Effects of eye dominance in visual perception

While it is clear that one eye is visually dominant, the function of dominance, if any, is not fully understood. We looked for effects of eye dominance on visual feature search, the easy task of detecting an element that differs significantly in a single dimension from surrounding distractors. Thirteen subjects were tested, each with similar visual acuities in their two eyes. Dominant eye was determined using the Hole-in-the-Card test. Using red-green glasses, subjects viewed a briefly presented 8 × 8 array of green and red lines oriented at 60°. Stimulus duration was varied, and stimuli were followed immediately by a masking stimulus. On half of the trials, one element was replaced by a red or green line oriented at 40°. We tested for differences in performance when subjects viewed the target with the dominant vs. the non-dominant eye. We found significantly better performance when the target was seen by the dominant eye. Surprisingly, this effect was seen for longer stimulus durations, leading to a higher long-duration asymptote. We conclude that the dominant eye has visual processing priority in binocular perceptual tasks, perhaps due to its greater effect in inhibitory interactions between the eyes.