/ 282 Attention of affairs in the effort which always comes with secondary attention. We naturalty dislike to work; work of any sort means effort. And effort is itself a sense-feeling, made up of unpleasantness, and of a complex of kinaesthetic and organicsensations. Experiments by the method of ex- pression show that breathing in secondary attention is likely to be inhibited, to become shallow; and there are other bodily changes, correlated in part with the unpleas- ant affection, in part with the motor restlessness.
As the nervous system developed, image supervened upon sensation, and conflict and rivalry were largely trans- ferred to the field of ideas. Congruity with consciousness now took its place among the determinants of primary at- tention. There was a radical change in the make-up of consciousness; and one aspect of the change was the weakening of the kinaesthetic and affective factors in at- tention. The effort that we make when we sit down to work, and the difficulty that we feel for the first few minutes of working, are the direct descendants of the older uneasiness and the older motor restlessness, but they are degenerate descendants, mere echoes of the primitive ex- periences. So degenerate are they, that some psychologists refuse to regard effort as a sense-feeling: Wundt makes tension a simple affection, and others see in it a new kind of mental element, a conative element or elementary process of will. There is no introspective warrant for either view. Effort, in whatever context we take it, proves to be analysable; it reduces to affection and sensation.
The last stage in this development is given with the passage from secondary to derived primary attention. We began with an affective sensorimotor reaction, the reaction § yS. Factors in the Attentive Consciousness 283 of the whole organism upon a single stimulus. From that we passed to sensorimotor conflicts, still strongly affective. Then images come in, and separate the sensory from the motor, the reception of stimulus from the movement of re- sponse. Henceforward secondary attention may be con- cerned mainly with the stimulus (receptive attention), or mainly with ideas (elaborative attention), or mainly with movements (executive attention): being secondary atten- tion, being, that is, attention under difficulties, it is always tinged with effort. Finally, secondary passes over into derived primary attention; and when it does, affection and kinaesthetic sensation cease to be necessary factors in the attentive consciousness. Thus, to begin with receptive at- tention, we may open our morning's mail with keen excite- ment, or we may attend to it with no change either of affective or of kinaesthetic experience. We may, in elab- orative attention, be absorbedly interested in an argument, and allow the body to grow stiff and cramped; or we may take the argument quietly and indifferently. We may, in executive attention, be wholly bent upon the successful performance of a skilled action, and may tire ourselves out in attempting it; or we may make the movements easily and as a matter of course. What we calMiabitual, me- chanical, perfunctory attention involves the two conscious levels of clearness and obscurity, but does not involve either affection or kinaesthesis.
It must be remembered that attention is not something rare and occasional in the mental life, but is the normal state of our consciousnesses. When we charge other persons with inattention, we do not mean that they are, literally, non-attentive; we charge them with inattention to a particular topic; and this inattention means, simply, that they are attending to something else. A 284 Attention strictly one-level consciousness is certainly abnormal, and prob- ably never occurs in the normal waking state; though it may be realised, or at least approximated, in idiocy (lower level) and in profound hypnosis (upper level). But if attention is thus the rule and not the exception, there is nothing surprising in its becoming a matter of habit, in its leaving us — in both senses of the word — unmoved.
The occurrence of kinaesthetic sensations as the object of atten- tion (for instance, of the executive type) must, of course, be care- fully distinguished from their arousal by the motor attitude of the organism in attention. It is the second sort of kinaesthesis whose weakening and disappearance we have traced.
§ 79. The Experimental Investigation of Attention. — In taking up the study of sensation, experimental psychology was greatly helped by physics and physiology. Instru- ments and methods of research were at hand, and needed but little modification to render them serviceable; and a large body of observations, scattered through the physical and physiological journals, could be transferred directly to their proper place in the new science. Hence, from the very outset, the problems of the quality and intensity of sensation were attacked with good hope of success; and although, as is always the case, all sorts of unforeseen difficulties arose, our knowledge of these attributes has steadily advanced.
The experimental study of affection began much later. Here, therefore, we have to make up for lost time. Still, we are entering on the work in the light of all the experi- ence that we have gained with sensation, and physiology has again come to our aid with the instruments needed by the expressive method. Another ten years will proba- bly suffice to lay the foundations of a stable affective psychology.
