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Does recovery from reward devaluation or partial reinforcement (PR) involve the counterconditioning of frustration? Transfer among tasks involving reward loss was used to uncover frustration counterconditioning. In Experiment 1, Phase 1 training in consummatory successive negative contrast (cSNC; 32-to-4% sucrose devaluation) eliminated Phase 2 iSNC in one-way avoidance (40-to-3 s safety-time reduction), but the opposite sequence generated no detectable transfer. In Experiment 2, transfer from Phase 1 cSNC to Phase 2 autoshaping extinction after continuous reinforcement increased lever pressing in previously downshifted animals relative to unshifted controls. However, Phase 1 training in autoshaping under partial reinforcement (PR) had no effect on Phase 2 cSNC. Transfer from PR to cSNC also failed when sucrose pellets were used in autoshaping (Experiment 3), when autoshaping acquisition was extended from 100 to 300 trials (Experiment 4), and when preshift training in cSNC was extended from 10 to 20 sessions (Experiment 5). In Experiment 6, Phase 1 training in PR for licking enhanced Phased 2 cSNC, also involving licking, and in Experiment 7 Phase 1 PR training in autoshaping enhanced Phase 2 cSNC after a 22-to-4% sucrose downshift. Whereas prior exposure to cSNC (consummatory task) increased resistance to extinction in autoshaped lever pressing, prior training in one-way avoidance, PR in autoshaping, or PR in taste conditioning (all anticipatory tasks) either had no effect or they enhanced the cSNC effect. Frustration counterconditioning developed during these tasks, but the type of transfer effect depends on task sequence.

Two experiments were conducted to examine whether using e-cigarettes with occasional use of regular cigarettes prevented relapse after extinction. In Experiment 1 (ABAC with a multiple-baseline design), six short-term smokers who wanted to stop smoking were asked to use e-cigarettes and were allowed to smoke 20 % of the usual number of regular cigarettes per day during the partial reinforcement period. Experiment 1 demonstrated that using e-cigarettes reduced the amount of smoking even after extinction. In Experiment 2 (ABAB design), which involved a single long-time smoker and partial reinforcement, the participant was unable to maintain low rates of smoking after the experiment. However, the excessive smoking (regular cigarettes > 15 per day) observed before the experiment was prevented. This study suggested that a partial reinforcement procedure (occasionally smoking cigarettes) prevented relapse after extinction without hardship in some smokers.

Experiments 1 and 2 involved independent groups that received primary reinforcement after a correct match with a probability of 1.0, .50 or .25. Correct matches that did not produce primary reinforcement produced a conditioned reinforcer. Both experiments revealed little evidence that acquisition or retention was adversely affected by use of intermittent reinforcement. Experiment 3 involved a group that received 100% reinforcement and two others that received 25% reinforcement, one of which received conditioned reinforcement and the other did not. Following acquisition and retention testing, birds in group 100% and group 25% with conditioned reinforcement were exposed to 25% reinforcement and no conditioned reinforcement. Results revealed that conditioned reinforcement was important in promoting acquisition but was irrelevant in maintaining performance. It was concluded that intermittent reinforcement, especially when combined with conditioned reinforcement during acquisition, supports levels of acquisition and retention comparable to that of continuous reinforcement. Theoretically, the findings are consistent with an extension of Blough's instance-based theory of discrimination performance and, practically, they suggest that use of intermittent reinforcement could result in increased efficiency and economy in labs using delayed matching.

The memories of the unconditioned stimulus (US) and its absence (No US), symbolized as S R and S N , respectively, may be retrieved on US or No US trials giving rise to four types of associations, S R → US, S R → No US, S N → US, and S N → No US. Here, following acquisition under partial reward (PRF), rats were shifted either to different schedules of PRF (Experiment 1) or extinction (Experiments 1 and 2). Inhibitory S R → No US associations formed in acquisition survived extinction and shifts to one, but not another type of PRF schedule (Experiments 1 and 2). Excitatory S R → US associations also survived extinction (Experiment 2). These findings, as well as the acquisition findings of Experiment 2, are consistent with the sequential model but not with the only other two theories said to be able to explain PRF findings, the frustration hypothesis of Amsel and the attention hypothesis of Mackintosh [see Haselgrove, M., Aydin, A., & Pearce, J. M. (2004). A partial reinforcement extinction effect despite equal rates of reinforcement during Pavlovian conditioning. Journal of Experimental Psychology: Animal Behavior Processes , 30 , 240–250]. Also, the reacquisition findings obtained here are inconsistent with two views applied to several learning phenomena, the rule-learning view and the position-item view.

