Second-order schedules: brief shock at the completion of each component

Pigeons worked on second-order schedules in which completion of fixed-interval component schedules was reinforced with food according to a variable-interval schedule of reinforcement. The completion of each fixed-interval component resulted in the presentation of a brief electric shock. In one condition (shock-paired), the completion of every fixed-interval component, including those that ended in food, resulted in the shock. In another condition (shock-nonpaired), completion resulted in shock except for those components that ended in food. Shock presentations resulted in a positively accelerated rate within fixed-interval components. This patterning within components was similar whether the shock was intermittently paired with food or not. Response rates tended to decrease as shock intensity increased. The characteristic fixed-interval response pattern within components did not occur when shock presentations were omitted at the end of each component (tandem schedule). When shocks were scheduled but food was no longer presented (extinction) response rates declined to a near-zero level. The performance under shock conditions is similar to that in other studies in which visual and auditory stimuli are presented at the completion of component schedules.     

The reduction of attack instigated aggression

Thirty subjects competed with an opponent in a reaction time task to avoid receiving shock. The opponent initially set only the highest possible intensity shock for the subjects. The opponent then adopted one of three strategies to reduce the intensity of shocks set by the subjects. In one condition the opponent set shock intensities which matched those set by the subject. In a second condition the opponent set shocks which were not contingent upon those set by the subject but which were identical to those set by the opponent who matched the subject's settings. The opponent in the third condition suddenly reduced the intensity of his settings and chose only the least intense possible shock for the subject. All three conditions resulted in reduced aggression. This decrement was greatest and most rapid among those subjects who were exposed to a precipitous decrease in the intensity of attack.     

Effects of nutritional and mechanical properties of food on ruminative behavior.

Previous studies have identified a reliable relation between the quantity of food ingested and ruminating in profoundly retarded individuals and have established some parametric characteristics of this relation. The present study investigated three different properties of food that may influence this relation. Experiment 1 examined the role of stomach distention produced by including in the subject's diet wheat bran in amounts equivalent to and exceeding the calculated amount of crude fiber in the starch-satiation diet reported by Rast, Johnston, Drum, and Conrin (1981) and Rast, Johnston, and Drum (1984). There was a decrease in ruminating, although this decrease was smaller and more gradual than in the starch-satiation condition. Experiment 2 showed that increasing calories without increasing food volume resulted in a gradual and moderate decrease in ruminating. Experiment 3 replicated and extended the first two experiments by varying both caloric intake and stomach distention as well as oropharyngeal and esophageal stimulation in a different sequence of conditions. All variables exerted some control over responding. However, the large and immediate effects of the starch-satiation procedure occurred only when subjects were permitted to consume unlimited quantities.     

Predator videos and electric shock function as punishers for zebrafish (Danio rerio)

Zebrafish (Danio rerio) are a promising animal model for studying the effects of gene–environment interactions on behavior. Two experiments were conducted to assess punishment effects of presenting predator videos (Indian leaf fish; Nandus nandus) and electric shock on operant approach responses in zebrafish. In Experiment 1, the predator video and shock stimuli were presented upon a response maintained by a single variable‐interval schedule of food reinforcement in different groups of fish. In Experiment 2, the predator video and shock stimuli were presented upon one of two response alternatives maintain by concurrently available variable‐interval schedules of food reinforcement in different groups of fish. Responding decreased when the predator video and shock stimuli were presented relative to their absence in both experiments. Moreover, responding on an unpunished alternative did not reliably decrease in Experiment 2. These results indicate that the decrease in responding resulted from the punishment contingency rather than from elicited species‐specific defense responses or conditioned avoidance. Thus, the predator video and electric shock functioned as punishers of operant behavior for zebrafish. Identifying punishers for this species could lead to research on how gene–environment interactions influence individual differences in sensitivity to punishment.     

Dynamic loading during running on various surfaces

The amplitude of the shock waves propagating through the human locomotor system while running along three various surfaces were evaluated using a small accelerometer externally attached to the runners' tibial tuberosity. Nine runners participated in this study. It was found that the running generates shock waves an order of magnitude higher than that during walking. The amplitudes of the shock waves generated during running were dependent on the surface. Running on the grass surface resulted in nearly 25 percent higher shock wave amplitude when compared with asphalt, while running on the artificial track resulted in only 5 percent higher shock waves amplitude than running on the asphalt surface. The described technique for acquiring data on the heel strike generated shock waves can be useful for the evaluation and comparison of different types of running track surfaces.     

