Normative variation of P3a and P3b from a large sample - Gender, topography, and response time

The P3a and P3b components were elicited in 120 (60 females, 60 males) young adults using a visual three-stimulus event-related brain potential (ERP) oddball paradigm in which subjects responded to an infrequent target. The major purpose of the paper was to provide a statistically strong characterization of these related P300 subcomponents. P3a components were obtained from the infrequently presented distracter stimulus, which was a large blue square. P3b components were obtained from the target stimulus, which was a blue circle that differed slightly in diameter from the standard stimulus blue circle. Amplitude measures demonstrated that P3a was maximum at Cz, and P3b was maximum at Pz; latency measures increased for both potentials from frontal to parietal recording sites. P3a and P3b from females were larger and later than those from male subjects, with topographic and appreciable individual difference variability observed. P3a was generally unrelated to response time. P3b amplitude was negatively correlated over right frontal areas with P3b latency and positively correlated over right parietal areas to response time. Theoretical implications are discussed.