When reinforcer rates are manipulated in within-subjects designs, persistence in subsequent extinction trials is sometimes greater to the response alternative associated with the higher reinforcer rate (“reversed” partial reinforcement extinction effect, RPREE). The RPREE is often held to be a contradiction to the conventional PREE. To explore the interaction between these effects, student subjects were exposed to a multiple high-density and low-density reinforcement schedule, then to extinction conditions. Subjects in two control conditions received the high- and low-density schedules only. For all groups, general extinction persistence was elevated, and a within-subjects RPREE occurred under the multiple schedule. The RPREE was caused by the low-density component increasing persistence to the high-density component; the high-density component did not decrease persistence to the low-density component. These results support the view that the RPREE may be a within-subjects effect of the conventional PREE.

Three experiments with rats examined reacquisition of an operant response after either extinction or a response-elimination procedure that included occasional reinforced responses during extinction. In each experiment, reacquisition was slower when response elimination had included occasional reinforced responses, although the effect was especially evident when responding was examined immediately following each response-reinforcer pairing during reacquisition (Experiments 2 and 3). An extinction procedure with added noncontingent reinforcers also slowed reacquisition (Experiment 3). The results are consistent with research in classical conditioning (Bouton, M. E., Woods, A. M., & Pineno, O. (2004). Occasional reinforced trials during extinction can slow the rate of rapid reacquisition. Learning & Motivation, 35 , 371–390) and suggest that rapid reacquisition after extinction is analogous to a renewal effect that occurs when reinforced responses signal a return to the conditioning context. Clinical implications are also discussed.

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.

Sequential theory’s memory model of learning has been successfully applied in response contingent instrumental conditioning experiments ( Capaldi, 1966 , Capaldi, 1967 , Capaldi, 1994 , 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 , 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.

In both discrimination learning and partial reinforcement, transitions may occur from nonrewarded to rewarded trials (NR transition). In discrimination learning, NR transitions may occur in two different stimulus alternatives (NR different transitions). In partial reward, NR transitions may occur in a single stimulus alternative (NR same transitions). Available instrumental learning data indicate that resistance to extinction is increased by both types of NR transitions following limited acquisition training. Following more extensive acquisition training, resistance to extinction appears to be increased by NR same transitions but not by NR different transitions. In Experiment 1, it was shown for the first time that following extensive acquisition training the effects of the two types of transitions are the same in the Pavlovian situation as in the instrumental situation. This finding indicates that on the current trial the rat remembered the conditioned stimulus (CS) and the unconditioned stimulus (US) from the prior trial and those memories along with the CS on the current trial become the signal for the current US. Experiments 2 and 3, which tested hypotheses about instrumental learning, identified why NR different transitions lose their capacity to promote vigorous responding following extensive acquisition training. This is because cues occurring on the rewarded trials of NR different transitions more validly signal reward than other situational cues and thus overshadow them. Finally, some implications of the present findings for understanding the role of NR different transitions in discrimination learning situations were discussed.

Two appetitive conditioning experiments with rats examined reacquisition after conditioned responding was eliminated by either extinction or by a partial reinforcement procedure in which reinforced trials were occasionally presented among many nonreinforced trials. In Experiment 1, reacquisition to a conditional stimulus (CS) that had been conditioned and extinguished was more rapid than acquisition in a group that had received no prior conditioning. However, the addition of occasional reinforced trials to extinction slowed this rapid reacquisition effect. Experiment 2 replicated the result and showed that a procedure in which the CS and the unconditional stimulus (US) were unpaired in extinction interfered even further with reacquisition. The results suggest that rapid reacquisition is ordinarily produced when reinforced trials provide a contextual cue that can renew responding by signaling other acquisition trials ( Ricker & Bouton, 1996 ). The effects of partial reinforcement in extinction are surprising from several theoretical perspectives and have useful clinical implications.

