[Ill.u.s.tration:

O O O O O O O O O O O O O

Fig. 42.--A dot figure, from Sanford. Look steadily at it.]

Or, make a "dot figure", composed of six or eight or more dots arranged either regularly or irregularly, and look steadily at the collection. Probably you will find that the dots seem to fall into figures and groups, and that the grouping changes frequently.

Objectively, of course, the dots are grouped in one way as much as another, so that any particular grouping is your own doing. The objective stimulus, in other words, is capable of arousing several grouping reactions on your part, and does arouse different reactions one after another

Shifting also appears in looking at an {253} "ambiguous figure", drawn so as to represent equally well a solid object in either of two different positions. The transparent cube, showing near and far edges alike, is a good example. Look steadily at such a drawing, and the cube will appear to shift its position from time to time. Numerous such figures can be constructed; the most celebrated is the ambiguous staircase. Look steadily at it, and suddenly you see the under side of a flight of stairs, instead of the upper; and if you keep on looking steadily, it shifts back and forth between these two positions.

[Ill.u.s.tration: Fig. 43.--The ambiguous cube figure.]

[Ill.u.s.tration: Fig. 44.--The ambiguous staircase figure.]

A still more striking case of shifting goes by the name of "binocular rivalry", and occurs when colors or figures that we cannot combine into a single picture are presented, {254} one to one eye, and the other to the corresponding part of the other retina. Hold red gla.s.s close in front of one eye and blue before the other, and look through both at once towards a bright background, and you will see red part of the time and blue part of the time, the two alternating as in the case of ambiguous figures.

[Ill.u.s.tration: Fig. 45.--Another ambiguous figure, which can be seen in three ways.]

The stereoscope is a great convenience in applying inconsistent stimuli to the two eyes, and by aid of this instrument a great variety of experiments can be made. It is thus found that, if the field before one eye is a plain color, while the other, of a different color, has any little figure on it, this figure has a great advantage over the rival plain color and stays in sight most of the time. Anything moving in one field has a similar advantage, and a bright field has the advantage over a darker one. Thus the same factors of advantage hold good in binocular rivalry as in native attention generally.

A different kind of shifting appears in what is called "fluctuation of attention". Make a light gray smudge on a white sheet of paper, and place this at such a distance that the gray will be barely distinguishable from the white {255} background. Looking steadily at the smudge, you will find it to disappear and reappear periodically.

Or, place your watch at such a distance that its ticking is barely audible, and you will find the sound to go out and come back at intervals. The fluctuation probably represents periodic fatigue and recovery at the brain synapses concerned in observing the faint stimulus.

Shiftings of the fluctuation type, or of the rivalry type either, are not to be regarded as quite the same sort of thing as the ordinary shiftings of attention. The more typical movement of attention is ill.u.s.trated by the eye movements in examining a scene, or by the sequence of ideas and images in thinking or dreaming. Rivalry and fluctuation differ from this typical shifting of attention in several ways:

(1) The typical movement of attention is quicker than the oscillation in rivalry or fluctuation. In rivalry, each appearance may last for many seconds before giving way to the other, whereas the more typical shift of attention occurs every second or so. In fact, during a rivalry or fluctuation experiment, you may observe thoughts coming and going at the same time, and at a more rapid rate than the changes in the object looked at. Attention does not really hold steady during the whole time that a single appearance of an ambiguous figure persists.

(2) Rivalry shifts are influenced very little, if at all, by the factor of momentary desire or interest, and are very little subject to control.

(3) In rivalry, the color that disappears goes out entirely, and in looking at a dot figure or ambiguous figure you get the same effect, since the grouping or appearance that gives way to another vanishes itself for the time being. But when, in exploring a scene with the eyes, you turn from one object to another, the object left behind simply retires to the background, without disappearing altogether; and, {256} in the same way, when attention shifts from one noise to another, the first noise does not lapse altogether but remains vaguely heard. Or when, in thinking of a number of people, one after another comes to mind, the first one does not go out of mind altogether when attention moves to the next, but remains still vaguely present for a few moments.

