AMPHETAMINE SELF-ADMINISTRATION BY HUMANS - MODULATION BY CONTINGENCIES ASSOCIATED WITH TASK-PERFORMANCE

The effect of task performance feedback and associated monetary earnin gs on drug self-administration were evaluated using eight subjects in a residential laboratory setting. The hypothesis was that if subjects believed that d-amphetamine impaired performance and reduced monetary earnings, d-amphetamine self-administration would decrease. Subjects p erformed computer tasks every day: on certain days that they received capsules, subjects were given bogus feedback regarding their performan ce (''better'' or ''worse'' than average). On sample days, subjects we re required to take d-amphetamine (10 mg BID) or placebo (0 mg BID) ca psules. On choice days, subjects could choose between either d-ampheta mine or placebo. Subjects received feedback on their task performance on 2 sample days and 2 of 4 choice days. Subjects received no feedback on the remaining two choice days. When subjects received no feedback, they chose d-amphetamine over placebo 78% of the time, and when they were given better feedback messages, they chose d-amphetamine 87.5% of the time. In contrast, d-amphetamine self-administration decreased si gnificantly to 25% when subjects were told that it impaired their perf ormance on work tasks and resulted in reduced earnings. In reality, d- amphetamine had little effect on work task performance. However, compa red to placebo, d-amphetamine significantly increased subjective ratin gs of ''Stimulated'' and ''Good Drug Effect'' and significantly decrea sed ratings of ''Tired'' and ''Sleepy.'' These results demonstrate tha t d-amphetamine served as a reinforcer under conditions in which drug self-administration did not influence monetary earnings, but that d-am phetamine self-administration could be modified by feedback/monetary e arnings. Thus, contingencies associated with performance have importan t implications for drug use in the workplace.