The traditionally held notion that binocular rivalry reflects central selective processes that take effect subsequent to the analysis of both monocular stimuli contrasts with the currently popular view that the suppressed stimulus suffers inhibition, or blocking, at a relatively peripheral level. The available evidence supports the traditional approach. Though peripheral responses such as changes in pupil diameter or accommodation may be correlated with rivalry suppression, they may not be held responsible for the suppression itself. Similarly, processes of adaptation and contralateral inhibition are unable to explain binocular rivalry. Most importantly, however, there is evidence that the suppressed stimulus in rivalry is being fully analyzed and evaluated. Perceptual experience is thereby shown to reflect processes over and above the analysis of sensory information, and binocular rivalry suggests itself as a useful context in which to isolate and investigate these processes.Binocular rivalry was assigned an important place in early discussions of perception and attention (Breese, 1899;Helmholtz, 1911; James, 1890;Sherrington, 1947), since it was considered to reflect a central selective process that took effect subsequent to the analysis of the two monocular stimuli. However, rivalry is now regarded by many to reflect peripheral sensory mechanisms (Abadi, 1976;Bishop, 1973;Jung, 1961; Wade, 197Sa). Thus, recent neurophysiological evidence has made it easy to conceive of a form of contralateral reciprocal inhibition between the two monocular channels, at or before the level at which the channels converge (