Propagation of local motion correspondence

We examined how the direction of apparent motion in one part of a scene can propagate and constrain motion direction in another part. The stimulus scene consisted of an array of dots all moving in the same physical direction at the same time. According to the proximity rule, the dots in the interior of the array should appear to move rightward and the dots at the edges should appear to oscillate horizontally. However, we found that: (1) with long frame durations, the interior dots also appeared to oscillate; (2) with shorter frame durations, the likelihood that the subjects perceived rightward motion at the center of the array increased; (3) oscillation was observed at the edges regardless of frame duration; (4) when opaque objects were placed on both the left and right sides of the array as occluders, only rightward motion was observed both in the center and at the edges of the occluders independent of frame duration; (5) in all cases, similar results were obtained with both foveal and peripheral viewing of either the center or the edge; and (6) with longer frame durations, the interior area within which oscillations were observed became larger. These findings suggest that signals for motion correspondence (oscillation) can gradually propagate to distant units (roughly 30 deg/sec). This can be explained by a locally-connected iterative network model.