Chapter II

. pp. 49-51) _that the imagination-process differs from the sensation-process by its intensity rather than by its locality._ However it may be with lower animals, the assumption that ideational and sensorial centres are locally distinct appears to be supported by no facts drawn from the observation of human beings. After occipital destruction, the hemianopsia which results in man is sensorial blindness, not mere loss of optical ideas. Were there centres for crude optical sensation below the cortex, the patients in these cases would still feel light and darkness. Since they do not preserve even this impression on the lost half of the field, we must suppose that there are no centres for vision of any sort whatever below the cortex, and that the corpora quadrigemina and other lower optical ganglia are organs for reflex movement of eye-muscles and not for conscious sight. Moreover there are no facts which oblige us to think that, within the occipital cortex, one part is connected with sensation and another with mere ideation or imagination. The pathological cases assumed to prove this are all better explained by disturbances of conduction between the optical and other centres (see p. 50). In bad cases of hemianopsia the patient's images depart from him together with his sensibility to light. They depart so completely that he does not even know what is the matter with him. To perceive that one is blind to the right half of the field of view one must have an idea of that part of the field's possible existence. But the defect in these patients has to be revealed to them by the doctor, they themselves only knowing that there is 'something wrong' with their eyes. What you have no idea of you cannot miss; and their not definitely missing this great region out of their sight seems due to the fact that their very idea and memory of it is lost along with the sensation. A man blind of his eyes merely, sees _darkness_. A man blind of his visual brain-centres can no more see darkness out of the parts of his retina which are connected with the brain-lesion than he can see it out of the skin of his back. He cannot see at all in that part of the field; and he cannot think of the light which he ought to be feeling _there_, for the very notion of the existence of that

## particular 'there' is cut out of his mind.[81]

Now if we admit that sensation and imagination are due to the activity of the same centres in the cortex, we can see a very good teleological reason why they should correspond to discrete kinds of process in these centres, and why the process which gives the sense that the object is really there ought normally to be arousable only by currents entering from the periphery and not by currents from the neighboring cortical parts. We can see, in short, why _the sensational process_ OUGHT TO _be discontinuous with all normal ideational processes, however intense_. For, as Dr. Münsterberg justly observes:

"Were there not this peculiar arrangement we should not distinguish reality and fantasy, our conduct would not be accommodated to the facts about us, but would be inappropriate and senseless, and we could not keep ourselves alive.... That our thoughts and memories should be copies of sensations with their intensity greatly reduced is thus a consequence deducible logically from the natural adaptation of the cerebral mechanism to its environment."[82]

Mechanically the discontinuity between the ideational and the sensational kinds of process must mean that when the greatest ideational intensity has been reached, an order of _resistance_ presents itself which only a new order of force can break through. The current from the periphery is the new order of force required; and what happens after the resistance is overcome is the sensational process. We may suppose that the latter consists in some new and more violent sort of disintegration of the neural matter, which now explodes at a deeper level than at other times.

Now how shall we conceive of the 'resistance' which prevents this sort of disintegration from taking place, this sort of intensity in the process from being attained, so much of the time? It must be either an intrinsic resistance, some force of cohesion in the neural molecules themselves; or an extrinsic influence, due to other cortical cells. When we come to study the process of hallucination we shall see that both factors must be taken into account. There is a degree of inward molecular cohesion in our brain-cells which it probably takes a sudden inrush of destructive energy to spring apart. Incoming peripheral currents possess this energy from the outset. Currents from neighboring cortical regions might attain to it if they could _accumulate_ within the centre which we are supposed to be considering. But since during waking hours every centre communicates with others by association-paths, no such accumulation can take place. The cortical currents which run in run right out again, awakening the next ideas; the level of tension in the cells does not rise to the higher explosion-point; and the latter must be gained by a sudden current from the periphery or not at all.

* * * * *

[49] Prof. Jastrow has ascertained by statistical inquiry among the blind that if their blindness have occurred before a period embraced between the fifth and seventh years the visual centres seem to decay, and visual dreams and images are gradually outgrown. If sight is lost after the seventh year, visual imagination seems to survive through life. See Prof. J.'s interesting article on the Dreams of the Blind, in the New Princeton Review for January 1888.

[50] Impression means sensation for Hume.

