indicated that with pleasantness goes slower heart beat and quicker breathing, with unpleasantness quicker heart beat and slower breathing. But not all investigators have got these results; and, anyway, it would be impossible to generalize to the extent of asserting that slow heart beat always gave a pleasant state of feeling, and rapid heart beat an unpleasant; for there is slow heart beat during a "morning grouch", and rapid during joyful expectation. Or, in regard to breathing, try this experiment: hasten your breathing and see whether a feeling of pleasantness results; slacken it and see whether unpleasantness results. The fact is that pleasantness can go with a wide range of organic states, so far as these are revealed by heart beat and breathing; and the same with unpleasantness. If there is any organic fact definitely characteristic of either state of feeling, it is a subtle fact that has hitherto eluded observation.

{177}

2. Pleasantness might represent smooth and easy brain action, unpleasantness slow and impeded brain action. According to this theory, unimpeded progress of nerve currents through the brain is pleasant, while resistance encountered at the brain synapses is unpleasant. A stimulus is pleasant, then, because the nerve currents started by it find smooth going through the brain centers, and another stimulus is unpleasant because it finds the going poor.

While this theory looks good in some ways, and fits some cases very well—as the great unpleasantness of blocked reaction, where you cannot make up your mind what to do—there are two big objections to it. The first objection is found in the facts of practice. Practising any reaction makes it more and more smooth-running and free from inner obstruction, and should therefore make it more and more pleasant; but, as a matter of fact, practising an unfamiliar act of any sort makes it more pleasant for a time only, after which continued practice makes it automatic and neither pleasant nor unpleasant. The smoothest reactions, which should give the highest degree of pleasant feeling according to the theory, are simply devoid of all feeling.

The second objection lies in the difficulty of believing unpleasant stimuli to give slow, impeded reactions. On the contrary, the instinctive defensive reactions to unpleasant stimuli are very quick, and give no sign of impeded progress of nerve currents through the brain centers.

3. There is one fact, not yet taken into account, that may point the way to a better theory. Feeling is impulsive. In pleasantness, the impulse is to "stand pat" and let the pleasant state continue; in unpleasantness, the impulse is to end the state. The impulse of pleasantness is directed towards keeping what is pleasant, and the impulse of unpleasantness is directed towards getting rid of the unpleasant. In indifference there is no tendency either to keep or to be {178} rid of. These facts are so obvious as scarcely to need mention, yet they may be the core of this whole matter of feeling. Certainly they are the most important facts yet brought out as relating feeling to conduct.

Putting this fact into neural terms, we say that pleasantness goes with a neural adjustment directed towards keeping, towards letting things stay as they are; while unpleasantness goes with an adjustment towards riddance. Bitter is unpleasant because we are so organized, by native constitution, as to make the riddance adjustment on receiving this particular stimulus. In plain language, we seek, to be rid of it, and that is the same as saying it is unpleasant. Sweet is pleasant for a similar reason.

There is some evidence that these adjustments occur in that part of the brain called the thalamus. [Footnote: See p. 65.]

Sources of Pleasantness and Unpleasantness

Laying aside now the difficult question of the organic and cerebral nature of the feelings, we turn to the simpler question of the stimuli that arouse them. A very important fact immediately arrests our attention. There are two different kinds of stimuli for pleasantness, and two corresponding kinds for unpleasantness. The one kind is typified by sweet and bitter, the other by success and failure. Some things are pleasant (or unpleasant) without regard to any already awakened desire, while other things are pleasant (or unpleasant) only because of such a desire. A sweet taste is pleasant even though we were not desiring it at the moment, and a bitter taste is unpleasant though we had no expectation of getting it and no desire awakened to avoid it. On the other hand, the sight of our stone hitting the tree is pleasant only because we were aiming at the tree, and {179} the sight of the stone going to one side of the tree is unpleasant just for the same reason.

Some things we want. Because we like them; Some things we like. Because we want them.

We want candy, because we like the sweet taste; but we like a cold drink because and when we are thirsty and not otherwise. Thirst is a want for water, a state of the organism that impels us to drink; and when we are in this state, we like a drink, a drink is pleasant then. How absurd it would be to say that we were thirsty because we liked to drink! when the fact is that we like to drink because we are thirsty. The desire to drink must first be aroused, and then drinking is pleasant.

What is true of thirst is true of hunger, or of any organic need. The need must first be aroused, and then its satisfaction is pleasant. This applies just as well to fighting, laughing, fondling a baby, and to all the instincts. It gives you no pleasure to strike or kick a person, or to swear at him, unless you are first angry with him. It gives you no pleasure to go through the motions of laughing unless you "want to laugh", i.e., unless you are amused. It gives you no pleasure to fondle the baby unless you love the baby. Let any instinct be first aroused, and then the result at which the instinct is aimed causes pleasure, but the same result will cause no pleasure unless the instinct has been aroused.

The same can be said of desires that are not exactly instinctive. At a football game, for example, when one of the players kicks the ball and it sails between the goal posts, half of the spectators yell with joy, while the other half {180} groan in agony. Why should the appearance of a ball sailing between two posts be so pleasant to some, and unpleasant to others? This particular appearance is by itself neither pleasant nor unpleasant, but because the desire to see this happen has been previously aroused in the partisans of one team, and the desire that it should not happen in the partisans of the other, therefore it is that the pleasantness or unpleasantness occurs. First arouse any desire, and then you can give pleasure by gratifying it, displeasure by thwarting it. This is the pleasure of success, and the unpleasantness of failure.

Pleasures of this class may be named secondary, because they depend upon pre-aroused desires.

Primary Likes and Dislikes

Though many of the most intense pleasures and displeasures of life are of the secondary type, this fact must not blind us to the existence of the primary pleasures and displeasures, typified by sweet and bitter. Any sensation with a pronounced feeling-tone is a primary pleasure or displeasure. We like or dislike it just for itself, and without regard to the gratification of any pre-aroused instinct or desire.

