Abstract
When some distractors (old items) appear before others (new items) in an inefficient visual search task, observers exclude the old items from the search (preview benefit), possibly because their locations are deprioritized relative to the locations of new items. Previous studies have shown that transient motion at the old items location disrupts preview benefit. What type of change degrades the preview benefit? We examined whether participants were able to ignore a task-irrelevant change in the scene, namely the motion initiation/cessation of dynamic noise in the background, while they were doing a preview search task in which the old items were presented for 1 s before the new items were added. All these items were superimposed on static or dynamic random luminance noise. The target to be searched for could be present only within the new items. Participants were requested to make speeded reaction to the target among distractors in several set sizes. Preview benefit was assessed by testing whether the search function under the preview condition explained above was significantly shallower than that under the baseline condition, under which all items appeared simultaneously. The results indicated that when the motion initiation of the dynamic noise was synchronized with the onset of the new items, this task-irrelevant event in the background degraded the preview benefit on search efficiency. In contrast, when the noise continually moved throughout each trial or when the motion cessation of the noise was synchronized with the onset of the new items, the preview benefit remained. Therefore, synchronizing the onset of the motion display with the onset of the new items was critical for the degradation of the preview benefit, suggesting that the onset of task-irrelevant background motion disrupts either inhibitory marking of the old items or attentional allocation to the new items.
Meeting abstract presented at VSS 2014