Punishment of shock-induced aggression

Squirrel monkeys were restrained in a chair equipped with a tail-shock apparatus and a pneumatic bite hose located in front of the subject's face. An aggressive response was recorded when the monkey bit the hose. Initial sessions in which no shocks were delivered produced some biting. When biting during these sessions stabilized at a near-zero level, regularly scheduled shocks were delivered to the monkey's tail, causing a consistently higher rate of biting. After several sessions under these conditions, a punishment phase was introduced in which the previous shock conditions were maintained, and every bite was followed immediately by another, more intense shock. Biting under these conditions was suppressed to a near-zero level. When the punishment contingency was removed, biting increased. With one subject, two additional bite-contingent stimuli were examined: (1) a milder shock that, when made contingent upon hose biting, also suppressed that response, and (2) a contingent tone that had no obvious suppressing or facilitating effect. Individual differences among subjects were extreme, but the effect of bite-contingent shock was consistent. Observations of the subjects during the punishment sessions indicated the existence of certain side effects that resulted from the use of punishment to suppress shock-induced aggression.     

Reduction of intraspecies aggression in rats by positive reinforcement of incompatible behaviors

Fighting responses were elicited by response-independent shocks delivered to pairs of rats. Food pellets were presented following different non-fighting responses to shock: some pairs of rats received pellets dependent upon a specific non-fighting response to shock; others received pellets dependent upon any non-fighting response to shock; and control pairs never received pellets. The mean probability of an elicited aggressive response to shock was reduced to 0.2 by food reinforcement for a specific non-fighting response, and to 0.5 by food reinforcement for any kind of non-fighting response. These values contrasted with the 0.8 probability of elicited aggression when pairs of rats received no food reinforcement. Consistent findings were obtained when treatment conditions were changed for individual pairs of rats.     

Effects of fixed-time shocks and brief stimuli on food-maintained behavior of rats

When a fixed-time schedule of shocks was presented to rats lever pressing for food on a random-interval schedule, a pattern of behavior developed with a high rate of pressing after shock declining to near zero before the next shock was delivered. Once this pattern had stabilized, one-quarter of the shocks were replaced with brief auditory stimuli (tones) in a random sequence. Tone maintained behavior similar to shock, although tone was never paired with shock. Both tone and shocks elicited responding when presented at various times as probe stimuli, and responding was usually totally suppressed if neither stimulus occurred at the beginning of the fixed-time interval. When other stimuli were paired with tone and shock, only those paired with tone gained discriminative control and elicited responding. These findings suggest that stimuli that signal a shock-free, or safe, period will maintain the pattern of behavior generated by shock on a fixed-time schedule. There is a parallel between this phenomenon and the control of behavior on second-order schedules of positive reinforcement with nonpaired brief stimuli.     

Responding under schedules combining response-dependent and response-independent shock delivery

Lever pressing of three squirrel monkeys with experience under continuous avoidance schedules was maintained by response-produced shock under a 5-minute variable-interval schedule. Responding decreased when half of the scheduled shocks were delivered independently of lever pressing and decreased further when all shocks were independent of lever pressing. Responding was lowest when all shocks were eliminated. When the proportion of response-dependent shocks increased, responding increased. This relation occurred even though the frequency and temporal distribution of shock delivery remained the same. Responding of two monkeys increased in a graded fashion as the frequency of shock was increased by arranging variable-time 5-minute, 2-minute, and 1-minute schedules jointly with the variable-interval 5-minute schedule. Thus, increasing the proportion of response-independent shocks decreased responding when the overall frequency of shocks stayed the same, but increased responding when the overall frequency of shock delivery increased.     

Oscillatory behavior during approach-avoidance conflict

During one stimulus, food rewards and electric shocks were intermittently delivered to rats regardless of their behavior. Subjects could either terminate or initiate this stimulus by pressing a lever. Effects of the relative frequency of food and shock were studied by manipulating the variable-interval schedules associated with each. Increases in the relative frequency of shocks led to decreases in the amount of time each rat spent in the stimulus. Subjects initiated and terminated the stimulus most often at intermediate relative frequencies of food and shock, rather than in situations where the conditions were either very favorable (e.g., only food was possible) or very unfavorable (e.g., only shock was possible). This technique thus provides quantitative data on oscillatory behavior during conflict which confirm and extend results previously obtained by qualitative observation.     

Classical Avoidance without a warning stimulus

White rats were scheduled to be shocked every 15 sec; but they were given a limited time interval between shocks when they could prevent the next scheduled shock from occurring if they pressed a lever. The duration of this limited avoidance period was varied, as was its location within the interval between scheduled shocks. Response rate, shock frequency, and the temporal distribution of lever presses were examined. Conditions were generated in which the formation of a temporal discrimination prevented the animals from maintaining successful avoidance behavior.     

