A Beginner's Psychology

by Edward Bradford Titchener

But are we at the end? Should we not say something about inattention, which in everyday life we take to be the opposite of attention? have we not still to describe the inattentive state? No: in the normal waking life there is, in strictness, no such thing as inattention. We give that name to an attention which is directed upon what we regard as an improper object. The inattentive person is merely attending to something else; the pattern remains the same. It is possible that, in certain abnormal cases, all mental processes alike run their course in relative obscurity; but even here we are not dealing with inattention; there is some weakness or obstruction of nerve-forces, which prevents sensations from reaching their full normal vividness.

[§ 22]. The Experimental Study of Attention.—The question of the range of attention,—how many sensations or images may occupy the focus at the same time,—was canvassed in the Middle Ages: witness our quotation from St. Thomas. The first appeal to experiment seems to have been made, in the late thirties of the past century, by the Scottish philosopher Sir Wm. Hamilton. “You can easily make the experiment for yourselves,” Hamilton tells his students, “but you must beware of grouping the objects into classes. If you throw a handful of marbles on the floor, you will find it difficult to view at once more than six, or seven at most, without confusion; but if you group them into twos, or threes, or fives, you can comprehend as many groups as you can units.” The experiment is not very rigorous; but more accurate work on the subject shows that Hamilton was not far wrong. If a field of simple visual stimuli is shown for a brief time, the practised observer is in fact able to grasp six of them; and if familiar groups are substituted for the separate stimuli (short words for letters, or playing-card fives for single dots), the range of visual attention remains the same.

In this case the stimuli are presented together in space; they may also be presented in time. If you listen to a metronome beating, say, 15 in the minute, you will be able with practice to hold six successive strokes in the focus of attention, but not more; if you try to group the seventh stroke with the preceding six you become confused; the series breaks, and cannot be welded together again. As the speed of the metronome is increased, the beats fall of themselves into groups of twos and threes; and you can still grasp and hold six of these rhythmical impressions. When the speed has reached some 200 in the minute, the rhythmical grouping becomes more complicated; as many as eight single beats may be bound together in a rhythmical unit; and the attention is adequate, again after practice, to five of these complex groups; the focus comprises no less than forty separate strokes of the pendulum. This result, we may note, agrees very well with the canons of musical and poetic composition. The musical phrase never contains more than six measures, and the poetical line or verse never contains more than six feet; a seven-measured phrase or a seven-footed line falls to pieces, ceases to be unitary. The rhythmical wholes of a higher order, the period in music and the stanza or strophe in poetry, never contain more than five phrases or verses; as a rule, neither contains more than four.

So much for range; we turn to consider duration; how long can a sensation maintain itself at the focus? how long can we attend to a single simple impression? The early experiments on this question were most ingenious. The observer was required to look steadily at a little disc of very light grey, shown against a white background, or to listen intently to the very faint sound of a stream of fine sand; and the theory was that, since these stimuli were barely distinguishable at the outset, any lapse of attention, any decline in the vividness of the sensations, would blot them out altogether; they would disappear. The sensations did disappear, after a few seconds; and then, after another few seconds, came back; and so the conclusion was drawn that attention fluctuates, that we can attend to a single simple impression only for a few seconds at a time. No doubt attention fluctuates; but these experiments, unfortunately, are not to the point; for the disappearance and reappearance of the sensations can be accounted for by changes in the sense-organ, by adaptation, by twitching of the eyes, and so on. Other experiments have therefore been suggested. If we have recourse to smell and touch, we find that the course of adaptation to an odour, or to the pressure of a small weight laid upon the skin, may be followed attentively, without noticeable fluctuation, for two or three minutes; and the observers report that they could have kept up their attention still longer. Again, however, objection may be raised; for as adaptation advances, the sensation grows fainter and fainter; and the attention is thus continually spurred to hold it; the observer is not attending to an unchanging process, but is sharpening his attention to something that becomes more and more difficult to fix. Here we are, for the present, at a standstill. There is no doubt that attention fluctuates; the bare fact is plain enough in our everyday experience; but we have no experimental ground for a more definite statement.

