Probing the time-course of the auditory oddball P3 with secondary reaction time

An elementary neural model of the P3 is proposed in which the P3 is held to manifest a brief, widely-distributed, inhibitory event. A preliminary and indirect test of the model is described using secondary-task methodology. Manual reaction times were measured to probe clicks delivered during the presumed time-course of an auditory oddball P3. We observed that reaction times to probes presented after oddball stimuli were significantly slowed as compared to reaction times to probes presented after standards. The latency of maximum reaction time slowing corresponded generally to the latency of the P3. The latency of maximum reaction time slowing did not respond to a manipulation varying the latency of the P3. Thus, some of the obtained results were consistent with the P3-inhibition hypothesis, whereas others were not. Secondary-task methodology may provide a valuable new approach to understanding the late event-related potentials.