Abstract
Attentional capture refers to the increase in reaction time in visual search when an irrelevant, but salient distractor is simultaneously present. Recent ERP studies have challenged the idea that attention was captured by the salient item: A marker of attentional selection, the N2pc, was observed in response to the search target, but not in response to the salient distractor. Alternatively, it may be that the N2pc is not sensitive enough to measure shifts of attention to irrelevant stimuli. We devised a task in which a search display was shown AFTER observers had initiated a reaching movement toward a touch screen. In a display of vertical bars, observers had to touch the oblique target while ignoring a color singleton. Because the hand was moving when the display appeared, reach trajectories revealed the online decision-making of the participants. We observed that salient, but irrelevant stimuli changed the reach trajectory at the same time as the decision to move toward the target was taken, about 205 ms after movement onset. The change in direction was corrected after another 147 ms. In a second experiment, we compared online decisions to color and orientation targets and observed that the decision to move toward the target occurred earlier for color targets. Salient stimuli support faster decisions than less salient stimuli and may therefore capture attention.
Meeting abstract presented at VSS 2012