Experiments have also been made to determine the bodily changes which occur in the state of secondary attention (p. 102). It is found that the volume of the brain increases, while the volume of the arm (save in experiments in which tactual stimuli are employed) decreases. Breathing becomes shallower; and expiration becomes relatively longer as compared with inspiration, so that the quotient I: E, time of inspiration divided by time of expiration, becomes less. There are changes in the rate of pulse; but they seem to differ according as the attention is ‘sensory’ or ‘intellectual,’—according, that is, as the focal process is a sensation or something more complicated, a perception or idea: in sensory attention the pulse beats more slowly, in intellectual attention more quickly, than its normal rate. It is natural that the blood, in attention, should be drawn from the members to the brain; it is natural, too, that this rule should be broken when a limb is itself the ‘object’ of attention; and we all know that there is a tendency, when we are attentive, to hold the breath; so that the changes of volume and breathing are not surprising. Nothing more can be said at present of the changes in rate of pulse.

[§ 23]. The Nervous Correlate of Attention.—It remains to say a word about the nature of the nerve-forces (§ 20) which underlie attention. Physiologists tell us that one nervous process may influence another in two opposite ways: by helping and by hindering, or, in technical terms, by reinforcement and inhibition. Let us take an elementary example of what they mean. Suppose that a frog has been reduced, by the removal of its cerebral hemispheres, to a mere nerve-and-muscle machine; it lives, but it cannot sense or feel, and it does not move ‘of its own accord.’ If, now, a weak pressure is applied to the frog’s hind foot, there is no visible response; the limb remains passive. But if at the same moment a light is flashed into the eye, the leg-muscles may be thrown into strong contraction. Here we must suppose that the two nervous processes, from skin and eye, have in some way helped each other; there is nervous reinforcement. If, again, a pressure is applied to a certain part of the frog’s body, the animal croaks. If a strong pressure is applied to another part of the body, it replies by a contraction of the muscles. If, however, the two pressures are applied together, the frog does not both croak and move; it does neither; there is no response to the stimuli. Here, therefore, we must suppose that the two nervous processes interfere with each other; there is nervous inhibition.

It seems plain that these two influences are at work among the nervous processes correlated with attention. The vivid sensations at the focus are sensations whose corresponding nervous processes have been reinforced, and the dim sensations of the background are sensations whose corresponding nervous processes have been inhibited. No doubt, the distribution of these forces, in a given instance, is really a matter of degree; the reinforced nervous process receives more reinforcement than inhibition, and conversely. No doubt, also, the removal of an existing inhibition may produce the same effect as the addition of a reinforcement, and conversely. We are still too much in the dark as regards the intimate character of the nerve-forces, we know too little of their actual course as nervous function in nervous structure, to be able properly to distinguish cases. There is evidence that inhibition may be extraordinarily effective: thus the late Dr. W. B. Carpenter relates that he “has frequently begun a lecture, whilst suffering neuralgic pain so severe as to make him apprehend that he would find it impossible to proceed; yet no sooner has he, by a determined effort, fairly launched himself into the stream of thought, than he has found himself continuously borne along without the least distraction, until the end has come, and the attention has been released; when the pain has recurred with a force that has overmastered all resistance, making him wonder how he could ever have ceased to feel it.” Reinforcement also may be carried to a high degree: how else could the listener follow the part assigned to some special group of instruments in the orchestra, while he still hears the full harmony? and how, still more, could the conductor single out the particular violin-player, who has mistaken a note, from the group of sixteen who are all playing precisely the same part?

We may suppose, therefore, that one and the same pattern of attention is due to very varied combinations of reinforcing and inhibiting nerve-forces. How then shall we account for the fact that, in any given instance, vividness and obscurity are inversely proportional (p. 100)? The reason seems to be—though we could not have learned it from the experiments on the frog—that a reinforcement and a corresponding inhibition always go hand in hand; you cannot reinforce one process without at the same time inhibiting others, and you cannot inhibit without reinforcing. The nerve-forces are thus interlinked or, as we might say, double-acting. We are struck by the inhibition in Carpenter’s case; but the case has another side; for the more successful the inhibition of the neuralgia, the better was the lecture delivered. So we are struck by the reinforcement in the case of the conductor; but that, too, has another side; for the keener his attention to the music, the more oblivious is he of his other surroundings. We shall come back later to this notion of the interlinking of the nerve-forces, and shall indicate the evidence upon which it rests.

In summary, we may repeat our general statement that vividness is paralleled by nervous reinforcement, and obscurity by nervous inhibition. Only we must realise that the processes actually going on in the brain may be very complicated; many separate forces may be at work behind the single mental pattern, and their action may be brought about in different ways; and we must remember also that every one of these separate forces is double-faced, reinforcing and inhibiting at the same time.