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 while 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.
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.
Impression means sensation for Hume.
Treatise on Human Nature, part i.§ vii.
Huxley's Hume, pp.
92-94.
On Intelligence (N.
Y.), vol.ii.p.139.
Principles, Introd.
§ 13.Compare also the passage quoted above, p.469
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 with open eyes; Are more easily had with open than with shut eyes;
Seem to move when the bend or eyes move; Need not follow movements of head or eyes.
The field within which they appear (with closed eyes) is dark, contracted, flat, close to the eyes, in front, and the images have no perspective; The field is extensive in three dimensions, and objects can be imagined in it above or behind almost m easily as in front.
The attention seems directed forwards towards the sense-organ, in observing after-images.In imagining, the attention feels as if drawn backwards towards the 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 to 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 project them on a near one, whilst no such change takes place in mental pictures
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.
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 cell 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 ray 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."
Progrès Médical, 21 juillet.I abridge from the German report of the case in Wilbrand: Die Seelenblindheit (1887).
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."
Psychologie du Raisonnement (1886), p.25.
Classics editors note: James' insertion.
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.
See an interesting case of a similar sort, reported by Farges, in l'Ecéphale, 7me Année, p.545.
Philosophical Transactions, 1841, p.65.
Studien über die Sprachvorstellungen (1880), and Studien über die Bewegungsvorstellungen (1882).
