Temporal dynamics of visual motion interpretation

To elucidate the mechanism involved in the perception of object motion, we psychophysically studied interaction of temporally distant visual motion signals. As a probe stimulus, we used a motion stimulus that can be perceived as moving horizontally or vertically. Subjects answered perceived motion direction for this ambiguous stimulus. When presented after an unambiguous stimulus for which the direction of motion was unambiguously perceived, the ambiguous stimulus was perceived moving in the same axial direction as that of the preceding one. This effect was very strong when the stimulus interval was less than 1 s, strongly maintained for 1 to 5 s and remained for 10 s. Even when the preceding stimulus was presented at a distant position up to 5.48° from the ambiguous stimulus, perceived motion direction for the ambiguous stimulus was influenced similarly. These results suggest that some mechanism works for reducing ambiguity in the interpretation of object motion by using temporally and spatially distant motion signals.