Interactions among variables in the P300 response to a continuous performance task.

This study investigated the effect of variable interstimulus intervals (ISIs) on behavioral reaction time (RT) and on the latency and amplitude of the auditory P300 using an auditory continuous performance task (ACPT) paradigm. Twenty subjects were instructed to respond to common stimuli and ignore a rare stimulus. Common stimuli were 1000-, 1500-, and 2000-Hz pure tones. The rare stimulus was a 250-Hz pure tone. ISIs of 1, 2, and 4 seconds were used for this investigation. A significant correlation between ISI, reaction time, P300 latency, correct rejections, and false alarm rates was found. A significant correlation between P300 latency, P300 amplitude, correct rejections, and false alarm rates was also observed. Likewise, a statistically significant increase in reaction time (RT) was observed as ISI increased. The ACPT paradigm in conjunction with the auditory P300 response can measure both behavioral and electrophysiologic changes that occur during active auditory attention and auditory cognitive processing tasks.