Rats given access to a 32% sucrose solution later reject a 4% solution significantly more than controls that have only received the 4% solution. In Experiment 1, this consummatory successive negative contrast (cSNC) effect was attenuated by previous exposure to 50% partial reinforcement. Furthermore, recovery from cSNC was also facilitated by partial reinforcement. In Experiment 2, the attenuating effects of partial reinforcement on cSNC were eliminated by administration of the benzodiazepine anxiolytic chlordiazepoxide (5 mg/kg) before nonreinforced trials. In Experiment 3, the attenuating effect of partial reinforcement was greater after a shift from 32 to 6% solution, than after a shift from 32 to 2% solution. The parallels between the effects of partial reinforcement on consummatory and instrumental behavior are discussed. Fil: Pellegrini, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Muzio, Ruben Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Mustaca, Alba Elisabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina Fil: Papini, Mauricio Roberto. Texas Christian University; Estados Unidos

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.

Rats were trained in a sign-tracking procedure in which the percentage of CS presentations paired with the US was either 40 or 80%. Occasional unpaired US presentations did or did not occur during the ITI. When no ITI reinforcers occurred, the rate of acquisition was similar for the two percentage reinforcement conditions, but only when measured in terms of the number of CS–US pairings, not the number of trials. When ITI reinforcers were added, acquisition rate was generally retarded but more so with the smaller percentage of reinforcement. Thus, invariance in reinforcements to acquisition occurs in Pavlovian conditioning only in the absence of background reinforcers. This result conflicts with the findings of Williams (1989) using a successive discrimination procedure and thus suggests that simple conditioning and discrimination learning have different properties with respect to partial reinforcement.

In Experiment 1 the sequence of trials to the positive (S+) and negative (S−) discriminanda was varied between groups during acquisition and reversal of a successive brightness discrimination. In Experiments 2 and 3, groups received different reward sequences in Phase 1 within S+. In general, groups given transitions from nonrewarded trials to rewarded trials (N-R transitions) in Phase 1 learned both the original discrimination and its reversal more slowly than groups given schedules devoid of N-R transitions. The results were discussed in relation to previously reported effects of partial reinforcement on acquisition and reversal of a discrimination and the role of sequential variables and internal, reward-produced cues in discrimination learning, reversal learning, and nonreversal shifts.

In two experiments 68 rats were trained to bar press or run down a straight runway for food or for water under conditions of either continuous reinforcement or partial reinforcement. In both experiments, there was greater persistence of behavior which had been reinforced with food than with water. In Expt 2, the partial reinforcement extinction effect (PREE) was observed with food reward, but not with water. Within the context of the experimental procedures used, it can be concluded that the rat has mechanisms for developing persistence which are dependent on the specific motivational system involved. This conclusion is related to theories of partial reinforcement effects and to possible biological origins of the mechanisms.

In the first experiment rats experienced large or small magnitude of negative reinforcement (shock reduction) in a straight alley. Half of the subjects in each magnitude group received continuous reinforcement, and the other half received a 50% partial reinforcement schedule (nonreinforcement consisting of no shock reduction in the goal box). In extinction the groups were ordered: large partial > small-partial > small-continuous > large-continuous. In the second experiment rats received large, small and nonreinforcement in various sequences using the runway-negative reinforcement procedure and were ordered: SNL>LNL>SNL>LNS in resistance to extinction (letters represent the magnitudes in the sequence experienced in acquisition). The results of these experiments indicate a commality between positive and negative reinforcement with respect to behavioral phenomena and theoretical accounts of those phenomena.

The present experiments were conducted to investigate the effects which changes in reinforcement schedule and criterion response have on the persistence of learned responses. In Experiment 1, subjects were required to learn concurrently two tasks. Both tasks involved making one of four possible responses for reinforcement. During the first acquisition phase subjects received either continuous (CRF) or partial (PRF) reinforcement for both tasks. At the start of the second acquisition phase, the criterion response for both tasks was changed. In addition, reinforcement schedules were altered such that some subjects experienced (a) the same schedule of reinforcement as in Phase 1 on both tasks, (b) the alternate schedule of reinforcement on both tasks (i.e., CRF to PRF, and PRF to CRF), or (c) a change in schedule of only one task (e.g., CRF on one task and PRF on the other) during Phase 2. Following Phase 2 all reinforcement was withheld, and the persistence of the most recently learned response was monitored. It was found that subjects who had received CRF during Phase 1 evidenced a conventional partial reinforcement extinction effect (PREE) when they received only CRF or PRF during Phase 2, whereas subjects receiving both schedules evidenced a generalized PREE. However, there were no significant differences among groups receiving PRF during Phase 1. In the second experiment, a comparison of resistance to extinction was made between continuous and partial reinforcement schedules with and without a change in the criterion response. The results demonstrate that a change in criterion response diminished the level of persistence of the most recently learned response. The data are reviewed with reference to current theories of persistence and to the extinction-induced resurgence phenomenon.

