Zhangziyi zhou¹ (), Chuan Hou¹; ¹The Smith-Kettlewell Eye Research Institute

When different images are presented to the two eyes, the perception alternates between the eyes, known as binocular rivalry. The duration of perception between the eyes can be influenced by various factors, including the stimuli (size, contrast, spatial frequency, etc.) and the viewing eye. Binocular rivalry dynamics can also be modulated by attending to features on one of the rival stimuli. Aside from binocular rivalry during presenting the rival stimuli, there is also a third condition that reveals a mixture of two eyes’ images and the observers are unsure of which image of the rival stimuli to report. The profile of this third condition (referred to as “binocular perception”) from rival stimuli are less documented. In this study, we investigated binocular rivalry and binocular perception by presenting a pair of orthogonal gratings in the two eyes in normal-vision observers. The rival stimuli presented for 30s with equal contrast (40%) in each eye and varied in 1°, 2.5°, 5°, 8° and 18° stimulus sizes. In experiment 1, we measured percentage proportion over the 30 s stimulus duration for 3 perceptual conditions: dominant eye viewing (defined by hole-in-card test), non-dominant eye viewing and binocular perception. In experiment 2, we investigated how attention affects these perceptual conditions. Our results showed that the dominant eye had more proportion than the non-dominant eye and the stimulus size matters. Selectively attending to the stimuli of the non-dominant eye increased its proportion with the most increasing at 5° stimuli. The proportion of binocular perception is negatively correlated with the stimulus size but shown no effect on attention. Our results in binocular perception reveal that the visual uncertainty in binocular rivalry decreases with increasing the size of rival stimuli and suggests that the size of rival stimuli should be around 5° or beyond to get ideal binocular rivalry.

Acknowledgements: Support by NIH Grant R01- EY025018 and R01- EY035346 to C. H.