The partial punishment effect following minimal acquisition training: Sodium amobarbital and the stimulus properties of early punished trials

In a runway investigation, six groups of rats received limited runway training such that partial punishment, partial reinforcement, or continuous reinforcement was accompanied by sodium amobarbital or saline. Following an interpolated phase of continuous reinforcement without injections, all groups were given punished extinction. The entire experiment was conducted under widely spaced conditions (ITI = 24 hr). It was found that partial punishment increased resistance to punished extinction relative to partially and continuously reinforced controls when acquisition was given under saline. When partial punishment training was accompanied by amobarbital this effect was eliminated. The drug was observed to have no effect on the punished extinction performance of the partial reinforcement and continuous groups, respectively. Moreover, the partial reinforcement effect (PRE) did not generalize to punished extinction. These data provide information concerning the difference between the stimuli associated with the early trials of punishment and nonreward and indicate that the former but not the latter contain emotional elements.     

Determinants of instrumental extinction in terrestrial toads (Bufo arenarum)

Previous research in a water-reinforced instrumental training situation with toads (Bufo arenarum) has shown that performance in both acquisition and extinction is poorer after partial, rather than continuous reinforcement training. In Experiment 1, the performance of a group receiving 24 trials on a 50% partial reinforcement schedule was poorer in acquisition and extinction than that of continuously reinforced groups matched for trials or reinforcements. However, partially reinforced toads extinguished at the same rapid rate as a continuously reinforced group that received training only on the days in which the partial toads received water reinforcement. In Experiment 2, extinction was faster after 10 reinforced acquisition trials than after 30 trials. This evidence suggests that the deleterious effects of partial reinforcement in toads can be explained by a combination of two factors, namely, the distribution of reinforced trials across days and the total number of reinforcements.     

Does delay of reinforcement produce durable persistence?

In a foru-phase experiment, phase I was runway training under four different reinforcement conditions: partial reinforcement (PRF), partial delayed reinforcement (PDR), constant delayed reinforcement (CDR), and consistent reinforcement (CRF). During phase 2 extinction, PRF and PDR groups did not differ; both groups were more persistent than group CDR, which was in turn superior to the CRF control. Phase 3 was CRF reacquisition for all groups. During phase 4 extinction, PRF group was more presistent than the other three groups which did not differ. A Pavlovian counter-conditioning hypothesis was proposed to account for the absence of durable persistence following PDR training.     

Transfer of the partial reinforcement extinction effect between escape (shock) and appetitive (food) conditioning

In the first experiment rats were given partial reinforcement or continuous reinforcement in either an escape or an appetitive paradigm. Subsequently, the rats received continuous reinforcement training under motivational conditions opposite those experienced earlier. Finally, responses were extinguished according to the motivational conditions experienced in the second phase. The results indicated that partial reinforcement in the initial phase operated to increase resistance to extinction in the last. In a second experiment this intermotivational partial reinforcement extinction effect was shown to survive interpolated experiences with extinction, a 1-week rest period, and continuous reinforcement reacquisition. A third experiment examined the influence of intramodal versus intermodal nonreinforcement-reinforcement sequences on the intermotivational partial reinforcement extinction effect. Interactive effects between similarity of aversive outcome (escape nonreinforcement, appetitive nonreinforcement) and reinforcement type (negative, positive) were found. The theoretical implications of the data from all three experiments are discussed.     

Punishment persistence and sequence: Some effects of P-length and N-length in the rat

In a runway investigation, two groups of rats received partial punishment training with P-lengths of 1, 2, and 3 (Group P123) and P-lengths of 1 (Group P1), respectively. Two additional groups received partial reinforcement with N-lengths of 1, 2, and 3 (Group N123) and N-length of 1 (Group N1). An additional group was given unpunished continuous reinforcement in the runway, but received control shocks in a separate apparatus. Following training all subjects received punished extinction (shock plus nonreward). The results indicated that P-length increased resistance to punished extinction, however N-length did not have the corresponding effect. In addition, partial reinforcement did not increase resistance to punished extinction relative to continuous reinforcement. These results were interpreted within a sequential-theoretical framework.     