Laws of Attention and Laws of Reaction in General

Shifting occurs also in reflex action. Let two stimuli be acting at once, the one calling for one reflex and the other for the opposed reflex (as flexion and extension of the same limb), and the result is that only one of these reactions will occur at the same time, the other being completely inhibited; but the inhibited reflex gets its turn shortly, provided the two stimuli continue to act, and, in fact, the two reactions may alternate in a way that reminds us of binocular rivalry or ambiguous figures. Three fundamental laws of reaction here come to light.

(1) The _law of selection_: of two or more inconsistent responses to the same situation (or complex of stimuli), only one is made at the same time.

(2) The _law of advantage_: one of the alternative responses has an initial advantage over the others, due to such factors as intensity and change in the stimulus, or to habits of reaction.

(3) The _law of shifting_: the response that has the initial advantage loses its advantage shortly, and an alternative response is made, provided the situation remains the same.

These three laws hold good of reactions at all levels, from reflex action to rational thinking.

The mobility of attention obeys these same laws; only, attention is livelier and freer in its movements than reflex action or than the shifting in rivalry. Attention is more mobile and less bound to rigid rules.

{257}

Sustained Attention

The mobility of attention is only half the story. When we speak, for instance, of a student as having good powers of attention, we are not thinking of mobility but rather of the opposite.

Eye movement, which we employed before as a picture of the movement of attention, affords also a picture of sustained attention. Remember how the eye moves in reading. Every second it shifts, but still it keeps to the line of print. Just so, attention keeps moving forward in the story we are reading, but sticks to the story. The more absorbed we are in the story, the more rapidly we read. Attention is sustained here, and still it moves. Sustained attention is not glued to one point, by any means, but is simply confined to a given object or theme, within which its motion may be as lively as ever.

What is it, then, that sustains attention? Evidently it is the factor of present desire or interest, already mentioned. It is a reaction-tendency, aroused to activity by some stimulus or other, unable to reach its goal instantly, but persisting in activity for a while and facilitating responses that are in its line, while inhibiting others. Such a tendency facilitates response, i.e., attention, to certain stimuli, and inhibits attention to others, thus causing them to be overlooked and neglected.

For the student, the ideal attention-sustainer is an interest in the matter presented. If, however, he cannot get up any absorbing interest in the subject-matter at once, he may generate the necessary motive force by taking the lesson as a "stunt", as something to be mastered, a spur to his self-a.s.sertion. In the old days, fear was often the motive force relied upon in the schoolroom, and the switch hanging {258} behind the efficient teacher's desk was the stimulus to sustained attention. There must be _some_ tendency aroused if attention is to be sustained. The mastery impulse is certainly superior to fear for the purpose, but better than either is a genuine interest in the subject studied.

In order to get up a genuine interest in a subject--an objective or inherent interest--it is usually necessary to penetrate into the subject for some little distance. The subject may not appeal to any of our native impulses, or to any interest that has been previously acquired, and how then are we to hold attention to it long enough to discover its inherent interest? Curiosity will give us a start, but is too easily satisfied to carry us far. Fear of punishment or disapproval, hope of reward or praise, being put on our mettle, or realizing the necessity of this subject for our future success, may keep us going till we find the subject attractive in itself.

So, when the little child is learning to read, the printed characters have so little attractiveness in themselves that he naturally turns away from them after a brief exploration. But, because he is scolded when his mind wanders from those marks, because other children make fun of his blunders, because, when he reads correctly, he feels the glow of success and of applause, he does hold himself to the printed page till he is able to read a little, after which his interest in what he is reading is sufficient, without extraneous motives, to keep his nose between the covers of the story book more, perhaps, than is good for him. The little child, here, is the type of the successful student.

Attention to a subject thus pa.s.ses through three stages in its development. First comes the instinctive exploratory sort of attention, favored by the native factors of advantage. Next comes the stage of forced attention, driven by {259} extraneous motives, such as fear or self-a.s.sertion. Finally arrives the stage of objective interest. In the first and last stages attention is spontaneous, in the middle stage forced. The middle stage is often called that of voluntary attention, since effort has to be exerted to sustain attention, while the first and last stages, being free from effort, may be called involuntary.