Punishment of elicited aggression

Aversive shocks are known to produce aggression when the shocks are not dependent on behavior and to suppress behavior when the shocks are arranged as a dependent punisher. These two processes were studied by presenting non-dependent shock to monkeys at regular intervals, thereby producing biting attacks on a pneumatic tube. Immediate shock punishment was stimultaneously delivered for each biting attack. The attacks were found to decrease as a function of increasing punishment intensity. These results show that aggression is eliminated by direct punishment of the aggression even when the stimulus that is used as a punisher otherwise causes the aggression.     

Preconditioning exposure to the unconditined stimulus affects the acquisition of a conditioned emotional response

Four experiments examined the UCS preexposure phenomenon using conditioned suppression of food-reinforced responding as a measure of excitatory conditioning, and electric shock as a UCS. In Experiment 1, groups of rats were preexposed to unsignaled 0.8-mA electric shocks for 0, 1, 3, 5, or 10 days, and then conditioned with a 0.8-mA electric shock. Preexposure to electric shock 1 day prior to conditioning enhanced the acquisition of a CER, whereas preexposure to electric shock for 3, 5, or 10 days prior to conditioning attenuated the acquisition of a CER as a direct function of the number of days of preexposure. In Experiments 2 and 2A, groups of rats were preexposed to unsignaled electric shocks of 0.3, 0.5, 0.8, or 1.3 mA for 10 days, and then conditioned with a 0.8-mA electric shocl. All groups preexposed to electric shock acquired the CER at a slower rate than a group not preexposed to electric shock. The greatest attenuation of CER conditioning occurred when the same intensity electric shock was used during both the preexposure and conditioning phases. In Experiment 3, groups of rats were preexposed to signaled electric shocks of either 0.5, 0.8, or 1.3 mA, and then conditioned with a 0.8-mA electric shock. All groups preexposed to electric shock acquired the CER at a slower rate than a group not preexposed to electric shock. As in Experiments 2 and 2A, the greatest attenuation of CER conditioning occurred when the same intensity electric shock was used during both the preexposure and conditioning phases. In Experiment 4, groups of rats were preexposed to series of 0.5, 0.8, or 1.3-mA electric shocks which they could escape by performing a chain-pull response. Rats in each of these groups had yoked partners which received the same number, intensity, and temporal pattern of electric shocks, but could not perform a response to escape shock. All groups were then conditioned with a 0.8-mA electric shock. Rats preexposed to escapable electric shocks showed equal or greater attenuation of CER conditioning than rats which could not escape shock during the preexposure phase. These results are discussed in terms of nonassociative and associative explanations of the UCS preexposure phenomenon.     

Experimental self-punishment and superstitious escape behavior

Rats were trained to escape from shock by pressing a bar. Bar holding was subsequently punished with very brief shocks. This treatment failed to depress bar-holding behavior. In some cases, although the escape shocks were delivered very infrequently, bar holding was maintained and resulted in the delivery of several thousand punishments per session. These and other effects of the punishment treatment were investigated. Finally, some of the possibilities of superstitious escape responding were explored by presenting inescapable shocks to rats that had been trained to escape shock by lever pressing. Although responding during these shocks had no programmed consequences, responding was sustained.     

Attack, avoidance, and escape reactions to aversive shock

Aversive stimuli are known to produce the behaviors of both escape and attack. The interaction between these two basic reactions was studied with rats and monkeys using many shock-escape and shock-avoidance procedures. All procedures produced attack if a target was present, the attacks occurring shortly after shock delivery. The number of attacks during escape or avoidance was a direct function of the number and duration of shocks received. Consequently, any aspect of the procedure that produced many shocks also produced many attacks such as initial acquisition, extinction, or an increase of the response requirement for escape. The escape tendency acquired prepotency over the tendency to attack since successful escape eliminated attack behavior. The attack tendency retarded escape behavior only during acquisition when the preoccupation with attack precluded the opportunity to learn the escape response. This mutual interference of escape and attack was eliminated when the attack and avoidance tendencies were combined by using biting attack as the shock-avoidance response. The result was unusually rapid conditioning of the biting-attack response. These interactions indicate that both the attack and escape tendency should be considered whenever aversive stimulation is delivered.     

