The facts I am now about to relate are obtained from the returns of 100 adult men, of whom 19 are Fellows of the Royal Society, mostly of very high repute, and at least twice, and I think I may say three times, as many more are persons of distinction in various kinds of intellectual work.  As already remarked, these returns taken by themselves do not profess to be of service in a general statistical sense, but they are of much importance in showing how men of exceptional accuracy express themselves when they are speaking of mental imagery.  They also testify to the variety of experiences to be met with in a moderately large circle.  I will begin by giving a few cases of the highest, of the medium, and of the lowest order of the faculty of visualising.  The hundred returns were first classified according to the order of the faculty, as judged to the best of my ability from the whole of what was said in them, and of what I knew from other sources of the writers; and the number prefixed to each quotation shows its place in the class-list.

VIVIDNESS OF MENTAL IMAGERY.

(From returns, furnished by 100 men, at least half of whom are distinguished in science or in other fields of intellectual work.)

Cases where the faculty is very high.

1.  Brilliant, distinct, never blotchy.

2.  Quite comparable to the real object.  I feel as though I was dazzled, e.g. when recalling the sun to my mental vision.

3.  In some instances quite as bright as an actual scene.

4.  Brightness as in the actual scene.

5.  Thinking of the breakfast-table this morning, all the objects in my mental picture are as bright as the actual scene.

6.  The image once seen is perfectly clear and bright.

7.  Brightness at first quite comparable to actual scene.

8.  The mental image appears to correspond in all respects with reality.  I think it is as clear as the actual scene.

9.  The brightness is perfectly comparable to that of the real scene.

10.  I think the illumination of the imaginary image is nearly equal to that of the real one.

11.  All clear and bright; all the objects seem to me well defined at the same time.

12.  I can see my breakfast-table or any equally familiar thing with my mind’s eye, quite as well in all particulars as I can do if the reality is before me.

Cases where the faculty is mediocre.

46.  Fairly clear and not incomparable in illumination with that of the real scene, especially when I first catch it.  Apt to become fainter when more particularly attended to.

47.  Fairly clear, not quite comparable to that of the actual scene.  Some objects are more sharply defined than others, the more familiar objects coming more distinctly in my mind.

48.  Fairly clear as a general image; details rather misty.