Abstract
When different types of rival visual stimuli – monocular, binocular, and stimulus rivalry – are juxtaposed in neighboring visual regions, perceptual dominance can become entrained among those neighboring regions, implying cooperativity among types of rivalry (Pearson & Clifford (2005) Psychol. Sci.; Andrews & Purves (1997) PNAS). What promotes spatial grouping across those heterogeneous bistable percepts? In particular, is there an asymmetry between different types of rivalry in governing the group dynamics of perceptual reversals? Alternatively, does the grouping presumably result from mutual interaction between the different rivalry types? To answer these questions, we monitored the time course of synchronized perception between binocular (BR) and stimulus rivalry (SR) after triggering a transient perceptual change (Expt. 1) or creating a static imbalance between rival percepts (Expt. 2) in one of the two rivalry types. In Expt. 1, when observers were experiencing coherent perception from juxtaposed BR and SR segments, a brief contrast increment (a "trigger") was introduced in one segment. When presented within the BR segment, the trigger readily induced perceptual state transitions not only in the BR segment but also in the SR segment; a trigger introduced within the SR segment, however, rarely induced a state transition anywhere including its own segment. We obtained a complementary pattern of results in Expt. 2, where a perceptual imbalance was created by a sustained contrast difference between rival stimuli in one segment: the contrast disparity biased the rivalry dynamics of the compound stimulus only when that disparity appeared within the SR segment. This double dissociation implies that BR and SR affect each other’s fate via different mechanisms, the former by transient-signal gain and the latter by sustained-signal gain.
Meeting abstract presented at VSS 2012