Porjesz and colleagues (1980) used a visual task involving geometric shapes to study P3 in alcoholics abstinent an average of 2 months. The shapes included squares, triangles, and rarely occurring irregular forms interspersed in random order. Subjects were instructed to press a button in response to the rarely occurring target stimulus; in consecutive test sequences, squares alternated with triangles as rare targets. P3’s were recorded in response to the triangle, both when it was the target and when it was a nontarget.
