Stimulus flicker alters interocular grouping during binocular rivalry

Abstract

When the two eyes are presented with sufficiently different stimuli, the stimuli will engage in binocular rivalry. During binocular rivalry, a subject's perceptual state alternates between awareness of the stimulus presented to the right eye and that presented to the left eye. There are instances in which competition is not eye-based, but instead takes place between stimulus features, as is the case in flicker & switch rivalry [1]. This has been taken as evidence that binocular rivalry can occur at multiple levels of the visual processing hierarchy, i.e. at lower, monocular levels, and higher, eye-independent levels. In this view [2], ∼20 Hz flicker decreases the relative weight of the lower, monocular levels, thereby increasing the relative importance of the eye-independent levels. Here we investigate interocular grouping using a Diaz-Caneja stimulus in conjunction with synchronous stimulus flicker. Our results indicate that stimulus flicker increases the total duration of interocularly bound percepts, and that this effect occurs for a range of temporal flicker frequencies. Furthermore, the use of contrast-inversion flicker causes a decrease of total dominance duration of the interocularly bound percepts. We conclude that different flickering regimes can be used to differentially stimulate lower and higher levels of visual processing involved in binocular rivalry. 1. N. K. Logothetis, D. A Leopold, and D. L. Sheinberg. (1996). What is rivalling during binocular rivalry? Nature. 380, 621-624. 2. H. R. Wilson. (2003). Computational evidence for a rivalry hierarchy in vision. Proc Natl Acad Sci U S A. 100, 14499-14503.