Attention

Quaeritur utrum intellectus noster possit multa simul intelligere. Respondeo dicendum quod intellectus quidem potest simul multa intelligere per modum unius, non autem multa per modum multorum.—St. Thomas Aquinas

§19. The Problem of Attention.—We have now finished our survey of the elementary processes of mind; all our complex experiences may be analysed into sensations, simple images, and simple feelings. There has been no special difficulty, so far, in exchanging the common-sense point of view for that of scientific psychology. You may not have realised, positively and intimately, that sensations and simple images are all meaningless; that we have described them simply as processes, as experiences going on; you may have been surprised, in view of the everyday distinction of perception from memory and imagination, to find that the simple image is only doubtfully to be distinguished from the sensation; and you may also have been surprised to learn that the feelings owe their manifold variety of tang and tincture to the sensations with which a simple feeling, pleasant or unpleasant, is blended. There is, however, no real difficulty, when once these things are pointed out, in taking up a scientific standpoint towards the mental elements.

As soon as we pass to consider attention, the case is changed; we come into definite conflict with popular psychology. Common sense regards attention as a voluntary concentration of the mind. For instance: I am sitting at my desk, thinking out and writing down the sentences of this paragraph. As I write, I am subject to all sorts of sensory stimuli; the temperature of the room, the pressure of my clothes, the sight of various pieces of furniture, the sounds from house and street, the scents coming from the room itself or borne in through the open window, organic excitations of various kinds. I could easily let my mind wander; I could lapse into reminiscence, or give the rein to my imagination. Yet I am perfectly well able to ignore all these distractions, and to concentrate upon my self-imposed task. Surely, says common sense, surely the whole situation implies a selective and spontaneous mental activity; I give my attention, of my own accord, to a certain topic that I have myself chosen; I could, if I liked, attend to something wholly different. That is the nature of attention as it is viewed by common sense.

Let us see, however, how things look when we try to describe attention, without making any effort to interpret or explain it. Suppose that, as I sit writing this paragraph, I am called to the telephone, or am interrupted by the entrance of a friend. My attention is thus diverted to a new object. What happens? Something happens that we can only describe as a shift of the vividness of our mental processes. A moment ago, my psychological ideas were vivid, set (as it were) in the focus of attention, while all other ideas and perceptions were dim and marginal; now the incoming ideas—my friend’s business or the subject of the message—drive to the front; they in their turn become vivid and focal, while the psychological ideas, just lately central and dominant, fall back, along with the perception of my sensory surroundings, into the dim background. Attention, therefore, if we consider it purely descriptively, hinges not upon mental activity, but upon the vividness of mental processes; and the state of attention may be described as a certain pattern or arrangement of mental processes; whenever our experience shows the pattern of vivid centre and dim background, of bright focus and obscure margin, then we have attention before us.

What, then, is vividness? The answer has been given already (p. 66): vividness is one of the universal aspects or attributes of sensation. Just as all sensations vary in intensity, so do all sensations vary in vividness. If you want a more positive answer; if you want to know how precisely vividness ‘feels’ in experience; observe your mental processes now, as you are puzzling over this book; the difference between foreground and background, focus and margin,—between the dominant ideas aroused by what you read, and the obscure perceptions derived from your surroundings,—will show itself at any rate in the rough. Be careful not to confuse vividness with intensity: when you are listening intently for a very faint sound, the sound, as it comes, is the most vivid experience you have, although it is near the lower limit of intensity; and when you are absorbed in your work, the sound of the dinner-gong in the hall may be very dim and obscure, although it is loud enough to be heard all over the house. Be careful, too, not to confuse sensory vividness with definiteness of meaning (p. 29). A patch of colour in an oil-painting may strongly attract your attention, may thus be extremely vivid, and may yet be altogether unintelligible; and another patch of colour, that you have passed over with ‘half a glance’ and that remains permanently in the background of experience, may carry the perfectly definite meaning of a dead soldier. Differences of vividness are neither differences of strong and weak in sensation, nor of distinct and indistinct in understanding; they are more like differences of robust and weakly, or of self-assertive and retiring.

These preliminary remarks are, perhaps, enough to show the nature of the problem that attention sets to a scientific psychology. We shall be concerned with sensory vividness; we have to find out under what circumstances a sensation or image becomes vivid, and under what circumstances it becomes obscure; we have to trace the pattern of attention in greater detail and with more accuracy; we have to ask how many sensations may be vivid at the same time, and how long they remain vivid; and so on. We must keep the common-sense view always in mind, so that the scientific alternative stands out clearly and distinctly against it; and we must take scientific account of all that common sense lays down.