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.

Two experiments investigated the effects of shifting from either nonreinforcement or partial reinforcement (PRF) to continuous reinforcement conditions (CRF). In the first experiment, three groups of rats were given food reinforcement under CRF conditions in a runway followed by regular extinction trials (RE), extinction trials where Ss were delayed for 30 sec before entering the empty goal box (DE), or CRF trials where Ss were delayed for 30 sec before entering the baited goal box (DF). Then all Ss were run on the delayed reinforcement condition (DF). In the final delayed reinforcement condition, group DE ran significantly faster than group DF, reflecting positive contrast. In the second experiment, four groups of rats were trained in a runway to receive either 4% or 18% sucrose reinforcers under either PRF or CRF conditions. Then all Ss were transferred to a Skinner box and bar presses were continuously reinforced, with each S continuing to receive the same sucrose concentration as before. The former PRF Ss, regardless of the reinforcer, bar pressed at a significantly higher rate in the Skinner box than the former CRF Ss. The evidence seemed to favor the view that the effectiveness of a reinforcer is not an absolute, unchanging quantity but rather depends on the historical context in which the reinforcer occurs.

To assess the cue as opposed to incentive effect of reward, rats were trained on an easy visual discrimination with food contingent on 50 or 100% of the correct responses, and white-noise contingent on 0, 50 or 100% of these responses. Additionally, the 50% food and noise schedules were structured for different groups to produce positive, zero, or negative correlations of the two events. Although the addition of noise did not affect learning with 100% food, the slower learning observed with 50% food was increasingly offset by greater percentages of noise, with the 50% groups showing faster learning under the negative than zero correlation and faster under the zero than positive correlation. Together with supporting speed data, these results indicate that a “neutral” stimulus can be substituted for food with little loss in performance. Consequently, the reinforcing effect of food is attributed in part to its function as a cue which, like noise, can increase the discriminability of the alternatives and provide information about the correctness of the response.

Twelve continuously reinforced rats were extinguished in a modified operant chamber, with an S D for goal-approach after each bar-press. Three groups of twelve rats each trained under FR 10 were extinguished with the S D for goal-approach after every 6, 10, or 14-bar-presses, respectively. Results showed: (1) number of bar-presses to extinction was a direct function of the bar-press to S D ratio during extinction, (2) number of food or goal-approaches was independent of both training and extinction conditions, and (3) prior to the breakdown in discrimination a revised response-unit hypothesis, based on a discrimination analysis of the effect of intermittent reinforcement, accurately predicted the number of bar-presses for each FR group.

The hypothesis that latent inhibition could be reduced by extinguishing the experimental context, that is, exposing the rats to the context between exposure to the conditional stimulus (CS) and conditioning, was tested. All experiments used the conditioned emotional response procedure. In Experiment 1, extinction was not effective when the animals were exposed to the clicker 40 times off the baseline of responding for food and when the clicker CS was partially reinforced with shocks during the test phase. In Experiments 2 and 3, latent inhibition could be reduced by extinction if the animals were exposed to the CS 24 or 16 times on-baseline, and if continuous reinforcement was used during the test. In Experiments 4, 5, and 6, we attempted to determine which variable was responsible for the discrepant results. In Experiment 4, extinction was effective with 20 or 40 on-baseline exposures to the CS, using continuous reinforcement during the test. In Experiment 5, extinction was not effective with exposure on- or off-baseline, using 24 exposures and partial reinforcement. Finally, in Experiment 6, extinction reduced latent inhibition using continuous, but not partial, reinforcement with 40 exposures off-baseline. From these results, we concluded that Wagner's model of habituation was not sufficient to account for latent inhibition and that a hybrid model, using both associative and cognitive representational processes, was necessary.

