Habituation of P3a and P3b from Visual Stimuli

The P300 event-related potential (ERP) was elicited using a visual three-stimulus oddball paradigm (target, standard, distractor) in which participants (n=16) made a button-press response to an infrequent target that was difficult to discriminate from a frequent standard, with the infrequent distractor stimulus presented throughout the series. Each trial block consisted of 200 trials, with a total of four trial blocks presented successively and initiated every 15 min. P300 amplitudes from the distractor (P3a) and target (P3b) stimuli were assessed across trial blocks, with the P3a demonstrating more rapid habituation than P3b over trial blocks. No habituation or stimulus type effects were obtained for the other ERP components. The results suggest that habituation of both components occur primarily in fronto-central areas and might originate from a common neural generator. The theoretical and practical implications are discussed in the context of previous findings.