Visual-haptic perceptual nonequivalence for shape information and its impact upon cross-modal performance.

The issues of visual-haptic perceptual equivalence and the impact of nonequivalence upon cross-modal performance were explored. A measure of cross-modal nonequivalence was developed from multidimensional scaling models of the perceptual structures of 24 nonrepresentative three-dimensional stimuli. In Experiment 1 the visual and haptic perceptual structures and measures of cross-modal nonequivalence were shown to be replicable. Experiments 2 and 3 employed sets of stimuli selected as cross modally similar or dissimilar (based upon the results of Experiment 1) and tested the impact of perceptual nonequivalence upon cross-modal performance with shape information. The experiments used somewhat different tasks and produced converging results. There was poorer cross-modal performance when cross modally dissimilar stimuli were involved than when only cross modally similar stimuli were involved, but there was no such pattern for intramodal performance. The findings are related to the theoretical notions of perceptual equivalence (Gibson, 1966; Marks, 1978) and the theoretical and practical importance of understanding the perceptual properties of stimuli used in cognitive tasks (Garner, 1970; Monahan & Lockhead, 1970).