Abstract
When the left and the right eye are simultaneously presented with incompatible images at overlapping retinal locations, an observer typically reports perceiving only one of the two images at a time. This phenomenon is called binocular rivalry. Perception during binocular rivalry is not stable; one of the images is perceptually dominant for a certain duration (typically in the order of a few seconds) after which perception switches towards the other image. This alternation between perceptual dominance and suppression will continue for as long the images are presented. A characteristic of binocular rivalry is that a perceptual transition from one image to the other generally occurs in a gradual manner: the image that was temporarily suppressed will regain perceptual dominance at isolated locations within the perceived image, after which its visibility spreads throughout the whole image. These gradual transitions from perceptual suppression to perceptual dominance have been labeled as traveling waves of perceptual dominance. In this study we investigate whether stimulus parameters affect the location at which a traveling wave starts. We varied the contrast, spatial frequency or motion speed in one of the rivaling images, while keeping the same parameter constant in the other image. We used a flash-suppression paradigm to force one of the rival images into perceptual suppression. Observers waited until the suppressed image became perceptually dominant again, and indicated the position at which this breakthrough from suppression occurred. Our results show that the starting point of a traveling wave during binocular rivalry is highly dependent on local stimulus parameters. More specifically, a traveling wave most likely started at the location where the contrast of the suppressed image was higher than that of the dominant one, the spatial frequency of the suppressed image was lower than that of the dominant one, and the motion speed of the suppressed image was higher than that of the dominant one. We suggest that a breakthrough from suppression to dominance occurs at the location where salience (the degree to which a stimulus element stands out relative to neighboring elements) of the suppressed image is higher than that of the dominant one. Our results further show that stimulus parameters affecting the temporal dynamics during continuous viewing of rival images described in other studies, also affect the spatial origin of traveling waves during binocular rivalry.
Highlights
When the two eyes are confronted with dissimilar images, each of the two images undergoes alternating periods of perceptual dominance and suppression
Our experiments show that the spatial origin of a perceptual transition is highly dependent on stimulus parameters
The starting point of transition was influenced by stimulus parameters in the CONST-to-VAR conditions, as well as in the VAR-to-CONST conditions
Summary
When the two eyes are confronted with dissimilar images, each of the two images undergoes alternating periods of perceptual dominance and suppression This phenomenon is called binocular rivalry and is highly popular among vision scientists since it has been argued that it can provide insights into the neural correlate of consciousness [1]. Perceptual alternations during binocular rivalry generally occur automatically and are subject to limited voluntary control [4,5,6]. A characteristic of binocular rivalry is that a rival image will completely dominate perception only under a limited set of conditions, a situation referred to as exclusive visibility. The speed of the traveling waves correlates with neural propagation speed in V1, V2 and V3 [14,15]
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