An exploration of the relationship between mental pollution and OCD symptoms.

Rachman [(1994). Pollution of the mind. Behaviour Research and Therapy, 32, 311-314] theorized that a subtype of compulsive washing exists which has its compulsions triggered by feelings of internal dirtiness, or 'mental pollution'. Since this construct was proposed, few empirical studies have examined it in relation to obsessive-compulsive contamination fear. This study represents a validation of the Mental Pollution Questionnaire (MPQ), which was developed for the measurement of mental pollution. Psychometric data were obtained from two studies using non-clinical samples. The final version of the MPQ consisted of eight items and two subscales related to washing and ideation. Higher mental pollution scores were associated with greater obsessions, contamination, and washing symptoms. In addition, MPQ scores were positively associated with inflated responsibility beliefs and thought-action fusion. Lastly, a third study found that both MPQ subscales predicted OC symptoms after controlling for general distress, trait guilt, and disgust sensitivity. Potential uses of the MPQ as a clinical and research instrument are discussed.