There are natural likes and dislikes—apart from the satisfaction of instincts—and there are others that are acquired. In other words, there are native tastes and acquired tastes. Individuals differ considerably in their native tastes, and still more in their acquired tastes. Liking for sweets is native, liking for fragrant odors is native, but liking for lemonade, or black coffee, or olives, or cheese, is acquired, and not acquired by everybody. Liking for bright colors is native, but liking for subdued colors, and the special pleasure in color harmonies, are acquired. So we might {181} run through the list of the senses, finding under each some sensations with native feeling-tone, and other sensations that acquire feeling-tone through experience.

Some people have a native liking for numbers and other facts of a mathematical nature. We say of such a one that he has a natural taste for mathematics. Another has a natural dislike for the same. Some have a taste for things of the mechanical sort, others fight shy of such things. Some have a natural taste for people, being sociable creatures—which means more than being gregarious—while others are little interested in mixing with people, observing their ways, and the give and take of friendly intercourse.

Now the question arises whether these native likes and dislikes, for odors, colors, tones, numbers, machinery, and people, are really independent of the instincts. Some psychologists have insisted that all the interest and satisfaction of life were derived from the instincts, laying special stress on the instincts of curiosity and self-assertion.

With respect to our "natural liking for mathematics", these psychologists would argue as follows: "First off, curiosity is aroused by numbers, as it may be by any novel fact; then the child, finding he can do things with numbers, gratifies his mastery impulse by playing with them. He encounters number problems, and his mastery impulse is again aroused in the effort to solve the problems. Later, he is able to 'show off' and win applause by his mathematical feats, and thus the social form of self-assertion is brought into play. This particular child may have good native ability for mathematics, and consequently his mastery impulse is specially gratified by this kind of activity; but he has no real direct liking for mathematics, and all his industry in this field is motivated by curiosity and especially by self-assertion."

The instinct psychologists have a strong case here, as {182} they would have also in regard to the liking for machinery. Still, the mathematical individual would not be convinced, for he would testify that numbers, etc., made a direct appeal to him. Numbers, geometric forms, and algebraic transformations are fascinating to him, and there is something beautiful, to his mind, in the relationships that are discovered. The same could be said of the liking for plant or animal life that appears in the "born biologist". If the objects of the world make a direct appeal to the man whose mind is attuned to them, then his interest and zeal in studying them are not wholly derived from the instincts. The instincts come into play, truly enough, in all scientific work, and add impetus to it, but the primary motive is a direct liking for the kind of facts studied.

"Primary likes and dislikes" are still more clearly in evidence in the arts than in the sciences. Take the color art, for example. There can be no manner of doubt that bright colors are natively pleasant. Can we explain the liking for color as derived from satisfaction of the instincts? Is it due simply to curiosity? No, for then the color would no longer be attractive after it had ceased to be a novelty. Is color liked simply for purposes of self-display? No, this would not explain our delight in the colors of nature. Or do color effects constitute problems that challenge the mastery impulse? This might fit the case of intricate color designs, but not the strong, simple color effects that appeal to most people. There is no escape from the conclusion that color is liked for its own sake, and that this primary liking is the foundation of color art.

Music, in the same way, is certainly based on a primary liking for tones and their combinations, as well as for rhythm. Novel effects also appeal to curiosity, musical performance is a means of display to the performer, and the problem set by a piece of music to the performer in the {183} way of execution, and to the listener in the way of understanding and appreciation, gives plenty of play to the mastery impulse. Besides, music gets associated with love, tenderness, war and religion; but none of the impulses thus gratified by music is the fundamental reason for music, since without the primary taste for tone and rhythm there would be no music to start with, and therefore no chance for these various impulses to find an outlet in this direction.

Still another field of human activity, in which native likes and dislikes play their part alongside of the instincts, is the field of social life. The gregarious instinct brings individuals together into social groups, and probably also makes the individual crave participation in the doings of the group. The sex instinct lends a special interest to those members of the group who are of the opposite sex, and the parental instinct leads the adults to take a protective attitude towards the little children. Also, it is probably due to the parental instinct that any one spontaneously seeks to help the helpless. Self-assertion has plenty of play in a group, both in the way of seeking to dominate and in the way of resisting domination; and the submissive tendency finds an outlet in admiring and following those who far surpass us. Thwarted self-assertion accounts for many of the dislikes that develop between the members of a group. But none of these instincts accounts for the interest in personality, or for the genuine liking that people may have for one another.

Let a group of persons of the same age and sex get together, all equals for the time being, no one seeking to dominate the rest, no one bowing to another as his superior nor chafing against an assumed superiority which he does not admit, no one in a helpless or unfortunate condition that arouses the pity of the rest. What an uninteresting affair! No instincts called into play except bare gregariousness! {184} On the contrary, such a group affords almost or quite the maximum of social pleasure. It affords scope for comradeship and good fellowship, which are based on a native liking for people, and not on the instincts.

Enough has perhaps been said to convince the reader that, besides the things we like for satisfaction of our instinctive needs and cravings, there are other things that we "just naturally like"—and the same with dislikes—and that these primary likes and dislikes have considerable importance in life.

Other Proposed Elementary Feelings

Pleasantness and unpleasantness are the only feelings generally accepted as elementary, though several others have been suggested.

Wundt's tri-dimensional theory of feeling.

This author suggested that there were three pairs of feelings: pleasantness and unpleasantness; tension and its opposite, release or relief; and excitement and its opposite, which may be called numbness or subdued feeling. Thus there would be three dimensions of feeling, which could be represented by the three dimensions of space, and any given state of feeling could be described by locating it along each of the three dimensions. Thus, one moment, we may be in a pleasant, tense, excited state; another moment in a pleasant, relieved and subdued state; and another moment in an unpleasant, tense and subdued state, etc. As each feeling can also exist in various degrees, the total number of shades of feeling thus provided for would be very great, indeed.

