the one is the proved facility of obtaining statistical insight into the processes of other persons' minds, whatever a priori objection may have been made as to its possibility; and the other is that scientific men, as a class, have feeble powers of visual representation.There is no doubt whatever on the latter point, however it may be accounted for.My own conclusion is that an over-ready perception of sharp mental pictures is antagonistic to the acquirement of habits of highly-generalized and abstract thought, especially when the steps of reasoning are carried on by words as symbols, and that if the faculty of seeing the pictures was ever possessed by men who think hard, it is very apt to be lost by disuse.The highest minds are probably those in which it is not lost, but subordinated, and is ready for use on suitable occasions.I am, however, bound to say that the missing faculty seems to be replaced so serviceably by other modes of conception, chiefly, I believe, connected with the incipient motor sense, not of the eyeballs only but of the muscles generally, that men who declare themselves entirely deficient in the power of seeing mental pictures can nevertheless give lifelike descriptions of what they have seen, and can otherwise express themselves as if they were gifted with a vivid visual imagination.
They can also become painters of rank of Royal Academicians.
...
"It is a mistake to suppose that sharp sight is accompanied by clear visual memory.I have not a few instances in which the independence of the two faculties is emphatically commented on; and I have at least one clear case where great interest in outlines and accurate appreciation of straightness, squareness, and the like, is unaccompanied by the power of visualizing.Neither does the faculty go with dreaming.I have cases where it is powerful, and at the same time where dreams are rare and faint or altogether absent.One friend tells me that his dreams have not the hundredth part of the vigor of his waking fancies.
"The visualizing and the identifying powers are by no means necessarily combined.A distinguished writer on metaphysical topics assures me that he is exceptionally quick at recognizing a face that he has seen before, but that he cannot call up a mental image of any face with clearness.
"Some persons have the power of combining in a single perception more than can be seen at any one moment by the two eyes....
"I find that a few persons can, by what they often describe as a kind of touch-sight, visualize at the same moment all round the image of a solid body.Many can do so nearly, but not altogether round that of a terrestrial globe.An eminent mineralogist assures me that he is able to imagine simultaneously all the sides of a crystal with which he is familiar.I may be allowed to quote a curious faculty of my own in respect to this.It is exercised only occasionally and in dreams, or rather in nightmares, but under those circumstances I am perfectly conscious of embracing an entire sphere in a single perception.It appears to lie within my mental eyeball, and to be viewed centripetally.
"This power of comprehension is practically attained in many cases by indirect methods.It is a common feat to take in the whole surroundings of an imagined room with such a rapid mental sweep as to leave some doubt whether it has not been viewed simultaneously.
Some persons have the habit of viewing objects as though they were partly transparent; thus, if they so dispose a globe in their imagination as to see both its north and south poles at the same time, they will not be able to see its equatorial parts.They can also perceive all the rooms of an imaginary house by a single mental glance, the walls and floors being as if made of glass.A fourth class of persons have the habit of recalling scenes, not from the point of view whence they were observed, but from a distance, and they visualize their own selves as actors on the mental stage.By one or other of these ways, the power of seeing the whole of an object, and not merely one aspect of it, is possessed by many persons.
"The place where the image appears to lie differs much.Most persons see it in an indefinable sort of way, others see it in front of the eye, others at a distance corresponding to reality.
There exists a power which is rare naturally, but can, I believe, be acquired without much difficulty, of projecting a mental picture upon a piece of paper, and of holding it fast there, so that it can be outlined with a pencil.To this I shall recur.
"Images usually do not become stronger by dwelling on them; the first idea is commonly the most vigorous, but this is not always the case.Sometimes the mental view of a locality is inseparably connected with the sense of its position as regards the points of the compass, real or imaginary.I have received full and curious descriptions from very different sources of this strong geographical tendency, and in one or two cases I have reason to think it allied to a considerable faculty of geographical comprehension.
"The power of visualizing is higher in the female sex than in the male, and is somewhat, but not much, higher in public-school boys than in men.After maturity is reached, the further advance of age does not seem to dim the faculty, but rather the reverse, judging from numerous statements to that effect; but advancing years are sometimes accompanied by a growing habit of hard abstract thinking, and in these cases not uncommon among those whom I have questioned -- the faculty undoubtedly becomes impaired.There is reason to believe that it is very high in some young children, who seem to spend years of difficulty in distinguishing between the subjective and objective world.Language and book-learning certainly tend to dull it.
