Abstract
PURPOSE: Rivalrous orthogonal chromatic gratings can cause perceptual misbinding of color to form. The rivalrous forms alternate but the color from both eyes is perceived within the dominant form. Further, an afterimage of the misbound percept follows the misbinding experienced during rivalrous viewing (St.Clair, Hong, Shevell, VSS 2007). Here, two alternative hypotheses are tested for the origin of the misbound afterimage: (i) rivalrous monocular afterimages are resolved to give misbinding (as during rivalrous viewing) or (ii) persistence of a response from a binocular neural representation for the misbound percept experienced during viewing.
METHOD: The frequency of misbound percepts was measured during and following the presentation of two equiluminant, chromatically rivalrous gratings presented dichoptically. In the first condition, the rivalrous gratings were pulsed on and off simultaneously; this resulted in misbound percepts during viewing. In the second condition, the left-eye grating and right-eye grating were presented in alternation (first to one eye and then to the other eye but not simultaneously to both eyes). Over the course of the viewing period, retinal stimulation was the same in both conditions.
RESULTS: When the stimuli to the two eyes were pulsed simultaneously, color misbinding was experienced during viewing and in the afterimage. When the grating to one eye alternated with the grating to the other eye, no misbound percept was experienced during viewing or in the afterimage.
DISCUSSION: The absence of misbound afterimage percepts following the alternating presentation of gratings indicates that rivalrous monocular afterimages are not resolved to give a misbound afterimage. Instead, the percept of a misbound afterimage follows from a persisting binocular neural representation formed during rivalrous viewing.
Supported by NIH grant EY-04802.