Molyneux's question : vision, touch, and the philosophy of perception / Michael J. Morgan.

  • Morgan, Michael J.
Date:
1977
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Molyneux's question : vision, touch, and the philosophy of perception / Michael J. Morgan. Source: Wellcome Collection.

    191/236 (page 175)
    AFTERWORD: RECENT DEVELOPMENTS ously allowed to feel it with a hand. Rock believed that this was a situation in which visual and tactile space were in conflict, and thought that, according to Berkeley, the tactile spatial impres¬ sion ought to dominate. In fact, the visual impression domi¬ nated, and the subjects reported seeing and feeling, not a square, but a rectangle. The premise behind this refutation is quite mistaken. We have seen that according to Berkeley there is no such thing as visual space, so there is no question of a conflict between visual and tactile space. What we have in Rock's experiment, according to Berkeley, is a conflict between two kinds of tactile information: the one coming directly from the hands, and the other coming from memory images aroused by information from the retinal image. The retinal image is one that has always been associated in the past with tactile rectangles. The fact that the subject perceives a rectangle and not a square thus indicates that previ¬ ous experience dominates over current impressions; there is nothing unreasonable about this hypothesis, and nothing inconsistent with Berkeley's position. It is exactly what Rock himself assumes when he argues that the reinverted retinal image looks upside down because memory traces dominate over present sensory information. Rock may have refuted the 'deriva¬ tion of visual space from tactile space', but, since this has nothing to do with Berkeley's hypothesis, the refutation is not damaging. It is otherwise with recent claims that very young children have well-developed depth perception and object constancy. T. G, R. Bower^^ has claimed to show this by conditioning babies The same phenomenon has recently been demonstrated in a group of people presumably well accustomed to judging shapes by touch: potters. See R. P. Power and A. Graham, 'Dominance of touch by vision: generalisation of the hypothesis to a tactually experienced population', Perception, 5 (1976) 161-6. An excellent general account of these experiments will be found in T. G. R. Bower's own book Development in Infancy (San Francisco: W. H. Freeman, 1974]. Concerning the infants' reactions when their hands failed to make contact with the illusory 3-D object, Bower states, 'All the infants were surprised and upset when their hand reached the location of the intangible object and failed, of course, to make contact with it' (p. 94]. Again, the babies are said to 'howl' at the experience (p. 114]. Bower has said in several places that experiments of this kind pose difficulties for Berkeley: for example, 'Contrary to the Berkeleian tradition, the world of the infant would seem to be 177