Early processing stages are modulated when auditory stimuli are presented at an attended moment in time: an event-related potential study.

The present study investigated with event-related potentials whether attending to a moment in time modulates the processing of auditory stimuli at a similar early, perceptual level as attending to a location in space. The participants listened to short (600 ms) and long (1,200 ms) intervals marked by white noise bursts. The task was to attend in alternating runs either to the short or to the long intervals and to respond to rare offset markers that differed in intensity from the frequent standard offset markers. Prior to the to-be-attended moment, a slow negative potential developed over the frontal scalp. Stimuli presented at the attended compared to the unattended moments in time elicited an enhanced N1 and an enhanced posteriorly distributed positivity (300-370 ms). The results show that attention can be flexibly controlled in time and that not only late but also early perceptual processing stages are modulated by attending to a moment in time.