EFFECTS OF LONG‐TERM SHOCK AND ASSOCIATED STIMULI ON AGGRESSIVE AND MANUAL RESPONSES¹

Abstract

Squirrel monkeys were exposed to response-independent, fixed-frequency shock that produced biting attack upon a pneumatic hose. Attacks decreased within and across sessions at low intensities and high frequencies of shock, but increased within and across sessions at higher intensities and lower shock frequencies. Stimuli paired with shock, when presented alone, came to produce biting, and stimuli correlated with shock parameters that produced increases in responding within sessions produced similar increases when presented alone. Further experiments showed that continuing exposure to shock also produced lever pressing or chain pulling, with longer shock exposure again producing higher response rates. Whereas biting generally decreased throughout the intershock interval, manual responding generally increased as shock time approached, but immediately before shock was often suppressed. Following shock, biting attack predominated over manual behavior. The results suggest a possible explanation for the extreme resistance of avoidance behavior to extinction, and may also partially explain the persistence of responding during schedules of response-produced shock. Relationships of the present findings to naturalistic observations of relations between fleeing, freezing, and fighting performances are discussed.

Pain-elicited aggression in the squirrel monkey: An implicit avoidance contingency

“…The data in both Experiments I and II suggest that the facilitation of aggressive behavior produced by periodic, unsignaled shock (Hutchinson, Renfrew, & Young, 1971) is a product of the "implicit" avoidance contingency and not the excitatory classical conditioning mechanism initially suggested. In Experiment II, for example, the biting response as a CR and as a UCR increased over sessions, and was conditioned only if the fixed-time intertrial interval was employed.…”

“…The backward pairing of CS and shock rules out the possibility of biting being classically conditioned to the CS (unless one wants to consider the possibility of strong, excitatory, backward conditioning), but leaves the implicit avoidance contingency described by Dunham intact. If as a result of such backward pairings we observe an increase in unconditioned biting, and the CS elicits biting when presented alone, we have some strong evidence for the operation of the avoidance contingency (or backward conditioning), independent of the classical conditioning mechanism discussed by Hutchinson et al (1971). The procedure is considered particularly stringent in the sense that it actually asks the animal to exhibit what can be considered a case of backward excitatory conditioning, a phenomenon not generally observed (cf.…”

“…It is, however, somewhat puzzling in that we used the long intertrial intervals used by Hutchinson et al (1971), who observed some evidence for conditioning. There are, however, at least three factors which might make it difficult to classically condition pain-elicited aggressive behavior in this and other experimental situations.…”

“…Under such conditions, the monkey will reliably attack (bite) a length of rubber tubing located in front of its face (Hutchinson, Azrin, & Hake, 1966). In the course of studying the effects of extended exposure to periodic shock upon the attack behavior of the squirrel monkey, Hutchinson, Renfrew, and Young, (1971) and Hutchinson and Emley (1972) have consistently observed two interesting changes in the biting behavior. First, when the shock is presented at relatively long intershock intervals and higher intensities, there is an increase or facilitation of elicited biting behavior over trials.…”

“…Similarly, one would not expect the contingency to be effective with short intershock intervals if such intervals permitted punishment of the elicited biting behavior early in training. It is not possible to determine from the procedures used by Hutchinson et al (1971) the extent to which the classical conditioning process they have described and/or the "implicit" avoidance contingency outlined earlier were operating to produce the facilitation of pain-elicited biting.…”