Abstract
Under normal viewing conditions, a person's left and right eyes are presented with very similar visual input. When the input provided to the two eyes is so different that they cannot be combined into one coherent picture of visual space, input from each eye competes to be perceptually dominant over the other. Such a perceptual competition is called binocular rivalry. The rate of perceptual switch seems to vary based on many extrinsic factors including the perceptual strength and context of the stimuli presented to the observer. However, when the stimulus conditions are fixed, the rate of switching is relatively stable for a given individual, but varies much more between individuals. Despite extensive research on extrinsic factors that can influence rate of binocular rivalry switch, relatively little has been done to investigate intrinsic (individual biological differences) factors that may be involved. Previous research has shown that factors such as bipolar disorder may slow binocular rivalry switch, indicating that intrinsic factors may be involved, however little information is available about the contribution of heritability to rivalry rates in normal populations. In the current study, rate-of-switch was recorded in a population of monozygotic and dizygotic twins under the same binocular rivalry conditions. Rate-of-switch when viewing a bistable Necker Cube was also recorded for each subject. Results suggest that there is a very strong heritability component related to switch rate in the case of binocular rivalry, but a much weaker genetic contribution to the switching rate of pictorial bistable images (Necker Cube).