Abstract
PURPOSE: When rivalrous stimuli containing luminance contrast are presented continuously to each eye, the percept alternates over time. When the same stimuli are pulsed on intermittently, however, the percept is stable (Leopold et al. 2002). A basic question is whether the stable percept during intermittent presentation is due to persistence of the response from one eye (Chen & He, 2004; Pearson & Clifford, 2004) or persistence of the percept. This study examines a binocular percept resulting from rivalrous equiluminant chromatic gratings, which give rise to form rivalry between the two eyes but with the colors within the form from both eyes (perceptual misbinding of color to form; Hong & Shevell, 2006). Is the binocular, misbound percept stable with intermittent viewing?
METHOD: A 2 cpd square-wave vertical grating was presented to one eye and a tooth-shaped vertically oriented grating (top half of grating phase-shifted by one-half cycle relative to bottom half) to the other eye. Each eye's stimuli were equiluminant (e.g., purple/white in one eye, green/white in the other eye). Initially, the stimuli were presented for a fixed period (several seconds) and then extinguished. Then they were presented for 0.5 sec every 2.5 sec (0.5 sec on, 2 sec off) for 1 minute.
RESULTS: When a binocular, misbound percept (misbinding of color to form) was last seen during the initial viewing period, the misbound percept was stabilized. When an inhomogeneous, piecemeal percept was last seen, a piecemeal percept was stabilized. When a monocular percept was last seen, the monocular percept was stabilized to some extent but much less so than reported with stimuli having high luminance contrast (e.g. Chen & He, 2004).
CONCLUSION: For equiluminant stimuli, which often result in a misbound or a piecemeal binocular percept, stabilization occurs at the binocular perceptual level.