Purpose: Cognitive models of mental contamination (feelings of dirtiness/washing behaviour that arise without direct contact with a contaminant) highlight the central role of perceptions of violation in the onset and maintenance of these feelings. Little research has been done to clarify violation-specific appraisals relevant to mental contamination. Perceptions of violation of one's moral self-concept may represent one such appraisal domain. This experiment aimed to examine the impact of these appraisals on feelings of mental contamination.

Methods: One hundred and fifty participants received false feedback that they scored high on a morality subscale of a bogus personality test. They then completed a writing task wherein their degree of moral self-violation was manipulated. They received a writing prompt corresponding to one of three randomly assigned conditions (violated self (VS), bolstered self (BS), general negative (GN)). Finally, participants completed measures of mental contamination.

Results: The manipulation was effective at violating participants' moral self-concept. Those in the VS condition reported significantly higher levels of feelings of mental contamination than those in the BS or GN conditions. There were no significant differences between conditions regarding urges to wash.

Conclusions: Findings highlight the relevance of moral self-violation in the understanding and treatment of mental contamination.