Ethanol decreases responding on behavior maintained under concurrent schedules of both positive reinforcer...

Six human volunteers were tested during 15min sessions under the behavioral contingencies of a concurrent fixed-ratio, fixed-ratio schedule of point-gain reinforcement and point-loss avoidance. Completion of each fixed-ratio 50 (FR 50) on the point-gain lever produced 10 points, which were exchanged for money ($.01 per point) after each week of the study. Point losses of 10 points were scheduled to occur during the session on a variable-time 60sec schedule. The total amount of money accumulated was continuously displayed on video monitor. Subjects were exposed to the concurrent schedule until responding under the schedules of point gain and point loss stabilized. After responding had stabilized under these contingencies (4-5 sessions), subjects were tested each day 30min following administration of ethanol, in doses of 0.32, 0.64 or 0.96g/kg, or placebo. Ethanol decreased responding in all subjects and produced dose-related decreases in overall response rates in three subjects. These effects were not related to self-reported current alcohol consumption. Response rates on the reinforcement and the avoidance schedules were both decreased by ethanol. Thus, under these conditions, behavioral effects of ethanol on concurrent FR responding did not depend on the nature of the consequent event.