When contexts collide: Spatial context prevails over temporal context in binocular rivalry.

Studying binocular rivalry lets us gain a glimpse into how our visual representation is constructed. It is well-known that what is presented around (spatial) and before (temporal) the rivaling stimuli influences what you perceive. How these spatial and temporal factors interact is, however, unknown. In two experiments, we investigate the influence of the spatial surround and flash suppression (as an example of a temporal effect) on binocular rivalry when they occur concurrently. We used gratings of opposing orientation as rivalry probes and varied the strength of the spatial surround by modulating its contrast and the strength of the flash suppression by modulating either the blank duration (Experiment 1; n =17) or the probe duration (Experiment 2; n = 17). We measured both the dominant percept and its clarity. For the single context (either spatial or temporal), we could replicate previous findings. Crucially, when spatial and temporal contexts were combined, we could show additive effects when they favored the same grating and opposing effects when they favored different gratings. In these cases, the spatial context exerted a stronger influence than the temporal context. Also, the clarity of reported percepts decreased when influences were conflicting. Exploratory analyses showed surprising differences in perceptual clarity for the different modulations of flash suppression (Experiment 1 vs. Experiment 2), challenging previous assumptions about the interchangeability of blank and probe duration. In general, the results emphasize the importance of looking at different factors shaping bistable perception not just in isolation, but concurrently.