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Abstract

Our visual systems integrate information from the two eyes to form a stable and continuous percept of the world around us. However, not all of this information is binocular. Because objects are often partially occluded by other objects, there are a host of monocular regions as well as the binocular regions surrounding them. Here we ask whether this monocularity affects our visual search performance, when we are searching for a monocular or a binocular target. In a reaction time experiment, participants were asked to find a target 'C' amongst 224 distractor O's as quickly as possible. The target C was presented in one of 2 conditions: 1) monocular b) binocular. For each condition the number of monocular distractors was varied between zero and 32. All other distractors were presented binocularly. For the monocular condition, we found very fast reaction times with 0 and 1 monocular distractors. Reaction times increased logarithmically as the number of monocular distractors increased. For the binocular condition, reaction times were initially slower than for the monocular condition, but did not increase significantly with number of monocular distractors. The spread of participants' reaction times mirrored this pattern with an increase in the variance of reaction times in the monocular target condition and a stable variance in the binocular target condition. Monocular distractors appear to disrupt our visual search when searching for a monocular target, but not when searching for a binocular target. It appears we able to ignore monocular information if it is task-irrelevant.