Auditory distraction by duration and location deviants: a behavioral and event-related potential study.

Auditory distractibility was investigated using four noise stimuli that differed in their duration and/or sound source. In the duration-task/location-deviant condition, participants were asked to discriminate between equiprobable short and long stimuli. Mostly, stimuli were presented from one location (Standards), but, infrequently, a stimulus was presented from another location (Deviant). In the location-task/duration-deviant condition, participants had to discriminate between stimuli presented equiprobably from the speaker in front of them or to their left. Here, most stimuli were of equal duration (Standards), but, infrequently, a stimulus duration changed (Deviant). The rare deviations in location and duration were irrelevant for the actual task. Whether they affected processes related to the actual task was assessed with performance- and event-related potential (ERP) measures. In both conditions, responses to Deviants were slowed compared to responses to Standards. Deviants elicited ERP components mismatch negativity (MMN), P3a and reorienting negativity (RON). These results show that the processing of both a sound's duration and a sound's location can be distracted by rare, but irrelevant, changes in its location and duration, respectively. Behavioral distraction effects were markedly smaller with duration Deviants. It is suggested that duration Deviants interfere with task-related processing at later stages than location Deviants, as the processing of task-relevant information (i.e. stimulus location) commences before deviation in the location-task/duration-deviant condition occurs. Interestingly, distraction effects also prevail in the first Standard stimulus after a Deviant, as indicated by the prolonged response times and late negativity in the ERPs.