P300 FROM ONE-STIMULUS, 2-STIMULUS, AND 3-STIMULUS AUDITORY PARADIGMS

P300 event-related potentials (ERPs) from 1-, 2-, and 3-tone oddball p aradigms were elicited and compared from the same subjects. In the 1-t one paradigm, only a target tone was presented, with the standard tone replaced by silence. The 2-tone paradigm was a typical oddball task, wherein the target and standard tones were presented every 2.0 s in a random order with a target-tone probability of 0.10. In the 3-tone par adigm, in addition to the infrequent target (p = 0.10) and the frequen t standard (p = 0.80), infrequent nontarget tones (p = 0.10) also were presented. The subject responded with a button press only to the targ et stimulus in each task. The target stimulus in each paradigm elicite d a P300 component with a parietal maximum distribution. No P300 ampli tude differences were found among paradigms, although peak latency fro m the 1-tone paradigm was shorter than those from the other two tasks. Both P300 peak amplitude and latency demonstrated strong positive cor relations between each pair of paradigms. The results suggest that P30 0 was produced by the same neural and cognitive mechanisms across task s. The possible utility of each paradigm in clinical testing is discus sed.