Reduced P3 amplitudes during disgust conditioning in individuals with contamination-related obsessive-compulsive symptoms: Evidence from an analogue study.

Although contemporary models of obsessive-compulsive disorder (OCD) have primarily emphasized fear, recent accounts suggest that abnormal disgust learning may also contribute to OCD pathology, particularly in contamination-related OCD (C-OCD). The present study examined the neural correlates of disgust learning in individuals with elevated contamination-related obsessive-compulsive symptoms. Event-related potentials (ERPs) were recorded while 28 participants high in contamination-related obsessive-compulsive symptoms (HC) and 30 participants low in such symptoms (LC) completed disgust acquisition and extinction tasks. Behavioral measures included unconditioned stimulus (US) expectancy and conditioned stimulus (CS) disgust ratings, alongside electrophysiological indices of conditioned disgust. During acquisition, the HC group showed higher US expectancy for the CS+ than the LC group. At the neural level, both groups showed larger P3 amplitudes to the CS+ than to the CS-, indicating enhanced attentional significance. However, the HC group exhibited smaller overall P3 amplitudes than the LC group, which may reflect greater avoidance during disgust learning. During extinction, US expectancy differences between the CS+ and CS- remained evident in both groups, whereas P3 differences were no longer observed, suggesting a dissociation between self-reported and neural responses. Overall, these findings indicate that individuals with elevated contamination fear show enhanced disgust acquisition and altered neural processing during disgust learning, which may help clarify how maladaptive disgust responses are formed and maintained in contamination-related OCD.