Abstract
Perception of bistable stimuli could be stabilized when they are intermittently presented (Leopold, Wilke et al., 2002). However, when the stimuli are presented at different spatial locations, perception could be stabilized locally but switches between locations (Chen & He, 2004). In this study, we examined whether contextual information, such as a bistable stimulus moving behind an occluder, would help stabilize the ambiguous perception across two spatial locations. Two different types of bistable stimuli were used, a bistable rotating cylinder (structure_from_motion) and dichoptically presented binocular rivalry stimuli. In the valid_context condition, the bistable stimuli slided into one side of an occluder and then emerged from the opposite side, creating the perception of an object moving back and forth behind the occluder. Subjects made perceptual judgment to the ambiguous pattern (direction of motion for the cylinder and the dominant pattern for binocular rivalry) when it appeared from each side of the occluder. In the invalid_context condition, the occluders were placed outside the two locations for the bistable stimulus so that the stimulus moved behind an occluder and then a new stimulus appeared at the second location without creating the impression that it was the same stimulus moving behind the occluder. Comparing to the invalid_context condition, valid context significantly stabilized the perceived rotating direction of the bistable cylinder across two locations; while the same contextual manipulation has no impact on perceptual switches of the binocular rivalry stimulus across two locations. These results suggest that the mechanism of perceptual stabilization of the structure_from_motion stimulus is more dependent on top_down factors while the stabilization of a binocular rivalry stimulus is much less sensitive to top_down contextual modulation.
Supported by NIH R01 EY015261.