Punishment: the interactive effects of delay and intensity of shock

A discrete-trial punishment procedure, with rats, was used to examine how delay-of-shock intervals of 0 to 28 sec and shock intensity interact to decrease the frequency and increase the latency of a positively reinforced response. For delay-of-shock intervals of 0, 7, 14, and 28 sec, there was a range of shock intensities, for some subjects, over which the punishing effect of shock was an increasing, monotonic function of shock intensity. For other subjects this transition was abrupt. Functions relating response frequency and latency measures to shock intensity were displaced toward higher values on the shock intensity axis with an increase in delay-of-shock interval. The effects of “gradual” and “abrupt” introduction to “severe” shock, as well as re-exposure to previously used shock intensities, were examined under both the immediate and delay-of-shock conditions. With delay-of-shock intervals of 7, 14, or 28 sec, shock intensities of approximately 0.50 milliamperes or greater were necessary to decrease substantially the number and increase the latency of the lever-pressing response. For the immediate punishment group this intensity was approximately 0.20 ma. These facts were related to Annau and Kamin's (1961) conditioned emotional response experiment in which a shock intensity of 0.49 ma or greater was required to suppress the rate of a positively reinforced response.     

Some aspects of self aversive stimulation in the hooded rat

Three hooded rats were trained to bar press for variable-ratio liquid reinforcement after which an electric shock was delivered following the response. Initially, the shock was presented on a FR 100 basis but the frequency was gradually increased until all responses were punished. Finally, a partial extinction procedure was conducted to determine if the shock resulted in increased bar pressing. No durable suppression of responding occurred, although one subject's rate was reduced during continuous shock. The overall trend for the three animals was one of increased responding. Changes in the pattern of responding were also observed suggesting that the suppressive effects of the punishment were largely restricted to the first response following reinforcement. Increased responding as a function of shock reintroduction during extinction was also observed.     

Discriminated punishment: avoidable and unavoidable shock

Warning stimuli for two punishment conditions were alternated with periods of appetitive responding by rats. In either warning stimulus, the first response produced a brief shock, terminated the stimulus, and started an interval during which the baseline appetitive schedule was in effect. Not responding resulted in stimuli of random duration, which terminated with a shock under one condition and without a shock under the other. Each subject was exposed to several shock intensities, with trials for the two conditions programmed during alternate portions of the session. In general, response frequency in the warning signal for either condition decreased with increasing intensity; however, at a given intensity, responding was more frequent in the stimulus invariably terminating with shock than in the stimulus terminating without shock when no response was made. The frequency difference was greatest at intensities intermediate between those producing minimal and maximal suppression.     

The role of hyperdipsia in aggression following septal lesions in rats

Lesions of the septum in animal subjects are known to produce an increase in aggressiveness and an increase in water intake. A series of experiments was carried out to examine the possibility that aggression was secondary to hyperdipsia. When rats with septal lesions were restricted to preoperative levels of water intake, aggression scores declined significantly. When animals without lesions were preloaded, with either water or saline, aggression increased. Neither decreased shock threshold nor increased cell hydration provided a full explanation for the results. It is suggested that the aversive nature of the stomach turgescence caused by increased water intake may be an additional mediating factor in septal aggression.     

Punishment of autoshaped key-peck responses of pigeons

The effects of different voltages of response-dependent and response-independent electric shock on the frequency of key-peck responses engendered by an autoshaping procedure were studied. In Experiments I and II, each response produced a brief electric shock, and response frequency generally decreased more with higher-voltage shock. Preshock frequencies of responding were generally recovered across successive sessions of relatively low-voltage shock delivery but not at higher shock voltages. The effects of response-dependent and response-independent shock were compared in Experiment III by using a yoked-control procedure in which each pigeon received each type of shock delivery at different times. Response-dependent shock generally produced greater decreases in response frequency. In the final experiment, one response-independent shock per autoshaping trial was scheduled. The number of autoshaped responses per trial was related to shock voltages. These results suggest that response-dependent and response-independent electric shock effectively decrease frequency of autoshaped responses.     