Though this theory has awakened great interest, it has not won unqualified approval. Excitement and the rest are real enough states of feeling—no one doubts that—but the question is whether they are fit to be placed alongside of pleasantness and unpleasantness as elementary feelings. It {185} appears rather more likely that they are blends of sensations. In the excited states that have been most carefully studied, that is to say, in fear and anger, there is that big organic upstir, making itself felt as a blend of many internal sensations. Tension may very probably be the feeling of tense muscles, for tension occurs specially in expectancy, and the muscles are tense then.

Whether elementary or not, these feelings are worthy of note. It is interesting to examine the striving for a goal and the attainment of the goal with respect to each "dimension" of feeling. Striving is tense, attainment brings the feeling of release. Striving is often excited, but fatigue and drowsiness (seeking for rest) are numb, and self-assertion may be neutral in this respect, as in "cool assumption". Reaching the goal may be excited or not; all depends on the goal, whether it be striking your opponent or going to sleep. On the other hand, reaching the goal is practically always pleasant (weeping seems an exception here), while striving for a goal is pleasant or unpleasant according as progress is being made towards the goal, or stiff obstruction encountered.

The feeling of familiarity, and its opposite, the feeling of strangeness or newness, also have some claim to be considered here. The first time you see a person, he seems strange, the next few times he awakens in you the feeling of familiarity, after which he becomes so much a matter of course as to arouse no definite feeling of this sort, unless, indeed, a long time has elapsed since you saw him last; in this case the feeling of familiarity is particularly strong.

The feelings of doubt or hesitation, and of certainty or assurance, also deserve mention as possibly elementary.

{186}

EXERCISES

1. Outline the chapter.

2. Complete the sentence, "I feel" in 20 different ways (not using synonyms), and measure the time required to do this.

3. What can be meant by speaking in psychology of only two feelings, when common speech recognizes so many?

4. If the states of mind designated by the words, "feeling sure", or "feeling bored", are compound states, what elements besides the feelings of pleasantness and unpleasantness may enter into the compounds?

5. Attempt an analysis of the "worried feeling", by your own introspection, i.e., try to discover elementary feelings and sensations in this complex state of mind.

6. Following Wundt's three-dimensional scheme of feeling, analyze each of the following states of mind (for example, a child just admitted to the presence of the Christmas tree would be in a state of mind that is pleasant, tense, and excited):

(a) Watching a rocket go up and waiting for it to burst.

(b) Just after the rocket has burst.

(c) Waiting for the dentist to pull.

(d) Just after he has pulled.

(e) Enjoying a warm bed.

(f) Lying abed after waking, not quite able as yet to decide to get up.

(g) Seeing an automobile about to run down a child.

7. Make a list of six primary dislikes, and a list of six dislikes that are dependent on the instincts.



REFERENCES

For a much fuller treatment of the subject, see E. B. Titchener, Textbook of Psychology, 1909, pp. 225-264.

{187}

CHAPTER X

SENSATION

AN INVENTORY OF THE ELEMENTARY SENSATIONS OF THE DIFFERENT SENSES

With reflex action, instinct, emotion and feeling, the list of native mental activities is still incomplete. The senses are provided by nature, and the fundamental use of the senses goes with them. The child does not learn to see or hear, though he learns the meaning of what he sees and hears. He gets sensation as soon as his senses are stimulated, but recognition of objects and facts comes with experience. Hold an orange before his open eyes, and he sees, but the first time he doesn't see an orange. The adult sees an object, where the baby gets only sensation. "Pure sensation", free from all recognition, can scarcely occur except in the very young baby, for recognition is about the easiest of the learned accomplishments, and traces of it can be seen in the behavior of babies only a few days old.

Sensation is a response; it does not come to us, but is aroused in us by the stimulus. It is the stimulus that comes to us, and the sensation is our own act, aroused by the stimulus. Sensation means the activity of the receiving organ (or sense organ), of the sensory nerves, and of certain parts of the brain, called the sensory centers. Without the brain response, there is apparently no conscious sensation, so that the activity of the sense organ and sensory nerve is preliminary to the sensation proper. Sensation may be called the first response of the brain to the external stimulus. It is usually only the first in a series of brain {188} responses, the others consisting in the recognition of the object and the utilization of the information so acquired.

Sensation, as we know it in our experience, goes back in the history of the race to the primitive sensitivity (or irritability) of living matter, seen in the protozoa. These minute unicellular creatures, though having no sense organs—any more than they have muscles or digestive organs—respond to a variety of stimuli. They react to mechanical stimuli, as a touch or jar, to chemical stimuli of certain kinds, to thermal stimuli (heat or cold), to electrical stimuli, and to light. There are some forces to which they do not respond: magnetism, X-rays, ultraviolet light; and we ourselves are insensitive to these agents, which are not to be called stimuli, since they arouse no response.

The Sense Organs

In the development of the metazoa, or multicellular animals, specialization has occurred, some parts of the body becoming muscles with the primitive motility much developed, some parts becoming digestive organs, some parts conductors (the nerves) and some parts becoming specialized receptors or sense organs. A sense organ is a portion of the body that has very high sensitivity to some particular kind of stimulus. One sense organ is highly sensitive to one stimulus, and another to another stimulus. The eye responds to very minute amounts of energy in the form of light, but not in other forms; the ear responds to very minute amounts of energy in the form of sound vibrations, the nose to very minute quantities of energy in certain chemical forms.

There is only one thing that a sense organ always and necessarily contains, and that is the termination of a sensory nerve. Without that, the sense organ, being isolated, would have no effect on the brain or muscles or any other {189} part of the body, and would be entirely useless. The axons of the sensory nerve divide into fine branches in the sense organ, and thus are more easily aroused by the stimulus.

Besides the sensory axons, two other things are often found in a sense organ—sometimes one of the two, sometimes the other and sometimes both. First, there are special sense cells in a few sense organs; and second, in most sense organs there is accessory apparatus which, without being itself sensitive, assists in bringing the stimulus to the sense cells or sensory nerve ends.



