LAUSR

Abstract Contamination concerns are among the most common symptoms of obsessive-compulsive disorder (OCD). Research has recently focused on mental contamination, defined as feelings of dirtiness and/or washing behaviour arising in the absence of direct contact with a contaminant. Mental contamination is highly prevalent; a substantial amount of washing behaviour related to contact contamination may actually be a manifestation of mental contamination. As such, washing may reflect an attempt to cleanse oneself of a feared corrupted self, rather than of any physical contaminant. Indeed, a recent treatment study found that reductions in feared self-perceptions also predicted reductions in contamination symptomatology; we propose that this link may be explained by mental contamination. We examined whether mental contamination, relative to established OCD belief domains, mediated the relationship between feared self-perceptions and contact contamination. In our sample of 626 undergraduate participants, feared self-perceptions significantly predicted contact contamination symptoms, with mental contamination and two OCD belief domains (perfectionism/intolerance of uncertainty, importance of/control over thoughts) as significant mediators. Importantly, mental contamination was the strongest mediator. These findings provide further evidence for the predictive power of vulnerable self-themes in OCD and highlight the important role of mental contamination in this relationship with regard to contamination symptoms.