Biomedical subjects

Robert A Rescorla

Publications and source records attributed to Robert A Rescorla.

15 recordsLinked to original sources

PubMed2006

Deepened extinction from compound stimulus presentation.

Three experiments with rats and 2 with pigeons explored the effect of presenting 2 extinguished excitatory stimuli in compound. Four learning situations were used: Pavlovian magazine approach, Pavlovian fear conditioning, and instrumental discriminative instrumental learning in rats, as well as Pavlovian sign tracking in pigeons. All 5 experiments confirmed D. Reberg's (1972) observation that even after extinction of the individual stimuli, presenting them in compound evoked substantial responding. Moreover, nonreinforcement of that compound deepened extinction of an element more substantially than did additional presentation of that element alone. Such compound exposure reduced spontaneous recovery, reduced reinstatement, and slowed subsequent reconditioning. The primary determinant seemed to be the enhanced associative strength rather than the enhanced conditioned responding that occurred during the nonreinforced compound.

Animals↗

PubMed2006

Stimulus generalization of excitation and inhibition.

Five sign-tracking experiments with pigeons investigated the breadth of stimulus generalization of excitatory and inhibitory conditioning. Using a compound stimulus test procedure, these experiments found evidence for a narrower generalization of associative strength in excitation than in inhibition. They also found a narrower associative gradient with a more strongly conditioned excitatory stimulus, although this did not seem to account for the difference between exciters and inhibitors. These results confirm earlier findings comparing generalization after acquisition and extinction and raise various theoretical issues about generalization.

Affect↗

PubMed2006

Spontaneous recovery from overexpectation.

In three Pavlovian magazine approach experiments, rats received conditioning of auditory and visual stimuli by pairing with a pellet. Then the stimuli received additional conditioning while presented in simultaneous compound and were tested either immediately or after a delay. The compound conditioning resulted in a decrement in responding to the individual stimuli (overexpectation). However, there was recovery of responding with the passage of time. These results suggest that the decrements produced by an overexpectation procedure share some properties with those produced by nonreinforcement.

Animals↗

PubMed2005

Spontaneous recovery of excitation but not inhibition.

Five magazine approach experiments with rats and 1 sign-tracking experiment with pigeons explored the possibility of an analogue to spontaneous recovery of excitatory conditioning from extinction: spontaneous recovery of inhibitory conditioning from training. Stimuli were 1st treated as conditioned inhibitors and then as conditioned exciters or as irrelevant to reinforcement. At issue was whether the passage of time after the 2nd treatment would allow partial restoration of the initial conditioned inhibition. The experiments differed in the design used to study recovery, the manner of reinforcing the inhibitor, the means of testing for recovery, the time interval allowed for recovery, and the species used. None of the experiments found evidence for recovery of the inhibitory learning with time, despite the concurrently measured presence of spontaneous recovery of excitatory conditioning after extinction. These experiments suggest that changes with time may be preferential to the learning that occurs during extinction.

Acoustic Stimulation↗

PubMed2004

Superconditioning from a reduced reinforcer.

In four autoshaping experiments pigeons received conditioned inhibition training of the form A++, AB-, where ++ is a strong reinforcer and - is nonreinforcement. Subsequent AB+ training, in which + is a moderate reinforcer, resulted in enhanced conditioning of A, relative to an A stimulus receiving no treatment, one receiving A+ treatment, and one receiving A++ treatment. This enhancement of conditioning to A constitutes a demonstration of "superconditioning". The presence of the inhibitory B sufficiently enhanced the reinforcing power of the moderate reinforcer (+) that it was able to further increase the excitation controlled by A. This occurred even though A had previously been paired with a stronger reinforcer (++). Superconditioning was also observed when A and B were extinguished prior to treatment with + or were originally neutral stimuli followed by + in the presence of an inhibitor trained elsewhere.

Animals↗

PubMed2004

Extinction and retraining of simultaneous and successive flavor conditioning.

In three experiments, rats received pairings of flavor conditioned stimuli with polycose unconditioned stimuli, in either a simultaneous or a sequential relation. Both temporal relations produced excellent conditioned increases in consumption of the flavors. Separate presentation of the flavors resulted in extinction in both cases. However, restoring the pairing of the flavor with polycose resulted in reconditioning only with the sequential, not with the simultaneous, relation.

Animals↗

PubMed2004

Spontaneous recovery varies inversely with the training-extinction interval.

