Attentional capture during visual search is attenuated by target predictability: evidence from the N2pc, Pd, and topographic segmentation.

Attentional capture by salient distractors has been confirmed by the occurrence of an N2pc to the salient distractor. To clarify some failures to replicate this finding, we varied target predictability to induce different search modes. In the unpredictable target condition, the target shape varied randomly from trial to trial, favoring singleton detection mode. In the predictable target condition, the target shape remained the same in a block of trials, favoring feature search mode. With unpredictable targets, we observed an N2pc toward the salient color distractor, confirming attentional capture in singleton search mode. With predictable targets, there was no N2pc to the salient distractor, but a distractor positivity (Pd), suggesting distractor suppression. Also, differences emerged in the topographic segmentation of N2pc and Pd. Further, the amplitude of the N2pc toward the target was larger with predictable than with unpredictable targets.