Revealing boundary-contour based surface representation through the time course of binocular rivalry

Beyond surface texture features such as grating orientation, the surface boundary contour of the binocular rivalry stimulus determines its perception. A boundary contour present only in one half-image supports an earlier manifestation of interocular suppression. [Display omitted] ► Global dominance percept takes ⩽30ms to occur with an MBC rivalry stimulus. ► Global dominance percept takes >150ms to occur with a BBC rivalry stimulus. ► A monocular probe is suppressed sooner when it is spatially closer to the MBC. ► Interocular inhibition likely begins quickly after the stimulus onset (⩽30ms). ► A representation of the dominant surface from the boundary contour is proposed. We varied the surface boundary-contour properties of binocular rivalry (BR) stimuli to measure the rivalry percept as a function of stimulus duration. Experiment 1 compared perception from BR stimuli with monocular boundary contour (MBC) and binocular boundary contour (BBC). We found global dominance is achieved with stimulus duration as short as 30ms for the MBC rivalry stimuli, whereas it takes more than 150ms for the BBC rivalry stimuli. This shows that global dominance can occur rapidly in the absence of a corresponding boundary contour in one half-image. Experiment 2 measured the detection of a monocular Gabor probe located centrally on a 1.5° versus 3.0° MBC rivalry stimulus. We found reliable binocular suppression is observed earlier with the 1.5° MBC stimulus, presumably because of the probe being spatially located nearer to the boundary contour. These findings, in conjunction with those in Su et al. (2011), support the notion that the representation of the dominant surface begins at the MBC and spreads toward the center of the image.