Attacker's intent and awareness of outcome,impression management,and retaliation

Female Japanese students who were engaged in a calculation task were given electric shocks by a female opponent. The subjects were informed that the opponent had an intent to shock them either severely or mildly. In addition, the opponent's awareness of the outcome of attack was independently manipulated: (1) the subjects received shocks whose intensity corresponded to the opponent's intent, (2) the subjects received shocks whose intensity was inversely proportional to the intensity intended by the opponent and were informed that the opponent did not know about it, or (3) the subjects received reversed shocks as in condition (2), but were further informed that the opponent was well aware of it. An ANOVA of the measure of retaliation in terms of the intensity of shocks delivered to the opponent indicated that (1) the subjects showed more aggression of greater intensity against an opponent who apparently had an aggressive intent than the one who did not, regardless of the actual level of shock intensity; (2) when the severe attack failed, the subjects lowered aggression when the opponent was apparently aware of it as opposed to when she was not; and (3) when the subjects received severe shocks accidentally, they increased aggression when the opponent was apparently aware of it compared to when she was not. These results led us to interpret retaliation as being mediated both by the attribution of intent to the attacker and by self-presentation to the attacker and the experimenter.     

The effect of rate of delivery of response-independent shocks upon avoidance responding

Two hooded rats were trained to bar-press to avoid electric shock on a continuous avoidance schedule with response-shock and shock-shock intervals equal. The rate of delivery of response-independent shocks superimposed on this schedule was varied. The response-independent shocks led to generally higher response rates but, with responses during shock omitted, the rates decreased as the response-independent shock rate was increased. The actual shock rate received by the subjects was linearly related to the maximum potential shock rate. There was an increasing, negatively accelerated function between percentage avoidance and response rate, but there was no consistent relation between the number of shocks avoided and response rate. Response rate decreased as the potential shock rate increased, but responding was maintained even when as few as 15% of the shocks could be avoided.     

Characteristics and response-displacement effects of shock-generated responding during negative reinforcement procedures: pre-shock responding and post-shock aggressive responding

Bar-pressing (Experiment I) or key-pressing (Experiments II and III) responses of monkeys were reinforced according to a fixed-interval schedule of negative reinforcement: the first response after a fixed interval of time terminated regularly spaced shocks for a fixed time designated as the reinforcement period. During extinction, shocks continued during the reinforcement period. That there were two types of responding generated by shock alone was indicated by (1) the level of responding maintained during extinction relative to conditions without shock, (2) the stability of two between-shock response patterns across reinforcement and extinction conditions, and (3) the development of these two between-shock patterns without a history of reinforcement. Subjects developed either a pre-shock or a post-shock response pattern when only the bar was available. However, when both a bite tube, an operandum requiring an aggressive topography, and a recessed key, an operandum that did not require an aggressive topography, were provided, the post-shock pattern was observed in tube biting and the pre-shock pattern was observed in key pressing. Removal of the bite tube produced post-shock key responding similar to that observed when only the bar was available. The displacement of post-shock, aggression-motivated responding confirmed the confounding effect of shock-generated responding in negative reinforcement procedures, and suggests that the use of concurrent response alternatives would reduce such confounding.     

Choice and the dependability of stimuli that predict shock and safety

This study assessed whether choosing a signalled shock condition over an unsignalled one is controlled by a stimulus that predicts the presence of shock (Experiment I), or by a stimulus that predicts the absence of shock (Experiment II). The dependability of these stimuli as predictors of either the presence or the absence of shock was parametrically varied over a wide range, and subjects (rats) were given an option to change from an unsignalled to a signalled condition. In the first experiment, all shocks were preceded by signals; however, the probability of a signal being followed by shock varied from 1.0 to 0.02. The data obtained indicate that the dependability of the signal as a predictor of shock is unimportant. Rats changed to the signalled condition when the signal was completely dependable (all signals followed by shock) and when the dependability of the signal was systematically degraded. In the second experiment, all signals were followed by shock; however, some shocks were not preceded by a signal. The data show that the dependability of a stimulus predicting the absence of shock is important in that, as dependability decreases, changing to the signalled condition also decreases.     

Instigation to aggress and escalation of aggression examined from a personological perspective: The role of irritability and of emotional susceptibility

Two studies were conducted using Buss hostility machine paradigm to investigate the role of individual differences in irritability and emotional susceptibility on the instigation to aggress by a self-esteem lowering manipulation and on the hypothesized escalation of aggression over trials. The role of sex was also examined. In the first study, 60 highly irritable and 60 low irritable subjects were given the opportunity to deliver electric shocks to an experimental confederate, half after being provoked by a negative judgement on their performance in a learning task, half without such an experience. Each group of subjects was divided equally between males and females. It was found that highly irritable subjects, both males and females, delivered higher shocks after provocation than low irritable subjects under similar circumstances. An upward drift of shock level over trials was found only in provoked males and only in highly irritable females. In the second study, 60 highly emotionally susceptible and 60 low emotionally susceptible males and females were given the opportunity to deliver electric shocks to an experimental confederate, half after experiencing provocation, half without such an experience. It was found that provoked subjects delivered higher shocks than unprovoked subjects and that highly emotionally susceptible subjects delivered higher shocks than low emotionally susceptible subjects. Whereas an upward drift of shock levels over trials was found only in provoked males, the same effect was found in females, whether provoked or not. These findings are discussed in terms of the importance of stable personality characteristics that may mediate aggressive response.     