Sense cells are present only in the eye, ear, nose and mouth—always in very sheltered situations. The taste cells are located in little pits opening upon the surface of the tongue. In the sides of these pits can be found little flask-shaped chambers, each containing a number of taste cells. The taste cell has a slender prolongation that protrudes from the chamber into the pit; and it is this slender tip of the cell that is exposed to the chemical stimulus of the {190} tasting substance. The stimulus arouses the taste cell, and this in turn arouses the ending of the sensory axon that twines about the base of the cell at the back of the chamber. The taste cell, or its tip, is extra sensitive to chemical stimuli, and its activity, aroused by the chemical stimulus, in turn arouses the axon and so starts a nerve current to the brain stem and eventually to the cortex.



The olfactory cells, located in a little recess in the upper and back part of the nose, out of the direct air currents going toward the lungs, are rather similar to the taste cells. They have fine tips reaching to the surface of the mucous membrane lining the nasal cavity and exposed to the chemical stimuli of odors. The olfactory cell has also a long slender branch extending from its base through the bone into the skull cavity and connecting there with dendrites of nerve cells. This central branch of the olfactory cell is, in fact, an axon; and it is peculiar in being an axon growing from a sense cell. This is the rule in invertebrates, but in vertebrates the sensory axon is regularly an outgrowth of a {191} nerve cell, and only in the nose do we find sense cells providing their own sensory nerve.



In the eye, the sense cells are the rods and cones of the retina. These are highly sensitive to light, or, it may be, to chemical or electrical stimuli generated in the pigment of the retina by the action of light. The rods are less highly developed than the cones. Both rods and cones connect at their base with neurones that pass the activity along through the optic nerve to the brain.

The internal ear contains sense cells of three rather similar kinds, all being "hair cells", Instead of a single {192} sensitive tip, each cell has a number of fine hair-tips, and it is these that first respond to the physical stimulus. In the cochlea, the part of the inner ear concerned with hearing, the hairs are shaken by sound vibrations that have reached the liquid in which the whole end-organ is immersed. In the "semicircular canals", a part of the inner ear that is concerned not with sound but with rotary movements of the head, we find hair cells again, their hair-tips being matted together and so located as to be bent, like reeds growing on the bottom of a brook, by currents of the liquid filling the canals. In the "vestibule", the central part of the inner ear, the hair-tips of the sense cells are matted together, and in the mat are imbedded little particles of stony matter, called the "otoliths". When the head is inclined in any direction, these heavy particles sag and bend the hairs, so stimulating them; and the same result occurs when a sudden motion up or down or in any direction is given to the head. Around the base of the sense cells, in any of these parts of the internal ear, are twined the fine endings of sensory axons, which are excited by the activity of the sense cells, and pass the activity on to the brain.

Accessory sense-apparatus.

Every sense except the "pain sense" has more or less of this. The hairs of the skin are accessory to the sense of touch. A touch on a hair is so easily felt that we often think of the hairs as sensitive; but really it is the skin that is sensitive, or, rather, it is the sensory axon terminating around the root of the hair in the skin. The tongue can be thought of as accessory apparatus serving the sense of taste, and the breathing apparatus as accessory to the sense of smell, "tasting" being largely a tongue movement that brings the substance to the taste cells, and "smelling" of anything being largely a series of little inspiratory movements that carry the odor-laden air to the olfactory part of the nasal cavity.

{193}

But it is in the eye and the ear that the highest development of accessory sense apparatus has taken place. All of the eye except the retina, and all of the ear except the sense cells and the sensory axons, are accessory.



The eye is an optical instrument, like the camera. In fact, it is a camera, the sensitive plate being the retina, which differs indeed from the ordinary photographic plate in recovering after an exposure so as to be ready for another. Comparing the eye with the camera, we see that the eyeball corresponds to the box, the outer tough coat {194} of the eyeball (the "sclerotic" coat) taking the place of the wood or metal of which the box is built, and the deeply pigmented "choroid" coat, that lines the sclerotic, corresponding to the coating of paint used to blacken the inside of the camera box and prevent stray light from getting in and blurring the picture. At the front of the eye, where light is admitted, the sclerotic is transformed into the transparent "cornea", and the choroid into the contractile "iris", with the hole in its center that we call "the pupil of the eye".



The iris corresponds to the adjustable diaphragm of the camera. Just behind the pupil is the lens of the eye, which also is adjustable by the action of a little muscle, called the "ciliary muscle". This muscle corresponds to the focussing mechanism of the camera; by it the eye is focussed on near or far objects. The eye really {195} has two lenses, for the cornea acts as a lens, but is not adjustable. The "aqueous and vitreous humors" fill the eyeball and keep it in shape, while still, being transparent, they allow the light to pass through them on the way to the retina. The retina is a thin coat, lying inside the choroid at the back of the eyeball, and having the form of a hollow hemisphere. The light, coming through the pupil and traversing the vitreous humor, strikes the retina from the inside of the eyeball. Other accessory apparatus of the eye includes the lids, the tear glands, and the muscles that turn the eyeball in any direction.



The ear is about as complex a piece of mechanism as the eye. We speak of the "outer", "middle" and "inner" ear. The outer, in such an animal as the horse, serves as a movable ear trumpet, catching the sound waves and concentrating them upon the ear drum, or middle ear. The human external ear seems to accomplish little; it can be cut off without noticeably affecting hearing. The most essential part of the external ear is the "meatus" or hole that allows the sound waves to pass through the skin to the tympanic membrane or drum head. The sound waves throw this membrane into vibration, and the vibration is transmitted, by an assembly of three little bones, across the air-filled cavity {196} of the middle ear to an opening leading to the water-filled cavity of the inner ear. This opening from the middle to the inner ear is closed by a membrane in which one end of the assembly of little bones is imbedded, as the other end is imbedded in the tympanic membrane; and thus the vibrations are transmitted from the tympanic membrane to the liquid of the inner ear. Once started in this liquid, the vibrations are propagated through it to the sense cells of the cochlea and stimulate them in the way already suggested.

