JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR THE OPPORTUNITY FOR AGGRESSION AS AN OPERANT REINFORCER DURING AVERSIVE STIMULATION'

Squirrel monkeys were provided with a chain-pulling response which produced an inanimate object that could be attacked. In the absence of pain-shock, little or no chain-pulling occurred. When pain-shocks were delivered, chain-pulling responses increased. The chain-pulling re-sponse was successively reinforced, extinguished, reinforced, and again extinguished by presenting or withdrawing the opportunity to attack as the reinforcing event. Aggression appears to be a distinctive motivational state which is produced by aversive stimulation and which can be used to condition and maintain new behavior. Aggression between animals results from many factors such as territoriality, competition over food, defense against an intruder, and endocrine changes (Scott, 1958). Aggression also results from sudden foot-shock presented to paired rats (Ulrich and Azrin, 1962). Two major problems have existed in the experimental analysis of this fighting phenom-enon in rats: (1) the reliance upon a human observer to record the occurrence of an at-tack; and (2) the somewhat equivocal nature of the attack since physical injury was inflicted only occasionally. Arbitrary decisions were required as to which behaviors were aggressive and which were not. It was later found that obvious physical injury was produced when other species were used, such as paired mon-keys (Azrin, Hutchinson, and Hake, 1963). The equivocal nature of the response was elim-inated but the very viciousness of the attack behavior between monkeys made repeated measurement impossible. The still later find-ing.(Azrin, Hutchinson, and Sallery, 1964) that monkeys would attack inanimate objects, sim-plified the problem of measuring the attack objectively and made it possible to obtain re-'This investigation was supported by grants from th