On the directionality of key pecking during signals for appetitive and aversive events

Pigeons were exposed to a signal paired with either blackout or blackout plus shock and to another signal paired with food superimposed on a baseline of concurrent variable-interval reinforcement of pecks on two keys. The signals were changes of color of one of the two keys. The rate of pecking both keys during the signal paired with blackout or blackout plus shock was lower than the baseline rate of pecking (a conditioned emotional response), but the decrease in pecking was greater on the signal key. When the intensity of shock was increased, the rate of pecking did not decrease further on the signal key but did decrease on the other key. Rate of pecking during the signal paired with food increased sharply on the signal key (an autoshaping effect) and decreased sharply on the other key. These results support a view that there are two effects of the interaction between classical and instrumental conditioning, a stimulus-directed effect and a generalemotional effect.     

An interresponse time analysis of variable-ratio punishment

An interresponse time analysis was used to study the effects of variable-ratio punishment schedules on the temporal pattern of reinforced responding. Twelve pigeons responded on a baseline variable-interval schedule of food reinforcement. A variable-ratio ten schedule of electric shock punishment was then introduced. The shock intensity was systematically increased to the highest intensity at which responding could be maintained. At this intensity, the mean variable-ratio value was increased and then decreased. Variable-ratio punishment resulted in an increased relative frequency of very short unreinforced interresponse times (response bursting). Increased response bursting accounted for instances of response rate facilitation. In addition, shock was followed by interresponse times of decreasing mean length over the first several responses after shock.     

EFFECTS OF PROBLEM-BASED SCHEDULING ON PATIENT WAITING AND STAFF UTILIZATION OF TIME IN A PEDIATRIC CLINIC

The patient scheduling system in a pediatric outpatient clinic was changed from time-based to problem-based in an A-B-A-B reversal design. During baseline, time-based scheduling was in effect with patients being scheduled in 15-min periods regardless of presenting problem. During intervention, a receptionist matched client problems with time slots so that a more extensive treatment was allocated more time. Problem-based scheduling resulted in a substantial decrease in mean number of minutes spent in clinic across all presenting problems. Waiting time increased to baseline levels when problem-based scheduling was removed and decreased again on reintroduction of the program. A follow-up check conducted 1 month after the end of the second intervention phase revealed that the effects were maintained. The problem-based schedule also resulted in an increase in the proportion of extra time that medical staff had available and produced a positive consumer response.     

Schedules of electric shock presentation in the behavioral control of imprinted ducklings

The behavioral effects of various schedules of electric shock presentation were investigated during and after the imprinting of Peking ducklings to moving stimuli. The behavior of following a moving imprinted stimulus was differentially controlled by a multiple schedule of punishment and avoidance that respectively suppressed and maintained following behavior. Pole-pecking, reinforced by presentations of the imprinted stimulus, was suppressed by response-produced shock (punishment); various schedules of response-independent shock and delayed punishment had an overall minimal effect. The delivery of response-independent shock in the presence of one of two stimuli, both during and after imprinting, resulted in a marked reduction in choice of the stimulus paired with shock. The experiments provide no support for a differentiation of imprinting from learning on the basis of the behavioral effects of aversive stimuli. Instead, as is the case with other organisms, the schedule under which shock is delivered to imprinted ducklings appears to be an important determinant of the temporal patterning of subsequent behavior.     

Learning behavior, escape behavior, and depression in an ulcer susceptible rat strain.

The aim of the present study was to explore the relationship between depression (helpless withdrawal behavior) and susceptibility to stress ulcer in rats. The WKY genetic strain of rats has been described as highly susceptible to stomach ulcer development during water restraint, i.e., when placed in a jar of water and forced to swim to keep their head above water, a setting in which Richter identified "giving up" behavior akin to hopelessness (Richter, 1957). Since WKY rats tended to float in the water instead of swimming in an attempt to escape, and were also found to be relatively inactive in open field tests, a series of experiments were performed to ascertain whether their diminished activity and their failure to swim reflected slowness, cognitive impairment, or something actually akin to depression. The latter interpretation was supported by evidence from tests of shock avoidance behavior, of capacity to learn discrimination in an operant setting, and by the capacity of an antidepressive drug to lessen floating time in the forced swim test and also to reduce the incidence of stomach ulcers.     