[Illustration: Fig. 31.—A small sample of the sense cells of the cochlea. The hairs of the sense cells are shaken by the vibration of the water, and pass the impulse back to the end-brushes of the auditory axons, The tectorial membrane looks as if it might act as a damper, but may be concerned, as "accessory apparatus," in the stimulation of the hair cells. The basilar membrane consists in part of fibers extending across between the ledges of bone; these fibers are arranged somewhat after the manner of piano strings, and have suggested the "piano theory" of hearing, to be mentioned later in the chapter. (Figure text: water space, membrane, Tectorial membrane, bone, soft tissue, basilar membrane, auditory axons to brain stem, nerve cells of auditory nerves, auditory hair cells with end brushes of auditory axons)]

Further study of the accessory apparatus of the eye and ear can be recommended as very interesting, but the little that has been said will serve as an introduction to the study of sensation.

{197}

Analysis of Sensations

Prominent among the psychological problems regarding sensation is that of analysis. Probably each sense gives comparatively few elementary sensations, and many blends or compounds of these elements. To identify the elements is by no means a simple task, for under ordinary circumstances what we get is a compound, and it is only by carefully controlling the stimulus that we are able to get the elements before us; and even then the question whether these are really elementary sensations can scarcely be settled by direct observation.

Along with the search for elementary sensations goes identification of the stimuli that arouse them, and also a study of the sensations aroused by any combination of stimuli. Our task now will be to ask these questions regarding each of the senses.

The Skin Senses

Rough and smooth, hard and soft, moist and dry, hot and cold, itching, tickling, pricking, stinging, aching are skin sensations; but some of these are almost certainly compounds. The most successful way of isolating the elements out of these compounds is to explore the skin, point by point, with weak stimuli of different kinds. If a blunt metal point, or the point of a lead pencil, a few degrees cooler than the skin, is passed slowly over the skin, at most points no sensation except that of contact arises, but at certain points there is a clear sensation of cold. Within an area an inch square on the back of the hand, several of these cold spots can be found; and when the exploration is carefully made, and the cold spots marked, they will be found to give the same sensation every time. Substitute a metal point a few {198} degrees warmer than the skin, and a few spots will be found that give the sensation of warmth, these being the warmth spots. Use a sharp point, like that of a needle or of a sharp bristle, pressing it moderately against the skin, and you get at most points simply the sensation of contact, but at quite a number of points a small, sharp pain sensation arises. These are the pain spots. Finally, if the skin is explored with a hair of proper length and thickness, no sensation at all will be felt at most points, because the hair bends so readily when one end of it is pressed against the skin as not to exert sufficient force to arouse a sensation; but a number of points are found where a definite sensation of touch or contact is felt; these are the touch spots.

No other varieties of "spots" are found, and the four sensations of touch, warmth, cold and pain are believed to be the only elementary skin sensations. Itch, stinging and aching seem to be the same as pain. Tickle is touch, usually light touch or a succession of light touches. Smooth and rough are successions of touch sensations. Moist is usually a compound of smooth and cold. Hard and soft combine touch and the muscular sensation of resistance.

Hot and cold require more discussion. The elementary sensations are warmth and coolness, rather than hot and cold. Hot and cold are painful, and the fact is that strong temperature stimuli arouse the pain spots as well as the warmth or cold spots. Hot, accordingly, is a sensation compounded of warmth and pain, and cold a sensation composed of coolness and pain. More than this, when a cold spot is touched with a point heated well above the skin temperature (best to a little over 100 Fahrenheit), the curious fact is noted that the cold spot responds with its normal sensation of cold. This is called the "paradoxical cold sensation". From this fact it is probable that a hot object excites the cold sensation, along with those of warmth and {199} pain; so that the sensation of heat is a blend of the three. Another curious fact is that a very cold object produces a burning sensation indistinguishable from that of a hot object; so that the sensation of great cold, like that of heat, is probably a blend of the three elementary sensations of warmth, cold and pain.

[Illustration: Fig. 32.—Diagram of various sorts of sensory end-organ found in the skin.

A is a hair end-organ; the sensory axons can be seen coiling around the root of the hair; evidently a touch on the hair, outside, would squeeze the coiled axon and stimulate it. The hair is a bit of "accessory apparatus."

B is a touch corpuscle, consisting of a coiled axon-end surrounded by a little cone of other tissue.

C is an end-bulb, presumably belonging to the temperature sense. It has, again, a coiled axon-end surrounded by other tissue. The "coils" are really much more finely branched than the diagram shows.

D is a free-branched nerve end, consisting simply of a branched axon, with no accessory apparatus. It is the pain-sense organ.

E is a corpuscle of a type found in the subcutaneous tissue, as well as in more interior parts of the body. It contains an axon-end surrounded by a layered capsule.]

The stimulus that arouses the touch sensation is a bending of the skin. That which arouses warmth or cold is of {200} course a temperature stimulus, but, strange as it may seem, the exact nature of the effective stimulus has not been agreed upon. Either it is a warming or cooling of the skin, or it is the existence of a higher or lower temperature in the skin than that to which the skin is at the moment "adapted". This matter will become clearer when we later discuss adaptation. The stimulus that arouses the pain sensation may be mechanical (as a needle prick), or thermal (heat or cold), or chemical (as the drop of acid), or electrical; but in any case it must be strong enough to injure or nearly to injure the skin. In other words, the pain sense organ is not highly sensitive, but requires a fairly strong stimulus; and thus it is fitted to give warning of stimuli that threaten injury.

Several kinds of sensory end-organ are found in the skin. There is the "spherical end-bulb", into which a sensory axon penetrates; it is believed to be the sense organ for cold. There is the rather similar "cylindrical end-bulb" believed to be the sense organ for warmth. There is the "touch corpuscle", found in the skin of the palms and soles, and consisting, like the end-bulbs, of a mass of accessory cells with a sensory axon ramifying inside it; this is an end-organ for the sense of touch. There is the hair end-organ, consisting of a sensory axon coiled about the root of the hair; this, also, is a touch receptor. Finally, there is the "free-branched nerve end", consisting simply of the branching of a sensory axon, with no accessory apparatus whatever; and this is the pain receptor. Perhaps the pain receptor requires no accessory apparatus because it does not need to be extremely sensitive.

