Overshadowing and associability change.

Three appetitive Pavlovian conditioning experiments with rats examined the associability of stimuli A and B that had a history of compound conditioning (AB+), relative to stimuli X and Y that had a history of conditioning in isolation (X+, Y+). Following this training, Experiment 1 revealed that conditioned responding was higher to X and Y than to A and B (overshadowing). In a subsequent AY+, AX?, BY? test discrimination, the AY/BY discrimination was solved more readily than the AY/AX discrimination. In Experiment 2, following AB+, X+, Y+ training, A and Y were presented as a compound and signaled the availability of reinforcement upon the performance of an instrumental response. Test trials in which A and Y were presented alone, and in extinction, revealed that A acquired greater control of instrumental responding than Y. Experiment 3 revealed that following AB+, X+, Y+ training, A and B served as more effective discriminative stimuli for instrumental responding than X and Y. Overall, these results imply that the associability of stimuli conditioned in compound is higher than stimuli conditioned in isolation. These results are discussed in terms of attentional theories of associative learning. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Are associative changes in acquisition and extinction negatively accelerated?

Performance to a conditioned stimulus typically shows a negatively accelerated change with Pavlovian conditioning or extinction. This is commonly attributed to negatively accelerated changes in the underlying associative learning. However, the absence of well-specified rules for mapping learning into performance makes it difficult to infer changes in the size of associative changes for stimuli occupying different points on the performance scale. This problem can be addressed by comparing responding to stimulus compounds, each consisting of 2 stimuli, 1 of which is poorly conditioned and 1 of which is well conditioned, when either the former or the latter receives a specified amount of additional training. This permits comparison at a common performance level. Two magazine-approach experiments in rats and 2 autoshaping experiments in pigeons used this technique to assess the form of the associative changes in acquisition and extinction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of Pavlovian and instrumental incentive learning under dopamine antagonists.

The administration of the dopamine antagonists, pimozide and α-flupenthixol, to rats reduced Pavlovian–instrumental transfer when a conditioned stimulus (CS) that had been paired with a noncontingent food reward was tested on instrumental performance. The administration of the antagonists during Pavlovian conditioning and/or testing abolished the enhancement of instrumental performance by the CS. The effect of both antagonists on instrumental incentive learning was then examined. After training in which the rats performed 2 responses for different food rewards, they consumed 1 type food under the antagonists and the other type under vehicle during reexposure. When instrumental responding was subsequently tested in extinction, performance was unaffected by whether the rats had been reexposed to the training reward under the antagonists. These results suggest that Pavlovian and instrumental incentive learning are not mediated by a common process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modulation by the stimulus properties of excitation

Three experiments with pigeons investigated the role of excitation in a Pavlovian modulatory paradigm where the reinforcement contingencies of a conditioned stimulus (CS) were signaled by modulatory stimuli. In Experiment 1, excitatory training of the modulator that signaled reinforcement, the positive modulator, had a greater facilitative impact on discrimination learning than did excitatory training of both modulators. Although this could have resulted from simple excitatory summation, Experiment 2 revealed that excitatory training of the negative modulator also enhanced learning more than did excitatory training of both modulators. In Experiment 3, responding to CSs that had come under the control of differentially excitatory modulators was similarly controlled by new stimuli that had received simple differential excitatory training. Results suggest that excitation can play a modulatory role in Pavlovian conditioning.     

Pavlovian to instrumental transfer of control in a human learning task.

Pavlovian learning tasks have been widely used as tools to understand basic cognitive and emotional processes in humans. The present studies investigated one particular task, Pavlovian-to-instrumental transfer (PIT), with human participants in an effort to examine potential cognitive and emotional effects of Pavlovian cues upon instrumentally trained performance. In two experiments, subjects first learned two separate instrumental response-outcome relationships (i.e., R1-O1 and R2-O2) and then were exposed to various stimulus-outcome relationships (i.e., S1-O1, S2-O2, S3-O3, and S4-) before the effects of the Pavlovian stimuli on instrumental responding were assessed during a non-reinforced test. In Experiment 1, instrumental responding was established using a positive-reinforcement procedure, whereas in Experiment 2, a quasi-avoidance learning task was used. In both cases, the Pavlovian stimuli exerted selective control over instrumental responding, whereby S1 and S2 selectively elevated the instrumental response with which it shared an outcome. In addition, in Experiment 2, S3 exerted a nonselective transfer of control effect, whereby both responses were elevated over baseline levels. These data identify two ways, one specific and one general, in which Pavlovian processes can exert control over instrumental responding in human learning paradigms, suggesting that this method may serve as a useful tool in the study of basic cognitive and emotional processes in human learning. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Effects of discrimination training on responding during a compound conditioned stimulus.