Changes Accompanying Practice upon Successive Samples of Verbal Material

Three groups of rats received either continuous, partial, or zero reinforcement in a first acquisition phase which was followed by an extended extinction phase. Then all Ss were given a reacquisition phase under continuous reinforcement conditions followed by a second extinction phase. While the usual partial reinforcement extinction effect (PREE) was found during the major part of the first extinction phase, it disappeared during the last few trials of that phase. No PREE was obtained during the second extinction phase in any of the three sections of the runway. The abolition of the PREE was attributed to the extinction of the r_F-s_F mechanism in the partial reinforcement group.     

Survival of the partial reinforcement extinction effect after contextual shifts

The effects of contextual shifts on the partial reinforcement extinction effect (PREE) were studied in autoshaping with rats. Experiment 1 established that the two contexts used subsequently were easily discriminable and equally salient. In Experiment 2, independent groups of rats received acquisition training under partial reinforcement (PRF) or continuous reinforcement (CRF). Significant PREEs were observed whether extinction occurred in the same or in a different context. In Experiment 3, after PRF or CRF acquisition training, each group received extinction of the same conditioned stimulus in both the same and different contexts. PREEs were observed under both conditions, although extinction was accelerated after a contextual shift. These results were discussed in relation to the role of mediational states in the PREE.     

Partial reinforcement effects in classical aversive conditioning in rabbits and human beings.

The partial reinforcement extinction effect (the PREE) in classical aversive conditioning was investigated in 2 experiments. In the first, the nictitating membrane responses of 120 rabbits were conditioned at a 250-msec. interstimulus interval (ISI) under continuous reinforcement, partial reinforcement with the unconditioned stimulus (US) omitted (Group PO), or partial reinforcement with the US delayed to 1,500 msec. (Group PD). These 3 groups were factorially extinguished under US-Omitted, US-Unpaired, or US-Delayed extinction regimens. A significant PREE was obtained, but only for PO training and US-Omitted extinction. The second experiment, employing human subjects in a masked eye blink conditioning task, produced parallel results. A general discrimination view of the classical PREE seems applicable, but one in which neither cognitive factors nor intertrial conditioning of reinforcement aftereffects play a significant role.     

Effect of schedule and magnitude of reinforcement on instrumental learning in the toad, Bufo arenarum

Extinction after training with continuous (CR) or 50% partial (PR) reinforcement, and with different magnitudes of reward, was studied in the amphibian Bufo arenarum, in a runway situation. In Experiment 1, a group of toads received massed-trial, CR training with access to water as the reward. Performance improved during acquisition, including an improvement on the first trial of each session. Extinction was rapid and there was evidence for spontaneous recovery of the running response. In Experiment 2, groups of toads received PR or CR training at a rate of one trial per day. PR impaired acquisition and resulted in poor responding during extinction, compared to CR. Experiment 3 factorially studied the effects of schedule (PR vs CR) and distribution of practice (15 s vs 300 s intertrial interval). Acquisition was impaired by PR training but had little effect on extinction performance. Different magnitudes of water reinforcement were used in Experiment 4 in a one-trial-per-day situation. Terminal acquisition performance was a monotonic function of reward magnitude, but there were no differences in extinction performance across groups. The results are discussed in relation to comparative and developmental data on the paradoxical effects of reward.     

The role of contextual associations in producing the partial reinforcement acquisition deficit

Three conditioned suppression experiments with rats as subjects assessed the contributions of the conditioned stimulus (CS)-context and context-unconditioned stimulus (US) associations to the degraded stimulus control by the CS that is observed following partial reinforcement relative to continuous reinforcement training. In Experiment 1, posttraining associative deflation (i.e., extinction) of the training context after partial reinforcement restored responding to a level comparable to the one produced by continuous reinforcement. In Experiment 2, posttraining associative inflation of the context (achieved by administering unsignaled outcome presentations in the context) enhanced the detrimental effect of partial reinforcement. Experiment 3 found that the training context must be an effective competitor to produce the partial reinforcement acquisition deficit. When the context was down-modulated, the target regained behavioral control thereby demonstrating higher-order retrospective revaluation. The results are discussed in terms of retrospective revaluation, and are used to contrast the predictions of a performance-focused model with those of an acquisition-focused model.     

