Abstract
Showing different images to either eye can induce perceptual switching, with alternating disappearances of each image. This phenomenon, known as binocular rivalry, has been the focus of extensive contemporary interest as it permits an opportunity to explore the relationship between changes in awareness and brain activity in the absence of changes to sensory input. Different explanations exist: disappearances might be related to selections of a particular stimulus or to selections of information from a specific eye. We believe there is a third possibility - that disappearances during rivalry could be driven by a process which facilitates visibility near the point of fixation. As the fixation point is a property that belongs neither to a particular stimulus nor to a specific eye, indifference to both would be an essential characteristic for the process we envisage. We demonstrate this indifference using image blur to cue distance from fixation. We break the links between this cue and both eye of origin and stimulus type. We find that perceptual dominance can track a better focused image as it is swapped between the eyes and that perceptual switches can be driven by alternating the focus of images fixed in each eye. Our findings suggest that perceptual suppression, during binocular rivalry, is not an irrelevant curiosity. Instead, we argue that it is a product of a functional adaptation, prevalent in daily life, which facilitates visibility near the point of fixation.
This research was supported by a Discovery Project Grant and Australian Postdoctoral Fellowship awarded to DHA by the Australian Research Council.