Four experiments examined responding in the presence of a triple-element compound ABC after discrimination training in which 2 compounds, AB and BC, signaled the delivery of food and 1 element alone, B, signaled the absence of food. In Exps 1 and 2, using rats, responding during ABC was more vigorous than in a control group for which A and C but not B had been individually paired with food. This finding was replicated in Exp 3, which used pigeons, and in Exp 4, where all 3 stimuli of the control condition were individually paired with food. The results are more consistent with a configural than with an elemental theory of learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retraining of extinguished Pavlovian stimuli.

Five Pavlovian magazine approach experiments with rat subjects examined the mechanism by which reconditioning restores extinguished responding. Experiments 1, 2, and 3 found that retraining did not destroy the spontaneous recovery with the passage of time that is characteristic of extinguished stimuli. Experiments 4 and 5 found evidence that retraining after extinction enhanced the strength of the originally trained associations. Together these results suggest that, just as extinction does not destroy original acquisition but superimposes some decremental process, so retraining does not destroy that decremental process but instead superimposes further associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned inhibition produced by extinction-mediated recovery from the relative stimulus validity effect: A test of acquisition and performance models of empirical retrospective revaluation.

Empirical retrospective revaluation is a phenomenon of Pavlovian conditioning and human causal judgment in which posttraining changes in the conditioned response (Pavlovian task) or causal rating (causal judgment task) of a cue occurs in the absence of further training with that cue. Two experiments tested the contrasting predictions made by 2 families of models concerning retrospective revaluation effects. In a conditioned lick-suppression task, rats were given relative stimulus validity training, consisting of reinforcing a compound of conditioned stimuli (CSs) A and X and nonreinforcement of a compound of CSs B and X, which resulted in low conditioned responding to CS X. Massive posttraining extinction of CS A not only enhanced excitatory responding to CS X, but caused CS B to pass both summation (Experiment 1) and retardation (Experiment 2) tests for conditioned inhibition. The inhibitory status of CS B is predicted by the performance-focused extended comparator hypothesis (J. C. Denniston, H. I. Savastano, & R. R. Miller, 2001), but not by acquisition-focused models of empirical retrospective revaluation (e.g., A. Dickinson & J. Burke, 1996; L. J. Van Hamme & E. A. Wasserman, 1994). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of D-cycloserine on the extinction of appetitive operant learning.

Four experiments with rat subjects examined whether D-cycloserine (DCS), a partial NMDA agonist, facilitates the extinction of operant lever-pressing reinforced by food. Previous research has demonstrated that DCS facilitates extinction learning with methods that involve Pavlovian extinction. In the current experiments, operant conditioning occurred in Context A, extinction in Context B, and then testing occurred in both the extinction and conditioning contexts. Experiments 1A and 1B tested the effects of three doses of DCS (5, 15, and 30 mg/kg) on the extinction of lever pressing trained as a free operant. Experiment 2 examined their effects when extinction of the free operant was conducted in the presence of nonresponse-contingent deliveries of the reinforcer (that theoretically reduced the role of generalization decrement in suppressing responding). Experiment 3 examined their effects on extinction of a discriminated operant, that is, one that had been reinforced in the presence of a discriminative stimulus, but not in its absence. A strong ABA renewal effect was observed in all four experiments during testing. However, despite the use of DCS doses and a drug administration procedure that facilitates the extinction of Pavlovian learning, there was no evidence in any experiment that DCS facilitated operant extinction learning assessed in either the extinction or the conditioning context. DCS may primarily facilitate learning processes that underlie Pavlovian, rather than purely operant, extinction. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Resistance to change within heterogeneous response sequences.

Three experiments investigated how instrumental and Pavlovian contingencies contribute to resistance to change (RTC) in different ordinal response positions within heterogeneous response sequences in pigeons. RTC in the initial and terminal response positions of a three-response sequence were compared in Experiment 1, which presented three colored key lights in succession in each trial; and in Experiment 2, which severely degraded Pavlovian contingencies by presenting the lights simultaneously at each ordinal position. Experiment 3 eliminated the instrumental contingency in a high-order sign-tracking procedure. When the instrumental contingency was in effect, RTC of the initial position was greater than the terminal position (Initial RTC > Terminal RTC) when the Pavlovian contingencies were strong and when they were degraded. When the instrumental contingency was eliminated, RTC patterns reversed, producing a graded pattern of RTC (Initial     

Evaluation of the relation between Pavlovian occasion-setting and instrumental discriminative stimuli: A blocking analysis.

