Pigeons were conditioned to peck a response key under a procedure that alternated periods of food reinforcement with periods of extinction. The pigeons attacked a nearby pigeon at the onset of extinction. Some also attacked a stuffed model of a pigeon. The duration of attack was an inverse function of the time since the last food reinforcement and a direct function of the number of reinforcements. The pigeons attacked after the last food delivery whether or not the conditioned pecking response was required and whether or not the extinction period was signaled. The food had to be eaten; the mere sight and sound of food being delivered did not produce attack. Prior satiation reduced attack. The phenomenon was not attributable to a past history of competition between pigeons since socially deprived pigeons also attacked. Superstitious reinforcement of attack was not found to be a factor. The results indicated that the transition from food reinforcement to extinction was an aversive event that produced aggression.When shock is delivered to the feet of an animal, attack results (Ulrich and Azrin, 1962 (Skinner, 1938), attacking of the response lever (Mowrer and Jones, 1943), increased vocalization between children (Azrin and Lindsley, 1956), and increased running speed after omission of a food reinforcement

Squirrel monkeys pressed a lever to produce food on several fixed-ratio schedules; they could also bite a rubber hose. Biting attack occurred during the postreinforcement pause and in early portions of the ratio response run. Also, biting attacks increased after transitions to higher values of the fixed-ratio requirement and in extinction. The results show that extinction-induced aggression effects occur in primates.Aggressive behavior is elicited by several different types of noxious stimulation (negative reinforcers). Ulrich and Azrin (1962) demonstrated that electric shock, as well as intense heat, would elicit attack by a rat against another rat. Azrin, Hake, and Hutchinson (1965) demonstrated that a physical blow could also elicit attack in monkeys.More recently, Azrin, Hutchinson, and Hake (1966) have shown that removing food from a food-deprived pigeon will produce attack against another pigeon. Subjects attacked when a transition was made from a high frequency of reinforcement to extinction.The present experiments sought to determine the effects of intermittent reinforcement of an independent operant response upon attack behavior. An additional objective was to discover whether extinction-induced aggression effects occurred in primates.Squirrel monkeys were trained to press a lever for food pellets delivered on various fixed-ratio schedules. Biting attack on a rubber hose could be recorded simultaneously during each of the different schedules. Occasionally, subjects were exposed to extinction.

No 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.

Punishment and escape were studied simultaneously by allowing a subject to escape from a stimulus situation in which responses were punished, into a stimulus situation in which responses were not punished. The frequency of the punished responses was found to be an inverse function of the intensity of punishment, whereas the frequency of the escape response was a direct function of the intensity of punishment. Both of these functions were obtained under three different schedules of food reinforcement. The strength of the escape behavior was evidenced by (1) the emergence of the escape response even when the frequency of foodl reinforcement decreased as a consequence of the escape response, (2) the maintenance of the escape response by fixed-interval and fixed-ratio schedules of escape reinforcement, and (3) the occurrence of escape responses at intensities of punishment that otherwise produced only mild suppression of the punished response when no escape was possible. This last finding indicates that a subject may be driven out of a situation involving punishment even though the punishment is relatively ineffective in suppressing the punished responses when no escape is possible.Aversive stimuli have been defined in several ways. One defining characteristic (Dinsmoor, 1954;Keller and Schoenfeld, 1950;Skinner, 1953;Holland and Skinner, 1961) is whether escape or avoidance conditioning results from the termination or postponement of the stimulus. A second defining characteristic is whether suppression results when responses produce the stimulus (Keller and Schoenfeld, 1950; Azrin and Holz, in press). This latter procedure is designated as punishment. The present experiment attempts to study both defining characteristics simultaneously. The same theoretical objective was pursued by Hefferline (1950) and Harrison and Abelson (1959) utilizing two components (bar-press and bar-release) of the same general response. The present study used two different responses to achieve greater independence: one response produced the aversive stimulus, a second avoided it. In order to establish motivation for producing the aversive stimulus, Ss were first conditioned to respond for food; then, the aversive stimulus was delivered for each ' The punishing stimulus was a brief 100 msec pulse of 60 cps ac (lelivere(I through a 1OK ohm series resistance to gold wires implanted beneath the skin and anchored around the pubis bone on each side of the bird (Azrin, 1959a). When the punishment procedure was used, the shock was delivered immediately after each response. Results Figure 1 shows the typical change in escape responses for one S as a function of the punishment intensity. It can be seen that less than three escape responses were emitted daily by this S when the punishment intensity was less than 40 v. At a critical intensity (40 v for this S, but 20 to 50 v for the other five), the escape responses increased to 60 per session (one escape response per reinforcement) and remained at that level as the intensity was increased further to 7...