Distraction

Distraction is an important topic for consideration in connection with sustained attention. A distraction is a stimulus that attracts attention away from the thing to which we mean to attend. There are always competing stimuli, and the various factors of advantage, especially desire or interest, determine which stimulus shall get attention at any moment.

In the excited insane condition known as "mania" or the "manic state", the patient is excessively distractible. He commences to tell you something, all interest in what he has to say, but, if you pull out your watch while he is talking, he drops his story in the middle of a sentence and shifts to some remark about the watch. He seems to have no impulse persistent enough to hold his thoughts steady. There are contrary insane conditions in which it is almost impossible to distract the patient from his own inner broodings, so much is he absorbed in his own troubles.

Distraction is a favorite topic for experiment in the laboratory. The subject is put to work adding or typewriting, and works for a time in quiet, after which disturbances are introduced. A bell rings, a phonograph record is played, perhaps a perfect bedlam of noise is let loose; with the curious result that the subject, only momentarily distracted, accomplishes more work rather than less. The distraction has acted as a stimulus to greater effort, and by this effort {260} is overcame. This does not always happen so in real life, but it shows the possibilities of sustained attention.

There are several ways of overcoming a distraction. First, greater energy may be thrown into the task one is trying to perform. The extra effort is apt to show itself in gritting the teeth, reading or speaking aloud, and similar muscular activity which, while entirely unnecessary for executing the task in hand, helps by keeping the main stream of energy directed into the task instead of toward the distracting stimuli. Effort is necessary when the main task is uninteresting, or when the distraction is specially attractive, or even when the distraction is something new and strange and likely to arouse curiosity. But one may grow accustomed or "adapted" to an oft-recurring distraction, so as to sidetrack it without effort; in other words, a habit of inattention to the distracting stimulus may be formed. There is another, quite different way of overcoming a distraction, which works very well where it can be employed, and that is to couple the distraction to the main task, so as to deal with both together. An example is seen in piano playing. The beginner at the piano likes to play with the right band alone, because striking a note with the left hand distracts him from striking the proper note with the right. But, after practice, he couples the two hands, strikes the ba.s.s note of a chord with the left hand while his right strikes the other notes of the same chord, and much prefers two-handed to one-handed playing. In short, to overcome a distraction, you either sidetrack it or else couple it to your main task.

Doing Two Things at Once

The subject of distraction brings to mind the question that is often asked, "Can any one do two things at once?" In this form, the question admits of but one answer, for we {261} are always doing at least two things at once, provided we are doing anything else besides breathing.

We have no trouble in breathing and walking at the same time, nor in seeing while breathing and walking, nor even in thinking at the same time. But breathing, walking, and seeing are so automatic as to require no attention. The more important question then, is whether we can do two things at once, when each demands careful attention.

The redoubtable Julius Caesar, of happy memory, is said to have been able to dictate at once to several copyists. Now, Caesar's copyists were not stenographers, but wrote in long-hand, so that he could speak much faster than they could write. What he did, accordingly, was undoubtedly to give the first copyist a start on the first letter he wished to send, then turn to the second and give him a start on the second letter, and so on, getting back to the first in time to keep him busy. Quite an intellectual feat, certainly! But not a feat requiring absolutely simultaneous attention to several different matters. In a small way, any one can do something of the same kind. It is not impossible to add columns of numbers while reciting a familiar poem; you get the poem started and then let it run on automatically for a few words while you add a few numbers, switch back to the poem and then back to the adding, and so on. But in all this there is no doing of two things, attentively, at the same instant of time.

You may be able, however, to combine two acts into a single coordinated act, in the way just described under the head of distraction, and give undivided attention to this compound act.

The Span of Attention

Similar to the question whether we can attentively perform more than a single act at a time is the question of {262} how many different objects we can attend to at once. The "span of attention" for objects of any given kind is measured by discovering how many such objects can be clearly seen, or heard, or felt, in a single instant of time.

Measurement of this "span" is one of the oldest experiments in psychology. Place a number of marbles in a little box, take a single peek into the box and see if you know how many marbles are there. Four or five you can get in a single glance, but with more there you become uncertain.