Habituation of auditory event-related potentials: a comparison of self-initiated and automated stimulus trains.

Habituation of auditory event-related potentials, recorded from the vertex, was investigated with two methods of initiating trains of stimuli (self-initiated and automated) and two interstimulus intervals (ISIs) within trains. In all conditions, habituation was asymptotic by the second stimulus in a train of 15 stimuli. The first EP in a train was unaffected by ISI, but the procedure for starting the train directly affected the amplitude and latency of N1, the latency of P2 and the occurrence of P3: all measures were greater in the automated condition than in the self-initiated. For the second through the fifteenth EPs, the procedure for starting the train had no effect, but the amplitude of P2 was directly affected by ISI.