A dissociation of performance and awareness during binocular rivalry.

When conflicting stimuli are presented to equivalent locations in each eye, people experience binocular rivalry, a phenomenon characterized by alternations in conscious awareness of each eye's image. Attempts at objective measurement using monocular probe-detection methods show that sensitivity to probe stimuli is reduced during periods when those stimuli are reportedly suppressed. But are observers really able to detect stimuli that are perceptually invisible, or does the probe presentation itself reverse rivalry dominance between the two eyes? Here, we measured both judgment accuracy and confidence in those judgments across multiple probe contrast levels, and we found evidence for high accuracy with reduced awareness during suppression that was not due to probe-induced switches in rivalry dominance. This dissociation points to the existence of blindsight-like behavior in normal observers.