Abstract
During binocular rivalry two images concurrently presented to two eyes can be combined as a coherent pattern as if perceptual experience follows Gestalt grouping principles. In the present study, we investigate whether grouping during binocular rivalry is mainly governed by eye-of-origin or pattern coherence (image-based influence) using pairs of stimuli that induce either monocular or interocular grouping. In the monocular grouping condition, a concentric ring pattern and a horizontal grating pattern were presented to each eye through a stereoscope. In this case, both eye-of-origin and pattern coherence work together to enhance the perception of each monocular stimulus. In the interocular grouping condition, each stimulus consisted of a concentric ring pattern and a horizontal grating pattern, left and right halves (Diaz-Caneja pattern). In this case, eye-of-origin promotes perception of monocular stimuli and pattern coherence promotes interocular grouping (perception of a whole concentric ring pattern or horizontal grating pattern). The results showed that the dominance duration of monocular stimuli was significantly longer than the dominance duration of mixed percepts in the monocular grouping condition as expected by combined effect of eye-of-origin and pattern coherence. However, in the interocular grouping condition, the dominance durations of monocular stimulus and interocularly grouped coherent pattern percepts were similar, indicating that eye-of-origin and pattern coherence similarly affect percepts during binocular rivalry. More interestingly, the analysis of individual differences in binocular rivalry dynamics in two conditions revealed a negative correlation. Specifically, the longer the duration of interocularly grouped percepts in the interocular grouping condition, the longer the monocular stimulus (less mixture percept) was seen in the monocular grouping condition. This negative correlation may indicate that individual differences in grouping during binocular rivalry is determined by pattern coherence, rather than eye-of-origin.