Saliency affects attentional capture and suppression of abrupt-onset and color singleton distractors: Evidence from event-related potential studies.

Attention is the process of selecting relevant information and suppressing irrelevant information. However, it is still controversial whether attentional capture by salient but task-irrelevant stimuli operates in a bottom-up fashion (stimulus-driven theory) or a top-down fashion (goal-driven theory) or if even salient distractors can be suppressed before capturing attention (signal suppression theory). In the present study, we investigated how saliency affects attentional capture (indexed by N2-posterior-contralateral [N2pc]) and suppression (indexed by distractor positivity [P ]) of abrupt-onset and color singleton distractors in a visual search task. Experiment 1 showed that an abrupt-onset distractor elicited both N2pc and P , while a color singleton distractor elicited only P . Moreover, the abrupt-onset distractor elicited a larger N2pc and a larger P relative to the color singleton distractor. In addition, both distractors elicited an early positive component, the positivity posterior contralateral (Ppc), which was also larger for abrupt onsets than for color singletons. Experiment 2 further demonstrated that when both the abrupt onset and color singleton were designed as targets, and thus required no attentional suppression, Ppc was elicited, but P was not. This corroborated the finding in Experiment 1 that the later P , not the early Ppc, reflected attentional suppression. Therefore, a more salient distractor demonstrates stronger early perceptual processing, can capture attention better and needs more attentional resources to be suppressed later. Based on these results, a three-stage hypothesis is proposed, in which the saliency of a distractor modulates processing at early perception, attentional capture, and suppression stages.