Thwarting the renewal (relapse) of conditioned fear with the explicitly unpaired procedure: Possible interpretations and implications for treating human fears and phobias

In three experiments using the barpress conditioned suppression task with albino rats, we studied the renewal (relapse) of conditioned fear in an ABA fear-renewal paradigm. We found that explicitly unpaired (EU) deliveries of conditioned stimuli (CSs) and unconditioned stimuli (USs) in Context B thwarted fear renewal in Context A. Evidence contraindicated a suggestion by Rauhut, Thomas, and Ayres (2001) that US habituation plays a key role in this effect. For example, renewal was thwarted only when EU CSs and USs were intermingled rather than given in succession. The possibility that EU treatments thwart renewal by creating a CS that inhibits fear in the test context also received no support. Thus, summation and retardation tests in Context A found no evidence that the EU CS became inhibitory, finding instead evidence for a residual excitation. Other possible interpretations of the results and some implications for clinical practice are noted.