The Principles of Psychology, Vols. 1-2

And again criticising an author who had treated of at tention as an activity absolutely subject to the conscious will, Helmholtz writes : " This is only restrictedly true. We move our eyes by our will ; but one without training cannot so easily execute the intention of making them converge. At any moment, however, he can execute that of looking at a near object, in which act convergence is involved. N» w just as little can we carry out our purpose to keep our attention steadily fixed upon a certain object, when our interest in the object is exhausted, and the purpose is inwardly formulated in this abstract way. But we can set ourselves new questions about the object, so that a new interest in it arises, and then the attention will remain riveted. The relation of attention to will is, then, less one of immediate than of mediate control."

These words of Helmlioltz are of fundamental impor tance. And if true of sensorial attention, how much more true are they of the intellectual variety ! The conditio sine qua non of sustained attention to a given topic of thought is that we should roll it over and over incessantly and con sider different aspects and relations of it in turn. Only in pathological states will a fixed and ever monotonously re curring idea possess the mind. And now we can see why it is that what is called sus tained attention is the easier, the richer in acquisitions and the fresher and more original the mind. In such minds, subjects bud and sprout and grow. At every moment, they please by a new consequence and rivet the attention afresh. But an intellect unfurnished with materials, stagnant, un original, will hardly be likely to consider any subject long. A glance exhausts its possibilities of interest. Geniuses are commonly believed to excel other men in their power of sustained attention.* In most of them, it is to be feared, the so-called ' power ' is of the passive sort. Their ideas coruscate, every subject branches infinitely before their fertile minds, and so for hours they may be rapt. But it is their genius making them attentive, not their attention making geniuses of them. And, when we come down to the root of the matter, we see that they differ from ordinary men less in the character of their attention than in the nature of the objects upon which it is successively bestowed. In the genius, these form a concatenated series, suggesting

* " ' Genius,' says Helvetius, ' is nothing but a continued attention (une attention suime}.' ' Genius/ says Buffon, 'is only a protracted patience (une longue patience).' 'In the exact sciences, at least,' says Cuvier, 'it is the patience of a sound intellect, when invincible, which truly consti tutes genius.' And Chesterfield has also observed that ' the power of ap plying an attention, steady and undissipated, to a single object, is the sure mark of a superior genius." (Hamilton : Lect. on Metaph., lecture xiv.)

each other mutually by some rational law. Therefore we call the attention ' sustained ' and the topic of meditation for hours ' the same.' In the common man the series is for the most part incoherent, the objects have no rational bond, and we call the attention wandering and unfixed. It is probable that genius tends actually to prevent a man from acquiring habits of voluntary attention, and that moderate intellectual endowments are the soil in which we may best expect, here as elsewhere, the virtues of the will, strictly so called, to thrive. But, whether the attention come by grace of genius or by dint of will, the longer one does attend to a topic the more mastery of it one has. And the faculty of voluntarily bringing back a wandering at tention, over and over again, is the very root of judgment, character, and will. No one is compos sui if he have it not. An education which should improve this faculty would be the education par excellence. But it is easier to define this ideal than to give practical directions for bringing it about. The only general pedagogic maxim bearing on attention is that the more interest the child has in advance in the sub ject, the better he will attend. Induct him therefore in such a way as to knit each new thing on to some acquisi tion already there ; and if possible awaken curiosity, so that the new thing shall seem to come as an answer, or part of an answer, to a question pre-existing in his mind.