[51] Treatise on Human Nature, part i. § vii.

[52] Huxley's Hume, pp. 92-94.

[53] On Intelligence (N. Y.), vol. ii. p. 139.

[54] Principles, Introd. § 13. Compare also the passage quoted above, vol. I, p. 469.

[55] The differences noted by Fechner between after-images and images of imagination proper are as follows:

_After Images._ _Imagination-images._

Feel coercive; Feel subject to our spontaneity;

Seem unsubstantial, vaporous; Have, as it were, more body;

Are sharp in outline; Are blurred;

Are bright; Are darker than even the darkest black of the after-images;

Are almost colorless; Have lively coloration;

Are continuously enduring; Incessantly disappear, and have to be renewed by an effort of will. At last even this fails to revive them.

Cannot be voluntarily changed. Can be exchanged at will for others.

Are exact copies of originals. Cannot violate the necessary laws of appearance of their originals--e.g., a man cannot be imagined from in front and behind at once. The imagination must walk round him, so to speak;

Are more easily got with shut than Are more easily had with open than with open eyes; with shut eyes;

Seem to move when the head or eyes Need not follow movements of head move; or eyes.

The field within which they appear The field is extensive in three (with closed eyes) is dark, contracted, dimensions, and objects can be flat, close to the eyes, in imagined in it above or behind front, and the images have no almost as easily as in front. perspective;

The attention seems directed forwards In imagining, the attention feels towards the sense-organ, in as if drawn backwards towards the observing after-images. brain.

Finally, Fechner speaks of the impossibility of attending to both after-images and imagination-images at once, even when they are of the same object and might be expected to combine. All these differences are true of Fechner; but many of them would be untrue of other persons. I quote them as a type of observation which any reader with sufficient patience may repeat. To them may be added, as a universal proposition, that after-images seem larger if we project them on a distant screen, and smaller if we project them on a near one, whilst no such change takes place in mental pictures.

[56] [I am myself a good draughtsman, and have a very lively interest in pictures, statues, architecture and decoration, and a keen sensibility to artistic effects. But I am an extremely poor visualizer, and find myself often unable to reproduce in my mind's eye pictures which I have most carefully examined.--W. J.]

[57] See also McCosh and Osborne, Princeton Review, Jan. 1884. There are some good examples of high development of the Faculty in the London Spectator, Dec. 28, 1878, pp. 1631, 1634, Jan. 4, 11, 25, and March 18, 1879.

[58] Take the following report from one of my students: "I am unable to form in my mind's eye any visual likeness of the table whatever. After many trials, I can only get a hazy surface, with nothing on it or about it. I can see no variety in color, and no positive limitations in extent, while I cannot see what I see well enough to determine its position in respect to my eye, or to endow it with any quality of size. I am in the same position as to the word _dog_. I cannot see it in my mind's eye at all; and so cannot tell whether I should have to run my eye along it, if I did see it."

[59] Progrès Médical, 21 juillet. I abridge from the German report of the case in Wilbrand: Die Seelenblindheit (188).

[60] In a letter to Charcot this interesting patient adds that his character also is changed: "I was formerly receptive, easily made enthusiastic, and possessed a rich fancy. Now I am quiet and cold, and fancy never carries my thoughts away.... I am much less susceptible than formerly to anger or sorrow. I lately lost my dearly-beloved mother; but felt far less grief at the bereavement than if I had been able to see in my mind's eye her physiognomy and the phases of her suffering, and especially less than if I had been able to witness in imagination the outward effects of her untimely loss upon the members of the family."

[61] Psychologie du Raisonnement (1886), p. 25.

[62] [I am myself a very poor visualizer, and find that I can seldom call to mind even a single letter of the alphabet in purely retinal terms. I must trace the letter by running my mental eye over its contour in order that the image of it shall have any distinctness at all. On questioning a large number of other people, mostly students, I find that perhaps half of them say they have no such difficulty in seeing letters mentally. Many affirm that they can see an entire word at once, especially a short one like 'dog,' with no such feeling of creating the letters successively by tracing them with the eye.--W. J.]

[63] It is hardly needful to say that in modern primary education, in which the blackboard is so much used, the children are taught their letters, etc., by all possible channels at once, sight, hearing, and movement.