Four experiments are reported which demonstrate the importance of the reinstatement of retrieval cues in partial-reinforcement experiments using spaced trials. Reinstatement occurs when the goalbox and startbox are of the same brightness (gray). Nonreinstatement occurs when the goalbox and startbox are of different brightnesses (black-and-white striped vs gray). Under reinstatement conditions, both a partial-reinforcement effect (PRE) and N-length effects were observed whether small reward or large reward was used. Under nonreinstatement conditions, a PRE was observed when large reward was used but not when small reward was used; N-length effects were not observed either with large or small reward. Finally, using a 24-hr intertrial interval, single alternation patterning was found only with a group receiving large reward, a long nonreward confinement duration, and reinstatement. These results are not consistent with the notion that massed and spaced trials are governed by separate mechanisms, and support an explanation of both massed and spaced trials based on E. J. Capaldi's sequential theory.

A within-subject partial reinforcement extinction effect was obtained in a conditional discriminative choice task. In choice acquisition, one group had learned a task in which one choice alternative was continuously reinforced (CRF) and the other alternative was partially reinforced (PRF). Most errors in the acquisition phase were the choosing of the CRF lever when the conditional stimulus signaled the PRF lever; in extinction this pattern of choice errors reversed. In extinction, most errors were choosing of the PRF lever when the conditional stimulus signaled the CRF lever. The predictions of frustration theory and sequential theory were compared with the choice data. The results were interpreted as consistent with the anticipatory frustration construct within an associative mediational theory.

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.

In contrast to a recent finding ( Macdonald, G. E., & De Toledo, L. Learning and Motivation , 1974 , 5 , 288–298.) the results of three experiments investigating various partial reinforcement (PRF) manipulations under conditions of thirst motivation demonstrated strong similarity to analogous manipulations involving food reward. Specifically, for animals receiving water reinforcement, PRF was shown to generate greater resistance to extinction than continuous reinforcement (Expt 1 & 3), the schedule of reinforcement was shown to interact with level of acquisition (Expt 1 and 2), and the magnitude of the partial reinforcement extinction effect was shown to be a function of reward magnitude (Expt 3). These results provide strong evidence that mechanisms which operate in partial reinforcement situations are highly similar, regardless of the type of appetitive reinforcement.

In Experiment 1, pigeons were autoshaped to two stimuli (A and B) each followed by delayed reinforcement on 50% of trials. A different stimulus (X) was presented in the interval between stimulus A and reinforcement (A-X-US) and not when stimulus A was nonreinforced (A---). The X stimulus was also presented following the stimulus B trials that were nonreinforced (B-X) and was absent when stimulus B was reinforced (B---US). Not only was the response rate to A higher, but so was the rate in the intervals immediately following A, whether or not these intervals contained X. This latter finding is inconsistent with the interpretation that pigeons discriminated between X when it followed A and when it followed B and leaves open the possibility that X acts as a “catalyst”. The same general design was employed in Experiment 2 as was used in Experiment 1 with the exception that the catalytic function of X was equated for A and B by presenting reinforcement on B-X trials. The A stimulus, however, still generated the higher response rate. A new interpretation is offered that suggests that variable reward magnitude will maintain attention to a stimulus and that attention will generate keypecking.

The effects of various probabilities of reinforcement on the persistence of learned behaviors were examined to investigate the generalization of persistence effects and other aspects of extinction behaviors observed in humans. Subjects were required to perform two tasks concurrently. Both tasks required the subject to make one of four responses for reinforcement. Performance for each task was reinforced using one of three schedules of reinforcement: 100, 60, or 40% probability of contingent reinforcement. Three of the groups received the same schedule of reinforcement for both tasks, (groups 100 100 , 60 60 , and 40 40 ). The other six groups experienced a combination of two different schedules (groups 100 60 , 60 100 , 100 40 , 40 100 , 60 40 , and 40 60 ). Both acquisition and extinction data suggest that there is a generalization of persistence across tasks. The data also confirm the presence of different extinction phases for tasks of this type, a short-term and a long-term phase. The short-term phase is characterized by a decrease in responding that is inversely related to reinforcement schedules. During the long-term phase, the rate of responding remained above chance levels, and a reemergence of the formerly reinforced response was observed as extinction continued. The duration of these phases appears to be related to the average of reinforcement schedules experienced in acquisition.

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.

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.

