Event-related potential evidence of sex differences in verbal and nonverbal memory tasks.

ERPs were recorded from 19 scalp electrodes while 48 subjects (24 females) performed visual recognition tasks for recurring verbal items and recurring abstract figures. Reaction times were longer in the figures than verbal task; the latencies of the ERP components (P2, N4, P3, P4) were also longer for the figures. A nonreversing asymmetry (R greater than L) was seen in both tasks. Significant task by electrode interactions (for P3, P4) were found, due to larger amplitudes anteriorly for the figures, but larger amplitudes posteriorly for the verbal task. All ERP latencies were longer for males than females. There were sex by task by electrode interactions in the amplitudes, due to larger ERPs (P2, N4) for females anteriorly for the figures, but slightly larger posteriorly for the verbal task. These results suggest that sex differences in cognitive abilities may be based on differences in biological mechanisms.