In this article I review research and theory on the "interference paradigms" in Pavlovian learning. In these situations (e.g., extinction, counterconditioning, and latent inhibition), a conditioned stimulus (CS) is associated with different unconditioned stimuli (USs) or outcomes in different phases of the experiment; retroactive interference, proactive interference, or both are often observed. In all of the paradigms, contextual stimuli influence performance, and when information is available, so does the passage of time. Memories of both phases are retained, and performance may depend on which is retrieved. Despite the similarity of the paradigms, conditioning theories tend to explain them with separate mechanisms. They also do not provide an adequate account of the context's role, fail to predict the effects of time, and overemphasize the role of learning or storage deficits. By accepting 4 propositions about animal memory (i.e., contextual stimuli guide retrieval, time is a context, different memories are differentially dependent on context, and interference occurs at performance output), a memory retrieval framework can provide an integrated account of context, time, and performance in the various paradigms.

This article provides a selective review and integration of the behavioral literature on Pavlovian extinction. The first part reviews evidence that extinction does not destroy the original learning, but instead generates new learning that is especially context-dependent. The second part examines insights provided by research on several related behavioral phenomena (the interference paradigms, conditioned inhibition, and inhibition despite reinforcement). The final part examines four potential causes of extinction: the discrimination of a new reinforcement rate, generalization decrement, response inhibition, and violation of a reinforcer expectation. The data are consistent with behavioral models that emphasize the role of generalization decrement and expectation violation, but would be more so if those models were expanded to better accommodate the finding that extinction involves a context-modulated form of inhibitory learning.

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Four conditioned suppression experiments examined the influence of contextual stimuli on the rat's fear of an extinguished conditioned stimulus (CS). When rats received pairings of a CS with shock in one context and then extinction of the CS in another context, fear of the CS was renewed when the CS was returned to and tested in the original context (Experiments 1 and 3). No such renewal was obtained when the CS was tested in a second context after extinction had occurred in the conditioning context (Experiment 4). In Experiment 2, shocks presented following extinction reinstated fear of the CS, but only if they were presented in the context in which the CS was tested. In each experiment, the associative properties of the contexts were independently assessed. Contextual excitation was assessed primarily with context-preference tests in which the rats chose to sit in either the target context or an adjoining side compartment. Contextual inhibition was assessed with summation tests. Although reinstatement was correlated with demonstrable contextual excitation present during testing, the renewal effect was not. Moreover, there was no evidence that contextual inhibition developed during extinction. The results suggest that fear of an extinguished CS can be affected by the excitatory strength of the context but that independently demonstrable contextual excitation or inhibition is not necessary for contexts to control that fear.

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Several theories of the development of panic disorder (PD) with or without agoraphobia have emerged in the last 2 decades. Early theories that proposed a role for classical conditioning were criticized on several grounds. However, each criticism can be met and rejected when one considers current perspectives on conditioning and associative learning. The authors propose that PD develops because exposure to panic attacks causes the conditioning of anxiety (and sometimes panic) to exteroceptive and interoceptive cues. This process is reflected in a variety of cognitive and behavioral phenomena but fundamentally involves emotional learning that is best accounted for by conditioning principles. Anxiety, an anticipatory emotional state that functions to prepare the individual for the next panic, is different from panic, an emotional state designed to deal with a traumatic event that is already in progress. However, the presence of conditioned anxiety potentiates the next panic, which begins the individual's spiral into PD. Several biological and psychological factors create vulnerabilities by influencing the individual's susceptibility to conditioning. The relationship between the present view and other views, particularly those that emphasize the role of catastrophic misinterpretation of somatic sensations, is discussed.

If the unconditioned stimulus (US) is presented independently of the conditioned stimulus (CS) following extinction, the conditioned response may be reinstated to the CS. Three experiments are reported that suggest that reinstatement is mediated by conditioning to contextual stimuli that are present during both US presentation and testing. Shocks presented to rats following the extinction of conditioned suppression reliably reinstated suppression to the CS, but only when they were presented in the context in which testing was later to occur. Reinstatement was also reversed by extinguishing fear to the context through nonreinforced exposure to the context between shock presentation and testing. Reinstatement was obtained in these experiments in spite of procedures that have been used in the past to minimize the influence of context conditioning. Moreover, fear of the context was never detected directly by depressed bar-press rates in the absence of the CS. The results do not support the hypothesis that reinstatement results from an increment in the strength of a memory of the US that has been weakened during extinction. Problems inherent in controlling and detecting levels of context conditioning that may influence behavior toward nominal CSs are discussed.

Extinction depends, at least partly, on new learning that is specific to the context in which it is learned. Several behavioral phenomena (renewal, reinstatement, spontaneous recovery, and rapid reacquisition) suggest the importance of context in extinction. The present article reviews research on the behavioral and neurobiological mechanisms of contextual influences on extinction learning and retrieval. Contexts appear to select or retrieve the current relationship of the conditional stimulus (CS) with the unconditional stimulus (US), and they are provided by physical background cues, interoceptive drug cues, emotions, recent trials, and the passage of time. The current article pays particular attention to the effects of recent trials and trial spacing. Control of fear extinction by physical context involves interactions between the dorsal hippocampus and the lateral nucleus of the amygdala. This interaction may be mediated by gamma-aminobutyric acid (GABA)-ergic and adrenergic mechanisms.