Conditioned lick suppression by water-deprived rats was used to investigate the phenomenon of superconditioning. In Experiment 1, animals received explicitly unpaired conditioned inhibition training with CS A or CS B and a footshock US. Both groups then received pairings of a CS A-light compound with shock. In testing, animals for which CS A was inhibitory displayed enhanced responding to the light, relative to animals for which CS A was associatively neutral. Thus, superconditioning relative to the conventional control group was demonstrated. However, an additional control group that first received inhibitory training with CS A and then the light alone paired with shock exhibited as much suppression to the light as the superconditioning group. This control, which was omitted from previous demonstrations of superconditioning, suggests that superconditioning is merely attenuated overshadowing of the added element by CS A as a result of prior inhibitory training with CS A. In Experiment 2, superconditioning was not obtained when partial reinforcement of CS A occurred during negative contingency training, despite the fact that in prior research the identically trained CS A had passed both summation and retardation tests for inhibition. In Experiment 3, exposure to CS A alone (i.e., latent inhibition treatment) sufficed to produce a superconditioning-like effect with respect to the light when the CS A-light compound was later paired with shock. In Experiment 4, conditioned inhibition and latent inhibition treatments of CS A were found to yield equivalent superconditioning-like effects with respect to the added element. Collectively, these studies suggest that superconditioning arises from a reduction in overshadowing and a comparable effect can be obtained through any initial treatment that diminishes the associability of the overshadowing CS.

Rats received either partial reward (PR) or partial delay (PD) in acquisition with one, two, or three delay or nonreward trials followed by an immediately rewarded trial or one delay or nonreward trial followed by an immediately rewarded trial. These four groups were then split in half and given either continuous delay or continuous nonreward (extinction) in a “response persistence” phase. In addition, two continuously reinforced groups, one experiencing continuous delay, and the other experiencing extinction were included. The results showed that response persistence was greater when PD groups were given continuous delay rather than extinction, but the opposite was true for PR groups. The “length” (1, 2, or 3 versus 1 nonreward or delay trial) also transferred to the response persistence phase with the length 1, 2, and 3 conditions being more persistent than the 1 length conditions. The results were discussed with respect to theoretical notions of response persistence.

In Experiment I acquisition and extinction of instrumental escape conditioning with rats (N = 64) were studied as a function of reinforcement magnitude under conditions of partial and continuous reinforcement. In Experiment II the effects of partial and continuous reinforcement were studied in rats (N = 96) during acquisition followed by small, medium, and large reductions in reinforcement magnitude. A water-tank escape apparatus was used with temperature as the relevant variable. It was found that (1) with large reinforcement magnitude a continuously reinforced group was superior in acquisition to one that was partially reinforced; there were no differences with small reinforcement; (2) disruptive effects of a nonreinforced trial (a) appear early in learning, (b) are quite strong after each nonreinforced trial, and (c) persist through several succeeding reinforced trials; (3) major competing behaviors persist throughout acquisition for small reinforcement magnitude regardless of schedule, decline with large reinforcement (more so with continuous than with partial), and return to a high level in extinction for all conditions; (4) the partial reinforcement extinction effect occurs after large reinforcement but not after small, and it appears only with large reductions in reinforcement magnitude which approach extinction conditions. Only the first part of the last finding appears to be consistent with the appetitive conditioning literature.

In two runway investigations, rats received reinforced trials and punished nonreinforced trials in acquisition followed by punished extinction. The major findings may be summarized as follows; the larger the reinforcement occurring on trials following punishment trials, the faster was running in acquisition, particularly toward the goal section, and the faster was running in punished extinction, particularly toward the start section. These findings are both similar to and different from previous findings employing analogous schedules of partial reinforcement (unpunished nonreinforcement). These similarities and differences may be understood, it was suggested, by considering simultaneously the conditions under which punishment stimuli acquire control over and thus elicit instrumental reactions, and the response suppressive properties of nonreinforcement and of punished nonreinforcement, respectively, as a function of two variables, density of nonreinforcement trials or punished nonreinforcement trials, and section of the runway.

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.

Two hundred rats served as Ss in an investigation of the effects of partial reinforcement on conditioned heart rate deceleration. These effects were examined with stimulus-generalization decrement and motivational level controlled. Continuous reinforcement (100%) was compared with three kinds of 50% random partial reinforcement: (a) “standard” partial reinforcement; (b) a condition where the unconditioned stimulus (US) was interpolated at the midpoint of the intertrial interval on nonreinforced trials; and (c) a treatment where the conditioned stimulus (CS) was interpolated on nonreinforced trials. For extinction the acquisition treatments were combined factorially with: (a) US-present or US-absent; and (b) US-interpolated or CS-interpolated procedures. Partial reinforcement failed to produce increased resistance to extinction. Presence of the US on nonreinforced trials in acquisition and extinction depressed performance. The results were interpreted as providing support for a contingency model of conditioning.

