Abstract
Binocular rivalry occurs when two eyes receive conflicting information, leading to perceptual alternations between two eyes' images. The locus of binocular rivalry has received intense investigation as it is pertinent to the mechanisms of visual awareness. Here we assessed the functional stage of binocular rivalry relative to blind spot filling-in. Blind spot filling-in is thought to transpire in V1, providing a reference point for the locus of rivalry. We conducted two experiments to explore the functional order of binocular rivalry and blind spot filling-in. Experiment 1 examined if the information filled-in at the blind spot can engage in rivalry with a physical stimulus at the corresponding location in the fellow eye. Resulting perceptual reports showed no difference between this condition and a condition where filling-in was precluded by presenting the same stimuli away from the blind spot, suggesting that the rivalry process is not influenced by any filling-in that might occur. In Experiment 2, we paired the fellow eye's rival stimulus, not with the filled-in surface at the blind spot, but with the 'inducer' that immediately surrounds the blind spot and that engenders filling-in. We also established two control conditions away from the blind spot: one involving a ring physically identical to the inducer, and one involving a disk that resembled the filled-in percept. Perceptual reports in the blind spot condition resembled those in the former, 'ring' condition, more than those in the latter, 'disk' condition, indicating that a perceptually suppressed inducer does not engender filling-in. Our behavioral data suggest that binocular rivalry functionally precedes blind spot filling-in. We conjecture that binocular rivalry involves processing stages at or before V1, which would be consistent with views of binocular rivalry that involve low-level competition, and with evidence that binocular rivalry correlates can be found as early as the lateral geniculate nucleus.
Meeting abstract presented at VSS 2017