Binocular rivalry of spiral and linear moving random dot patterns in human observers.

Binocular rivalry describes the alternating perception of two competing monocular images. It is hypothesized to arise at multiple levels of the visual pathway due to competition between neuronal populations representing the displayed images. We tested whether an enhanced neural representation of expanding motion yields a bias over other spiral motion (i.e., contraction and rotation) and linear motion stimuli during binocular rivalry. We presented random dot patterns of different motion types (i.e., linear and spiral), matched in contrast and speed, to human subjects through a mirror stereoscope. During spiral rivalry, expansion rivalry periods dominated over those of contraction and rotation, and contraction dominated over rotation. During linear motion rivalry, up, down, left, and right directions had similar rivalry periods. All spiral motions dominated over linear motions. Interestingly, when these motion types rivaled against each other, the rivalry periods of spiral motion slightly decreased while those of linear motion significantly increased. This rivalry also caused the bias for expansion relative to other spirals to disappear. Our results suggest a correlation between neuronal representations of different moving patterns and their perception during binocular motion rivalry and provide further evidence that rivalry periods are constrained by the ecologic relevance of stimuli.