Stimulus Pairing in Sequential Phi Motion

Abstract

Two correlated random-dot Julesz patterns, that produce apparent lateral motion of a textured surface when flashed once in succession at an appropriate ISI, were flashed repetitively in temporal alternation. If the two ISI's in the stimulus sequence were each appropriate to apparent motion, perceived to-and-fro motion of the textured surface would be expected. It was found, however, that, when the two ISI's were sufficiently different, continuous unidirectional flow-motion was perceived, indicating that the visual system was effectively partitioning the stimulus sequence into a series of identical ‘phi-pairs’ on the basis of the shorter ISI. The temporal limits of the phenomenon were investigated. Binocular, binaural, and tactile analogues of this phenomenon of perceptual pairing of successive stimuli according to temporal proximity are discussed.