Abstract
Purpose: To explore the mechanisms of multi-stable perceptual organization in motion perception. Methods: Observers viewed ambiguous kinetic depth displays, which contained two clusters of moving dots. The dots moved such that each cluster appeared to rotate in depth, in one of two directions. The task was to report the direction of rotation in the clusters under two viewing conditions: (a) continuous viewing, (b) brief presentations Results: (1) Clusters with aligned axes appeared to rotate in the same direction and flip direction synchronously. The degree of synchronization declined, as the axes were misaligned; clusters with orthogonal axes were seen to flip independently. (2) When the motion of one cluster was paused, its direction tended to flip, if the axes were not aligned. If the axes were aligned, the clusters flipped or did not flip together. (3) When the clusters were occluded, so that they appeared to connect behind the occluder, their synchronization increased. (4) When a single cluster was presented in alternation at two locations, it was perceived either (a) as a single moving object, which tended to rotate continuously, or (b) as two objects, which tended to rotate in different directions. Conclusions: Interactions between the processes of motion perception at different locations depend upon spatial relations between the emergent properties of objects at these locations. Perceptual rivalry and switching occur within objects, and thus cannot be fully explained by an object independent mechanism, such as hemispheric competition