Its remote effects are too incalculable to be recorded. The practical and theoretical life of whole species, as well as of individual beings, results from the selection which the habitual direction of their attention involves. In Chapters XIY and XV some of these consequences will come to light. Suffice it meanwhile that each of us literally chooses, by his ways of attending to things, what sort of a universe he shall appear to himself to inhabit.

better than otherwise we could — both more successive things and each thing more clearly. It also (e) shortens 'reactiontime.' a and b. Most people would say that a sensation at tended to becomes stronger than it otherwise would be. This point is, however, not quite plain, and has occasioned some discussion. * From the strength or intensity of a sensation must be distinguished its clearness ; and to in crease this is, for some psychologists, the utmost that attention can do. When the facts are surveyed, however, it must be admitted that to some extent the relative inten sity of two sensations may be changed when one of them is attended to and the other not. Every artist knows how he can make a scene before his eyes appear warmer or colder in color, according to the way he sets his attention. If for warm, he soon begins to see the red color start out of everything ; if for cold, the blue. Similarly in listening for certain notes in a chord, or overtones in a musical sound, the one we attend to sounds probably a little more loud as well as more emphatic than it did before. When we men tally break a series of monotonous strokes into a rhythm, by accentuating every second or third one, etc., the stroke on which the stress of attention is laid seems to become stronger as well as more emphatic. The increased visi bility of optical after-images and of double images, which close attention brings about, can hardly be interpreted otherwise than as a real strengthening of the retinal sensations themselves. And this view is rendered par ticularly probable by the fact that an imagined visual object may, if attention be concentrated upon it long enough, acquire before the mind's eye almost the brill iancy of reality, and (in the case of certain exceptionally gifted observers) leave a negative after-image of itself when it passes away (see Chapter XVIII). Confident expectation of a certain intensity or quality of impression will often make us sensibly see or hear it in an object which really

falls far short of it. In face of such facts it is rash to say that attention cannot make a sense-impression more intense. But, on the other hand, the intensification which may be brought about seems never to lead the judgment astray. As we rightly perceive and name the same color under various lights, the same sound at various distances ; so we seem to make an analogous sort of allowance for the vary ing amounts of attention with which objects are viewed ; and whatever changes of feeling the attention may bring we charge, as it were, to the attention's account, and still perceive and conceive the object as the same.

"A gray paper appears to us no lighter, the pendulum-beat of a clock no louder, no matter how much we increase the strain of our at tention upon them. No one, by doing this, can make the gray paper look white, or the stroke of the pendulum sound like the blow of a strong hammer, — everyone, on the contrary, feels the increase as that of his own conscious activity turned upon the thing." * Were it otherwise, we should not be able to note inten sities by attending to them. Weak impressions would, as Stumpf says,f become stronger by the very fact of being observed.

" I should not be able to observe faint sounds at all, but only such as appeared to me of maximal strength, or at least of a strength that increased with the amount of my observation. In reality, however, I can, with steadily increasing attention, follow a diminuendo perfectly well." The subject is one which would well repay exact experi ment, if methods could be devised. Meanwhile there is no question whatever that attention augments the clearness of all that we perceive or conceive by its aid. But what is meant by clearness here ?

c. Clearness, so far as attention produces it, means dis tinction from other things and internal analysis or subdivision. These are essentially products of intellectual discrimination, involving comparison, memory, and perception of various relations. The attention per se does not distinguish and analyze and relate. The most we can say is that it is a condition of our doing so. And as these processes are to be described later> the clearness they produce had better not be farther discussed here. The important point to no tice here is that it is not attention's immediate fruit*

d. Whatever future conclusion we may reach as to this, we cannot deny that an object once attended to ivill re main in the memory, whilst one inattentively allowed to pass will leave no traces behind. Already in Chapter YI (see pp. 163 ff.) we discussed whether certain states of mind were 'unconscious,' or whether they were not rather states to which no attention had been paid, and of whose passage recollection could afterwards find no vestiges. Dugald Stewart says : f "The connection between attention and memory has been remarked by many authors." He quotes Quintilian, Locke, and Helvetius ; and goes on at great length to explain the phenomena of 'secondary automa tism ' (see above, p. 114 ff.) by the presence of a mental action grown so inattentive as to preserve no memory of itself. In our chapter on Memory, later on, the point will come up again.

