4 - (OP18) Gradually Lessening the Severity of Feared Outcomes in Exposure Therapy Might Benefit Individuals with Anxiety and Fear: A Preregistered Test and Exploratory Analysis

Fear extinction is a key mechanism of exposure therapy, the first-line treatment for fear-based psychopathology. While exposure therapy is effective at reducing symptoms, many experience the return of fear. Experimentally examining the fundamental processes whereby fear is acquired and extinguished may offer understanding of how exposure therapy can be optimized to prevent the relapse of anxiety and fear-related disorders.

In the laboratory, fearful responding to a neutral, conditional stimulus (CS) is induced by its repeated pairing of an aversive, unconditional stimulus (US) during acquisition and extinguished over repeated presentations of the CS without the US during extinction. Fearful responding to the CS returns later, nevertheless, as it can recover spontaneously as time elapses (i.e., spontaneous recovery), be reinstated by the US alone (i.e., reinstatement), or be re-acquired rapidly upon re-pairing of the CS and US. Prior animal work showed that gradual extinction, which gradually reduced the intensity of the US before it was omitted during CS presentations, prevented the return of fear. Here, a preregistered, multiple-day experiment examined whether gradual extinction attenuated spontaneous recovery, reinstatement, and reacquisition in humans.

Participants (N=122, Mage=19.97) were randomly assigned to three groups, Standard Extinction (SE; only CS no US), Gradual Extinction (GE), and Gradual-reverse Extinction (GR; US intensity gradually increased). All participants underwent acquisition first, where a CS+ was consistently paired with the US and a CS- presented alone, to induce differential responding to CS+ vs. CS-. Extinction occurred on the next day, where differential responding was to be extinguished, and tests a week after that. Skin conductance response (SCR) was recorded continuously, and expectancy ratings of US likelihood, US unpleasantness, subjective fear were collected before and after each trial of the CSs.

Preregistered tests revealed no evidence of group differences in the spontaneous recovery, reinstatement, or reacquisition of SCR or expectancy. Nonetheless, exploratory analyses suggested that, although differential responding returned at the first test trials, threat expectancy differentiation (CS+ vs. CS-) across subsequent trials was consistently lower in GE than SE and GR. Furthermore, differential expectancy was re-extinguished after a few trials for GE but persisted for SE and GR.

While discrepant results across the present and prior work may be due to design differences (e.g., gradual reduction over trials vs. across days), null findings in our confirmatory tests highlight potential boundary conditions of gradual extinction and underscore a translational gap between animal and human research. However, exploratory results shed light on the shifted time course of learning following the return of fear, offering a framework for future theory generation and continued efforts to optimize relapse prevention strategies. In sum, gradually lessening the severity of feared outcomes (e.g., criticism, rejection) during exposures to cues believed to predict them (e.g., public speeches) might facilitate the reduction of self-report symptoms following a relapse, should it occur.