[64] See an interesting case of a similar sort, reported by Farges, in l'Encéphale, 7me Année, p. 545.

[65] Philosophical Transactions, 1841, p. 65.

[66] Studien über die Sprachvorstellungen (1880), and Studien über die Bewegungsvorstellungen (1882).

[67] Prof. Stricker admits that by practice he has succeeded in making his eye-movements 'act vicariously' for his leg-movements in imagining men walking.

[68] Bewegungsvorstellungen, p. 6.

[69] Bain: Senses and Intellect, p. 339.

[70] Studien über Sprachvorstellungen, 28, 31, etc. Cf. pp. 49-50, etc. Against Stricker, see Stumpf, Tonpsychol., 155-162, and Revue Philosophique, xx. 617. See also Paulhan, Rev. Philosophique, xvi. 405. Stricker replies to Paulhan in vol. xviii. p. 685. P. retorts in vol. xix p. 118. Stricker reports that out of 100 persons questioned he found only _one_ who had _no_ feeling in his lips when silently thinking the letters M, B, P; and out of 60 only _two_ who were conscious of no internal articulation whilst reading (pp. 59-60).

[71] I think it must be admitted that some people have no vivid substantive images in _any_ department of their sensibility. One of my students, an intelligent youth, denied so pertinaciously that there was _anything_ in his mind _at all_ when he thought, that I was much perplexed by his case. I myself certainly have no such vivid play of nascent movements or motor images as Professor Stricker describes. When I seek to represent a row of soldiers marching, all I catch is a view of stationary legs first in one phase of movement and then in another, and these views are extremely imperfect and momentary. Occasionally (especially when I try to stimulate my imagination, as by repeating Victor Hugo's lines about the regiment,

"Leur pas est si correct, sans tarder ni courir, Qu'on croit voir des ciseaux se fermer et s'ouvrir,")

I seem to get an instantaneous glimpse of an actual movement, but it is to the last degree dim and uncertain. All these images seem at first as if purely retinal. I think, however, that rapid eye-movements accompany them, though these latter give rise to such slight feelings that they are almost impossible of detection. Absolutely no leg-movements of my own are there; in fact, to call such up arrests my imagination of the soldiers. My optical images are in general very dim, dark, fugitive, and contracted. It would be utterly impossible to _draw_ from them, and yet I perfectly well distinguish one from the other. My auditory images are excessively inadequate reproductions of their originals. I have _no_ images of taste or smell. Touch-imagination is fairly distinct, but comes very little into play with most objects thought of. Neither is all my thought verbalized; for I have shadowy schemes of relation, as apt to terminate in a nod of the head or an expulsion of the breath as in a definite word. On the whole, vague images or sensations of movement inside of my head towards the various parts of space in which the terms I am thinking of either lie or are momentarily symbolized to lie together with movements of the breath through my pharynx and nostrils, form a by no means inconsiderable part of my _thought-stuff_. I doubt whether my difficulty in giving a clearer account is wholly a matter of inferior power of introspective attention, though that doubtless plays its part. Attention, _ceteris paribus_, must always be inferior in proportion to the feebleness of the internal images which are offered it to hold on to.

[72] Geo. Herm. Meyer, Untersuchungen üb. d. Physiol. d. Nervenfaser (1843), p. 233. For other cases see Tuke's Influence of Mind upon Body, chaps. ii. and vii.

[73] Meyer, _op. cit._ p. 238.

[74] Meyer, _op. cit._ pp. 238-41.

[75] That of Dr. Ch. Féré in the Revue Philosophique, xx. 364. Johannes Müller's account of hypnagogic hallucinations floating before the eyes for a few moments after these had been opened, seems to belong more to the category of spontaneous hallucinations (see his Physiology, London, 1843, p. 1394). It is impossible to tell whether the words in Wundt's Vorlesungen, i. 387, refer to a personal experience of his own or not; probably not. _Il va sans dire_ that an inferior visualizer like myself can get no such after-images. Nor have I as yet succeeded in getting report of any from my students.

[76] Senses and Intellect, p. 338.

[77] See above, note 55.

[78] V. Kandinsky (Kritische u. klinische Betrachtungen im Gebiete der Sinnestäuschungen (Berlin, 1885), p. 135 ff.) insists that in even the liveliest pseudo-hallucinations (see below,