5 Top-down influences on rivalry perception.4 Temporal properties of binocular rivalry.3 Spatial properties of binocular rivalry.Portions of this essay are adapted from a review of binocular rivalry appearing in the journal Mind and Brain, which is no longer in print (Blake, 2001). Using single-cell recording techniques in nonhuman primates and brain imaging techniques in humans, neuroscientists have identified time-varying changes in neural responses correlated with alternations in perceptual dominance during rivalry. In recent years, neuroscientists have adopted binocular rivalry as a means for identifying neural concomitants of visual awareness. A few think rivalry reveals the operation of an intrinsic neural oscillator controlling a host of rhythmic behaviors (Pettigrew, 2001). Most believe that binocular rivalry, along with other forms of perceptual multistability, reflects neural processes involved in resolving visual conflict arising from inherently ambiguous sensory signals (e.g., Leopold & Logothetis, 1999). Nonetheless, the neural processes underlying rivalry may still be operating to promote single vision by eliminating double vision ( diplopia) and local interocular conflicts concerning the positions of objects in 3D visual space. Alternations in rivalry dominance usually occur after a few seconds of steadying viewing, but during natural viewing, the eyes rarely remain fixed for more than a few hundred milliseconds. People with normal binocular vision do not usually experience rivalry alternations under ordinary viewing conditions, even though many local regions in each eye may undergo suppression. It is also one of a few psychophysical phenomena that have been usefully exploited to study visual processing outside of awareness other such phenomena include metacontrast masking, motion induced blindness, and flash suppression. Binocular rivalry is a compelling example of multistable perception wherein physically invariant stimulation leads to fluctuations in perception. Rather than perceiving a stable, single amalgam of the two stimuli, one experiences alternations in perceptual awareness over time as the two stimuli compete for perceptual dominance.

Randolph Blake, Vanderbilt University, Nashville, TNīinocular rivalry is a visual phenomenon that occurs when dissimilar monocular stimuli are presented to corresponding retinal locations of the two eyes.