Retracted October 1990. (See record 1991-03475-001.) Conducted 2 experiments with 72 male Sprague-Dawley rats, using a blocking design (A+, then AB+) to assess the relation between Pavlovian occasion-setting and instrumental discriminative stimuli. Prior conditioning of both associative and occasion-setting functions of A in a serial feature-positive procedure blocked acquisition of an instrumental discriminative function by a novel stimulus (B) trained in compound with A. Neither prior conditioning of only an A/unconditioned stimulus/stimuli (UCS) association nor prior conditioning of Stimulus A using a Pavlovian simultaneous feature-positive procedure, which does not endow A with an occasion-setting function, blocked acquisition of an instrumental discriminative function by B. Prior acquisition of an instrumental discriminative function by A blocked acquisition of a Pavlovian occasion-setting function by a novel stimulus (B) trained in compound with A but did not block acquisition of an association between B and the UCS. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some consequences of associations between the excitor and the inhibitor in a conditioned inhibition paradigm.

Four experiments with 64 female Carneaux pigeons in an autoshaping preparation explored Pavlovian conditioned inhibition. Exp I paired 2 line orientations with food but deleted food after separate presentation of 1 of 2 colors and after a compound of a 2nd color with 1 of the line orientations. The color nonreinforced in compound with an orientation gained more inhibition than did the separately presented color, as measured by its ability to interfere with responding to both orientations. However, transfer of that color's inhibition to the new orientation was incomplete. Moreover, exposure to an extinction treatment prior to the transfer test did not diminish its inhibition. Exps II, III, and IV assessed the role of potential color–orientation associations in both of these latter phenomena and attempted to reduce their contribution through separate presentations. Such presentations did improve transfer of a color's inhibition to a new excitor but had no effect on the extinction of that inhibition. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative changes in elements and compounds when the other is reinforced.

Four experiments investigated the symmetry of associative changes in stimulus compounds and elements in a Pavlovian conditioned magazine-approach situation with rats. Experiment 1 used multiple groups to examine the associative changes in a conditioned element (A) as a result of its subsequent reinforcement in compound with a neutral X. These were compared with the changes in an AX compound when one of its elements (A) was subsequently reinforced alone. Although reinforcing A enhanced responding to the AX compound, compared with a control compound, reinforcing AX failed to enhance responding to A, compared with a control element. Experiments 2 and 3 made similar comparisons in a fully within-subject design, finding greater changes in a previously trained AX compound when A was subsequently conditioned than in a B element when BY was subsequently conditioned. Experiment 4 found associative decrements in A when it was reinforced in the presence of a moderately conditioned X. The results observed in each of these experiments are more consistent with an elemental model of conditioning than with a recently proposed configural model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of the rates of associative change during acquisition and extinction.

Five experiments used a compound test procedure to compare the rate parameters for the associative changes resulting from reinforcement and nonreinforcement. Experiments I and 4, using a magazineapproach procedure in rats, found initial acquisition to proceed more rapidly but to generalize less broadly than extinction. Experiments 2 and 5 repeated these observations in an autoshaping preparation with pigeons. Experiment 3 found no evidence for differential disruption of acquisition and extinction in testing. These results were obtained in a test procedure that compares responding with stimulus compounds in order to remove the differences in overall performance, which have complicated inferences about associative changes in earlier experiments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reward produced memories regulate memory-discrimination learning, extinction, and other forms of discrimination learning.

In memory-discrimination learning, reward-produced memories are differentially rewarded such that they are the only stimuli available to support discriminative responding. Memory-discrimination learning was used in this study as follows: Reward-produced memories that were assumed to regulate instrumental performance in previously reported extinction and discrimination learning investigations were isolated and explicitly differentially reinforced (prior to a shift to extinction) in each of 4 runway investigations with rats. Results obtained here in the explicit discrimination learning stage and in the subsequent extinction stage were consistent with the prediction of the memory view and with prior discrimination learning and extinction findings. The memory interpretation was applied to memory-discrimination learning, to extinction, and to 2 other types of discrimination learning. It appears that a theory must use reward-produced memories to explain all 4 types of discrimination learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mirror expression of adrenoleukodystrophy and adrenoleukodystrophy related genes in mouse tissues and human cell lines

