15. Tactile adaptation. Support two fingers on the edge of a table, and lay on them a match or some other light object. Let this stimulus remain there, motionless, and notice whether the tactile sensation remains steady or dies out. What is the effect of making slight movements of the fingers, and so causing the stimulus to affect fresh parts of the skin?

16. Temperature sense adaptation. Have three bowls of water, one quite warm, one cold, one medium. After holding one hand in the warm water and the other in the cold, transfer both simultaneously to the medium water and compare the temperature sensations got by each hand from this water. State the result in terms of adaptation.

17. Overtones. These can be quite easily heard in the sound of a large bell. What use does the sense of hearing make of overtones?

REFERENCES For a somewhat fuller discussion of the topic of sensation, see Warren's _Human Psychology_, 1919, pp. 151-214; and for a much fuller discussion, see t.i.tchener's _Textbook of Psychology_, 1909, pp.

46-224.

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For a really thorough consideration of the facts and theories of color vision, see J. Herbert Parsons, _An Introduction to the Study of Colour Vision_, 1915.

For a more complete statement of the Ladd-Franklin theory, see the article on "Vision", in Baldwin's _Dictionary of Philosophy and Psychology_, 1902.

For a recent study that has revolutionized the psychology of the sense of smell, see _Der Geruch_, by Hans Henning, 1916, or a review of the same by Professor Gamble in the _American Journal of Psychology_, 1921, Vol. 32, pp. 290-296.

For an extensive discussion of the "Psychology of Sound", sec the book with this t.i.tle by Henry J. Watt, 1917.

For a full account of taste, see Hollingworth and Poffenberger's _Sense of Taste_, 1917.

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CHAPTER XI

ATTENTION

HOW WE ATTEND, TO WHAT, AND WITH WHAT RESULTS

"Attention!" shouts the officer as a preliminary to some more specific command, and the athletic starter calls out "Ready!" for the same purpose. Both commands are designed to put the hearer in an att.i.tude of readiness for what is coming next. They put a stop to miscellaneous doings and clear the way for the specific reaction that is next to be called for. They nullify the effect of miscellaneous stimuli that are always competing for the hearer's attention, and make him responsive only to stimuli coming from the officer. They make the hearer clearly conscious of the officer. They arouse in the hearer a condition of keen alertness that cannot be maintained for more than a few seconds unless some further command comes from the officer. In all these ways "attention" in the military sense, or "readiness" in the athletic sense, affords a good picture of the psychology of attention.

Attention is preparatory, selective, mobile, highly conscious. To attend to a thing is to be keenly conscious of that thing, it is to respond to that thing and disregard other things, and it is to expect something more from that thing.

Attention is, in a word, exploratory. To attend is to explore, or to start to explore. Primitive attention amounts to the same as the instinct of exploration. Its natural stimulus is anything novel or sudden, its "emotional state" is curiosity or expectancy, and its instinctive reaction consists {245} of exploratory movements. Its inherent impulse is to explore, examine, or await.

Attention belongs fundamentally among the native forms of behavior.

The child does not have to learn to attend, though he must learn to attend to many things that do not naturally get his attention. Some stimuli naturally attract attention, and others attract attention only because of previous experience and training. In considering the whole subject of attention, then, we shall in part be dealing with native responses, and in part with responses that are acquired. But the great laws of attention, which will come to light in the course of the chapter, are at the same time general laws of reaction, and belong under the head of native characteristics.

The Stimulus, or What Attracts Attention

We can attend to anything whatever, but are more likely to attend to some things than to others. As stimuli for attention, some objects are much more effective than others, and the question is, in what way one object has the advantage over another. There are several ways, several "factors of advantage", we may call them.

_Change_ is the greatest factor of advantage. A steady noise ceases after a while to be noticed, but let it change in any respect and immediately it arrests attention. The ticking of the clock is a good example: as long as it keeps uniformly on, it is unnoticed, but if it should suddenly beat faster or louder or in a different key, or even if it should stop altogether, it would "wake us up" with a start. The change in the stimulus must not be too gradual if it is to be effective, it must have a certain degree of suddenness. It may be a change in intensity, a becoming suddenly stronger or weaker; or it may be change in quality, as in tone, or {246} color, or odor; or it may be a change in position, a movement in s.p.a.ce. When one who is holding our arm gives it a sudden squeeze to attract our attention, that is a change of intensity; when we step from the bank into the water, the sudden change from warmth to cold, that gets our attention without fail, is a change of quality; and something crawling on the skin attracts attention by virtue of its motion. Anything moving in the field of view is also an unfailing stimulus to attention.

