To remove or not to remove? Removal of the unconditional stimulus electrode does not mediate instructed extinction effects.

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.