Learning behavior,escape behavior,and depression in an ulcer susceptible rat strain

The aim of the present study was to explore the relationship between depression (helpless withdrawal behavior) and susceptibility to stress ulcer in rats. The WKY genetic strain of rats has been described as highly susceptible to stomach ulcer development during water restraint, i.e., when placed in a jar of water and forced to swim to keep their head above water, a setting in which Richter identified “giving up” behavior akin to hopelessness (Richter, 1957). Since WKY rats tended to float in the water instead of swimming in an attempt to escape, and were also found to be relatively inactive in open field tests, a series of experiments were performed to ascertain whether their diminished activity and their failure to swim reflected slowness, cognitive impairment, or something actually akin to depression. The latter interpretation was supported by evidence from tests of shock avoidance behavior, of capacity to learn discrimination in an operant setting, and by the capacity of an antidepressive drug to lessen floating time in the forced swim test and also to reduce the incidence of stomach ulcers.     

Malleability of conditioned associations: path dependence

Using conditioned suppression of barpressing to investigate the stability of a conditioned stimulus-unconditioned stimulus (CS-US) association, we gave water-deprived rats either a few pairings of the CS with a strong footshock US or many pairings with a weak footshock US so that barpress suppression in response to the CS was equated. Experiment 1 established training parameters that yielded this equivalence. Specifically, rapid acquisition to a preasymptotic level of responding with strong shock produced suppression comparable to the asymptotic level reached more slowly with weak shock. Experiment 2 showed that although equivalent performance was obtained from extensive conditioning with a weak shock or limited conditioning with strong shock, only extensive conditioning with weak shock resulted in retarded acquisition of an association between that same CS and a footshock level perceived as midway between the two initial training shock intensities as implied by asymptotic performance in Experiment 1. Experiment 3 demonstrated that the observed retardation in animals given many conditioning trials with weak shock was CS specific. Collectively, these findings indicate that the malleability of learned behavior is not simply a function of initial associative strength but is dependent on path during initial acquisition.     

The effects of stimuli followed by response-independent shock on shock-avoidance behavior

Four rhesus monkeys were trained on a non-discriminated shock-avoidance schedule (baseline). Stimuli followed by response-independent shock were then presented with the avoidance baseline no longer in effect. The main portion of the experiment consisted of superimposing (independently of responding) the stimuli followed by response-independent shock on the avoidance baseline. Different temporal values of stimulus duration and delay of shock (produced by an avoidance response) were presented successively, using each subject as his own control. When the stimulus duration was short or the delay of shock was long, so that avoidance rate during the stimulus could assume any value without resulting in baseline (avoidable) shocks during the stimulus, a lowered or "suppressed" rate of responding developed during the stimulus. When the stimulus duration was long or the delay of shock was brief, so that avoidable shocks resulted from a response decrement during the stimulus, high or "facilitated" rates of responding developed for a large proportion of the time that the stimulus was present.     

Aggression as a function of the intensity and pattern of attack

Forty Ss competed with an opponent in a reaction time task to avoid receiving shock. The opponent provided either consistently high intensity attack, increasing, decreasing, or consistently low attack. The S's shock settings for the opponent on each trial and ratings of the opponent after the task served as dependent measures. High intensity attack resulted in high intensity counterattack and negative ratings of the opponent. Low intensity attack resulted in low intensity counterattack and relatively positive ratings for the opponent. Decreasing attack resulted in decreasing counterattack and positive ratings of the opponent. Increasing attack resulted in increasing counterattack and comparatively high aggression ratings of the opponent.     

Fear as a discriminative stimulus for an appetitive instrumental response

Two experiments tested the hypothesis that anticipation of shock could be established as a discriminative stimulus for an appetitive instrumental response. In multiphase experiments, bar pressing for food was brought under the discriminative control of intermittent and gradually increasing electric shock. In a second phase, tones were estalished as either a CS+, or CS? for shock. Subsequently, the CSs were introduced on to the operant baseline. Animals trained with shock as the S^D showed an increase in responding to the CS+ and a slight decrease to the CS?. Conversely, animals trained with shock as the S^Δ showed decreased responding to the CS+ and slight increase to the CS?. These findings are seen as supportive of the Discriminative Stimulus hypothesis of learned resistance to punishment.