Exclusion criteria for the present study were: any neurological, acute, uncorrected or chronic medical illness; any Axis I psychiatric or developmental disorders; any current or recent (within six months) treatment with centrally active medications; a history of psychosis or schizophrenia in first-degree relatives; and a positive urine drug screen on the day of the study. Three of the participants had a diagnosis of alcohol abuse; this was not exclusionary given our interest in predicting range of variation in risk for alcohol use disorder. Written informed consent, approved by the University of Michigan Medical School Institutional Review Board, was obtained prior to the study.