An analysis of sequential variables in Pavlovian conditioning employing extended and limited acquisition training

Sequential theory’s memory model of learning has been successfully applied in response contingent instrumental conditioning experiments (Capaldi, 1966, Capaldi, 1967, Capaldi, 1994 and Capaldi and Miller, 2003). However, it has not been systematically tested in nonresponse contingent Pavlovian conditioning experiments. The present experiments attempted to determine if several sequential variables affect responding in Pavlovian situations as they do in instrumental ones. Of primary concern here were the effects on extinction of number of NR transitions (the number of times a nonreinforced trial is followed by a reinforced trial), N-length (the number of successive nonreinforced trials that precede a reinforced trial), and percentage of reinforcement (50 versus 100%) following either extended acquisition training (Experiment 1, 720 trials) or limited acquisition training (Experiment 3, 24 trials). In agreement with a sequential analysis, N-length increased resistance to extinction more than number of NR transitions following extensive training with the opposite occurring following limited training. In Experiment 1, greater resistance to extinction was associated with 50% than with 100% reinforcement, a partial reinforcement extinction effect (PREE). Experiment 2 examined an anomalous finding obtained in Experiment 1. A major theoretical difference between instrumental and Pavlovian conditioning has been held to be the greater ease of producing a PREE in instrumental than in Pavlovian conditioning (Kimble, 1961 and Mackintosh, 1974). However, the findings obtained here suggest that the probability of obtaining a PREE and other Pavlovian extinction effects, as in instrumental conditioning, increases along with the effectiveness of the sequential variables employed.     

Sequential effects of non-reward in a skinner box

The partial reinforcement extinction effect was examined within subjects in a simultaneous discrimination in a two bar Skinner box. Discrete trials were used, rats being required to press the bar under the illuminated cue light; one bar was correlated with 100% the other with 50% reinforcement. The three groups differed in the probability of a change in the cue light between trials during acquisition. When this probability was low, the 50% bar was preferred in extinction, while when it was higher (0.433 or 0.875) the 100% bar was preferred. These results confirm Capaldi's (1966) hypothesis of the partial reinforcement extinction effect, and support a suggested explanation of some conflicting results on partial reinforcement effects in a Skinner box.     

Between-subject PREE and within-subject reversed PREE in spaced-trial extinction with pigeons

Three experiments explored the partial reinforcement extinction effect (PREE; greater resistance to extinction after partial, rather than continuous, reinforcement training), in a spaced-trial situation with pigeons. Experiments 1 and 2 report conventional PREEs with 24-h intertrial intervals and between-subject designs. The corresponding outcome (food reinforcement or nonreinforcement) was delivered after satisfaction of a fixed-ratio 10 (Experiment 1) or a fixed-ratio 1 (Experiment 2). Experiment 3 reports a reversed PREE in a within-subject design with a fixed-ratio 10 requirement. Extinction occurred faster for the response paired with 50% partial reinforcement than for the response paired with continuous reinforcement. A third response paired with a small reinforcer (1 pellet/trial) in 100% of the trials extinguished faster than a response paired with a large reinforcer (15 pellets/trial). These results are discussed in the context of spaced-trial instrumental performance (key pecking and running), in pigeons.     

Partial reinforcement and extinction in vasomotor conditioning

In order to investigate cognitive versus traditional accounts of responding in extinction and the discrimination hypothesis for the partial reinforcement effect, 40 human subjects were randomly divided into two groups and were treated according to thermal vasomotor conditioning procedures using either 25 trials of continuous reinforcement or 100 trials of 25% partial reinforcement. At the onset of extinction, half of each group was given traditional noninformed extinction, while the other (informed) half had the thermal stimulator removed. The usual greater resistance to extinction was obtained after partial reinforcement than after continuous reinforcement in the two noninformed groups; however, immediate extinction of responding was obtained from the first extinction trial in the two informed groups. These results are consistent both with the discrimination hypothesis for the partial reinforcement extinction effect and with cognitive explanations of responding in extinction. Consequences for the behavioral therapies are discussed.     

Perseveration of the partial reinforcement effect in extinction with rats over two phases of extinction and two stages of continuous reinforcement

One group of 10 male albino rats was given partial reinforcement while the other 10 rats received continuous reinforcement in a straight alley. Subjects then experienced five consecutive stages of Extinction 1, Continuous Reinforcement 1, Extinction 2, Continuous Reinforcement 2, and finally, Extinction 3. Analysis showed the partial reinforcement effect in extinction was sustained over two stages of extinction and two stages of continuous reinforcement, since subjects receiving partial reinforcement ran faster than rats given continuous reinforcement throughout all three of the extinction periods. The results seem to support those of Amsel's (1967) and Cabpaldi's (1967) theoretical formulations of the partial reinforcement effect in extinction.     

