Restricted Retrieval Enhances Extinction Memory Generalization across Time and Context

During traditional extinction, the conditioned stimulus (CS) activates both the original fear memory and the newly acquired extinction memory. Fear memory, being more robust, interferes with the encoding, consolidation, and retrieval of extinction memory, which results in a transient, fragile, and hard-to-retrieve extinction memory. Consequently, fear often returns after extinction. This study examined whether targeted retrieval of safety outcomes during extinction training could strengthen extinction memory and mitigate fear relapse. Thirty-nine participants underwent a four-day procedure involving fear acquisition (60% reinforcement rate), two extinction sessions, and a fear renewal test. The control group followed a standard extinction protocol, while the experimental group received identical training only in the first and last 1 or 2 trials per CS type in each session. In the intermediate trials, they repeatedly retrieved the safety outcome following the preceding CS presentation. Conditioned responses were assessed using skin conductance responses (SCR) and subjective assessments (threat expectancy, valence, and arousal). Both behavioral and physiological measures consistently demonstrated that restricted retrieval practice during extinction enhanced extinction retention and attenuated fear renewal. These findings highlight the potential benefits of integrating restricted retrieval into extinction training.