Abstract
The presence of a salient but task-irrelevant item (singleton distractor) causes attentional capture, increasing the time required to detect a target during visual search. However, the literature shows that observers can overcome attentional capture via top-down controls based on attentional set. Specifically, when observers are required to search for a shape among nontarget shapes, the color singleton distractor has negligible impact and may even be advantageous for target detection. The present study examined a factor that causes this difference in search performance. Here, we hypothesized that whether a singleton distractor can be ignored or can even facilitate the search depends on the strength of top-down control. We predicted that stronger top-down control would yield active suppression of a singleton distractor as indexed by faster reaction times in the presence of the distractor. To manipulate the strength of top-down control, we introduced two types of search tasks, i.e., simultaneous and preview search tasks. The former consisted of a single display where all the stimuli were presented simultaneously, and the latter consisted of a preview display containing a subset of distractors followed by an additional display containing the remaining distractors and a target. The singleton distractor, if any, appeared in the additional display. We reasoned that observers would form a stronger attentional set during the preview display. The results revealed that reaction times were unaffected by the presence of a singleton distractor in the simultaneous search task. Importantly, the reaction times for the singleton distractor condition were faster than those for the no-singleton condition in the preview search task. These findings suggest that a singleton is actively suppressed by stronger top-down control due to the maintenance of preview search templates, resulting in more efficient search performance. An ordinary simultaneous search may not induce such active suppression
Meeting abstract presented at VSS 2018