P300 response: habituation.

This study used the "oddball" counting paradigm to examine the possible habituation of the auditory P300 response. Twenty subjects kept a mental record of the number of rarely occurring tone pips presented in a series of more frequently occurring tone pips. Data were collected continuously until responses to 150 rare tone pips were obtained. Findings indicated that the P300 complex decreased in amplitude as a result of repeated stimulation. The decline was logarithmic, not linear, which suggests a stabilization of the amplitude over time. We suggest that the attenuation of amplitude was habituation and not a result of a recovery cycle.