Distractors processing modulate the onset of inhibition of return in discrimination tasks

Inhibition of return (IOR) refers to a slowed response to a target appearing at a previously attended location. Previous research has shown distractors processing modulated the onset of IOR. We investigated whether the effect of distractors in IOR in discrimination tasks was changed by the location and number. The results showed that the trend of the general IOR effect was approximately the opposite in the two experiments. IOR magnitude was significant when only one distractor was present at opposite location or central location in discrimination task (experiment 1), but IOR was significant at longer SOA (1000ms) when three distractors were present in discrimination task (experiment 2). In experiment 1, the results indicated earlier onset time of IOR when one distractor was presented, indicating that a distractor to the location opposite the target or at the central fixation location hastens the spatiotemporal correspondence integration between the cue and target. In experiment 2, the results indicated a delay onset time of IOR when three distractors were presented, multi-distractors counteracted the spatiotemporal correspondence integration between the cue and target. Different manner of cue target integration was adopted by participants when location and number of distractors were taken into account.