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Abstract: Although conditioned fear can be effectively extinguished by unreinforced exposure to a threat cue, fear responses tend to return when the cue is encountered some time after extinction (spontaneous recovery), in a novel environment (renewal), or following presentation of an aversive stimulus (reinstatement). As extinction represents a context-dependent form of new learning, one possible strategy to circumvent the return of fear is to conduct extinction across several environments. Here, we tested the effectiveness of multiple context extinction in a two-day fear conditioning experiment using 3-D virtual reality technology to create immersive, ecologically-valid context changes. Fear-potentiated startle served as the dependent measure. All three experimental groups initially acquired fear in a single context. A multiple extinction group then underwent extinction in three contexts, while a second group underwent extinction in the acquisition context and a third group underwent extinction in a single different context. All groups returned 24h later to test for return of fear in the extinction context (spontaneous recovery) and a novel context (renewal and reinstatement/test). Extinction in multiple contexts attenuated reinstatement of fear but did not reduce spontaneous recovery. Results from fear renewal were tendential. Our findings suggest that multi-context extinction can reduce fear relapse following an aversive event – an event that often induces return of fear in real-world settings – and provides empirical support for conducting exposure-based clinical treatments across a variety of environments. [Copyright &y& Elsevier]

Abstract: The present human fear conditioning study examined whether the valence of an extinction cue has a differential effect on attenuating renewal that is induced by removal of the extinction context. Additionally, the study aimed to assess whether such attenuating effect is based on a modulatory or safety-signal role of the cue. In acquisition, extinction, and test stages of the experiment, human participants received pairings of human faces, presented against a particular background color, with the presence or absence of an aversive auditory stimulus. Experimental groups differed in the valence of a cue that was presented during extinction, in whether or not extinction took place against a different background color than present during acquisition and testing, and in whether the extinction cue was present or absent at test. The conditioned response consisted of auditory-stimulus expectancy ratings. It was hypothesized that a positively valued extinction cue yields faster extinction, stronger attenuation of renewal, and better transfer of its inhibitory power to non-extinguished stimuli than a negatively valued cue. All three hypotheses were confirmed, suggesting that the positive, but not the negative, cue had become a safety signal. The results were discussed in the framework of extinction-based exposure treatments. [Copyright &y& Elsevier]

Abstract: Two experiments were conducted to study overshadowing of extinction in a conditioned taste aversion preparation. In both experiments, aversive conditioning with sucrose was followed by extinction treatment with either sucrose alone or in compound with another taste, citric acid. Experiment 1 employed a simultaneous compound extinction treatment and found results indicative of overshadowing of extinction. By contrast, Experiment 2, in which extinction treatment involved serial compound presentations, failed to obtain evidence of overshadowing of extinction. The results of Experiment 2 indicate that the serial presentation of two tastes was processed as equivalent to the separate presentation of the tastes. The results are discussed in relation to: (1) Convergent evidence from research on latent inhibition, (2) competing theories of learning and, (3) their possible adaptive value in food-selection learning. [Copyright &y& Elsevier]