e) Under this head, the shortening of reactiontime, there is a good deal to be said of Attention's effects. Since Wundt has probably worked over the subject more thor oughly than any other investigator and made it peculiarly his own, what follows had better, as far as possible, be in his words. The reader will remember the method and re sults of experimentation on ' reaction-time,' as given in Chapter III. The facts I proceed to quote may also be taken as a supplement to that chapter. Wundt writes :

u When we wait with strained attention for a stimulus, it will often happen that instead of registering the stimulus, we react upon some entirely different impression,— and this not through confounding the one with the other. On the contrary, we are perfectly well aware at the moment of making the movement that we respond to the wroi>g stimulus. Sometimes even, though not so often, the latter may be an- * Compare, en clearness as the essential fruit of attention, Lotze's Metaphysic, § 273.

other kind of sensation altogether, — one may, for example, in experi menting with sound, register a flash of light, produced either by accident or design. We cannot well explain these results otherwise than by assuming that the strain of the attention towards the impres sion we expect coexists with a preparatory innervation of the motor centre for the reaction, which innervation the slightest shock then suffices to turn into an actual discharge. This shock may be given by any chance impression, even by one to which we never intended to re spond. When the preparatory innervation has once reached this pitch of intensity, the time that intervenes between the stimulus and the contraction of the muscles which react, may become vanishingly small."*

" The perception of an impression is facilitated when the impres sion is preceded by a warning which announces beforehand that it is about to occur. This case is realized whenever several stimuli follow each other at equal inteivals, — when, e.g. we note pendulum movements by the eye, or pendulum-strokes by the ear. Each single stroke forms here the signal for the next, which is thus met by a fully prepared at tention. The same thing happens when the stimulus to be perceived is preceded, at a certain interval, by a single warning: the time is always notably shortened. ... I have made comparative observa tions on reaction-time with and without a warning signal. The im pression to be reacted on was the sound made by the dropping of a ball on the board of the ' drop apparatus.' .... In a first series no warning preceded the stroke of the ball; in the second, the noise made by the apparatus in liberating the ball served as a signal. . . . Here are the averages of two series of such experiments :

"... In a long series of experiments, (the interval between warn ing and stimulus remaining the same) the reaction-time grows less and Jess, and it is possible occasionally to reduce it to a vanishing quantity (a few thousandths of a second), to zero, or even to a negative value. f .... The only ground that we can assign for this phenomenon is the preparation (vorbereitende Spannung) of the attention. It is easy to understand that the reaction-time should be shortened by this means; but that it should sometimes sink to zero and even assume negative values, may appear surprising. Nevertheless this latter case is also explained by what happens in the simple reaction-time experiments" just referred to, in which, " when the strain of the attention has reached

f By a negative value of the reaction-time Wundt means the case of tke reactive movement occurring before the stimulus. its climax, the movement we stand ready to execute escapes from the control of om will, and we register a wrong signal. In these other ex periments, in wriicn a warning foretells the moment of the stimulus, it is also plain that attention accommodates itself so exactly to the latter's reception that no sooner is it objectively given than it is fully apperceived) and with ihn apperception the motor discharge coin cides."*

Usually, when the impression is fully anticipated, atten tion prepares the motor centres so completely for both stimulus and reaction that the only time lost is that of the pl^siological conduction downwards. But even this inter val may disappear, i.e. the stimulus and reaction may be come objectively contemporaneous ; or more remarkable still, the reaction may be discharged before the stimulus has actually occurred. t Wundt, as we saw some pages back (p. 411), explains this by the effort of the mind so to react that we may feel our own movement and the signal which prompts it, both at the same instant. As the execution of the movement must precede our feeling of it, so it must also precede the stimulus, if that and our movement are to be felt at once.

The peculiar theoretic interest of these experiments lies in their shoiving expectant attention and sensation to be continuous or identical processes, since they may have identical motor effects. Although other exceptional observations show them likewise to be continuous subjectively, Wundt's experiments do not : he seems never, at the moment of reacting prematurely, to have been misled into the belief that the real stimulus was there. As concentrated attention accelerates perception, so, conversely, perception of a stimulus is retarded by anything which either baffles or distracts the attention with which we await it.

