Human event-related potentials and distraction during selective listening.

Event-related brain potentials were recorded from healthy human subjects while they attended to one of two auditory stimulus channels (defined by location, left and right of a fixation point, and pitch) in order to detect rare target events. The distracting properties of periodic noise (vs. continuous noise, experiment 1) and backward speech (vs. forward speech, experiment 2) presented from a third speaker located behind the subjects were investigated. A typical attention effect with a larger negativity for attended tones was observed in both experiments. Backward speech led to a significantly reduced target detection rate for the first four stimuli after onset of the distractor accompanied by a reduced event-related brain potential (ERP)-attention effect and a reduced fronto-central N2b component for the target stimuli. This indicates that irrelevant information leads to an attention decrement of about 1 s duration.