Performance of alcoholic Korsakoff patients was compared with that of patients with Huntington's disease. Broca's aphasia or alcoholism (without clinical signs of memory impairment) on delayed alternation (DA) and delayed response (DR) tests. Korsakoffs were impaired on both tasks, and Huntington patients were impaired on DA only. In a separate experiment, performance by Korsakoffs was compared to that of alcoholic and normal controls on four DRL schedules. Korsakoffs tended to be overresponsive, making errors of commission early within a schedule, and consequently, obtaining fewer reinforcements than the controls.