Examination of Gibson's psychophysical hypothesis.

The experimental evidence regarding Gibson's psychophysical hypothesis is examined. The presentation is divided into 2 sections dealing with static and transforming stimulation, respectively. Under the former heading the stimulation for surface, slant, and depth is considered. Under the latter heading the investigations of motion perspective, continuous perspective transformations, and size-transformations are examined. 2 general conclusions emerged from this examination: the psychophysical hypothesis has not been unequivocally confirmed and Gibson's theory requires revision to make explicit several recurrent implicit premises. One of the major contemporary theoretical accounts of perception is Gibson's (1950b, 1959, 1963) psychophysical theory. Unlike other theories, for example, Gestalt and transactionalism, Gibson has attempted to develop a S-R account of perception; one which does not introduce intervening variables such as sensory organization or neo-Helmholtzian assumptive worlds. The central proposition of Gibson's (1959) theory is the generalized psychophysical hypothesis: for every aspect or property of the phenomenal world of an individual in contact with his environment, however subtle, there is a variable of the energy flux at his receptors, however complex, with which the phenomenal property would correspond if a psychophysical experiment could be performed [p. 465]. The objective of this paper is to evaluate the evidence for this hypothesis. The similarity between Gibson's hypothesis and the older discredited constancy hypothesis is evident. Gibson's hypothesis, however, is less vulnerable. 1 This article was written with the support