Supporting extinction memory updating to promote extinction generalization in a category-based fear conditioning paradigm

A challenge in exposure-based treatments is the effective generalization of extinction learning, as it tends to be highly specific to stimuli or situations used during exposure. This study takes a first step toward enhancing extinction generalization by promoting the updating of extinction memory. 35 participants underwent a three-day, within-subject, category-based fear conditioning paradigm. Two conditioned stimulus (CS) categories were paired with an electric shock during acquisition training (CS+1; CS+2), while one CS category was not (CS-). On day two, extinction training was followed by a prompt to retrieve the inhibitory learning association and to imagine the same experience with multiple novel stimuli for the CS+1 category in order to promote extinction memory updating. Importantly, these stimuli were not directly presented but solely imagined based on a two-word description. On day three, participants were tested for initial fear recall. We observed a pronounced return of fear for new stimuli from the CS+2 category. However, skin conductance response (SCR), fear-potentiated startle (FPS), shock expectancy and fear ratings were decreased for imagined stimuli of the category with extinction memory updating (CS+1) compared to the other category (CS+2). Moreover, extinction memory updating led to a diminished fear response for new CS+1 stimuli as indexed by SCR as well as for previously seen images during acquisition as indexed by FPS and subjective measures. These findings suggest that mental imagery involving novel stimuli may help to facilitate extinction generalization. Further research is needed to explore the underlying mechanisms and the potential to be clinically applicable to improve treatment outcomes.