Concurrent reinforcement and alcohol: interactive effects on human aggressive behavior.

The relationship between alcohol and human aggressive behavior was studied under conditions in which nonaggressive response requirements maintained by point presentation were manipulated. Six normal adult male recreational alcohol users pressed buttons that produced points (redeemable for money) on their own counters or ostensibly subtracted points (money) from another fictitious subject described as participating in the same study at another location. During random components of each session, subjects were required to press a button 50, 200 or 500 times in order to produce point increments on their own counters. Ten responses on a second button were required to subtract a point from the other subject during all components. Aggressive responding was engendered by occasional point subtractions which were attributed to the fictitious subject. Alcohol (0, 0.125, 0.25 and 0.5 g/kg of 95% ethanol) produced dose-related increases in aggressive responding. Aggressive responding was also significantly related to the concurrent schedule of point presentation. Finally, a significant interaction between alcohol and concurrent point presentation contingencies was observed. These results indicate that aggressive responding is affected by ongoing reinforcement contingencies not directly related to aggressive behavior and that reinforcement schedule interaction may be one factor mediating the situation-dependent nature of alcohol's effects on aggressive behavior.