In memory-discrimination learning, reward-produced memories are differentially rewarded such that they are the only stimuli available to support discriminative responding. Memory-discrimination learning was used in this study as follows: Reward-produced memories that were assumed to regulate instrumental performance in previously reported extinction and discrimination learning investigations were isolated and explicitly differentially reinforced (prior to a shift to extinction) in each of 4 runway investigations with rats. Results obtained here in the explicit discrimination learning stage and in the subsequent extinction stage were consistent with the prediction of the memory view and with prior discrimination learning and extinction findings. The memory interpretation was applied to memory-discrimination learning, to extinction, and to 2 other types of discrimination learning. It appears that a theory must use reward-produced memories to explain all 4 types of discrimination learning.     

Relations Between Pavlovian-Instrumental Transfer and Reinforcer Devaluation.

Relations between posttraining reinforcer devaluation and Pavlovian-instrumental transfer were examined in 2 experiments. When a single reinforcer was used, extended training of the instrumental response increased transfer but reduced devaluation effects. When multiple instrumental reinforcers were used, both reinforcer-specific transfer and devaluation effects were less influenced by the amount of instrumental training. Finally, although reinforcer devaluation decreased both Pavlovian conditioned responses and baseline instrumental responding, it had no effect on either single-reinforcer or reinforcer-specific transfer. These results indicate that transfer and reinforcer devaluation can reflect different aspects of associative learning and that the nature of associative learning can be influenced by parameters such as the amount of training and the use of multiple reinforcers. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The effects of FG7142 on overexpectation of Pavlovian fear conditioning.

Six experiments studied the role of GABAA receptor activation in expression of overexpectation of Pavlovian fear conditioning. After separate pairings of CSA and CSB with shock in Stage I, rats received pairings of the compound AB with shock in Stage II, producing overexpectation of fear. The expression of overexpectation was attenuated, in a dose-dependent manner, by the benzodiazepine partial inverse agonist FG7142. FG7142 had no effect on responding to a CS paired with a low magnitude US or a CS subjected to associative blocking. These results suggest that the negative prediction error generated during overexpectation training may impose a mask on fear rather than erasing the original fear learning. They support claims that overexpectation shares features with extinction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simple and configural association learning in rats with bilateral quisqualic acid lesions of the nucleus basalis magnocellularis

We hypothesized that bilateral quisqualic acid lesions of the nucleus basalis magnocellularis (NBM) in rats would impair configural but not simple association learning. In experiment 1, rats were tested in a negative patterning operant discrimination where they were food-reinforced for responding to a light or a tone (L+, T+) but not for responding to the configural stimulus consisting of the light and tone presented simultaneously (LT-). Consistent with our hypothesis, NBM-lesioned rats showed a transient but significant impairment, responding normally to L+ and T+ but responding more often to LT-, in addition to responding more often during the inter-trial interval (ITI) than controls. In experiment 2, rats were tested in a simple operant discrimination where rats were food-reinforced for responding to a light (L+) but not for responding to a tone (T-). Although NBM-lesioned rats again responded normally to L+ as predicted, NBM-lesioned rats were transiently impaired, making more T- responses and more ITI responses than controls. Together, these results suggest that the NBM is involved in both configural and simple association learning but that this involvement is limited to learning to withhold responding to non-reinforced contextual or discrete stimuli. Finally, rats from experiment 2 underwent extinction trials, where results showed no difference between NBM-lesioned and control groups, suggesting that the NBM is not involved in the extinction of conditioned responding to previously reinforced stimuli.     

Relative validity effects with either one or two more valid cues in Pavlovian and instrumental conditioning.

Two experiments investigated the relative validity effect with either 1 or 2 continuously reinforced cues in Wistar rats using appetitive Pavlovian and instrumental preparations. Discrimination training involved 3 compound cues containing a common element (1AX: 1BX: 2CX). In the first true-discrimination group (TD-1), CX was followed by food, but AX and BX were not. In the second true-discrimination group (TD-2), AX and BX but not CX were followed by food. In the third pseudodiscrimination group (PD), food followed 50% of each compound. Compared with the PD group there were lower levels of responding to X in Groups TD-1 and TD-2, which did not differ. That is, both TD treatments showed equivalent relative validity effects. There was evidence for a relative validity effect on the context. The Rescorla-Wagner model incorrectly predicts a smaller relative validity effect after the TD-2 than the TD-1 treatment. Comparator theory predicts these results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)