§ 20. The Development of Attention.—If we consider a large number of cases of attention, we find that they fall into three great groups; and each one of these groups seems to represent a stage in the development of mind at large, a level of mental evolution. We speak accordingly of primary, of secondary, and of derived primary attention. Let us consider them in order.

(1) Primary attention.—There are certain classes of stimuli that force attention upon us; they take us by storm, and we can offer no resistance; when they appear, we must attend, whatever our preoccupation may be. Intensive stimuli belong to this class: very loud sounds, very bright lights, strong tastes and smells, severe pressures, extreme temperatures, intense pains, one and all take possession of us, dominate us in their own right. A stimulus that is often repeated is also likely to attract the attention, even if at first it went unremarked. Sudden stimuli, and sudden changes of stimulus, have the same effect. So with movement: the animal or bird that crosses the landscape, the melody that rises and falls to a steady accompaniment, the insect that crawls over our hand as we lie on the grass, all alike constrain our attention. A novel stimulus has the same power; it stands alone and unrelated; it startles or arrests us.

Here then is a fairly long list—high intensity, repetition, suddenness, movement, novelty—of controls to which the human organism is subject. Let any one of them come into play, and the corresponding sensation is made vivid, shoots to the focus, engrosses us. We may very quickly shake off the control, and return to the business that it interrupted; but we cannot altogether escape it. The irresistible appeal of these various modes of stimulation shows us attention at its first developmental level.

(2) Secondary attention.—This casual and forced attention is not, however, what we ordinarily mean when we speak of ‘giving attention’ to something. We mean rather the sustained attention that we pay to a task, a lecture, a puzzle; we often mean an attention that goes against the grain, in which we seem to do the forcing, holding our mind by main force upon a tedious and uninteresting subject. Is not this secondary attention very different from primary attention? Let us see.

If you think how many sense-organs man has, all of them open to manifold stimulation at the same time; and if you think, further, how many different lines of interest man has, all of them likely to bring up ideas of memory or ideas of imagination; you will realise that only very powerful stimuli, those that make an unescapeable biological appeal to the organism, can compel attention—that is, can thrust their sensations to the focus—as if in disregard of competition. Such stimuli are hors de concours; all the rest have to face their rivals. This fact gives us the answer to our question. Secondary attention is in reality nothing else than a conflict of nerve-forces, each one of which, if it were acting alone, would make its sensation or image the most vivid bit of experience at the moment, but each one of which is continually checked and thwarted by other forces that are urging their own sensations or images to the front. We might say, in brief, that secondary attention is a conflict of two or more primary attentions; but we must remember that the actual fighting is done in the nervous system; we shall say more of that presently. We can observe some part of this struggle; our mind wanders, our eye is caught by some chance movement and we lose the thread of our work, we surprise ourselves thinking of something else, we look at our watch to see how the hour is going; in a word, the focal processes are instable; now one and now another perception or idea becomes more vivid than the rest; and the continual shift of vividness is proof of the conflict of the underlying nerve-forces.

And the outcome? The outcome is that the stronger side always wins. Not necessarily the stronger side as we observe it; there may be a more impressive array of ideas on the side that finally gives way; but the side that has the stronger nerve-forces. It is quite certain that nervous forces or tendencies—think of the force of habit!—may guide and direct the course of our thoughts, even though they do not themselves contribute to thought, even though (that is) they have no sensory or imaginal correlates. We shall have more to say of these guiding tendencies later; meantime let us give an illustration of their power. Suppose that an observer comes into the laboratory to take part in a certain experiment, and that the experimenter carefully explains to him what he is to do. The next day he comes again, and the explanation is repeated. The next day he comes again; this time the experimenter says nothing; the experiment just goes on in the usual way; and so on the following days. Suppose, however, that on the twentieth day the experimenter says: ‘Are you thinking about what I told you to do?’ The observer, fearing that he has done wrong, and feeling very repentant, says: ‘No! to tell the truth I had forgotten all about it; it had absolutely gone out of my mind; have I been making mistakes?’ He had not made any mistake; but his reply shows that a certain tendency, impressed upon his nervous system by the experimenter’s original explanation, had been effective to direct his ideas long after the idea of the explanation itself had disappeared. And what happens here, in a few days’ work in the laboratory, is happening every day of our lives in the wider experience outside of the laboratory.

We see, therefore, that there is nothing spontaneous or active about secondary attention. It is merely primary attention over again, but primary attention under difficulties; it is a direct consequence of the multiplication of perceptions and ideas, and of the complexity of the nervous system.

