Page:Popular Science Monthly Volume 18.djvu/80

70 disinclined to talk about them, recollecting how they were laughed at on the few occasions when they did so. The fact of their being common to scattered members of the same family has often been discovered for the first time through my inquiries. I should say that I have found no general accordance between particular letters and colors. The relationship between them appears to be in each case a haphazard one; but having been once formed it is durable.

Another and much more common oddity is the tendency to visualize numerals in a peculiar manner, which characterizes, as I have roughly reckoned, about one woman in every fifteen, and one man in every thirty. Those who do so are never able to dissociate any single number from its own particular place in the field of their mental view, so that when they think of a series of numbers they always visualize them in a certain form. Either the numbers are all visible at once, as if they were printed on cards and hung in space, according to some grotesque pattern, or the mind travels along a blank but familiar path to the place where the number that is thought of is known to reside, and then it starts into view. There are many weird varieties of this singular tendency to visualize numbers in forms, which I have lately described, and will not here repeat. Suffice it to say, that they date from an earlier period than that to which recollection extends. They manifest themselves quite independently of the will; they are invariably the same in the same person, but are never the same in two different persons, and the tendency to see them is strongly hereditary. I have now a collection of hundreds of them, not only from English men and women, boys and girls, but from American, French, German, Italian, Austrian, and Russian correspondents. They are found useful in the simpler kinds of mental arithmetic.

Those who see number-forms have usually some equally persistent scheme for dates, based more or less upon the diagrams of the schoolroom. I am well acquainted with an accomplished student of history whose mnemonic form for all historical events is a simple nursery diagram, which has blossomed, as it were, into large excrescences whereon the subsequently acquired facts are able to find standing-room. These diagrams are really helpful, because their shape is correlated with the subject they portray. They are not like the jingling nonsense verses and bad puns upon which many persons base their memory of facts.

The persistency of the forms under which numerals and dates are visualized testifies to a want of flexibility in mental imagery which is characteristic of many persons. They find that the first image they have acquired of any scene is apt to hold its place tenaciously in spite of subsequent need of correction. They find a difficulty in shifting their mental view of an object, and examining it at pleasure in