A block of continuously reinforced nonpunished trials was interpolated between acquisition of a runway response with either partial reinforcement or intermittent punishment and subsequent tests for resistance of that response to the suppressive effects of either extinction or continuous punishment. As previous investigations have shown, both the partial reinforcement effect (PRE) and the intermittent punishment effect (IPE) were sustained through the block of continuously reinforced nonpunished trials. Furthermore, the increased resistance to extinction following intermittent punishment and the increased resistance to punishment following partial reinforcement were also sustained through the interpolated continuous reinforcement. These results support a hypothesized similarity of punishment and frustrative nonreward and were interpreted in an extension of Amsel's conditioning model theory of the role of nonreinforcement in the PRE.

Continuous, random 50%, and single alternation (SA) schedules of reinforcement were employed in an investigation of classical appetitive conditioning of the jaw movement response in the rabbit. It was found that: ( a ) random 50% and SA reinforcement schedules led to lower levels of acquisition performance than continuous reinforcement; ( b ) evidence of response patterning to the SA schedule appeared only within and not across acquisition sessions; and ( c ) extinction performance decreased at a faster rate under continuous than under the partial reinforcement schedules. The findings are discussed with regard to Spence's (1960) account of partial reinforcement effects in instrumental reward conditioning, and Capaldi's (1966) sequential hypothesis of partial reinforcement extinction effects.

Two experiments evaluated the possibility that prior discrimination training on red versus green would block the development of stimulus control by tone versus noise when both stimulus dimensions simultaneously predicted reinforcement. The key pecking response of pigeons was used in a discriminated trial procedure. In Phase 1 of Exp. I, Group D learned a go no -go discrimination based on red versus green, Group N was not run, Group R received reinforced trials only, and Group P received partial reinforcement. In Phase 2, all groups learned a go no -go discrimination based on tone-plus-red versus noise-plus-green. When tested after Phase 2, Group D showed less auditory control than any other group. The difference between Groups D and P was confirmed in Exp. II. These results show that blocking occurred, while ruling out a number of other factors that may have caused apparent blocking in previous experiments.

In the first of two experiments, four groups of 10 rats each were given 50 trials of one-way avoidance training and 150 extinction trials. The independent variable was π, the conditional probability of shock given a failure to respond within 5 sec after the onset of the CS. The values of π for the four groups were 1.0, 0.7, 0.4, and 0.1. A second experiment was a replication with 20 rats per group receiving 200 extinction trials after at least 100 training trials. During acquisition smaller values of π resulted in slower learning, but all groups seemed to reach the same asymptotic response level of over 95% avoidance. The number of shocked errors was approximately the same for all groups independent of π. During extinction, no partial reinforcement effect was observed. Only 30 to 50% of the animals extinguished in 150 or 200 trials, and there were no orderly differences in extinction as a function of the value of π during acquisition.

In order to investigate the hypothesis that rats discriminate nonreinforced goal-box placements from runway trials and to show that such differentiation can affect resistance to extinction, animals received partial reinforcement during acquisition and placements to an unbaited goal box either ( a ) positively, ( b ) negatively, or ( c ) randomly related to reinforced runway (R) trials. During acquisition, animals in conditions a and b ran faster on R trials than on nonreinforced runway trials. The subjects in condition c showed the greatest resistance to extinction. Reinstatement of the placement procedure after extensive extinction testing produced an immediate increment in runway performance for the animals in condition a . These results clearly indicated that rats are capable of differentiating placement events from runway trials, and that such differentiation can affect resistance to instruction.

When a stimulus signals the availability of reward the information transmitted by it is assumed to enhance the reinforcing value of the stimulus. And when a stimulus signals nonreward its transmitted information is assumed to be punishing. Qualitative and quantitative derivations from these principles account for the emission of observing responses and some associated data not explained by other hypotheses. These principles are also shown to account for the fact that animals trained on partial reinforcement in the straight runway may run faster than those trained on consistent reinforcement ( Goodrich, 1959 ).