Restricted Retrieval Enhances Extinction Memory Generalization across Time and Context

Abstract

During traditional extinction, the conditioned stimulus (CS) activates both the original fear memory and the newly formed extinction memory. Because fear memory is typically more robust, it interferes with the encoding, consolidation, and retrieval of extinction memory, resulting in a fragile and transient safety trace. Consequently, fear often returns after extinction. This pilot study examined whether repeated retrieval practice of the most recent nonreinforced CS during extinction could strengthen extinction memory and reduce fear relapse. Thirty-nine participants completed a four-day paradigm comprising fear acquisition (60% reinforcement rate), two extinction sessions, and a fear renewal test. The two groups (experimental vs. control) differed only during the extinction phase. Specifically, the experimental group received training identical to that of the Ctrl group during the first two and last two trials of the first extinction session, and the first and last two trials of the second session (for each CS type). During the intermediate trials, the experimental group recalled whether the preceding CS+/CS- trial was safe and then predicted the outcome of the current trial accordingly. Conditioned responses were assessed using skin conductance responses and subjective assessments (US expectancy, valence, and arousal). Both behavioral and physiological indices consistently suggested that restricted retrieval practice during extinction improved extinction memory retention and attenuated fear renewal. These findings suggest the potential benefits of incorporating restricted retrieval practice into extinction-based interventions to improve their long-term efficacy.