"Warmup" and "cooldown" in Sidman avoidance behavior of rats: A dual-process interpretation

The present experiment investigated relations between "warmup" in unsignalled Sidman avoidance in rats and the intensity of shock. Magnitude of shock-rate change was quantified by comparing the rat's behavior during the initial third and the final two thirds of the same session. Warmup was said to occur whenever the shock rate during the initial 20 min was higher than the shock rate during the final 40 min of a 60 min session. "Cooldown" was defined as lower shock rate during the initial 20 min than during the final 40 min. Warmup was observed when shocks were intense, cooldown was observed when shocks were low intensity, and neither was observed when medium-intensity shocks were administered. Response-rate changes were correlated with shock-rate changes, but were smaller. The results are interpreted within the framework of a dual-process theory of habituation.     

Discrimination of response-contingent and response-independent shock by rats: effects of chlordiazepoxide HCL and sodium amylobarbitone

Rats, trained to press a lever for sucrose reward on a random interval (RI) schedule, were presented while lever-pressing with two stimuli, each associated with a different schedule of shock delivery: in the presence of one stimulus (S_e), shock occurred on an RI schedule irrespective of the rat's behaviour; in the presence of the other (S_p) shocks were programmed by the same schedule but delivered only when the rat pressed the lever. Both stimuli suppressed lever-pressing. In addition, the rats developed significantly different response rates in the two stimuli, thus demonstrating a discrimination between response-contingent and response-independent shock. Group data showed faster responding in S_e than in S_p, supporting the view that response-contingent shock produces greater suppression than response-independent shock. Individual animal analyses, however, demonstrated that this was the case in the majority of animals, but not in all. Response suppression was alleviated by amylobarbitone sodium (15 mg/kg) or chlordiazepoxide HCI (5 mg/kg); the latter drug alleviated suppression significantly more in S_p than S_e and eliminated the difference between the response rates controlled by the two stimuli.     

The effects of tail shock on target-biting behavior of confined mice

Mice that are confined in a narrow cylinder readily bite inanimate targets. The following studies were conducted to determine the effects of tail shock on the target biting behavior of two strains of mice. During 20-min daily sessions, ten tail shocks were administered on a fixed-time 2-min schedule. One group of mice received a tone-conditioned stimulus (CS) which terminated with the onset of the shock, and a second group of mice did not. Target bites were collected in eight 15-sec bins over the 2-min trial and cumulated over the session. It was observed that tail shock was followed by an increase in target biting and that there was a comparatively high intershock interval biting rate. In addition, intershock interval biting was suppressed for the duration of the CS. These observations are discussed in terms of the utility of this paradigm for the psychopharmacological assessment of aggressive behavior.     

Free operant avoidance as a function of the response-shock=shock-shock interval

Two temporal parameters of free operant or Sidman avoidance behavior are the interval by which responses postpone shocks (Response-Shock interval) and the interval between shocks when no responses occur (Shock-Shock interval). Avoidance behavior was examined in three white rats under conditions where the Response-Shock and Shock-Shock intervals were always equal. With intervals from 10 to 60 sec response rates and shock rates were similar, decreasing, negatively accelerated functions of increasing Response-Shock=Shock-Shock interval. Over this range, response and shock rates were linearly related to the reciprocal of the Response-Shock=Shock-Shock interval. It was shown, however, that this relation cannot hold at extremely long intervals. Both the ratio of responses emitted to shocks received and the percentage of shocks possible which were avoided increased at long Response-Shock=Shock-Shock intervals. These findings may be related to the fact that long intervals provide optimal conditions for conditioning avoidance behavior in the rat.     

Lever attacking and pressing as a function of conditioning and extinguishing a lever-press avoidance response in rats

Six experimental rats were conditioned to press one of two available levers to avoid shock. The levers registered bites as well as presses. For four of these rats, shock was contingent on lever bites when a specified time period had elapsed after the previous shock. An extinction period, in which only periodic noncontingent shocks were presented, followed avoidance training. Six yoked-control rats received the same sequence of shocks as did the corresponding experimental rats in both the conditioning and extinction phases. All six experimental rats repeatedly bit the avoidance lever. Four bit it more than the nonavoidance lever during conditioning, and five bit it more during extinction. Five of the six experimental rats consistently bit the levers many more times during each session than did their respective control rats, suggesting that avoidance conditioning facilitated lever biting. Rates of lever biting and pressing by all of the experimental rats and by some of the control rats were highest immediately following shock throughout both phases. During later portions of the intervals following shock, characteristic effects of conditioning and extinction were observed. This finding suggests that extinction of avoidance behavior by unavoidable shock presentations can be demonstrated more readily when shock-elicited responding is extricated from the data.