P300 differences between non-alcoholic young men at average and above-average risk for alcoholism: effects of distraction and task modality.

1. P300 event-related electroencephalographic potentials were recorded from 79 young adult males, cross-classified with respect to the presence/absence of a family history of alcoholism (FHA) and the presence/absence of a personal history of antisocial personality (ASP) disorder. P300s were elicited using visual and auditory oddball tasks. Each oddball task was repeated with a tracking task added as a distractor. 2. In general, distraction increased the latencies and reduced the amplitudes of P300s elicited by the oddball stimuli. The P300 latency increase occurred only in low risk ASP- and FHA- groups. There was no adaptive increase in P300 latency in the higher risk ASP+ and FHA+ groups. 3. Group differences in P300 were restricted to visual tasks. No interpretable group differences in P300 latency or amplitude were found during the auditory tasks.