Starting Fear Is a Stronger Predictor of Long-Term Fear than Rate of Change in Fear in Human Fear Conditioning

In rodent studies, faster extinction rate has been shown to predict less long-term fear. However, this has scarcely been studied in humans. The present report investigated the association between extinction rate and long-term fear in humans. We secondarily evaluated specificity of extinction rate by including other fear conditioning values as predictors, including acquisition intercept, acquisition rate, and extinction intercept. Results show that slower extinction rate predicted less long-term fear when tested alone in the model. However, when including other fear conditioning variables, extinction rate no longer predicted long-term fear. Instead, greater fear at the beginning of acquisition was the most robust predictor of greater long-term fear (all three measures of fear), followed by greater fear at the beginning of extinction (US expectancy only). These effects occurred for both the danger signal (i.e., CS+) and safety signal (i.e., CS-). The results de-emphasize rate of change in fear during both acquisition and extinction as predictors of long-term fear and instead suggest that the magnitude of fear at the start of acquisition and, secondarily, extinction are more important predictors of long-term fear. This report has relevance for improving our understanding and treatment of anxiety disorders.