Despite strong support for the efficacy of cognitive behavioural therapy (CBT) for social anxiety disorder (SAD), little is known about mechanisms of change in treatment. Within the context of a randomized controlled trial of CBT, this study examined patients' beliefs about the fixed versus malleable nature of anxiety-their 'implicit theories'-as a key variable in CBT for SAD. Compared to waitlist (n = 29; 58% female), CBT (n = 24; 52% female) led to significantly lower levels of fixed beliefs about anxiety (Mbaseline = 11.70 vs. MPost = 7.08, d = 1.27). These implicit beliefs indirectly explained CBT-related changes in social anxiety symptoms (κ(2) = .28, [95% CI = 0.12, 0.46]). Implicit beliefs also uniquely predicted treatment outcomes when controlling for baseline social anxiety and other kinds of maladaptive beliefs (perceived social costs, perceived social self-efficacy, and maladaptive interpersonal beliefs). Finally, implicit beliefs continued to predict social anxiety symptoms at 12 months post-treatment. These findings suggest that changes in patients' beliefs about their emotions may play an important role in CBT for SAD.
Keywords: CBT; beliefs; emotion; implicit theories; social anxiety.