Effects of US-Presentation and CS-termination contingencies on avoidance extinction following partial and continuous reinforcement

The present study assessed the role of both the US-presentation (punishment) and CS-termination contingencies on the maintenance of the shuttlebox avoidance responding in gerbils following acquisition under either partial reinforcement (PR) or continuous reinforcement (AV). Following PR, a stronger relationship obtained between delay of CS termination CR frequency than was found between delay of punishment and extinction performance. Following AV training, however, delay of CS termination and delay of punishment were equally effective determinants of avoidance extinction. These results were interpreted in terms of both the enhanced efficacy of the CS-termination contingency, possibly due to its increased informational value, and the attenuation of punishment suppression in PR-trained Ss.     

Effects of medial and lateral septal lesions on the partial reinforcement extinction effect at short inter-trial intervals

Rats sustained electrolytic lesions either in the medial septal (MS) area (of a kind known to eliminate the hippocampal theta rhythm) or in the dorso-lateral septal (LS) area (of a kind known to spare theta) and were compared to sham-operated controls in three experiments in the straight alley with food reward on continuous (CRF) or partial (PRF) reinforcement and inter-trial intervals of 3-8 min. With 6 acquisition trials MS lesions increased resistance to extinction and enhanced the partial reinforcement extinction effect (PREE). With 48 acquisition trials MS lesions did not alter resistance to extinction after either CRF or PRF training, but LS lesions abolished the PREE by increasing resistance to extinction in rats trained with CRF and decreasing it in rats trained with PRF. With 96 acquisition trials LS lesions were without effect on resistance to extinction after either CRF or PRF training, as previously reported by Henke (1974) using total septal lesions. Thus the impairment in the PREE previously shown after large septal lesions is due to damage to the lateral, not the medial, septal area.     

Partial Reinforcement in Appetitive Pavlovian Conditioning with Rats

Four experiments examined the effects of a partial reinforcement schedule on extinction using appetitive Pavlovian conditioning. Extinction was slower after partial than after continuous reinforcement when the schedules were administered to different groups (Experiment 1). The opposite result was found in Experiments 2 and 3 when both schedules were presented to the same group in the same context. When the schedules were presented to the same group in different contexts, then extinction was again slower after partial reinforcement (Experiment 3). Experiment 4 demonstrated that a change of context facilitates extinction to a greater extent after conditioning with a partial reinforcement schedule than with a continuous one. The results are explained by assuming that the nonreinforced trials of a partial reinforcement schedule create an internal state that serves as a contextual cue.     

Durable partial reinforcement effects and social dominance in the rat

Following partial reinforcement (PRF) or consistent reinforcement (CRF) of an approach response in a straight runway and experimental extinction, rats were given the arena food-dominance test in Experiment 1 and both the arena test and the tunnel-dominance test in Experiment 2. PRF subjects were dominant in the tunnel test, but subordinate in the arena test, regardless of which dominance test was given first. These durable and pervasive effects of partial reinforcement training can be interpreted in terms of frustration theory.     

Resistance to change and relapse of observing

Four experiments examined relapse of extinguished observing behavior of pigeons using a two-component multiple schedule of observing-response procedures. In both components, unsignaled periods of variable-interval (VI) food reinforcement alternated with extinction and observing responses produced stimuli associated with the availability of the VI schedule (i.e., S+). The components differed in the rate of food arranged (Rich = VI 30 s; Lean = VI 120 s). In Experiment 1, following baseline training, extinction of observing involved removal of both food and S+ deliveries, and reinstatement was examined by presenting either response-independent food or S+ deliveries. In Experiment 2, extinction involved removal of only food deliveries while observing responses continued to produce S+. Reinstatement was examined by delivering food contingent upon the first two food-key responses occurring in the presence of the S+. Experiment 3 assessed ABA renewal of observing by extinguishing food-key and observing responses in the presence of one contextual stimulus (i.e., B) and then returning to the original training context (i.e., A) during continued extinction. Experiment 4 examined resurgence by introducing food reinforcement for an alternative response during extinction, and subsequently removing that alternative source of food. Across experiments, relative resistance to extinction and relapse of observing tended to be greater in the component previously associated with the higher rate of primary reinforcement. Relapse of observing or attending to stimuli associated with primary reinforcement appears to be impacted by frequency of primary reinforcement in a manner similar to responding maintained directly by primary reinforcement.