Ocularity modulates the dominance of spatial over temporal influences in binocular rivalry.

The perception of a binocular rivalry (BR) stimulus can be influenced by other stimuli in temporal or spatial proximity. Here, we investigate how spatial (surround inhibition [SI]) and temporal context (flash suppression [FS]) interact. Previously, we modulated these influences by varying surround contrast in SI and timing parameters in FS. In the present study, we make use of the fact that the strengths of the two contexts can also be manipulated in the same way, namely by modulating ocularity. We varied FS strength by showing the prime to the same eye as the identical probe or to the other eye. Spatial influence was varied by presenting the surround to the same eye as the matching center, to the other eye, or to both. Temporal and spatial influences were mostly additive when biasing perception in the same direction. Some combinations were so strong that the dominant percept could be predicted almost perfectly. This may help in deliberately creating desired perceptual outcomes in future studies. Spatial context tended to dominate in conflicting situations. When both context types were presented interocularly (and presumably weaker), however, temporal context had the edge. This may reflect the unexpectedly strong interocular FS: the interocular constellation weakened FS much less than SI, suggesting differences in hierarchical processing levels. Thus, comparing interocular conditions may have been less informative than anticipated. Still, when the conflicting influences were both working intraocularly, spatial context dominated, consistent with previous findings.