Mental contamination

The concept of mental contamination, originally studied in the context of the psychological consequences of sexual abuse (Fairbrother & Rachman, 2004), was quickly extended to OCD, specifically fear of contamination and related washing/cleaning rituals, and has become an important line of research.

What is contamination anxiety?

Rachman (2004) defined fear of contamination as an intense and persistent feeling of being contaminated, infected, or endangered by direct or indirect contact with a person, place, or object that is perceived as dirty, unclean, infected, or harmful.

Fear of contamination has subsequently been divided into two distinct types: physical contamination (or contact contamination), which is what we usually refer to when we talk about OCD, and mental contamination, which is what we will be discussing in this article.

What are the differences?

Physical contamination implies an external sensation of dirtiness caused by direct or indirect (or even imagined) physical contact with a tangible, easily identifiable contaminating substance, person, or object, such as germs, bacteria, toxic substances, bodily fluids (especially blood, feces, semen, and urine).

Spiritual contamination, on the other hand, is a sense of psychological contamination, involving an internal emotional feeling of “dirtiness” without any physical contact (e.g., triggered by certain thoughts, words, memories, or images).

This sense of contamination is not directly observable by others; it is described as something diffuse, barely identifiable in any part of the body.

Individuals with mental contamination may report a need to wash and may engage in complex mental and control rituals to reduce unpleasant emotions, although they generally never manage to feel completely “clean” and okay.

Situations that can trigger the state of mental contamination can be violations suffered, whether psychological (e.g., a betrayal that left the person feeling humiliated, shamed, manipulated, degraded) or physical (e.g., sexual assault), Then there are the episodes of so-called self-contamination, i.e., mental events such as profane, sexualized, or violent thoughts (e.g., aggressive obsessions) that morally “contaminate” the person, so unworthy and unacceptable are they.

Lady Macbeth Effect

The best-known example of spiritual contamination, in part because it is literary, is Lady Macbeth.

In Shakespeare’s famous tragedy, Lady Macbeth, an accomplice in the murder of King Duncan of Scotland and other misdeeds, desperately tries to wash away the imaginary blood stain by incessantly washing her hands.

The woman realizes with deep dismay that no matter how much blood is removed from her hand, nothing can ever erase the smell that she still feels on her hands as an indelible mark of her actions.

What Shakespeare describes in the tragedy of Macbeth was experimentally confirmed in a 2006 study by Zhong and Liljenquist, in which the authors demonstrated a link between physical cleanliness and moral cleanliness: exposure to immoral events stimulates a threat to one’s moral integrity by inducing the need to wash, even though there is no real external dirt and washing has only a symbolic “cleansing” function.

In fact, from the results of some studies, it seems that physical cleansing can restore moral purity without the need to engage in compensatory behaviors (such as an altruistic gesture of helping another).

Mental contamination: an important component of OCD

A study published in the Journal of Obsessive-Compulsive and Related Disorders (Melli, Carraresi, Stopani, & Bulli, 2014) aimed to investigate the prevalence of mental contamination in a sample of patients with obsessive compulsive disorder (OCD) through contamination and to analyze the mediating role of mental contamination in the relationship between the trait tendency to feel disgust and obsessive symptomatology. Of the 63 OCD patients in the sample, more than 60 percent reported the presence of mental contamination. The results also confirmed the hypothesis that mental contamination partially mediates the relationship between disgust propensity and obsessive-compulsive symptoms.

In other words, OCD subjects who are more likely to experience disgust when they experience events that make them feel mentally contaminated (e.g., physical or psychological injury, immoral thoughts, morally unacceptable images or impulses) may feel very dirty and disgusted and resort to maladaptive behaviors (e.g., washing compulsions) that keep obsessive symptomatology active.

Thus, it appears from the study that mental contamination plays an important role in OCD subjects with fear of contamination, particularly as a mediator of the relationship between disgust propensity and contamination thoughts/behaviors.

This finding may confirm what has been emphasized in the literature about the importance of accurate assessment of critical events that precipitate the onset of OCD with fear of contamination.

Mental contamination, as mentioned earlier, seems to arise as a result of “contaminating” life events in which the person felt morally wrong (as a result of actions committed) or violated, humiliated (as a result of actions suffered).

What are the implications for the treatment of OCD?

Given the “traumatic” nature of the state of mental contamination, it is worth considering the extent to which feelings of guilt and disgust toward certain stimuli in OCD patients may represent a type of affect without memory (Clark, 1999).

In other words, certain situations may activate the emotional experience associated with the traumatic memory, even if the patient is limited to the contingent problem that triggers the fear of contamination at that moment.

It might be interesting to consider whether whatever the obsessive-compulsive patient feels compelled to do to avoid a situation in which he or she might feel guilty (or disgusted) represents a coping mode with respect to a negative self-evaluation encoded in the critical event that precipitated the onset of the disorder.

In this regard, the purpose of the compulsive activity might be to repair a deeply “contaminated” self-image as activated at the time of the event that precipitated the disorder, or to avoid actions that might reactivate the same negative image of the person, making him or her feel disgusted, humiliated, and potentially a source of contempt from the community to which he or she belongs.

The fact that mental contamination is associated with negative self-evaluation as a result of critical events activates reflection on how much this internal sense of dirtiness is related to a problem of non-processing/integration into autobiographical memory of the past critical event(s), and how much DOC subjects with mental contamination use washing and other neutralizing behaviors to try to get away from the thoughts and feelings associated with the memory (“wash away the past”).

Understanding the role of mental contamination in contamination OCD allows for the development of potentially more effective treatments.

Here, the possibility of supplementing exposure and response prevention-which we know is the proven effective treatment for OCD-with work on reprocessing traumatic events using techniques such as imagery rescripting or EMDR may increase the success rate of standard cognitive-behavioral intervention.


  1. Clark, D. (1999). Anxiety disorders: why they persist and how to treat them. Behaviour Research and Therapy, 37, S5-S27.
  2. Fairbrother, N., & Rachman, S. J. (2004). Feelings of mental pollution subsequent to sexual assault. Behaviour Research and Therapy, 42, 173-190.
  3. Melli, G., Carraresi, C., Stopani, E., & Bulli, F. (2014). Disgust propensity and contamination-related OCD symptoms: the mediating role of mental contamination. Journal of Obsessive-Compulsive and Related Disorders, 3, 77-82.
  4. Rachman, S. J. (2004). Fear of contamination. Behaviour Research and Therapy, 42, 1227–1255.
  5. Zhong, C, & Liljenquist, K. (2006). Washing away your sins: Threatened morality and physical cleansing. Science, 313, 1451-1452.
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