The dissertation is a three-paper investigation of potential methods for improving exposure therapy outcomes for anxiety disorders. If proven effective, these methods can be utilized to modify exposure therapy for anxiety disorders in order to enhance treatment effects and reduce relapse rates.
Study 1 tested a prediction of the Rescorla-Wagner model: that presenting two fear-provoking stimuli simultaneously (compound extinction) would maximize learning during extinction. Participants were presented with single extinction trials only or single extinction trials followed by compound extinction trials. Additionally, participants were randomized to caffeine or placebo ingestion prior to extinction. Results indicated participants presented with compound trials demonstrated significantly less fear responding at spontaneous recovery whereas ingestion of caffeine provided limited protection (only on valence ratings). At reinstatement, only compound extinction trials predicted attenuated fear responding.
Study 2 investigated whether occasional reinforced trials during extinction enhances learning, as has been demonstrated in recent literature in animal models. Participants were randomly assigned to typical exposure procedures (i.e., no CS-US pairings) or occasional CS-US pairings during extinction. Results indicated participants presented with occasional reinforced trials maintained elevated fear responding throughout exposure but demonstrated attenuated spontaneous recovery and rapid reacquisition effects at follow-up testing.
Study 3 was based on recent evidence in animal models suggesting that sustained arousal and enhanced fear responding throughout extinction predicts better long-term outcomes, which is contrary to traditional exposure therapy in which reduction of fear responding is used as an index of learning. Participants completed exposure with or without the presence of additional excitatory stimuli which were intended to enhance arousal and fear responding throughout exposure. A set of regression analyses investigating whether any exposure process measures predicted outcome indicated that sustained arousal throughout exposure and variability in subjective fear responding throughout exposure predicted lower levels of fear at follow-up testing.
In sum, these studies indicate that exposure therapy will be most effective when exposure sessions are unpredictable, variable, include multiple fear-provoking stimuli, and include some aversive events (e.g., social rejection, panic attack). Although fear responding may remain elevated throughout exposure, such procedures may predict better treatment outcomes and reduce the likelihood of relapse.