Reward Processes and Rehearsal in Exposure Therapy

Treatment response rates for cognitive behavioral therapy (CBT) across anxiety disorders average approximately 50% post-treatment and at follow-up. Thus, recent research has amplified efforts toward improving treatment methodology in an attempt to optimize clinical outcomes. Many efforts have targeted exposure therapy, an evidence-based behavioral technique during which a participant is strategically and repeatedly exposed to a feared stimulus in order to generate new non-fear associations with that stimulus.

Mechanisms of exposure therapy have been conceptualized using inhibitory retrieval models of extinction learning. These models, derived from Pavlovian conditioning, posit that extinction is dependent upon formation of an inhibitory association where the feared conditional stimulus (CS) no longer predicts the aversive unconditional stimulus (US). The new inhibitory CS-noUS association then competes with the original CS-US association. Research has demonstrated that greater expectation of US occurrence (US expectancy) followed by the unexpected omission of the US (i.e., expectancy violation) is associated with greater learning of the inhibitory association. Exposure therapy is a clinical proxy of extinction; in order to compete with the original association between public speaking (CS) and rejection (US), participants engage in repeated exposures to the CS without the US (no rejection) and form a new inhibitory association wherein public speaking no longer predicts rejection. Strategies to enhance this inhibitory learning process include mental rehearsal, where information from a previous exposure trial is recounted to reinforce the newly learned inhibitory association.

There is also promising evidence which suggests that reward processes may facilitate extinction learning, though studies have yet to be conducted in a clinical sample. Experimental studies have demonstrated that greater relief, a positive emotion that occurs following US omission, is associated with greater expectancy violation. This suggests that positive emotions during exposure (e.g., relief) may directly influence the extinction learning process. Reduced positive affect has been associated with decreased updating of US expectancies, leading to slower learning during extinction. In contrast, elevated positive affect has been associated with enhanced encoding, rehearsal, and retrieval processes, which may lead to faster learning during extinction and prevent return of fear (i.e., relapse). Strategies designed to enhance reward sensitivity and positive affect may therefore be an important avenue of future research to improve exposure therapy outcomes. While not yet applied during exposure, strategies aimed to increase reward sensitivity via positive-focused rehearsal have led to decreased anxiety, depression, and negative affect and increased positive affect. Recent work has shown that rehearsal without a positive focus immediately following exposure leads to reductions in anxiety. Therefore, rehearsal following exposure that specifically focuses on positive emotions to increase reward sensitivity has the potential to lead to even greater symptom improvement.

The current study seeks to examine the role of relief during extinction learning and to test whether positive-focused rehearsal exercise may be implemented to improve treatment outcomes in exposure therapy in a population of individuals who demonstrate excessive fear of public speaking. There are three main goals of the study: 1) examine the relationship of reward sensitivity and positive affect with relief following exposures, 2) examine the relationship between relief after exposure and learning rate (i.e., learning that the feared stimulus does not predict an aversive outcome), and 3) test the efficacy of a positive rehearsal exercise following exposure compared to a neutral rehearsal exercise.

Participants will engage in a series of short public speaking exposures that take place over two sessions. After every two exposures, participants will be asked to complete either a positive or neutral rehearsal exercise, consisting of recalling either positive or neutral aspects of the speech exposures. At multiple points throughout the study, participants will complete ratings of reward sensitivity, positive affect, relief, and expectancy of the aversive outcome.