Page:Mind (Old Series) Volume 12.djvu/167

 TUXNOTES. ON A CASE OF ALLEGED HYPNOTIC HYPERACUITY OF VISION. In an interesting paper which appears in the Revue Philosophique for November last, M. Bergson of Clermont-Ferrand gives an account of a case of supposed thought-transference or clairvoyance which turns out to be much more probably explicable by hypnotic hyperacuity of vision. The large majority of my readers no doubt conceive thought-transference to be a mere delusion, but they may feel some interest in tracing the abnormal physiological conditions which in this curious instance led at first to the belief that a transmission of ideas or images was taking place by other than the recognised channels of sense. And to the few who have satisfied themselves that such transmission does sometimes occur it is specially important to sift away all the spurious cases which, while apparently supporting, must in the end discredit the novel theory. Briefly, then, MM. Bergson and Robinet found that a boy, who was sup- posed to be a clairvoyant, or a telepathic percipient, could read figures and words under the following conditions. One of the observers hypnotised the boy, stood with his back nearly against the light, opened a book at random, held it nearly vertically facing himself, at about four inches from his own eyes, but below him, and looked sometimes at the page and some- times into the boy's eyes. The book had often to be slightly shifted ; but ultimately the boy could generally read the number of the page. Asked where he saw it, he pointed to the back of the book, just opposite the number's true position. Asked where the binding of the book was, he put his hand underneath the book, and indicated the place where the binding would have been, had the book faced him. It occurred to M. Bergson and he deserves full credit for being the first to insist on this precaution that, small though the figures were, the boy might really be reading them as reflected on the cornea of the hypnotiser. Experiments with slightly altered position showed that in fact the boy could not read the letters unless adjustment and illumination were carefully made as favourable as possible. The letters were 3 mm. in height, noth- ing is said of their thickness, and their corneal image would be about O'l mm. in height, as M. Bergson computes, under the conditions employed. This seems a very small image to see distinctly ; but Mr. J. N. Langley and Mr. H. E. Wingfield, who have kindly tried some careful experiments to test this point, inform me that they can read in each other's cornea the reflexion of printed letters of about 10 nun. in height. We know from Binet and Fere's experiments, &c., how greatly the hypnotic state does sometimes increase acuity of vision ; and we may, I think, conclude that the boy pro- bably did read the letters on his hypnotiser's cornea. What, then, are we to make of the boy's statement that he saw the words as though in a book facing him ? M. Bergson feels sure that this was the boy's real belief. There w r as no suspicion of charlatanism, and in fact the boy disliked the experiments, and now, as M. Bergson writes to me, refuses to renew them. M. Bergson supposes, and I think justly, that this was a case of simulation inconsciente ; the hypnotised subject genuinely referring his sensations to the source to which his first hypnotiser (a believer in thought-transference) had suggested to him that they were due. And, in fact, this unconscious simulation which leads the subject to refer his unusual sensations to the special cause which his hypnotiser, or some