Abstract
During binocular rivalry, the relative dominance time of the two images are strongly influenced by lower level image factors such as image contrast (i.e., the image with a higher contrast has a longer relative dominance time). In the current study, we investigated whether lateralized cortical processing for different categories of objects could also influence rivalry alternation dynamics. Since it is known that face processing is biased towards the right hemisphere (e.g., right fusiform face area stronger than left) and processing of visual word form is biased towards the left hemisphere (e.g., visual word form area is usually localized in the left fusiform cortex), we hypothesized that the dynamics of rivalry between faces and words will show a face advantage for left visual field presentation and a word advantage for right visual field presentation. Specifically, a face and a Chinese character of the same size were dichoptically presented either to the left or right visual field, 2.5 degrees from fixation. Subjects viewed the stimuli and recorded the perceptual alternations with key presses. As predicted, the results show that there was an interaction between the visual field of presentation and the relative dominance of the type of stimuli: the relative dominance time for faces over Chinese characters was longer when they were presented in the left visual field while the relative dominance time for Chinese characters over faces was longer for right visual field presentation. We conclude that object category selective cortical areas participate in binocular rivalry competition processes and are part of the mechanisms that determine the dynamics of rivalry competition.
Research supported by grants EY015261 and NSF/BCS-0818588.