The location and distribution of extinction-induced aggressive behavior in humans : evidence for a stage model of extinction

Typescript (photocopy).Two experiments were designed to investigate the effects of extinction on aggressive responding in humans. In Experiment 1 subjects (male college students) received either continuous (CRF) or partial (PRF) reinforcement (tokens) on a human shuttle task. Concurrently subjects could escape a moderately aversive tone. Escape involved making either a non-aggressive button pressing response or an aggressive striking response of at least 25 lbs. During CRF and PRF training button pressing was the preferred mode of escape. Although the two groups did not differ in terms of the frequency of striking responses, group PRF was found to exhibit a greater intensity of striking responses. When reinforcement for shuttle responding was discontinued CRF and PRF subjects exhibited an increase in the frequency and intensity of striking responses. The onset of aggressive responding was found to occur earlier in extinction following CRF training than PRF training but the distribution of aggressive responding for both groups resembled an inverted U-shaped function. With regard to shuttle responding, the onset of extinction produced an abrupt increase in the frequency of responding. Group CRF exhibited a greater in initial increase in response frequency. PRF subjects, however, were more persistent in responding on the shuttle task than group CRF throughout the remainder of extinction as evidenced by shorter response latencies, higher frequency of responding, and fewer failures. The onset of shuttle avoidance was also found to occur earlier following CRF training than following PRF training. Experiment 2 was designed to test the validity of the striking response as an aggressive behavior in humans. The procedure of Experiment 2 was identical to the first experiment except that escape involved a choice between two non-aggressive instrumental responses requiring minimal effort (pressing a button or turning a knob). All subjects exhibited a preference for one or the other escape responses during acquisition. Discontinuation of reinforcement produced a gradual increase in the less-preferred escape response and a gradual decrease in the preferred mode of escape in group CRF but not group PRF..