"If, e.g., we make reactions on a sound in such a way that weak and strong stimuli irregularly alternate so that the observer can never expect a determinate strength with any certainty, the reaction-time for all the various signals is increased, — and so is the average error, I f The reader must not suppose this phenomenon to be of frequent occurrence. Experienced observers, like Exner and Cattell, deny having met with it in their personal experience.

append two examples. ... In Series I a strong and a weak sound alternated regularly, so that the intensity was each time known in ad vance. In II they came irregularly. " Still greater is the increase of the time when, unexpectedly into a series of strong impressions, a weak one is interpolated, or vice versa. In this way I have seen the time of reaction upon a sound so weak as to be barely perceived rise to 0.4" or 0.5", and for a strong sound to 0 25". It is also matter of general experience that a stimulus expected in a general way, but for whose intensity attention cannot be adapted in advance, demands a longer reaction-time. In such cases . . . the reason for the difference can only lie in the fact that wherever a prepa ration of the attention is impossible, the time of both perception and volition is prolonged. Perhaps also the conspicuously large reactiontimes which are got with stimuli so faint as to be just perceptible may be explained by the attention tending always to adapt itself for some thing more than this minimal amount of stimulus, so that a state ensues similar to that in the case of unexpected stimuli. . . . Still more than by previously unknown stimuli is the reaction-time prolonged by wholly unexpected impressions. This is sometimes acci dentally brought about, when the observer's attention, instead of being concentrated on the coming signal, is dispersed. It can be realized purposely by suddenly thrusting into a long series of equidistant stimuli a much shorter interval which the observer does not expect. The mental effect here is like that of being startled ; — often the startling is outwardly visible. The time of reaction may then easily be length ened to one quarter of a second with strong signals, or with weak ones to a half-second. Slighter, but still very noticeable, is the retardation when the experiment is so arranged that the observer, ignorant whether the stimulus is to be an impression of light, sound, or touch, cannot keep his attention turned to any particular sense-organ in advance.

One notices then at the same time a peculiar unrest, as the feeling of strain which accompanies the attention keeps vacillating between the several senses. " Complications of another sort arise when what is registered is an impression anticipated both in point of quality and strength, but ac companied by other stimuli which make the concentration of the atten tion difficult. The reaction-time is here always more or less prolonged. The simplest case of the sort is where a momentary impression is regis tered in the midst of another, and continuous, sensorial-stimulation of considerable strength. The continuous stimulus may belong to the

same sense as the stimulus to be reacted on, or to another. When it is* of the same sense, the retardation it causes may be partly due to the distraction of the attention by it, but partly also to the fact that the stimulus to be reacted on stands out less strongly than if alone, and practically becomes a less intense sensation. But other factors in reality are present ; for we find the reaction-time more prolonged by the con comitant stimulation when the stimulus is weak than when it is strong I made experiments in which the principal impression, or signal for re action, was a bell-stroke whose strength could be graduated by a spring against the hammer with a movable counterpoise. Each set of obser vations comprised two series ; in one of which the bell-stroke was regis tered in the ordinary way, whilst in the other a toothed wheel belong ing to the chronometric apparatus made during the entire experiment a steady noise against a metal spring. In one half of the latter series (A) the bell-stroke was only moderately strong, so that the accompanying noise diminished it considerably, without, however, making it indistin guishable. In the other half (B) the bell-sound was so loud as to be heard with perfect distinctness above the noise.

"Since, in these experiments, the sound B even with noise made a considerably stronger impression than the sound A without, we must see in the figures a direct influence of the disturbing noise on the pro cess of reaction. This influence is freed from mixture with other factors when the momentary stimulus and the concomitant disturbance appeal to different senses. I chose, to test this, sight and hearing. The mo mentary signal was an induction-spark leaping from one platinum point to another against a dark background. The steady stimulation was the noise above described.

