Brain correlates of early auditory processing are attenuated by expectations for time and pitch

The present study investigated how auditory processing is modulated by expectations for time and pitch by analyzing reaction times and event-related potentials (ERPs). In two experiments, tone sequences were presented to the participants, who had to discriminate whether the last tone of the sequence contained a short gap or was continuous (Experiment 1: go/nogo, Experiment 2: choice reaction). Expectations were induced by varying the temporal and pitch regularity of the sequence. Results were consistent across both experiments. Expectations for both time and pitch were associated with faster responding. Both temporal and pitch expectations led to an attenuation of the auditory N1, thus indicating a modulation of early, perceptual processing by temporal and pitch expectations. Effects of temporal expectations were also evident in a P300-like deflection, suggesting that temporal expectations also affect decision- or response-related processing stages.