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Psychological Investigations   241

or left, in short to be a generic image of a four-oar formed by a combination into a single picture of many sight-memories of such boats. "I argue," he writes, "that the mind of a man whose visualising faculty is free in its action forms these generalised images of its own accord out of its past experiences" (p. 320).

Galton states the forms of the visualising faculty which he thinks ought to be aimed at in education

"The capacity of calling up at will a clear, steady and complete mental image of any object that we have recently examined and studied. We should be able to visualise that object freely from any aspect; we should be able to project any of its images on paper and draw its outline there; we should further be able to embrace all sides of the object simultaneously in a single perception, or at least to sweep all sides of it successively with so rapid a mental glance as to arrive at practically the same result. We ought to be able to construct images from description or otherwise, and to alter them in whatever way we please. We ought to acquire the power of combining separate, but more or less similar images into a single generic one. Lastly we should learn to carry away pictures at a glance of a more complicated scene than we can succeed at the moment in analysing'." (p. 322.)

A final point which Galton makes in this extraordinarily interesting paper is that the will cannot render vivid a faint image; its action is negative being limited to the suppression of. what is not wanted and would confuse '

"It cannot create thought, but it can prevent thoughts from establishing themselves which lead in a false direction; so it keeps the course clear for a logical sequence of them. But if appropriate ideas do not come of their own accord, the will is powerless to evoke them. Thus we forget a familiar name, it is impossible to recall it by force of will. The only plan in such a case is to think of other things, till some chance association suggests the name. The mind may be seriously dulled by over-concentration, and it will only recover its freshness by such change of scene and occupation as will encourage freedom and discursiveness in the flow of ideas." (p. 324.)

The paper concludes with the extract which we have cited in the fuller form from the Inquiries into Human Faculty (see our p. 211).

Galton's investigation of visualised numerals or number forms sprang directly from his inquiries as to mental imagery. Several of his correspondents referred to their "number forms," i.e. the schemes in which they visualised the numerals from 1 to 200, or in some cases to a thousand or even a million. Closely allied to these number forms were arrangements of months of the year and of the days of the week. Others visualised in much the same way the years of their life and even the centuries of history. Not a few of these "forms" were associated with colours or shading. Galton collected both before and after the publication of his Inquiries into Human Faculty large quantities of these forms, and there is very ample correspondence with regard

' About this Galton writes: "A useful faculty, easily developed by practice, is that of retaining a mere retinal picture. A scene is flashed upon the eye; the memory of it persists, and details which escaped observation during the brief time when it was actually seen may be analysed and studied at leisure in the subsequent vision." This point needs very full investigation. Personally I have tried in vain to get any detail of scene or action, which I had -not individually taken in on the occurrence. I feel grave doubts whether the details "which escaped observation" would not be supplied later because they were probable accompaniments, and to give evidence in a court of law of what happened by aid of such a visualising faculty would be for me a very real danger.

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