The reader who doubts the presence of these organic feelings is requested to read the whole of that passage again.

It has been said, however, that we may attend to an object on the periphery of the visual field and yet not accommodate the eye for it. Teachers thus notice the acts of children in the school-room at whom they appear nct to be looking. Women in general train their peripheral visual attention more than men. This would be an objection to the invariable and universal presence of movements of adjustment as ingredients of the attentive process. Usually, as is well known, no object lying in the marginal portions of the field of vision can catch our attention without at the same time 'catching our eye'—that is, fatally provoking such movements of rotation and accommodation as will focus its image on the fovea, or point of greatest sensibility. Practice, however, enables us, with effort, to attend to a marginal object whilst keeping the eyes immovable. The object under these circumstances never becomes perfectly distinct the place of its image on the retina makes distinctness impossible-but (as anyone can satisfy himself by trying) we become more vividly conscious of it than we were before the effort was made. Helmholtz states the fact so strikingly that I will quote his observation in full. He was trying to combine in a single solid percept pairs of stereoscopic pictures illuminated instantaneously by the electric spark. The pictures were in a dark box which the spark from time to time lighted up; and, to keep the eyes from wandering between whiles, a pin-hole was pricked through the middle of each picture, through which the light of the room came, so that each eye had presented to it during the dark intervals a single bright point. With parallel optical axes the points combined into a single image; and the slightest movement of the eyeballs was betrayed by this image at once becoming double. Helmholtz now found that simple linear figures could, when the eyes were thus kept immovable, be perceived as solids at a single flash of the spark. But when the figures were complicated photographs, many successive flashes were required to grasp their totality.

"Now it is interesting," he says, "to find that, although we keep steadily fixating the pin-holes and never allow their combined image to break into two, we can, nevertheless, before the spark comes, keep our attention voluntarily turned to any particular portion we please of the dark field, so as then, when the spark comes, to receive an impression only from such parts of the picture as lie in this region. In this respect, then, our attention is quite independent of the position and accommodation of the eyes, and of any known alteration in these organs; and free to direct itself by a conscious and voluntary effort upon any selected portion of a dark and undifferenced field of view. This is one of the most important observations for a future theory of attention." *

Hering, however, adds the following detail:

"Whilst attending to the marginal object we must always," he says, "attend at the same time to the object directly fixated. If even for a single instant we let the latter slip out of our mind, our eye moves towards the former, as may be easily recognized by the after-images produced, or by the muscular sounds heard. The case is then less properly to be called one of translocation, than one of unusually wide dispersion, of the attention, in which dispersion the largest share still falls upon the thing directly looked at," +

and consequently directly accommodated for. Accommodation exists here, then, as it does elsewhere, and without it we should lose a part of our sense of attentive activity. In fact, the strain of that activity (which is remarkably great in the experiment) is due in part to unusually strong contractions of the muscles needed to keep the eyeballs still, which produce unwonted feelings of pressure in those organs.

2. But if the peripheral part of the picture in this experiment be not physically accommodated for, what is meant by its sharing our attention? What happens when we 'distribute' or 'disperse' the latter upon a thing for which we remain unwilling to adjust'? This leads us to that second feature in the process, the ideational preparation' of which we spoke. The effort to attend to the marginal region of the picture consists in nothing more nor less than the effort to form as clear an idea as is possible of what is there portrayed. The idea is to come to the help of the sensation and make it more distinct. It comes with effort, and such a mode of coming is the remaining part of what we know as Physiol. Optik, p. 741.

*

+ Hermann's Handbuch, ш. 1, 548.

our attention's 'strain' under the circumstances. Let us show how universally present in our acts of attention this reinforcing imagination, this inward reproduction, this anticipatory thinking of the thing we attend to, is.

It must as a matter of course be present when the attention is of the intellectual variety, for the thing attended to then is nothing but an idea, an inward reproduction or conception. If then we prove ideal construction of the object to be present in sensorial attention, it will be present everywhere. When, however, sensorial attention is at its height, it is impossible to tell how much of the percept comes from without and how much from within; but if we find that the preparation we make for it always partly consists of the creation of an imaginary duplicate of the object in the mind, which shall stand ready to receive the outward impression as if in a matrix, that will be quite enough to establish the point in dispute.

In Wundt's and Exner's experiments quoted above, the lying in wait for the impressions, and the preparation to react, consist of nothing but the anticipatory imagination of what the impressions or the reactions are to be. Where the stimulus is unknown and the reaction undetermined, time is lost, because no stable image can under such circumstances be formed in advance. But where both nature and time of signal and reaction are foretold, so completely does the expectant attention consist in premonitory imagination that, as we have seen (pp. 341, note, 373, 377), it may mimic the intensity of reality, or at any rate produce reality's motor effects. It is impossible to read Wundt's and Exner's pages of description and not to interpret the 'Apperception' and 'Spannung' and other terms as equivalents of imagination. With Wundt, in particular, the word Apperception (which he sets great store by) is quite interchangeable with both imagination and attention. All three are names for the excitement from within of ideational brain-centres, for which Mr. Lewes's name of preperception seems the best possible designation.

