A Primer on Binocular Rivalry, Including Current Controversies Randolph Blake Vanderbilt Vision Research Center Vanderbilt University Nashville TN 37240 USA running head: Binocular Rivalry email:
[email protected] voice: 615-343-7010 FAX: 615-343-5029 Binocular Rivalry Abstract. Among psychologists and vision scientists, binocular rivalry has enjoyed sustained interest for decades dating back to the 19th century. In recent years, however, rivalry’s audience has expanded to include neuroscientists who envision rivalry as a “tool” for exploring the neural concomitants of conscious visual awareness and perceptual organization. For rivalry’s potential to be realized, workers using this “tool” need to know details of this fascinating phenomenon, and providing those details is the purpose of this article. After placing rivalry in a historical context, I summarize major findings concerning the spatial characteristics and the temporal dynamics of rivalry, discuss two major theoretical accounts of rivalry (“eye” vs “stimulus” rivalry) and speculate on possible neural concomitants of binocular rivalry. key words: binocular rivalry, suppression, conscious awareness, neural model, perceptual organization 1. Introduction The human brain has been touted as the most complex structure in the known universe (Thompson, 1985). This may be true, but despite its awesome powers the brain can behave like a confused adolescent when it is confronted with conflicting visual messages. When dissimilar visual stimuli are imaged on corresponding retinal regions of the two eyes, the brain lapses into an unstable state characterized by alternating periods of perceptual dominance during which one visual stimulus or the other is seen at a time. This confusion is understandable, for the eyes are signalling the brain that two different objects exist at the same location in space at the same time.