Repetitive Thought about an Aversive Learning Experience Maintains Conditioned Responding

Clinical anxiety is often believed to be based on fear conditioning, a procedure of pairing an originally neutral stimulus (conditioned stimulus, CS) with an aversive unconditioned stimulus (US), which results in the CS eliciting a conditioned fear response in the absence of the US. Recently, it was shown that repeatedly thinking about an aversive conditioning event maintains subsequent fear responding. A crucial question is how such effects should be interpreted. Does rehearsal of a CS-US-contingency result in a strengthened memory trace of the conditioning experience or in changes in the US-representation (e.g., US-inflation or increased US-coherence)? The current study was set up to investigate the underlying mechanism of this rehearsal effect. After acquisition training with two CS+s paired with the same US, participants rehearsed one of both CS-US-contingencies. The CS+ that was part of the rehearsed contingency elicited more US-expectancy than the CS+ that was not rehearsed. As changes in the US-representation could not explain our data, we suggest that a strengthening of the memory trace of the CS-US-association underlies this effect. Repetitive thought about a conditioning experience seems to result in sustained conditioned responding due to a strengthened CS-US-association. We propose that the repetitive nature of thought processes such as worry might partly explain its unconstructive role in anxiety.