Manipulating expectancy violations to strengthen the efficacy of human fear extinction

Recent theoretical and clinical articles have emphasized a role for expectancy violations in improving the effectiveness of exposure therapy. Expectancy violations are critical to extinction learning and strengthening these violations has been suggested to improve the formation and retention of extinction memories, which should result in lasting symptom reductions after treatment. However, more detailed mechanistic insights in this process are needed to better inform clinical interventions. In two separate fear-conditioning experiments, we investigated whether stronger expectancy violations (Exp1) or fostering awareness of expectancy violations (Exp2) during extinction could reduce the subsequent return of fear. We measured fear potentiated startle (FPS) and skin conductance responses (SCR) as physiological indices of fear, and US expectancy ratings to assess our manipulations. While we successfully created stronger expectancy violations in Exp1, we found no evidence that these stronger violations reduced the return of fear at test. Interestingly, fostering awareness of violations (Exp2) reduced differential SCRs, but not FPS responses. These findings provide novel insights into the effect of US expectancies on fear extinction in the lab, but they also illustrate the complexity of capturing clinically relevant processes of change with fear-conditioning studies.