[Encyclios]

Mental contamination

In a study by Melli and colleagues (2014) they investigate whether there is a component of mental contamination (CM), a cognitive mechanism through which disgust is felt without a contaminating object actually being present, therefore triggered even if only by thinking or remembering something disgusting, dirty or immoral. Consequently, the patient with Obsessive-Compulsive Disorder can resolve this feeling by implementing a compulsion. In this study, mental contamination was measured through the Vancouver Obsessional Compulsive Inventory – Mental contamination scale VOCI-MC. The authors found that in a clinical sample of patients, with the presence of the contamination symptom, mental contamination was also present in 61.9% of the sample. But even more interestingly, if mental contamination is included as a mediator, the correlation between PD and contamination in OCD is strengthened (Melli et al., 2014). The authors proposed that individuals with high mental contamination, when placed in a harmless situation, may feel more disgusted than individuals with low CM. So they hypothesized to test whether such individuals might enact more intense or frequent compensatory compulsions, and if so, create more effective treatment proposals (Melli et al., 2014).

But this result, and the subsequent hypothesis, concern mental contamination without the sample being subjected to a situation, but through statistical mediation analysis between several scales, the VOCI-MC, the DOCS for contamination, and the Disgust Proponsity Questionnaire. It might be interesting to incorporate an experimental design, such as Verwoerd et al.’s (2013) potentially contaminating scenarios, into a clinical sample, or into a sample with high VOCI-MC scores.

But before testing the role of mental contamination in a harmless situation, or in evoking a memory of something harmful, its relationship to PD and actual contact contamination must be clarified. Indeed, once one has distinguished between fear and disgust of something threatening, in terms of avoidance of harm or disgust (Melli et al., 2015a), CM might act on only one or both types of avoidance (Melli at al., 2017).

In a sample of patients with Obsessive-Compulsive Disorder, in which there were patients with primary symptoms of contamination, there is a strong correlation between CM, PD, and disgust avoidance, which is significantly greater than that which exists between CM, PD, and harm avoidance (Melli et al., 2017). Furthermore, from the mediation and bootstrapping analysis, mental contamination decreased the standard error in the relationship between PD and fear of contamination based on disgust avoidance, compared to the relationship without a mediator. So, the results suggest that individuals with high PD in potentially harmful/disgusting situations (contaminating or morally unacceptable), may feel mentally contaminated, and at the same time perceive themselves to be highly disgusted, and both mechanisms could be reactivated by the mere thought, or memory, of that event or similar events (Melli et al., 2017).

In summary, all of the work presented reports how disgust can be a fundamental dimension of Obsessive-Compulsive Disorder, specifically:

• patients with Obsessive-Compulsive Disorder and contamination symptoms have a high propensity for disgust (Olatunji et al., 2016),
• depending on which assessment you use, and which symptoms you investigate, propensity for disgust is a widespread component of Obsessive-Compulsive Disorder beyond contamination symptoms (Olatunji et al., 2016, Melli et al., 2015b, Melli et al., 2016),
• it is possible to distinguish two types of avoidance of the disgusting/contaminating stimulus, one related to fear of harm/disease, and one related to avoidance of feeling disgust (Melli et al., 2015a),
• in patients with Obsessive-Compulsive Disorder and contamination symptoms, the propensity to disgust is not mediated by obsessive thoughts (Melli et al., 2016), or guilt traits (Melli et al., 2015b),
• but that another cognitive bias, mental contamination, may be a mediator between disgust propensity and disgust avoidance in patients with Obsessive-Compulsive Disorder (Melli et al., 2014, Melli et al., 2017),
• or that cognitive error, disgust-based reasoning is present in individuals with a high fear of contamination (Verwoerd et al., 2013).

So the evaluations of what can be disgusting and contaminating in Obsessive-Compulsive Disorder are an ’emphasis of normal mechanisms. In fact, if we think of Rozin’s model (1987, 2000, 2009), the function of disgust is to move away, and therefore to avoid, the harmful stimulus. The evaluation of whether to move away or not is based on two laws that he defines as “magical”, therefore not empirically provable. The two sympathetic laws, in fact, “impose” that: once in contact with something contagious, one will always remain contaminated (law of contagion); and two objects that appear the same in form, will also be the same in substance, so if one is disgusting and dangerous, the other will be too (law of similarity) (Rozin & Fallon, 1987; Rozin & Haidt, 2000). It seems obvious how, if the two laws are applied in contexts that are not so dangerous, an individual may still magnify them, and thus feel a greater sense of dangerousness in terms of a high propensity for disgust. Moreover, if we think of Obsessive-Compulsive Disorder, in which there is a reasoning based on disgust and/or mental contamination, the avoidant or compulsive acting out appear as a possible dysfunctional solution.