(3) Derived primary attention.—One of the strongest proofs that there is no real difference between primary and secondary attention is that, in course of time, these difficulties vanish. Habit, as we say, becomes second nature; the thoughts that at first moved haltingly and with all sorts of interruption gradually become absorbing; work that was once done with pains and labour grows fascinating, and makes an unquestioned demand upon us. So the period of struggle ends, and we slip back again into primary attention; only this derived form is controlled, not by the great biological stimuli, but by impressions that fit in with our acquired interests. The collector, the inventor, the expert are roused to keen attention by stimuli which the rest of the world pass without special notice. Most of the striking coincidences of life are accounted for by this law; you are thinking about certain things, and something happens that, because you are thus thinking and because it is akin to the subject of your thought, captures your attention. ‘What an amazing coincidence!’ you cry; but if you had been occupied with some other topic, there would have been no coincidence. The man in Mr. Kipling’s story who wondered, years after the event, ‘how in the world he could have written such good stuff as that’, had written under this same law of attention; for when you are thoroughly absorbed in a subject, relevant facts and ideas crowd upon you; the mind stands open to them, while it is fast locked against the irrelevant; and you surpass yourself. There is, to be sure, another side to the picture; the enthusiastic adoption of a belief or theory throws into brilliant relief all the facts that tell in its favour, but blinds you to the considerations that make against it.

In sum, then, attention appears in the human mind at three stages of development: as primary attention, determined by any stimulus that is biologically powerful; as secondary attention, during which a perception or idea dominates the mind in face of opposition; and as derived primary attention, when this perception or idea has gained practically undisputed ascendency over its rivals. Looking at life in the large, we may say that the period of training or education is a period of secondary attention, and that the following period of mastery and achievement is a period of derived primary attention. Looking at experience more in detail, we see that education itself consists, psychologically, in an alternation of the two attentions; habit is made the basis of further acquisition, and acquisition, gained with effort, passes in its turn into habit; the cycle recurs, so long as the nervous system remains plastic. Secondary attention thus appears as a stage of transition, of conflict, of waste of nervous energy, though it appears also as the necessary preliminary to a stage of real knowledge. Meanwhile and all the while there is no escape from interruption by the original primary attention; but the interruptions grow less and less disturbing as civilisation proceeds.

§ 21. The Nature of Attention.—Our next task, in the words of p. 93, is to trace the pattern of attention, to describe as accurately as possible the arrangement of our vivid and obscure sensations. Notice that, in popular parlance, attention covers only the vivid processes of the moment; psychologically, however, the term includes both the vivid and the obscure, those that we are ‘distracted from’ as well as those that we are ‘attending to,’ This being understood, we may attempt a description.

It seems that, in most cases, the state of attention is twofold and only twofold. There is a cluster of sensations at the centre, all of approximately the same vividness, and there is a mass of sensations in the background, all of approximately the same obscurity. Suppose that you are looking at one of the puzzle-pictures that are published in certain magazines,—trying to find a face outlined in the branches of a tree. At first, the whole picture is vivid, and the rest of your experience is obscure. Suddenly you find what you are seeking; and what happens? In all likelihood, the picture drops with a jerk into the general dimness of the background, while the face that you have discovered stands out by itself in all imaginable vividness; you forget the picture, and see nothing but the face. The state of attention, then, in this its usual form, may be represented by two concentric circles; a small inner circle stands for the focus of attention, a large outer circle circumscribes its margin. There is experimental evidence that, when our sensations are thus arranged, their vividness and obscurity are, as the arithmetics say, inversely proportional; the more vivid the central processes, the more obscure are the marginal; or, in untechnical language, the more we are concentrated upon any one thing, the less liable are we to distraction by other things. This twofold arrangement seems to be, for most of us, the regular pattern of attention; but certain observations in the laboratory, which are borne out by statements in various text-books of psychology, make it practically certain that there is another, less frequent and more complicated type of arrangement. Here the picture does not drop clear down into the background, when the face is found, but remains poised somewhere between focal vividness and marginal obscurity; so that three degrees of vividness—sometimes even four have been reported—may be distinguished in one and the same state of attention. In such cases, attention must be represented by three or four concentric circles; the inner and the outer still show the focus and margin of the total state; the others indicate that there are sensations present whose vividness lies somewhere between those extremes. Whether the focal processes suffer from the rivalry of the moderately vivid sensations; whether, that is, attention in its threefold or fourfold pattern is necessarily, even at the best, of a lower degree than the best attention of the twofold kind, we do not know.

Our description of attention is so far complete; but there are two further questions that naturally occur. Do we not attend to what ‘interests’ us? In that case, however, attention must imply feeling. And is not sustained attention tiring? In that case, attention would seem to imply muscular sensation. These are undoubtedly points to be considered, and we must try to get at the facts. Are feeling and kinÆsthesis necessary in attention, or are they merely chance accompaniments of the attentive state?

