Effects of Alcohol and Methylphenidate on Complex Judgments

Abstract

Methylphenidate HCl (12 mg/70 kg and 20 mg/70 kg), ethyl alcohol (60 g/70 kg), and a placebo (lactose) were given to 50 college student volunteers. Each S received each treatment once during 4 separate sessions, and treatment order was counterbalanced. Ss were experienced bridge players, who were given sets of bidding problems, which varied in storage load, ambiguity level, and answer format (open-ended vs multiple choice). Performances were scored according to (1) frequency of active bids vs passes, and (2) a figure-of-merit assigned to each possible response, as developed from expert consensus. Ss wrote impromptu editorials on assigned topics from which word-count measures of verbal production were derived, and also made periodic self-ratings on mood adjective check lists. No significant drug effects were found on bidding accuracy, although methylphenidate increased the frequency of non-passes. Alcohol produced significant efforts on eight mood clusters while methylphenidate produced little or no measurable effect. Verbal production, however, was reliably increased by methylphenidate but not significantly affected by alcohol.