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Abstract:
Under certain viewing conditions, visual stimuli that are normally highly salient can be rendered invisible for perception. In the paradigm of binocular rivalry (BR), for instance, the unique perception of a stimulus shown to one eye entails the subjective disappearance of that shown to the other. In a variant of BR termed “flash suppression” (FS, Wolfe, 1984), the balance of perceptual dominance can be adjusted by introducing a delay of several hundred milliseconds between the presentation of the two eyes’ patterns. Central to FS is the existence of interocular spatial conflict between the competing patterns. Here we report that asynchronous stimulus presentation can initiate perceptual disappearance of highly salient targets in the absence of either interocular or spatial conflict. Specifically, we found that a variety of visual patterns, including faces, gratings, and rotating geometric objects, disappear immediately from view when a small number of randomly distributed dots are flashed in the periphery. While this effect was present for both monocular and binocular viewing, it was most consistent when the target was presented monocularly and the dots binocularly. The duration of target disappearance, as well as its dependence on stimulus onset asynchrony, closely resembled FS, but was distinctly different from metacontrast masking.
We are currently investigating the neurophysiological basis of this phenomenon in a macaque monkey trained to report the disappearance of a variety of visual targets in the context of this paradigm.
