Behavioral and electrophysiological effects of distractor variation on auditory selective attention

Two experiments investigated the effects on auditory selection of varying distractor values in memory. Participants performed a set of control (single distractor) and distractor-variation (multiple distractors) tasks, classifying targets by pitch (Experiments 1A and 2) or loudness (Experiment 1B) while ignoring previously presented (and spatially separate) distractors. When both targets and distractors varied in pitch, the degree of variation among the distractors increasingly disrupted classification accuracy and reaction time to the targets. Physiologically, the degree of distractor variation boosted the N1 response to distractors, the P2 response to both targets and distractors, and the slow-wave response to targets (400-600 ms after stimulus onset). The results suggest that target representations are diminished in distinctiveness as distractors activate a wider range of the task-relevant continuum in working memory.