Evaluating the mediating effects of perceived vulnerability to disease in the relation between disgust and contamination-based OCD

•Contamination fear was predicted by disgust propensity and germ aversion.•Germ aversion was a significant partial mediator of this relation.•The mediation effect was robust in a non-clinical sample and sample of individuals with clinically-elevated OCD symptoms. Contamination-based obsessive-compulsive disorder (OCD) is thought to develop and be maintained by excessive propensity to experience disgust, particularly in response to perceived contaminants, and dysfunctional threat appraisals pertaining to illness. The present studies attempted to integrate these lines of research by testing the degree to which contamination-based OCD is associated with individual differences in disgust propensity and sensitivity, affective distress in response to perceived contaminants, and perceived threat of illness. In Study 1, a convenience sample of 185 adults completed self-report scales assessing obsessive-compulsive symptoms, disgust propensity and sensitivity, germ aversion, and perceived infectability. Multivariate regression showed that disgust propensity and germ aversion were the only significant predictors of contamination-based obsessions and compulsions. Exploratory analyses suggested that there was a significant indirect effect of disgust propensity on contamination-based obsessions and compulsions via germ aversion. Findings from Study 1 were replicated using a sample of twenty-six obsessive-compulsive participants. Despite the substantially smaller sample, the proportion of the total effects attributable to the mediating effect of germ aversion was comparable, consistent with a significant partial mediation in both samples. These results together suggest that contamination-based OCD symptoms are likely maintained and motivated by basic affective processes.