§ 79- The Experimental Investigation of Attention 285 Interest in attention goes further back. As soon as the work upon sensation had been fairly started, experimental psychology turned to the investigation of attention. Here, however, it found no outside assistance; physics and physiology had nothing to offer; there was only a popular psychology to build upon* And so the experimentalists made the mistake — natural, almost inevitable, but still a mistake — of grappling with the total attentive conscious- ness, all at once, instead of beginning with a psychology of clearness, and developing it on the lines of the psychol- ogy of intensity and quality. The consequence is that we know less about attention than we should; a good many of the earlier studies have to be done over again, little bit by bit; the problems have to be split up, and made more manageable. Even so, the experimenter of to-day is ham- pered by the past; he wishes to keep all the results of previous work that can be kept, and therefore, while he makes his problems as narrow and definite as possible, he shapes them in accordance with psychological tradition. Rut science must set out from the sirnj2J^and_moye_gradji- ally to the complex." A total consciousness is the most complicated thing that psychology has to deal with, and its treatment should come last of all. If we want to understand attention, we must begin at the other end, with an exhaustive study of the attribute of sensory clearness.
A few names and dates may be given in illustration. The psy- chology of intensity is connected especially with the name of Fechner, who published his Elemente der Psychophysik in i860. The psychology of quality is connected, similarly, with the name of Helmholtz, who published the Handbuch der physiologischen Optik in 1856-1867, and the Zur Lehre von den Tonempfindungen 286 Attention in 18C3. The experimental study of attention may be dated from 1861, when H'undt (Beitrdge zur Theo7'ie der Sinneswahrnehmung, 1862; Hu man u.-d Animal Psychology, 1896, 270) began the series of researches that hav - culminated in his doctrine of apperception. The experimental study of affection may be dated, in the same rough way, from the appearance m\. 1892 of A. Lehmann's Die Hauptgesetze des menschlichen Gefuhlsleben:, which took the prize offered by the Royal Danish Academy of Sciences;n 1887 for a scientific work upon the feelings.
In the meantime, a glance at Fig. 40 will show that the attentive consciousness sets a number of experimental problems. There is, for instance, the problem of the area of the attentive-wave, or of the range of attention. The question: How many things can we attend to at once? has often been asked, and has been very variously an- swered. A busy man will tell you, if you interrupt him, that he can't possibly attend to more than one thing at a time. On the other hand, it is related that Julius Caesar and the first Napoleon could carry in their heads the topics of a dozen despatches, and could dictate them without con- fusion to as many secretaries. There is also the problem of the length of the attentive-wave, or of the duration of attention. For how long a time can attention be main- tained? In everyday experience, the object of attention is continually changing. Does attention lapse, as we pass from object to object? Then there is the problem of the height of the attention-wave, or of the degree of attention. How many different degrees can be distinguished, and how can they be measured? We speak roughly of close or rapt or absorbed or concentrated attention, and we con- trast it with wandering or fitful or divided attention. But this, after all, is much like saying that our sensations of § 80. The Range of Attention 287 light are black, white and grey; we want a more exact statement, and if possible a statement in numerical terms. The present condition of our knowledge, on these and kindred topics, is briefly set forth in the following sections.
§ 80. The Range of Attention. — Our problem is to determine how many impressions can be attended to together, without decrease of the clearness which each one of them would possess if the attention were directed to it alone. We can approach the problem in two ways, by a simultaneous and a successive method. Thus, we may present a number of stimuli to a sense-organ at the same time, and gradually add to them, until it becomes impossible to attend to all at once. In the case of sight, for instance, we may show the observer a number of dots, lines, letters, numerals, simple geometrical figures, bands of colour, etc., laid upon the same background. Or we may give the stimuli in succession, gradually increasing their number till the point is reached at which the first drops into obscurity as the last is given. This method answers best with auditory stimuli. In both forms of the experiment, the object of enquiry is the same; we wish to determine the limit of complexity at which the attention becomes unable to cope with the stimuli offered to a parti- cular sense-organ. And in both the same result is reached; the attention is able to embrace six, simultaneous or suc- cessive impressions, of a relatively simple kind and of unitary character.