Now since we find, in the skin, "spots" responsive to four quite different stimuli, giving four quite different sensations, and apparently provided with different types of end-organs, it has become customary to speak of four skin senses in place of the traditional "sense of touch". We {201} speak of the pain sense, the warmth sense, the cold sense, and the pressure sense, which last is the sense of touch proper.

The Sense of Taste

Analysis has been as successful in the sense of taste as in cutaneous sensation. Ordinarily we speak of an unlimited number of tastes, every article of food having its own characteristic taste. Now the interior of the mouth possesses the four skin senses in addition to taste, and many tastes are in part composed of touch, warmth, cold or pain. A "biting taste" is a compound of pain with taste proper, and a "smooth taste" is partly touch. The consistency of the food, soft, tough, brittle, gummy, also contributes, by way of the muscle sense, to the total "taste". But in addition to all these sensations from the mouth, the flavor of the food consists largely of odor. Food in the mouth stimulates the sense of smell along with that of taste, the odor of the food reaching the olfactory organ by way of the throat and the rear passage to the nose. If the nose is held tightly so as to prevent all circulation of air through it, most of the "tastes" of foods vanish; coffee and quinine then taste alike, the only taste of each being bitter, and apple juice cannot be distinguished from onion juice.

But when the nose is excluded, and when cutaneous and muscular sensations are deducted, there still remain a few genuine tastes. These are sweet, sour, bitter and salty—and apparently no more. These four are the elementary taste sensations, all others being compounds. The papillae of the tongue, with their little "pits" already spoken of, correspond to the "spots" of the skin, with this difference, however, that the papillae do not each give a single sensation. Some of them give only two, some only three of the four tastes; and the bitter taste is aroused principally from {202} the back of the tongue, the sweet from the tip, the sour from the sides, the salty from both tip and sides.

The stimulus to the sense of taste is something of a chemical nature. The tasteable substances must be in solution in order to penetrate the pits and get to the sensitive tips of the taste cells. If the upper surface of the tongue is first dried, a dry lump of sugar or salt laid on it gives no sensation of taste until a little saliva has accumulated and dissolved some of the substance.

Exactly what is the chemical agent that produces a given taste sensation is a problem of some difficulty. Many different substances give the sensation of bitter, and the question is, what there is common to all these substances. The sweet taste is aroused not only by sugar, but by glycerine, saccharine, and even "sugar of lead" (lead acetate). The sour taste is aroused by most acids, but not by all, and also by some substances that are not chemically acids. Thus the chemistry of taste stimuli involves something not as yet understood.

Though there is this uncertainty regarding the stimulus, on the whole the sense of taste affords a fine example of success achieved by experimental methods in the analysis of complex sensations. At the same time it affords a fine example of the fusion of different sensations into characteristic blends. The numerous "tastes" of every-day life, though found on analysis to be compounded of taste, smell, touch, pain, temperature and muscle sensations, have the effect of units. The taste of lemonade, for example, compounded of sweet, sour, cold and lemon odor, has the effect of a single characteristic sensation. It can be analyzed, but it ordinarily appears as a unit. This is true generally of blends; indeed, what we mean by blending is that, while the component sensations are still present and can be found by careful attention, they are not simply present together {203} but are compounded into a characteristic total. Each elementary sensation entering into the blend gives up some of its own quality, as, in the case of lemonade, neither the sweet nor the sour is quite so distinct and obtrusive as either would be if present alone. The same is true of the lemon odor, and it is true generally of the odor components that enter into the "tastes" of food. Were the odor components in these tastes as clear and distinct as they are when the same substance is smelled outside the mouth, we could not fail to notice that the "tastes" were largely composed of odor. The obtrusive thing about a blend is the total effect, not the elementary sensations that are blended.

The Sense of Smell

The great variety of odors long resisted every attempt at psychological analysis, largely because the olfactory end-organ is so secluded in position. You cannot apply stimuli to separate parts of it, as you can to the skin or tongue. But, recently, good progress has been made, [Footnote: By Henning.] by assembling almost all possible odors, and becoming thoroughly acquainted with them, not as substances, but simply as odors, and noting their likenesses and differences. It seems possible now to state that there are six elementary odors, as follows:

1. Spicy, found in pepper, cloves, nutmeg, etc.

2. Flowery, found in heliotrope, etc.

3. Fruity, found in apple, orange oil, vinegar, etc.

4. Resinous, found in turpentine, pine needles, etc.

5. Foul, found in hydrogen sulphide, etc.

6. Scorched, found in tarry substances.

These being the elements, there are many compound odors. The odor of roasted coffee is a compound of resinous and scorched, peppermint a compound of fruity and spicy.

{204}

Each elementary odor corresponds to a certain characteristic in the chemical constitution of the stimulus.

The sense of smell is extremely delicate, responding to very minute quantities of certain substances diffused in the air. It is extremely useful in warning us against bad air and bad food. It has also considerable esthetic value.

Organic Sensation

The term "organic sensation" is used to cover a variety of sensations from the internal organs, such as hunger, thirst, nausea, suffocation and less definite bodily sensations that color the emotional tone of any moment, contributing to "euphoria" and also to disagreeable states of mind. Hunger is a sensation aroused by the rubbing together of the stomach walls when the stomach, being ready for food, begins its churning movements. Careful studies of sensations from the internal organs reveal astonishingly little of sensation arising there, but there can be little doubt that the sensations just listed really arise where they seem to arise, in the interior of the trunk.

Little has been done to determine the elementary sensations in this field; probably the organic sensations that every one is familiar with are blends rather than elements.

