A comparison of bilateral versus unilateral target and distractor presentation in the remote distractor paradigm.

The remote distractor effect (RDE) is a robust finding of an increase in saccade onset latencies (20-40 ms) when a distractor is presented simultaneously with a target, compared to when a target is presented on its own (Walker, Deubel, Schneider, & Findlay, 1997). Distractors presented at fixation produce the largest RDE and the effect decreases as distractors are moved into the periphery. Data from two experiments that contrast with these standard findings are reported. Under bilateral target presentation, larger RDE magnitudes occurred for peripheral than for central distractors, whereas under unilateral presentation, the pattern reversed. The findings are discussed with reference to discrimination processes, attentional factors and current models of oculomotor control. It is suggested that in bilateral target presentation the competition between the distractor and the target results in the programming of a saccade to the distractor, as well as a saccade to the target. Time taken to cancel the saccade to the distractor produces the increased saccade latency for peripheral distractors in that condition.