Event‐Related Potentials (ERP_s) to Interruptions of a Steady Rhythm

Abstract

ABSTRACT Auditory event‐related potentials (ERP s ) were recorded from the scalps of persons who received repetitive sequences of sounds through earphones. Occasionally and unpredictahly. some ofthe sounds in the sequence occurred at a shorter or longer interstimulus internal (ISI) than usual. In Experiment 1, it was shown that premature noise bursts (ISI = 300 msec) elicited a large, biphasic ERP consisting of an “N e ” component at about 130 msec and a “P E ” wave at about 200 msec. The N E ‐P E complex was several times larger than the N1‐P2 waves elicited either by the regular bursts (ISI ‐ 600 msec) or by delayed noise bursts (ISI = 600 msec) in a sequence where the regular ISI was 300 msec. In Experiment 2, the peak amplitude of the N E wave elicited by infrequent early tones was considerably increased when attention was directed toward the tones. In Experiment 3, the amplitude ofthe N E ‐P E , complex to infrequent early tones in a regular sequence (ISI s of 1200 msec) was either unchanged or actually increased when ISI s were shortened from 600 to 300 msec. It was proposed that the N E ‐P E complex belongs to a class of ERP s that are specifically elicited by a mismatch event in a repetitive stimulus sequence.