The Sense of Sight

Of the tremendous number and variety of visual sensations, the great majority are certainly compounds. Two sorts of compound sensation can be distinguished here: blends similar to those of taste or smell, and patterns which scarcely occur among sensations of taste and smell, though they are found, along with blends, in cutaneous sensation. Heat, compounded of warmth, cold and pain sensations, is an {205} excellent example of a blend, while the compound sensation aroused by touching the skin simultaneously with two points—or three points, or a ring or square—is to be classed as a pattern. In a pattern, the component parts are spread out in space or time (or in both at once), and for that reason are more easily attended to separately than the elements in a blend. Yet the pattern, like the blend, has the effect of a unit. A spatial pattern has a characteristic shape, and a temporal pattern a characteristic course or movement. A rhythm or a tune is a good example of a temporal pattern.

Visual sensations are spread out spatially, and thus fall into spatial patterns. They also are in constant change and motion, and so fall into temporal patterns, many of which are spatial as well. The visual sensation aroused, let us say in a young baby, by the light entering his eye from a human face, is a spatial pattern; the visual sensation aroused by some one's turning down the light is a pure temporal pattern; while the sensation from a person seen moving across the room is a pattern both spatial and temporal. Finding the elements of a visual pattern would mean finding the smallest possible bits of it, which would probably be the sensations due to the action of single rods and cones, just as the smallest bit of a cutaneous sensation would be due to the exciting of a single touch spot, warmth spot, cold spot or pain spot.

Analyzing a visual blend is quite a different job. Given the color pink, for example, let it be required to discover whether this is a simple sensation or a blend of two or more elementary sensations. Studying it intently, we see that it can be described as a whitish red, and if we are willing to accept this analysis as final, we conclude that pink is a blend of the elementary sensations of white and red. Of the thousands and thousands of distinguishable hues, shades {206} and tints, only a few are elements and the rest are color blends; and our main problem now is to identify the elements. Notice that we are not seeking for the physical elements of light, nor for the primary pigments of the painter's art, but for the elementary sensations. Our knowledge of physics and painting, indeed, is likely to lead us astray. Sensations are our responses to the physical stimulus, and the psychological question is, what fundamental responses we make to this class of stimuli.

Suppose, without knowing anything of pigments or of the physics of light, we got together a collection of bits of color of every shade and tint, in order to see what we could discover about visual sensations. Leaving aside the question of elements for the moment, we might first try to classify the bits of color. We could sort out a pile of reds, a pile of blues, a pile of browns, a pile of grays, etc., but the piles would shade off one into another. The salient fact about colors is the gradual transition from one to another. We can arrange them in series better than we can classify them. They can be serially arranged in three different ways, according to brightness or intensity, according to color-tone, and according to saturation.

The intensity series runs from light to dark. We can arrange such a series composed entirely of reds or blues or any other one color; or we can arrange the whole collection of bits of color into a single light-dark series. It is not always easy to decide whether a given shade of one color is lighter or darker than a given shade of a different color; but in a rough way, at least, every bit of whatever color would have its place in the single intensity series. An intensity series can, of course, be arranged in any other sense as well as in sight.

The color-tone series is best arranged from a collection consisting entirely of full or saturated colors. Start the {207} series with any color and put next to this the color that most resembles it in color-tone, i.e., in specific color quality; and so continue, adding always the color that most resembles the one preceding. If we started with red, the next in order might be either a yellowish red or a bluish red. If we took the yellowish red and placed it beside the red, then the next in order would be a still more yellowish red, and the series would run on to yellow and then to greenish yellow, green, bluish green, blue, violet, purple, purplish red, and so back to red. The color-tone series returns upon itself. It is a circular series.



A saturation series runs from full-toned or saturated colors to pale or dull. Since we can certainly say of a pale blue that it is less saturated than a vivid red, etc., we could, theoretically, arrange our whole collection of bits of color in a single saturation series, but our judgment would be very uncertain at many points. The most significant saturation series confine themselves to a single color-tone, {208} and also, as far as possible, to a constant brightness, and extend from the most vivid color sensation obtainable with this color-tone and brightness, through a succession of less and less strongly colored sensations of the same tone and brightness, to a dead gray of the same brightness. Any such saturation series terminates in a neutral gray, which is light or dark to match the rest of the particular saturation series.

White, black and gray, which find no place in the color-tone series, give an intensity series of their own, running from white through light gray and darker and darker gray to black, and any gray in this series may be the zero point in a saturation series of any color-tone.

A three-dimensional diagram of the whole system of visual sensations can be built up in the following way. Taking all the colors of the same degree of brightness, we can arrange the most saturated, in the order of their color-tone, around the circumference of a circle, put a gray of the same brightness at the center of this circle, and then arrange a saturation series for each color-tone extending from the most saturated at the circumference to gray at the center. This would be a two-dimensional diagram for colors having the same brightness. For a greater brightness, we could arrange a similar circle and place it above the first, and for a smaller brightness, a similar circle and place it below the first, and we could thus build up a pile of circles, ranging from the greatest brightness at the top to the least at the bottom. But, as the colors all lose saturation when their brightness is much increased, and also when it is much decreased, we should make the circles smaller and smaller toward either the top or the bottom of the pile, so that our three-dimensional diagram would finally take the form of a double cone, with the most intense white, like that of sunlight, at the upper point, with dead black at the lower point, {209} and with the greatest diameter near the middle brightness, where the greatest saturations can be obtained. The axis of the double cone, extending from brightest white to dead black, would give the series of neutral grays. All the thousands of distinguishable colors, shades and tints, would find places in this scheme.



Simpler Forms of the Color Sense

Not every one gets all these sensations. In color-blindness, the system is reduced to one or two dimensions, instead of three. There are two principal forms of color-blindness: total, very uncommon; and red-green blindness, fairly {210} common. The totally color-blind individual sees only white, black, and the various shades of gray. His system of visual sensations is reduced to one dimension, corresponding to the axis of our double cone.

