Pupillary reactions depend on disgust sensitivity in conceptual pavlovian disgust conditioning

Exposure-based interventions rely on inhibitory learning, often studied through Pavlovian conditioning. While disgust conditioning is increasingly linked to psychiatric disorders, it has been less researched than fear conditioning. In this study, we applied a categorical Pavlovian disgust conditioning paradigm with two CS categories (animals and tools) and disgusting images as US (e.g., feces). During categorization, acquisition, and extinction phases, we measured eye movements and pupil responses in 44 participants. Consistent with previous results, subjective disgust and US expectancy increased from categorization to acquisition for CS+, along with greater pupil dilation for CS+ than CS-. Higher disgust sensitivity was associated with more generalized and longer lasting disgust experiences, as well as higher expectancy for disgusting images. Pupil response during acquisition and extinction depended on disgust sensitivity: Participants with lower disgust sensitivity showed greater pupil dilation. These findings suggest that individuals with high disgust sensitivity and prolonged expectancy may exhibit physiological differences from less sensitive individuals as early as the acquisition phase. This could inform contamination-based OCD treatments by integrating interventions which focus on attentional deployment or physiological reactions. To our knowledge, this is the first study using pupillometry and eye tracking in categorical disgust conditioning.