It all depends upon the stage of development at which attention appears. At first, in primary attention, the organism perceived the strong or sudden or novel or moving thing, as sight or sound or touch, and also felt it, as disturbing or startling or surprising; attention implied a sense-feeling. At the same time, the organism took up an attitude to the stimulus, in the literal sense; faced it, as peering and listening and frightened animals face such stimuli to-day. At this stage, then, the shift of vividness is always accompanied both by feeling and by sensations,—sensations due to internal bodily changes and to muscular attitude. Then comes secondary attention, with its conflict between various claimants for the inner circle of attention; and the conflicting stimuli will, naturally, arouse a medley of sense-feelings and set up a struggle of more or less incompatible motor attitudes. In civilised man, the scene of the conflict has been largely transferred from perception to idea; but the effort that we make when we apply ourselves to a task, the difficulty that we have in settling down, the fatigue that results from sustained work upon a difficult theme, all these things are reminders of the general uneasiness and restlessness that characterise secondary attention at the perceptive level. Only when we come to derived primary attention do feeling and kinÆsthesis cease to be necessary factors in the attentive state. What we call mechanical, habitual, expert, professional attention means extremely vivid experience; but it need not involve either feeling or kinÆsthetic sensation. Attention is no longer turbid with organic processes; the stream of mind has cleared itself. Common sense would say, and rightly, that a cool and critical poise has replaced the older animal excitement, and would emphasize the value of this change. We do not question the value; but we are at the end of our psychological enquiry when we have shown what the change in experience actually is, and how it is brought about.

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.

Questions and Exercises

(1) “So numerous and varied are the ramifications of attention, that we find it defined by competent authorities as a state of muscular contraction and adaptation, as a pure mental activity, as an emotion or feeling, and as a change in the clearness of ideas. Each of the definitions can be justified from the facts, if we put the chief emphasis now upon one phase and now upon another of its varied expressions” (W. B. Pillsbury, Attention, 1908, 1). Discuss this passage.

(2) Give instances, from your own experience, of the three levels of attention. Trace the development (still from your own experience) of derived primary from secondary attention.

(3) Describe carefully the attitudes (a) of the scout (secondary visual attention) and (b) of the eavesdropper (secondary auditory attention). How do you account for their difference?

(4) A child that has fallen and hurt itself stops crying if you offer it a toy; a soldier who in the heat of battle has received a serious wound may know nothing of it, and may go on fighting till he drops from exhaustion; many a martyr has suffered at the stake with calm serenity. How far are these cases explicable by the laws of attention?

(5) Criticise Sir Wm. Hamilton’s experiment. Do not be satisfied till you have found several reasons for distrusting its result.

(6) Do the lower animals ever give evidence of derived primary attention?

(7) You can follow the movement of a single instrument in the orchestra better, when it has been playing a solo before, than when the whole group of instruments begin together. Why is this? Give other instances of the same law.

(8) It has been proposed to measure the degree of attention by measuring the degree of effort which accompanies it. What have you to say to the proposal?

(9) How could you tell, by outward observation, whether a child is attentive or inattentive? and whether it is adequate to its task or is in difficulties? Do not just list the symptoms; make your answer psychological.

(10) Determine the range of attention (a) by help of an ordinary metronome, set at various rates. You must not count the beats, since every count would mean a separate attention. Determine the range also (b) by help of the letter-diagram and cardboard screen figured by W. Wundt, An Introduction to Psychology, 1912, 19. Notice the remark (p. 23) that the experimenter must practise covering and uncovering the diagram.

(11) Paint or paste a small disc of light grey on a white cardboard ground. Move so far away that the spot is only just distinguishable. Call out Gone! and Back! as it disappears and reappears, and have the times noted on the seconds-dial of a watch. Explain the fluctuation, in your own words, as due to adaptation and eye-movement. Can you devise a simple method of showing (by means of the negative after-image) that unnoticed eye-movements really occur?

(12) St. Thomas asks whether the mind can grasp more than one thing at a time; and replies that it can, if the various things are regarded as making up a single whole, but that it cannot, if they are regarded in their variety and particularity. Can you put all this into psychological language? And can you find any difference between St. Thomas’ question and our own question as to the range of attention?

References

Sir W. Hamilton, Lectures on Metaphysics, i., 1859, 254; W. B. Carpenter, Principles of Mental Physiology, 1888, ch. iii.; W. James, Principles of Psychology, i., 1890, ch. xi.; W. Wundt, Lectures on Human and Animal Psychology, 1896, Lect. xvii.; Outlines of Psychology, 1907, § 15; W. B. Pillsbury, Attention, 1908; E. B. Titchener, Lectures on the Elementary Psychology of Feeling and Attention, 1908, Lects. v.-viii.; Text-book of Psychology, 1910, 265 ff.