Method of Simultaneous Stimuli. — Experiments are made by means of the tachistoscope, an instrument which, as its name implies, permits the exposure of a limited field for very brief periods of time. The time of exposure must be short, since Attention otherwise the eye may sweep rapidly over FlG. 42. Demonstrations! Tachistoscope. A black cur- tain, mounted on strong spring rollers, is stretched In hind a square opening in a black wooden screen. The upper Fig. (front) shows the curtain and the white fixation-mark. The lower Fig. (back) has the card-carrier thrown back to show the square open- ing in the curtain itself.
the stimuli, leaving some to be remem- bered while others are directly attended to; in this case we should be dealing, not with the grasp of a single attention, but with a series of atten- tions. And the ex- posed field must be so small that it is readily taken in by the eye at a glance, without eye-move- ment, since otherwise the obscurity of the outlying stimuli may be a matter, not of the limit of attention, but of indirect vision If letters are em- ployed as stimuli, they must form a meaning- less series, such as RKZT. It has been found that a familiar word of three or four letters can be appre- hended by the atten- tion as if it were a single letter or geo- metrical figure; it is attended to, not as a series of letters, but as a single impression.
§ 8o. The Range of Attention 289 For the same reason, the attentioncan deal with numerals better "• than with disconnected letters; any combination of numerals" means something, makes sense.
^TKe" maximal range of the visual attention, for a practised observer, comprises six impressions; individual ranges differ fc between the limits of four and six. Experiments with simul- taneous impressions ol touch have given a like result; a practised observer is able to localise six scattered points correctly. This observation, however, needs confirmation.1 Method of Successive Stimuli. — The running weight upon the tongue of a bell-metronome is set for two hundred beats in the minute. The experimenter marks off two series of beats by sounding the bell simultaneously with the first beat of each series. The observer is required to say whether the two successive series are equal or unequal. He must not count, of course; counting would mean that a separate attention was given to every beat.
Accurate judgment is impossible in the case of series which consist of more than six impressions. And if the metronome could be run very slowly, — say, at fifteen in the minute, — the range of attention would be no more than six single beats. But just as in the previous experiment a short word was equivalent, for the attention, to a single letter, so here a group of beats may, under certain conditions, be equivalent for the attention to a single beat. As the rate of the metronome is increased, we can- not help reading into the succession of strokes a more or less * complicated rhythm. At first, with rates that are still fairly slow, the beats group themselves into twos or threes, and the attention is still adequate to six impressions, — six rhythmical units of two 1 It is natural to recall, in this connection, that the point-characters of the Braille and the New York Point alphabets for the blind both alike ring the changes on a single symmetrical arrangement of six dots; and it is tempting to suppose that the limit of six was set by the limit of the range of tactual attention. But, as a matter of fact, the suggestion of the sixfold unit came from visual memory of the double-six domino: no preliminary experiments were made on touch. It also seems certain that blind readers do not, in general, distinguish the separate dots, but apprehend the total form of the letter, as if the dotted lines were continuous, V * 290 Attention beats (twelve beats in all) or six rhythmical units of three beats (eighteen beats in all). Finally, at the rate specified above, the attention can cover only five impressions, five rhythmical units: but these may now consist of eight or even, it is said, of twenty- four single beats; so that the series of five impressions consists of forty or even of one hundred and twenty metronome strokes. The groups of eight and of twenty-four are apprehended as units, akin to the short word of the previous method.
This result agrees very well with the canons of musical and poetical practice. The musical phrase never contains more than .six measures, the poetical verse or line never contains more than . Isix feet; a seven-measured phrase or a seven-footed line falls to vpieces, ceases to be unitary. Ami the rhythmical wholes of a higher order, the period in music and the stanza or strophe in poetry, never contain more than_five^4DlirjiS£S_or verses; as a rule, neither contains more than four.
Minor Differences of Clearness at the Upper Conscious Level. — We have seen that the short word, the complexes of geometrical figures, and the rhythmical unit have, for the attention, the value of single impressions. Since they stand at the upper level of con- sciousness, their component parts are all clear. But they are by no means equally clear. Think, for instance, of a simple rhythmi- cal unit, such as we might read, in music, ONE — and two — and three — and four — and. Here the first member is the strongest and clearest, the fifth stands next in order, and the second, fourth, sixth and eighth are relatively weak and obscure. This means that the upper level of the attentive consciousness is, as a rule, wrinkled into smaller waves, and not smooth, as it is drawn in Fig. 40. There are degrees of clearness within the clear. And this, again, may account for the belief, held by some psychologists (§ 77), that all possible degrees of clearness may coexist in the same consciousness. See, however, p. 302.