_Strength_, or high intensity of a stimulus, is another important factor of advantage. Other things being equal, a strong stimulus will attract attention before a weak one. A loud noise has the advantage over a low murmur, and a bright flash of light over a faint twinkle.

In the case of visible objects, size has about the same effect as intensity. The large features of the landscape are noticed before the little details. The advertiser uses large type, and pays for big s.p.a.ce in the newspaper, in the effort to attract the attention of the reader.

[Footnote: Often he pays more than the s.p.a.ce is worth; at least doubling the size of his "ad" will not, on the whole, double the amount of attention he gets, or the number of readers whose attention he will catch. The "attention value" of an advertis.e.m.e.nt has been found by Strong to increase, not as fast as the increase in s.p.a.ce, but about as the square root of the s.p.a.ce occupied.]

Another similar factor is _repet.i.tion_. Cover a billboard with several copies of the same picture, and it attracts more attention than a single one of the pictures would. Repeat a "motive" in the decoration of a building, and it is more likely to be noticed. Repeat a cry or call several times, and after a while it may be noticed, though not at first. The "summation of stimuli" has much the same effect as increasing the intensity of a single stimulus.

If, however, a stimulus is repeated or continued for a long time, it will probably cease to hold attention, because of its {247} monotony, or, in other words, because it lacks the element of change.

_Striking quality_ is an advantage, quite apart from the matter of intensity. Saturated colors, though no stronger in intensity of light than pale colors, are stronger stimuli for attention. High notes are more striking than low. Itch, tickle and pain get attention in preference to smooth touch. "Striking" cannot be defined in physical terms, but simply refers to the fact that some kinds of stimulus get attention better than others.

_Definite form_ has the advantage over what is vague. A small, sharply defined object, that stands out from its background, attracts the eye more than a broad, indefinite expanse of light such as the sky. In the realm of sound, "form" is represented by rhythm or tune, and by other definite sequences of sound, such as occur in the jingles that catch the little child's ear.

The factors of advantage so far mentioned are native, and a stimulus possessing one or more of them is a natural attention-stimulus. But the individual also learns what is worth noticing, and what is not, and thus forms _habits of attention_, as well as habits of inattention. The automobile driver forms the habit of attending to the sound of his motor, the botanist forms the habit of noticing such inconspicuous objects as the lichens on the tree trunks. On the other hand, any one forms the habit of not noticing repeated stimuli that have no importance for him. Move into a house next the railroad, and at first you notice every train that pa.s.ses; even at night you awake with a start, dreaming that some monster is pursuing you; but after a few days the trains disturb you very little, night or day. The general rule covering attention habits is this: anything that you have to work with, or like to play with, acquires the power to attract your attention, while anything that you do nothing {248} with loses whatever hold on your attention it may have possessed by virtue of its intensity, quality, etc.

Besides these permanent habits of attention, there are temporary adjustments determined by the _momentary interest_ or desire. Stimuli relevant to the momentary interest have an unwonted hold upon attention, while things out of line with this interest may escape attention altogether, even though the same things would ordinarily be noticed. What you shall notice in the store window is governed by what you are looking for as much as by the prominence of the object in the total display. When you are angry with a person, you notice bad points about him that you usually overlook, and any aroused desire adjusts or "sets" attention in a similar way. The desire or interest of the moment _facilitates_ attention to certain stimuli and _inhibits_ attention to others, and is thus an important factor of advantage.

The interest of the moment is often represented by a question. Ask yourself what spots of red there are in the field of view, and immediately various red spots jump out and strike the eye; ask yourself what pressure sensations you are getting from the skin, and immediately several obtrude themselves. A question sets attention towards whatever may furnish an answer.

To sum up, we may say that three general factors of advantage determine the power of any stimulus to attract attention. There is the native factor, consisting of change, intensity, striking quality, and definite form; there is the factor of habit, dependent on past experience; and there is the factor of present interest and desire.

The Motor Reaction in Attention

Attention is obviously a reaction of the individual to the stimulus that gets his attention; and it is in part a motor {249} reaction. The movements that occur in attending to an object are such as to afford a better view of it, or a better hearing of it, or, in general, such as to bring the sense organs to bear on it as efficiently as possible.

We may distinguish two sorts of motor reaction that occur in attention: the general attentive att.i.tude, and the special adjustments of the sense organs. An audience absorbed in a speech or musical performance gives a good picture of the general _attentive att.i.tude_.

