Disentangling effects of auditory distraction and of stimulus-response sequence

When we pay attention to one task, irrelevant changes may interfere. The effect of changes on behavioral and electrophysiological responses has been studied in two separate research fields: Research on Distraction states that a rare irrelevant change takes attention away from the primary task. Research on Sequences states that any change in stimulus or response incurs a cost or benefit depending on the kind of change. To disentangle distraction from sequence effects, we made task-irrelevant changes rare in one condition and frequent in another while also assessing stimulus and response changes from trial to trial. Participants used key presses to classify syllables presented in two different, irrelevant voice pitches. We found that distraction and sequence interacted to alter reaction times and errors on the primary task and also to alter ERP markers of distraction (P3a). The sequential effects cannot, however, fully account for distraction.