Abstract
Contingent on stereo compatibility, two images presented dichopitcally can lead to either binocular integration generating stable stereopsis or interocular suppression inducing binocular rivalry with a bistable perception alternating between the two images. The relationship between binocular integration and binocular rivalry is unclear but may evince how our brain processes binocular inputs to form unified visual awareness. Here, a series of psychophysical experiments were conducted to investigate the interactions between binocular rivalry and stereopsis. In Experiment 1, observers performed a stereo detection task for stimuli presented in the vicinity of rivalrous vs. non-rivalrous stimuli. We found that the presence of binocular rivalry significantly elevated observers' detection threshold of stereo, suggesting inhibition to the formation of stereopsis in surrounding visual field. Moreover, this inhibition effect increased with higher contrast of the rivalrous stimuli, which presumably led to stronger interocular suppression, indicating that the effect of interocular suppression on stereopsis may be progressive instead of all-or-none. In Experiments 2a & 2b, observers were instructed to track binocular rivalry which occurred around stereo vs. non-stereo stimuli. Results show that perceiving stereopsis through binocular integration balanced the dynamics of eye dominance for rivalry in surrounding visual field, rendering more equivalent dominance of the two eyes. These findings reveal a new and interesting interaction effect between interocular suppression and binocular integration, complementing previous reports of the coexistence of rivalry and stereopsis at a same location. Taken together, interocular suppression and binocular integration are neither mutually exclusive nor fully independent from each other, suggesting that the two processes may share an overlapping mechanism for forming unified conscious visual representation from binocular inputs.