You notice that most people look fixedly towards the speaker, as if listening with their eyes, and that many of them lean forward as if it were important to get just as close as possible. All the little restless movements cease, so that you could "hear a pin drop", and at the tensest moments even the breath is checked. The att.i.tude of attention is one of tense immobility, with the whole body oriented towards the object of attention. When the object of attention is something not present but thought of, a somewhat similar rigid att.i.tude is a.s.sumed; the body is apt to lean forward, the neck to be held stiff, and the eyes to "stare at vacancy", i.e., to be fixed on some convenient object as a mere resting place, while attention is fixed outside the visual field altogether.

But we spoke of attention as mobile, and it would be strange if its mobility did not show itself in the motor reaction. It does in fact show itself in the _sense organ adjustments_ which amount to exploratory reactions. Attention to an object in the hand is shown by "feeling of it", to a substance in the mouth by tasting movements, to an odor by sniffing movements, to a sound by c.o.c.king the head and turning the eyes towards the source of sound. The most instructive of this type of attention-reactions are those of the eyes. The eye is focused on the object that arouses attention, the lens being accommodated for its distance by the action of the little ciliary muscle inside the {250} eyeball; the two eyes are converged upon the object, so that the light from it strikes the fovea or best part of each retina; and the eyes are also turned up, down or sidewise, so as, again, to receive the light from the object upon the fovea.

This last cla.s.s of eye movements is specially instructive and shows specially well the mobility of attention. Let a bright or moving object appear somewhere in the field of view--immediately the eyes turn towards it with a quick jump, fixate it for a few seconds and then jump elsewhere unless the object is found to be specially significant. Watch the eyes of one who is looking at a picture or scene of any sort, and you will see his eyes jumping hither and thither, as his attention shifts from one part of the scene to another. Ask him to abstain from this jumpy movement and let his eyes "sweep over" the scene, and he will confidently try to follow your instructions, but if you watch his eyes you will find them still jumping. In fact, "sweeping the glance" is a myth. It cannot be done.

At least, there is only one case in which it can be done, and that is when there is a moving object to look at. Given an object moving at a moderate speed across the field of view, and the eyes can follow it and keep pace with it pretty accurately. But without the moving object as stimulus, the eyes can only execute the jump movement. There are thus two types of exploratory eye movement: the "jump" in pa.s.sing from one object to another, and the "pursuit movement" in examining a moving object.

In reading, the eye moves by a series of short jumps from left to right along the first line of print, makes a long jump back to the beginning of the second line and another series of short jumps along that line, and so on. To appreciate the value of this jerky movement, we need to understand that each short jump occupies but a thirtieth to a fiftieth {251} of a second, while the "fixation pauses" between jumps last much longer, with the result that over ninety per cent. of the time spent on a line of print is fixation time, and less than ten per cent, is occupied in jumping from one fixation to the next. Now, it has been found that nothing of any consequence is seen during the eye jumps, and that the real seeing takes place only during the fixations. The jump movement, therefore, is simply a means of pa.s.sing from one fixation to another with the least possible loss of time.

The eye sees an object distinctly only when at rest with respect to the object. If the object is still, the eye must be still to see it distinctly, and to see its different parts must fixate one after the other, jumping from one part to another. But if the object is in motion, the eye may still be able to see it distinctly by means of the pursuit movement, which is a sort of moving fixation.

The Shifting of Attention

Eye movement affords a good picture of the mobility of attention.

Ordinarily the eye shifts frequently from one part of the field of view to another. When simply exploring a scene, it shifts about in what seems an indiscriminate way, though really following the principle of deserting each object as soon as it has been examined, and jumping to that other object which next has the advantage on account of movement, brightness, color, definite form, or habit of attention. In reading, however, the eye is governed by a definite interest, and moves consecutively along the series of words, instead of shifting irregularly about the page.

A moving object, or an object that is doing something, or even a complex object that presents a number of parts to be examined in turn, can hold the eye for some time. But it is almost impossible to hold the eye fixed for any length of time on a simple, motionless, unchanging object.

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Attention is mobile because it is exploratory; it continually seeks something fresh for examination. In the presence of a complex of sights and sounds and touch stimuli, it tends to shift every second or two from one part of the situation to another. Even if you are lying in bed with your eyes closed, the movement of attention still appears in the rapid succession of thoughts and images, and some shift usually occurs as often as once a second.

A few simple experiments will serve to throw the shifting of attention into clearer relief. Look fixedly at a single letter written on a blank sheet of paper, and notice how one part after another of the letter stands out; notice also that attention does not stick absolutely to the letter, since thoughts obtrude themselves at intervals.