Where the impression to be caught is very weak, the way not to miss it is to sharpen our attention for it by preliminary contact with it in a stronger form.

"If we wish to begin to observe overtones, it is advisable, just before the sound which is to be analyzed, to sound very softly the note of which we are in search. . . . The piano and harmonium are well fitted for this use, as both give overtones that are strong. Strike upon the piano first the g' [of a certain musical example previously given in the text]; then, when its vibrations have objectively ceased, strike powerfully the note c, in whose sound g' is the third overtone, and keep your attention steadily bent upon the pitch of the just heard g'; you will now hear this tone sounding in the midst of the c. . . . If you place the resonator which corresponds to a certain overtone, for example g' of the sound c, against your ear, and then make the note c sound, you will hear g' much strengthened by the resonator. . . . This strengthening by the resonator can be used to make the naked ear attentive to the sound which it is to catch. For when the resonator is gradually removed, the g' grows weaker; but the attention, once directed to it, holds it now more easily fast, and the observer hears the tone g' now in the natural unaltered sound of the note with his unaided

ear.

...

Wundt, commenting on experiences of this sort, says

that

"on carefully observing, one will always find that one tries first to recall the image in memory of the tone to be heard, and that then one hears it in the total sound. The same thing is to be noticed in weak or fugitive visual impressions. Illuminate a drawing by electric sparks separated by considerable intervals, and after the first, and often after the second and third spark, hardly anything will be recognized. But the confused image is held fast in memory; each successive illumination completes it; and so at last we attain to a clearer perception. The primary motive to this inward activity proceeds usually from the outer impression itself. We hear a sound in which, from certain associations, we suspect a certain overtone; the next thing is to recall the overtone in memory; and finally we catch it in the sound we hear. Or perhaps we see some mineral substance we have met before; the impression awakens the memory-image, which again more or less completely melts with the impression itself. In this way every idea takes a certain time to penetrate to the focus of consciousness. And during this time we always find in ourselves the peculiar feeling of attention. . . . The phenomena show that an adaptation of attention to the impression takes place. The surprise which unexpected impressious give us is due essentially to the fact that our attention, at the moment when the impression occurs, is not accommodated for it. The accommodation itself is of the double sort, relating as it does to the intensity as well as to the quality of the stimulus. Different qualities of impression require disparate

* Helmholtz: Tonempfindungen, 3d ed. 85-9 (Engl. tr., 2d ed. 50, 51; see also pp. 60-1).

adaptations.

And we remark that our feeling of the strain of our inward attentiveness increases with every increase in the strength of the impressions on whose perception we are intent."*

The natural way of conceiving all this is under the symbolic form of a brain-cell played upon from two directions. Whilst the object excites it from without, other brain-cells, or perhaps spiritual forces, arouse it from within. The latter

fluence is the 'adaptation of the attention.' The plenary energy of the brain-cell demands the co-operation of both factors: not when merely present, but when both present and attended to, is the object fully perceived.

A few additional experiences will now be perfectly clear. Helmholtz, for instance, adds this observation to the passage we quoted a while ago concerning the stereoscopic pictures lit by the electric spark.

.

"These experiments," he says, "are interesting as regards the part which attention plays in the matter of double images. For in pictures so simple that it is relatively difficult for me to see them double, I can succeed in seeing them double, even when the illumination is only instantaneous, the moment I strive to imagine in a lively way how they ought then to look. The influence of attention is here pure; for all eye movements are shut out."

In another place the same writer says:

"When I have before my eyes a pair of stereoscopic drawings which are hard to combine, it is difficult to bring the lines and points that correspond, to cover each other, and with every little motion of the eyes they glide apart. But if I chance to gain a lively mental image (Anschauungsbild) of the represented solid form (a thing that often occurs by lucky chance), I then move my two eyes with perfect certainty over the figure without the picture separating again."

Again, writing of retinal rivalry, Helmholtz says:

"It is not a trial of strength between two sensations, but depends on our fixing or failing to fix the attention. Indeed, there is scarcely any phenomenon so well fitted for the study of the causes which are capable of determining the attention. It is not enough to form the conscious intention of seeing first with one eye and then with the other; we must form as clear a notion as possible of what we expect to see. Then it will actually appear."§

§ Popular Scientific Lectures, Eng. Trans., p. 295.