Abstract
In visual perception, position and motion interact reciprocally. While motion is a construct consisting of a series of sequential changes in position, the perception of motion is considered to be more than just a series of changes in the perceived stimulus position. To investigate the evolving process of motion percept starting from the onset of motion, we had observers detect a small transient gap (13 ms long) within an otherwise smooth motion sequence. Observers were highly sensitive to a gap that occurred early in the motion (≤ 200 ms from motion onset). However, their sensitivity to detect the gap deteriorated as the motion continued (≥ 300 ms), indicating perceived motion became smoother and filled in over the course of motion. Moreover, the same temporal pattern of decline in detection performance was observed for transient change in shape or color. Experiments suggest that motion blur does not account for the effect, as blur has different temporal characteristics, and blur decreases, not increases with time. Our results together imply that the visual system processes a moving stimulus initially as a series of snapshots, but then gradually develops a holistic percept of motion as the motion continues. Once the motion system is sufficiently activated, stimuli presented at different times begin to be integrated into a single, coherent entity. Our results therefore suggest perception of object motion begins as a series of discrete, unintegrated snapshots in a way akin to that of an akinetopsic patient.
University of Houston funds