" When one reflects that in the experiments with one and the same sense the relative intensity of the signal is always depressed [which by itself is a retarding condition] the amount of retardation in these last observations makes it probable that the disturbing influence upon atten tion is greater ivhen the stimuli are disparate than when they belong to the same sense. One does not, in fact, find it particularly hard to register immediately, when the bell rings in the midst of the noise ; but when the spark is the signal one has a feeling of being coerced, as one turns away from the noise towards it. This fact is immediately con-

nected with other properties of our attention. The effort of the latter is accompanied by various corporeal sensations, according to the sense which is engaged. The innervation which exists during the effort of attention is therefore probably a different one for each sense-organ." * "Wundt then, after some theoretical remarks which we need not quote now, gives a table of retardations, as fol lows: It seems probable, from these results obtained with ele» mentary processes of mind, that all processes, even the higher ones of reminiscence, reasoning, etc., whenever at tention is concentrated upon them instead of being diffused and languid, are thereby more rapidly performed, f

Still more interesting reaction-time observations have been made by Miinsterberg. The reader will recollect the fact noted in Chapter III (p. 93) that reaction-time is shorter when one concentrates his attention on the expected movement than when one concentrates it on the expected signal. Herr Miinsterberg found that this is equally the case when the reaction is no simple reflex, but can take place only after an intellectual operation. In a series of experiments the five fingers were used to react with, and

f It should be added that Mr. J. M. Cattell (Mind, XT. 33) found, on repeating Wundt's experiments with a disturbing noise upon two practised observers, that the simple reaction-time either for light or sound was hardly perceptibly increased. Making strong voluntary concentration of attention shortened it by about 0.013 seconds on an average (p. 240). Performing mental additions whilst waiting for the stimulus lengthened it more than anything, apparently. For other, less careful, observations, compare Obersteiner, in Brain, i. 439. Cattell's negative results show how far some persons can abstract their attention from stimuli by which oth ers would be disturbed.— A Bartels (Versuche ilber die Ableukung d. Aufmerksamkeit, Dorpat, 1889) found that a stimulus to one eye sometimes prevented, sometimes improved, the perception of a quickly ensuing very faint stimulus to the other.

the reacter had to use a different finger according as the signal was of one sort or another. Thus when a word in the nominative case was called out he used the thumb, for the dative he used another finger ; similarly adjectives, substantives, pronouns, numerals, etc., or, again, towns, rivers, beasts, plants, elements ; or poets, musicians, phi losophers, etc., were co-ordinated each with its finger, so that when a word belonging to either of these classes was mentioned, a particular finger and no other had to perform the reaction. In a second series of experiments the reac tion consisted in the utterance of a word in answer to a question, such as " name an edible fish," etc. ; or " name the first drama of Schiller," etc.; or "which is greater, Hume or Kant?" etc. ; or (first naming apples and cherries, and several other fruits) " which do you prefer, apples or cherries ?" etc. ; or " which is Goethe's finest drama ?" etc. ; or " which letter comes the later in the alphabet, the letter L or the first letter of the most beautiful tree ?" etc. ; or "which is less, 15 or 20 minus 8 ?" * etc. etc. etc. Even in this series of reactions the time was much quicker when the reacter turned his attention in advance towards the answer than when he turned it towards the question. The shorter reactiontime was seldom more than one fifth of a second ; the longer, from four to eight times as long.

To understand such results, one must bear in inind that in these experiments the reacter always knew in advance in a general way the kind of question which he was to re ceive, and consequently the sphere within lohich his possible answer lay.f In turning his attention, therefore, from the outset towards the answer, those brain-processes in him which were connected with this entire ' sphere ' were kept sub-excited, and the question could then discharge with a minimum amount of lost time that particular answer out of the ' sphere ' which belonged especially to it. When, on the contrary, the attention was kept looking towards the ques tion exclusively and averted from the possible reply, all