Page:Mind (New Series) Volume 8.djvu/513

 THE SPATIAL HAEMONY OF TOUCH AND SIGHT. 499 between touch and sight, is built up associationally ; and only by actual experience does a person learn what visual position corresponds to any given tactual position. 1 As far as the actual feeling of appropriateness is concerned, any other visual position would do quite as well ; but the association once established, a definite visual expectation is aroused by each tactile impression, and an appearance in any other than this anticipated locality seems distinctly incongruous. We have come to expect to see the object just there, and if we really see it elsewhere, we feel that sight has ceased to accord with touch, whereas, in truth, sight has merely ceased to accord with what its own previous reports had led us to expect. Since the definite direction which the expectation takes is due merely to the course of our previous experience, the actual harmony may come about under the most varied conditions under any, in fact, which permit the growth of expectation and of an experience which constantly meets the suggestions thus aroused. This view of the case makes room for our normal ex- perience and for the results of experiments like that here reported ; but some might feel that it is contradicted by evidence gained from persons cured of blindness. For if the harmony between touch and sight is a matter of smooth and rapid cross-reading from one sense to the other, gained by noting the location of simultaneous changes in the two sensory fields, a mind just entering on visual experience ought to be unable to translate visual positions into tactual, and the reverse. He must by actual trial learn what move- ments are necessary to bring his hand to a given visual place, by watching his hand (after recognising it by sight) and inhibiting those movements which are seen to carry its image away from the selected visual region, and continuing those movements which bring the image nearer its goal. But accurate off-hand pointing and grasping, under guidance of sight alone, would be impossible. Yet there are statements in certain reports of operations for cataract which might well be adduced in proof of an immediate muscular appreciation of visual direction. Ware, for example, relates that his patient, a child of seven years, recognised as a square piece of paper a letter held before him, and said that it was longer in one direction than in the other. " On being desired to point to the corners, he did it with 1 For a more detailed presentation of this as an associational corre- spondence of local signs, see The Psychological Review, Sept., 1897, p. 472
 * l seq.