Distractor P3 is associated with attentional capture by stimulus deviance

Objective: A simple distractor elicits a large P3 when the standard and target are difficult to discriminate in the three-stimulus oddball paradigm. This study investigated whether the distractor P3 reflects attentional capture by stimulus deviance or cognitive interference with maintaining the standard representation. Methods: Event-related brain potentials were recorded from 12 participants who performed a visual three-stimulus oddball paradigm. Four task conditions were defined by a combination of two presentation types of distractor stimuli (central or bilateral) and two levels of standard/target discrimination difficulty (easy or difficult). Bilateral distractors had stimulus deviance but did not interfere with maintenance of the standard representation. Results: Central distractors elicited a P3, the amplitude of which was larger in the difficult task than in the easy task. In contrast, bilateral distractors elicited a large P3 in both the easy and difficult tasks. Conclusions: Distractor P3 reflects attentional capture by stimulus deviance, rather than cognitive interference with maintaining the standard representation. Significance: This is the first report showing that simple distractors can elicit large anteriorly distributed P3 in an easy task. The present findings contribute to the clinical application of distractor P3 to assess the cognitive function of deviant processing. (c) 2008 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.