The initial interactions underlying binocular rivalry require visual awareness.

Current theories of binocular vision suggest that the neural processes that resolve interocular conflict do not involve a single brain region but occur at multiple stages of visual processing. Here, using an adaptation paradigm, we explore the initial mechanisms involved in selecting a stimulus for perceptual dominance during binocular rivalry. When one or both eyes briefly viewed an adapting grating stimulus prior to the presentation of the adapting grating to one eye and an orthogonal, non-adapted grating to the other eye, participants more often reported perceptual dominance of the non-adapted grating. Crowding reduced awareness of the adapting grating. On trials in which subjects were unaware of the orientation of the adaptor grating, there was no effect of the adaptor on perceived dominance during rivalry; participants were just as likely to report dominance of the adapted or non-adapted grating. This implies that the initial events in binocular rivalry involve later stages of visual processing.