P300 component of event-related potentials in passive tasks

Auditory P300 components were recorded in two kinds of passive tasks (a sequence task and a novel task) and were compared to that in a standard oddball task. The P300, the amplitude of which was largest at Pt, was elicited in the two passive tasks. The P300 amplitude in the two passive tasks was not significantly smaller than that in the oddball task. No significant correlation was found between either the P300 latency or the P300 amplitude in the oddball task and those in the two passive tasks. These results suggested that the psychological significance of the P300 component in the passive tasks is different from that in the oddball task; however, the P300 in passive tasks is a useful tool in studying information processing in severely mentally ill subjects.