Intertrial priming due to distractor repetition is eliminated in homogeneous contexts

Targets are found more easily in a visual search task when their feature is repeatedly presented, an effect known as intertrial priming. Recent findings suggest that priming of distractors can also improve search performance by facilitated suppression of repeated distractor features. The efficacy of intertrial priming for targets can be potentiated by the expectancy of a specific target feature; systematic repetition shows larger intertrial priming than random repetition. For distractors, the underlying mechanism is less clear. We used the systematic lateralization approach to disentangle target- and distractor-related processing with subcomponents of the N2pc. We found no modulation of the N_T component, which reflects prioritization of target processing. The N_D component, which reflects attentional capture by irrelevant stimuli, however, showed intertrial priming: N_D monotonically decreased with repetition of a distractor color, but only if a specific distractor feature was expected, and if the context induced a search that was vulnerable to attentional capture. These observations suggest that distractor priming only improves visual search if volitional control is relatively high. The results also suggest that intertrial priming for distractors is due to decreased attentional capture by repeatedly presented distractors, whereas target processing remains unaffected.