Gradients of Fear Potentiated Startle During Generalization, Extinction, and Extinction Recall—and Their Relations With Worry

• Generalization of conditioned fear was evident during acquisition and extinction phases.
• Generalization was no longer present one week later during extinction recall, but startle was still potentiated to the CS+ compared to the safest stimulus.
• Higher levels of worry were associated with greater discriminative fear conditioning and less generalization.

It is well established that fear conditioning plays a role in the development and maintenance of anxiety disorders. Moreover, abnormalities in fear generalization, extinction, and extinction recall have also been associated with anxiety. The present study used a generalization paradigm to examine fear processing during phases of generalization, extinction, and extinction recall. Specifically, participants were shocked following a CS+ and were also presented with stimuli that ranged in perceptual similarity to the CS+ (i.e., 20%, 40%, or 60% smaller or larger than the CS+) during a fear generalization phase. Participants were also presented with the same stimuli during an extinction phase and an extinction recall phase 1 week later; no shocks were presented during extinction or recall. Lastly, participants completed self-report measures of worry and trait anxiety. Results indicated that fear potentiated startle (FPS) to the CS+ and GS ± 20% shapes was present in generalization and extinction, suggesting that fear generalization persisted into extinction. FPS to the CS+ was also evident 1 week later during extinction recall. Higher levels of worry were associated with greater FPS to the CS+ during generalization and extinction phases. Moreover, individuals high in worry had fear response gradients that were steeper during both generalization and extinction. This suggests that high levels of worry are associated with greater discriminative fear conditioning to threatening compared to safe stimuli and less fear generalization to perceptually similar stimuli.