tion. A color may cause a shrill sound to be heard. I was told lately of a lady who was overcome by such a sound on entering a room where decorations, hangings, and furniture were red in color. On the other hand, certain sounds may awaken the idea of colors. I have heard of a man who seemed to see the color green when he heard a violin played; another person always had a sensation of red at the sound of a trumpet. Another person,[1] who had become blind, had retained this persistent association, and when the vowel sounds were pronounced slowly he had, accompanying each, a sensation of color like a transparent colored sheet a short distance in front of his face. Each vowel sound had its own corresponding tint, which was always the same for that vowel: a was red; e, gray; i, black; o, white; u, green. When the vowel sounds were uttered in rapid succession there appeared to be a confused, rapidly changing faint screen of color, but it did not obtrude itself on his consciousness unless he expressly directed his attention to it. This association persisted after this man had become blind. Many such instances have been recently collected by Flournay in his interesting book, Des Phénomènes de Synopsie. It is said that twelve per cent of people have such a power of color-hearing. It is certainly a fact that the most of us have an unpleasant involuntary feeling on hearing certain sounds. We all dislike the creaking noise of a slate pencil drawn across the slate or the sound produced by a man filing a saw, I think this is more than mere dislike of sound—it is a real sensation of a non-auditory and painful character a forced, unnatural association.
Thirdly: The study of child life and of the mental development of the infant is the third line of research which has been of great service in the investigation of mental action. It is not possible for one accustomed to think without regarding his mental processes to suddenly stop in the course of thought and analyze accurately his methods of thinking. The rapidity of associations, their determination in certain lines by habit and by use, and their enormous number in the active mind, baffle all analysis. But if we watch the growth of thought in the child, if we notice the accumulation of memory pictures, the gradual building up of concepts and the formation of the links in the chain of reasoning, we can get at the elements of many complicated mental processes Thus the study of the mental growth of the child throws light upon the study of adult thinking.
And here, too, the value must be recognized of the study of those imperfect minds which are arrested in their development at certain points. Thus, there are children whose powers of perception appear to grow with their growth, whose powers of recogni-
- ↑ Lancet, March 31, 1894.
