Extinction Cues do not Reduce Recovery of Extinguished Conditioned Fear in Humans

We evaluated whether an extinction cue can reduce (or prevent) the recovery of previously extinguished fear conditioning using an ABC renewal design in humans. Two experiments were carried out. In Experiment 1, two groups were presented with geometric shapes as conditioned stimulus (CS), followed by a small electric shock as unconditioned stimulus (US) during the acquisition phase. Conditioned fear was measured as ratings of US expectancy and changes in skin conductance response (SCR). During the extinction phase, both groups received presentations of the CS without the US, while an extinction cue (EC) was presented. Both groups were tested in both the extinction context (extinction test) and a new context (renewal test) immediately and 48 hours after the end of the extinction phase (spontaneous recovery). Half of the subjects were tested in the presence of the EC (Group Extinction cue) while the other half were tested in the presence of a neutral cue (Group Neutral cue). The results suggested that the EC reduced the recovery of fear produced by a context change, but that this reduction was not maintained over time. Experiment 2 increased the salience of the EC and the contexts, however, results showed that the EC was unable to reduce the renewal of fear conditioning. These results are discussed as a function of the experimental manipulations performed, and their theoretical and practical implications.