Introversion, attention and the late positive component of event-related potentials.

Variation in P3 amplitude across normal individuals under the same experimental conditions has been routinely observed. The possibility that such variation reflects individual differences in the allocation of attention was examined by comparing P3 amplitude in introverts and extraverts, who are thought to differ in the allocation of attention during monotonous tasks. Event-related potentials were recorded while the subjects participated in a lengthy stimulus prediction task. P3 amplitude was determined by principal components analysis and it was found to be significantly larger for the introverts than for the extraverts. This finding is interpreted as evidence that P3 amplitude is sensitive to individual differences in the allocation of attention.