Red-green blindness, very uncommon in women, is present in three or four percent of men. It is not a disease, not curable, not corrected by training, and not associated with any other defect of the eye, or of the brain. It is simply a native peculiarity of the color sense. Careful study shows that the only color sensations of the red-green blind person are blue and yellow, along with white, black and the grays. His color circle reduces to a straight line with yellow at one end and blue at the other. Instead of the color circle, he has a double saturation series, reaching from saturated yellow through duller yellows to gray and thence through dull blues to saturated blue. What appears to the normal eye as red, orange or grass green appears to him as more or less unsaturated yellow; and what appears to the normal eye as greenish blue, violet and purple appears to him as more or less unsaturated blue. His color system can be represented in two dimensions, one for the double saturation series, yellow-gray-blue, and the other for the intensity series, white-gray-black.

Color-blindness, always interesting and not without some practical importance (since the confusions of the color-blind eye might lead to mistaking signals in navigation or railroading), takes on additional significance when we discover the curious fact that every one is color-blind—in certain parts of the retina. The outermost zone of the retina, corresponding to the margin of the field of view, is totally color-blind (or very nearly so), and an intermediate zone, between this and the central area of the retina that sees all the colors, is red-green blind, and delivers only blue and yellow sensations, along with white, black and gray. Take {211} a spot of yellow or blue and move it in from the side of the head into the margin of the field of view and then on towards the center. When it first appears in the margin, it simply appears gray, but when it has come inwards for a certain distance it changes to yellow. If a red or green spot is moved in similarly, it first appears gray, then takes on a faint tinge of yellow, and finally, as it approaches the center of the field of view, appears in its true color. The outer zone gets only black and white, the intermediate zone gets, in addition to these, yellow and blue, and the central area adds red and green (and with them all the colors).



Now as to the question of elements, let us see how far we can go, keeping still to the sensations, without any reference to the stimulus. If a collection of bits of color is presented to a class of students who have not previously studied this matter, with the request that each select those colors that seem to him elementary and not blends, there is practically unanimous agreement on three colors, red, yellow and blue; and there are some votes for green also, but almost none for orange, violet, purple, brown or any other colors. {212} except white and black. That white and black are elementary sensations is made clear by the case of total color-blindness, since in this condition there are no other visual sensations from which white and black could be compounded, and these two differ so completely from each other that it would be impossible to think of white as made up of black, or black of white. Gray, on the other hand, appears like a blend of black and white. In the same way, red-green blindness demonstrates the reality of yellow and blue as elementary sensations, since neither of them could be reduced to a blend of the other with white or black; and there are no other colors present in this form of color vision to serve as possible elements out of which yellow and blue might be compounded. That white, black, yellow and blue are elementary sensations is therefore clear from the study of visual sensations alone; and there are indications that red and green are also elements.

Visual Sensations as Related to the Stimulus

Thus far, we have said nothing of the stimulus that arouses visual sensations. Light, the stimulus, is physically a wave motion, its vibrations succeeding each other at the rate of 500,000000,000000 vibrations, more or less, per second, and moving through space with a speed of 186,000 miles per second. The "wave-length", or distance from the crest of one wave to the crest of the next following, is measured in millionths of a millimeter.

The most important single step ever taken towards a knowledge of the physics of light, and incidentally towards a knowledge of visual sensations, was Newton's analysis of white light into the spectrum. He found that when white light is passed through a prism, it is broken up into all the colors of the rainbow or spectrum. Sunlight consists of a {213} mixture of waves of various lengths. At one end of the spectrum are the long waves (wave-length 760 millionths of a millimeter), at the other end are the short waves (wavelength 390), and in between are waves of every intermediate length, arranged in order from the longest to the shortest. The longest waves give the sensation of red, and the shortest that of violet, a slightly reddish blue.

Outside the limits of the visible spectrum, however, there are waves still longer and shorter, incapable of arousing the retina, though the very long waves, beyond the red, arouse the sensation of warmth from the skin, and the very short waves, beyond the violet, though arousing none of the senses, do effect the photographic plate. Newton distinguished seven colors in the visible spectrum, red, orange, yellow, green, blue, indigo and violet; but there is nothing specially scientific about this list, since physically there are not seven but an unlimited number of wave-lengths included in the spectrum, varying continuously from the longest at the red end to the shortest at the violet; while psychologically the number of distinguishable colors in the spectrum, though not unlimited, is at least much larger than seven. Between red and orange, for instance, there are quite a number of distinguishable orange-reds and reddish oranges.

If now we ask what differences in the stimulus give rise to the three kinds of difference in visual sensation that were spoken of previously, we find that color-tone depends on the wave-length of the light, brightness on the energy of the stimulus, i.e., on the amplitude of the vibration, and saturation on the mixture of long and short wave-lengths in a complex light-stimulus—the more mixture, the less saturation.

These are the general correspondences between the light stimulus and the visual sensation; but the whole relationship is much more complex. Brightness depends, not only on the energy of the stimulus, but also on wave-length. The {214} retina is tuned to waves of medium length, corresponding to the yellow, which arouse much brighter sensation than long or short waves of the same physical energy. Otherwise put, the sensitivity of the retina is greatest for medium wavelengths, and decreases gradually towards the ends of the spectrum, ceasing altogether, as has been said, at wavelengths of 760 at the red end and of 390 at the violet end.

Saturation, depending primarily on amount of mixture of different wave-lengths, depends also on the particular wavelengths acting, and also on their amplitude. So, the red and blue of the spectrum are more saturated than the yellow and green; and very bright or very dim light, however homogeneous, gives a less saturated sensation than a stimulus of medium strength.

Color Mixing

Color-tone depends on the wave-length, as has been said, but this is far from the whole truth; the whole truth, indeed, is one of the most curious and significant facts about color vision. We have said that each color-tone is the response to a particular wave-length. But any color-tone can be got without its particular wave-length being present at all; all that is necessary is that wave-lengths centering about this particular one shall be present. A mixed light, consisting of two wave-lengths, the one longer and the other shorter than the particular wave which when acting alone gives a certain color-tone, will give that same color-tone. For example, the orange color resulting from the isolated action of a wave-length of 650 is given also by the combined action of wave-lengths of 600 and 700, in amounts suitably proportioned to each other.