Automatic processing of rare versus novel auditory stimuli reveal different mechanisms of auditory change detection.

Automatic detection of rare stimuli or changes in an auditory stimulation can distract ongoing task processing by attracting attention away from task relevant information. Typically, the effectiveness of auditory change detection is tested by rare and unpredictable deviations (compared with an otherwise regular auditory presentation) or by rare environmental sounds. The present study demonstrates that both types of stimuli are capable of triggering automatic orientation of attention and that rare environmental sounds are more effective than deviations in distraction of attention. This finding suggests different mechanisms underlying the detection of auditory change. Moreover, novelty as constituted by unique environmental sounds did not add to the effectiveness of automatic change detection, involuntary control of attention, and distraction.