Four experiments found the magnitude of spontaneous recovery after extinction to be greater with a shorter interval between initial conditioning and extinction. Experiments 1 and 2 used a Pavlovian magazine approach procedure with rat subjects, Experiment 3 used an instrumental training procedure with rats, and Experiment 4 used a sign-tracking procedure with pigeons. These results are not anticipated by many accounts of spontaneous recovery that attribute it to the fading of learning that occurred during extinction.

Animals↗

PubMed2003

Contemporary study of Pavlovian conditioning.

Pavlov's first report on conditioning emphasized its role in allowing the animal to adjust to its environment. Contemporary theories have seen this adjustment in terms of developing accurate knowledge of the environment. Three aspects of that thinking are explored: how the animal acquires initial knowledge, how it changes its knowledge when conditions of the world change, and how it makes use of multiple knowledge representations.

Adaptation, Psychological↗

PubMed2003

More rapid associative change with retraining than with initial training.

Retraining was compared with initial acquisition in 4 magazine approach experiments with rats and 1 autoshaping experiment with pigeons. The levels of performance were matched prior to reinforcement and nonreinforcement for stimuli with a history of both training and extinction and stimuli with only a minimal history of training. Under these conditions, a previously extinguished stimulus was more vulnerable both to the incremental effects of reinforcement and to the decremental effects of nonreinforcement compared with a stimulus that had only been minimally trained.

Animals↗

PubMed2003

Elemental and configural encoding of the conditioned stimulus.

Five experiments explored the effect of conditioning AB and CD compounds on responding to transfer AD and BC compounds and to elements. These experiments used several conditioning procedures: flavour aversion and instrumental discriminative learning in rats and autoshaping in pigeons. All of the experiments found greater responding to the trained AB and CD than to the transfer AD and BC compounds, a result that agrees with some configural models, but not with an elemental model. All experiments also found greater responding to the transfer AD and BC compounds than to the elements, a result that agrees with elemental, but not configural, models.

Animals↗

PubMed2003

Protection from extinction.

The effect of the presence of a conditioned inhibitor on extinction of excitatory conditioning was studied in one magazine approach and three autoshaping experiments using rats and pigeons. In each case, the presence of an inhibitor reduced responding to an exciter during extinction but allowed substantial recovery of responding to that exciter when subsequently tested separately. Control stimuli with a history of being irrelevant to reinforcement or being nonreinforced had less of a protective effect. This constitutes a clear demonstration of protection from extinction, a phenomenon of substantial theoretical and applied importance.

Animals↗

PubMed2002

Effect of following an excitatory-inhibitory compound with an intermediate reinforcer.

Pavlovian-conditioned inhibition training of the form A++, AB- (where ++ is a strong reinforcer and - is nonreinforcement) was conducted in 3 experiments with rats and 1 with pigeons. Then AB+ training was given (in which + is an effective reinforcer that is weaker than ++). The + reinforcer was achieved by reducing the frequency, lessening the amount, or lengthening the delay with which ++ was delivered. All 4 experiments found the AB+ treatment to enhance responding to both the excitatory A and the inhibitory B in comparison with untreated control stimuli. However, when appropriate assessments were made, the increase was more substantial for the inhibitory B. This pattern of results presents challenges for most current theories of associative learning.

Animals↗

PubMed2002

Savings tests: separating differences in rate of learning from differences in initial levels.

Three experiments used a Pavlovian magazine-approach procedure in rats to explore, in 3 theoretically interesting cases, the inferences made from savings tests. In each experiment, a compound test procedure allowed the separation of differences in rate of acquiring new associative learning from differences in initial level of associative strength. Experiment 1 found that the slower acquisition after prior nonreinforced exposure (latent inhibition) reflected differences in learning rate, not initial level. By contrast, Experiments 2 and 3 found that the higher performance observed to a previously trained and extinguished stimulus, and lower performance observed to a conditioned inhibitor, both arose primarily because of differences in initial associative value. These experiments illustrate the usefulness of a novel testing procedure in sharpening the conclusions from savings procedures.

Animals↗

PubMed2002

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 1 and 4, using a magazine-approach 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.

Acoustic Stimulation↗

PubMedDate not supplied

Spontaneous recovery.

Spontaneous recovery from extinction is one of the most basic phenomena of Pavlovian conditioning. Although it can be studied by using a variety of designs, some procedures are better than others for identifying the involvement of underlying learning processes. A wide range of different learning mechanisms has been suggested as being engaged by extinction, most of which have implications for the nature of spontaneous recovery. However, despite the centrality of the notion of spontaneous recovery to the understanding of extinction, the empirical literature on its determinants is relatively sparse and quite mixed. Its very ubiquity suggests that spontaneous recovery has multiple sources.

Animals↗