Whether there are, in the same way, degrees of obscurity within the obscure, wrinkles or wavelets at the lower level of Fig. 40, is still uncertain. In any event, these minor waves at the two levels V^ are quite shallow, and cannot mask the gross difference between kc*fre levels themselves.
§ 8 1. The Duration cf Attention 291 § 81. The Duration of Attention. —.an ..-...ntal p~_ \ ed for how long a time a single wave of attention could last, he would have replied with: of seconds only. Mar.
oeriments have been m e vould have said, and all have led to the same r es d It: that attend n is not pe I nt, t interrr. ittent, — g and falling _ wing, at short intervals. If you attend as closely as you can to a simple. it - not re:lear, : becomes all ar and.re; the ttention I If the same question i the reply must be that, while. -. good deal more a~: the s "A subject, we do not knc: ttention ma;-: r.dnue.
It may, and remain it f or twc t I ree minutes. In the --.-5 judgment, it ma; remain con- stant for much longer periods.
It has 50 smal r so weak, 01 eir surrounding that the k ghtesl me.". consc for it is fei r to say mat r do 1 rorst e- I g 1 it is tc sra ■ t we see or heai pown been e. t and colour. ' I noise, me [then ten rrenl tnret rime:. gazing fin I f light fj te gi id, or Ksf a all tr ears to the fainl _ e your rieuma: the ii nee of the sc n upon a kyn. _ in the next 1 For the sensal ertain cast ear and reappear. The earliei this J. in all Attention FlG. 43. Masson's Disc. The broken radius, painted black on white, gives three of the sense-departments mentioned, and they found it with images as well as with sensations. They accordingly assumed that it must be due to some common factor, and — naturally enough — ascribed it to the intermittence of attention. There were, it is true, objectors, who pointed out that the attention need not be involved. The eye has a mechanism of ac- commodation in the lens and its muscular attachments, and the ear has a similar mechanism in the muscle known as the tensor tym- pani, which pulls upon the drum- skin: why might not the intermit- rise, when the disc is rotated, to a tence of the minimal sensation be series of grey rings, which grow due tQ periphera] changes, to shifts lighter and lighter towards the periphery. The observer follows the of accommodation? But the reply grey out from the centre, and stead- seemed conclusive: visual fluctuily fixates some point upon the ation was observed during tempooutermost ring that he can distin-,...• h rary paralysis of the muscles of accommodation, and even in the case of aphacic subjects, patients whose eyes had lost the lens; and auditory fluctuation was proved to occur despite the lack of a tympanic membrane. The theory of an intermittent attention had apparently won the day.
Nevertheless, the peripheral theory would not down. New ex- periments were made on touch; and it was found that the mini- mal sensations set up by tiny weights and by a weak electric current do not fluctuate at all. If there is no outside disturbance, no itching or tingling or movement of the skin, the sensations run their course without interruption, until they fade out by adaptation. During these experiments it was observed that a steady attention might be kept up for at least two or three minutes. New experi- ments were also made on vision; and it was found that visual sensations, too, tend to fade out into their background by adapta- tion, but that the course of adaptation in their case is interrupted, § 82. The Degree of Attention 293 — interrupted by involuntary eye-movement. The involuntary movements were timed, their direction was noted, and their extent was measured: in all three respects there was agreement between occurrence of movement and disappearance of sensation. Reap- pearance is due in part to the recovery of the retinal elements during movement, in part to the faulty adjustment of the eye; the eyeball does not return after movement to precisely the position that it had before movement, and the stimulus may therefore affect retinal elements which have not as yet been exposed to adapta- tion. It was found, further, that the negative after-image, the after-effect of local adaptation (§ 18), behaves in precisely the same way as the primary sensation; intrinsically, the course of the after-image is continuous, but it is interrupted when and in so far as eye-movement takes place.
So far, then, there is no need to invoke the attention, in order to explain fluctuation; we must suppose that the older observers were misled by preconceived opinion, or perhaps fell into errors of technique. But what, now, of tone and noise? Well, the fluctuation of tone and noise is still under discussion. Some observers have failed to get fluctuation with either; others get fluctuation with both. The reason for this difference of result may, possibly, be physical: it is extraordinarily difficult to main- tain either a tone or a noise at absolutely uniform intensity; and a very slight change in objective intensity will, of course, bring a faint tone or noise to complete disappearance.
