Abstract
We report a set of results showing that increasing the number of distracting elements in a visual search task improves oculomotor search performance. A search target was presented together with distractors and subjects were required to move their eyes to the target. When the target was presented with a single distractor in a neighbouring location, the first saccade was often inaccurate. However increasing the number of distracting elements from 1 to 15 considerably improved the ability to locate the target with the first saccade. We considered two hypotheses to account for this paradoxical finding. Perceptual grouping processes might operate amongst the distractors. However, when we modulated the heterogeneity of distractors in the 15 distractor displays on four dimensions separately, performance did not deteriorate. The second hypothesis arose from the observation that the first saccades in large displays generally showed longer latency. When we introduced distractors contralateral to the target, this induced a “remote distractor effect” whereby saccade latency increased. Search performance was superior in this condition to that when all distractors were ipsilateral. We suggest that oculomotor search performance is improved with greater distractor number because contralateral onsets increase initial saccade latency and in consequence allow improved perceptual selection.