People with social anxiety disorder often conduct lengthy post-mortems after social events going over and over what they said and did wrong and castigating themselves for often imaginary faux pas mercilessly. Psychologists call this process post-event processing, or PEP for short. This reinforces people's negative beliefs about their social performance and distracts from any positive aspects of their social lives. A study of 125 people in Canada looked at 75 people attending a group therapy session for social anxiety and 50 people experiencing exposure therapy for the condition. Significant PEP occured after both events and the more anxious people were before both tasks the worse their PEP. The levels of PEP were about the same after both events and the participants' PEP was found to be specifically related to their social performance rather than being a general negative train of thought about life as a whole.
Kocovski, Nancy L. and Rector, Neil A. - Post-event processing in social anxiety disorder: idiosyncratic priming in the course of CBT Cognitive Therapy and Research February 2008, 32(1), 23-36