Here we are, for the present, at a standstill. We do not know how long a single wave of attention, carrying a single sensation of sight or sound or touch, may continue. Nor do we know for how long a steady level of attention may be maintained under the conditions of everyday life, where the object of attention is con- stantly changing. The single wave may continue at least for two or three minutes; the writer would not be surprised if it should turn out that the steady level may be maintained for two or three hours.
§ 82. The Degree of Attention. — The measurement of attention is one of the most pressing problems in experi- 294 Attention mental psychology. If we could measure a man's ca- pacity of attention, and could discover at any moment what proportion of that capacity he was using: if, that is, we could determine the greatest possible height of the attention-wave, in Fig. 40, and could find out its actual height in the case before us: then we should have a re- sult of the greatest scientific importance and of the utmost practical value. Many experiments have been made, but the problem is still far from solution.
One difficulty has grown out of the popular use of the word attention. When the term is used without qualifica- tion, we naturally think of it as secondary attention; we think of the attention that the teacher enjoins on the pu- pil, of the effort of attention. Primary attention, whether original or derived, is so natural an attitude, so much a matter of course, that we hardly notice it: at most, when we see it in others, we say that so-and-so is absent-minded, or is in a brown study. This mistake, of identifying atten- tion with secondary attention, is especially natural to the man of science, who is always puzzling and searching. So it comes about that psychologists have proposed to measure the degree of attention by measuring the degree of effort which accompanies it. We can measure sensa- tion; kinaesthetic sensations indicate the degree of atten- tion; hence, if we measure them, we have also measured attention.
The argument is fallacious, for the simple reason that the higher degrees of attention do not involve effort. When we have reached the stage of derived primary attention, effort has disappeared. The kinaesthetic sen- sations indicate, not degree of attention, but rather inertia of attention; strained attention is, as we have seen, atten- § 82. The Degree of Attention 295 tion under difficulties; the very fact that we try to attend means that we are not giving full attention. It would, accordingly, be nearer the truth to say that, the more pro- nounced the effort, the lower is the degree of attention.
Whether this statement is strictly true is, however, a moot ques- tion. Everyday observation shows that we attend best under slight distraction. If we are too comfortable, if the conditions are, so to speak, too favourable for attention, we do not attend; we let our mind wander. Now experiment shows that observers in the laboratory also do their best under slight distraction; a modicum of effort, a little bit of resistance to overcome, calls out their full powers. If the two observations are parallel, then we must say that effort is neither directly nor inversely proportional to the height of the attention-wave; the relation of effort to degree of attention is equivocal. There would be nothing to sur- prise us in this result; consciousness is exceedingly complex, and the nervous system upon which consciousness depends is exceed- ingly complicated. But are the observations parallel? The laboratory observers will not, in any case, give more than second- ary attention; and the slight distraction, thrown in by the experi- menter, may help them because it standardises the difficulties under which they attend; they are henceforth working against a single, constant difficulty, instead of meeting all sorts of distracting influences. On the other hand, a chair that is too luxurious to work in is a chair that favours primary attention, and letting the mind wander is simply a form of primary attention, — it is atten- tion to ideas that fit in with the present contents of consciousness. On the whole, then, these observations do not appear to contradict the statement that, the greater the effort, the lower is the degree of attention. Still, this statement does not, of itself, bring us appreciably nearer to a measurement of attention.
In theory, the most promising method of measuring the attention would seem to be this: to determine, intro- spectively, how many degrees of clearness can be distin- 296 Attention guished in the various departments of sense, and then to bring every degree of clearness into relation with a definite sort and amount of distraction. We should thus have degree of clearness correlated with intensity of distracting stimulus; in other words, we should know the highest degree of attention attainable with a given amount of dis- traction; and we might accordingly use the numerical value of the distractor as a measure of the degree of atten- tion. If we knew, for instance, that a certain sensation may exist in ten different degrees of clearness: and if we had at our disposal ten stimuli which, introduced by way of distraction, would reduce this sensation from the corre- sponding degree of clearness to total obscurity: then we might calculate, from the effect of a particular distractor in the particular case, what fraction of maximal attention the observer was giving to the matter in hand. The method is cumbrous, and difficult to work out; but the writer believes that it may, some day, be successfully applied.