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Following differential fear conditioning, the instruction that the unconditional stimulus will no longer be presented (instructed extinction) reduces differential electrodermal responding to CS+ and CS−, but does not affect differential conditional stimulus valence evaluations. Reductions in differential electrodermal responding have been attributed to the provision of verbal instructions; however, during instructed extinction the unconditional stimulus electrode is often removed as well. This removal could reduce the participants' general arousal levels rendering the detection of differential electrodermal responding difficult. The current study examined this alternative interpretation by comparing the electrodermal responses and conditional stimulus valence evaluations of an instruction/electrode-on group, an instruction/electrode-off group, and a control group who were not instructed. Following instructed extinction, differential electrodermal responding was eliminated in both instruction groups, an effect that was not influenced by the attachment/removal of the electrode. Replicating previous findings, conditional stimulus valence was not affected by instructed extinction. The results suggest that verbal instructions, not unconditional stimulus electrode removal, reduce differential electrodermal responding during instructed extinction manipulations. [ABSTRACT FROM AUTHOR]

Abstract: Disruption of the reconsolidation of conditioned fear memories has been suggested as a non-pharmacological means of preventing the return of learned fear in human populations. A reconsolidation update paradigm was developed in which a reconsolidation window is opened by a single isolated retrieval trial of a previously reinforced CS+ which is then followed by Extinction Training within that window. However, follow-up studies in humans using multi-methods fear conditioning indices (e.g., fear-potentiated startle, skin conductance, US-expectancy) have failed to replicate the retrieval+extinction effects. In the present study, we further investigated the retrieval+extinction reconsolidation update paradigm by directly comparing the acquisition, extinction, and return of fear-potentiated startle in the absence or presence of US-expectancy measures (using a trial-by-trial response keypad) with and without retrieval of a previously acquired CS-US association. Participants were fear conditioned to two visual cue CS+’s, one of which was presented as a single, isolated retrieval trial before Extinction Training and one that was extinguished as usual. The results show that the inclusion of US-expectancy measures strengthens the CS–US association to provide enhanced fear conditioning and maintenance of fear memories over the experimental sessions. In addition, in the groups that used on-line US-expectancy measures, the retrieval+extinction procedure reduced reinstatement of fear-potentiated startle to both previously reinforced CS+’s, as compared to the extinction as usual group. [Copyright &y& Elsevier]

Abstract: Little is known about the role of discrete stimulus features in the regulation of fear. This study examined the effects of feature learning on the acquisition and extinction of fear conditioning. Human participants were fear conditioned to a yellow triangle (CS+) using an electrical shock. We manipulated feature learning through differential conditioning. The nonconditioned control stimulus (CS−) was a red triangle in one group (Color-Relevant), but a yellow circle in the other group (Shape-Relevant). Next, two generalization stimuli were tested that shared the shape- or color-feature with the CS+ (a blue triangle and a yellow square). Online shock-expectancy ratings and skin conductance responding showed that the CS− determined the pattern of fear generalization: the same-color stimulus elicited more fear in Group Color-Relevant, versus the same-shape stimulus in group Shape-Relevant. Furthermore, extinguishing these two generalization stimuli had no detectable effect on fear of the CS+. These results show that fear generalization is influenced by feature learning through differential conditioning, and that exposures to different features of a stimulus are not sufficient to extinguish fear of that stimulus as a whole. [Copyright &y& Elsevier]