From various studies emerges the link between disgust and Obsessive-Compulsive Disorder, important for the use of new treatments, to be integrated to the standard ones.
One of the clinical samples in which it has been demonstrated that there is a high propensity for disgust, is that of patients with obsessive-compulsive disorder, in particular with symptoms of fear of contamination.
The fear of contamination
One of the clinical samples in which a high propensity for disgust has been shown to be present is that of patients with obsessive-compulsive disorder, particularly with symptomatology of fear of contamination (Olatunji & Sawchuk, 2005). In fact, 50% of patients report that pathological behaviors toward hygiene are due to recurrent thoughts of contamination avoidance (Olatunji & Sawchuk, 2005). Furthermore, it has been hypothesized that the propensity for disgust itself may be one of the factors maintaining pathology (Olatunji & Sawchuk, 2005), if not even one of the factors increasing the incidence of patient drop-out (Ludvick, Boshen & Neuman, 2015).
Disgust is one of the six basic emotions (Ekman, 1993), with a precise physiological response, parasympathetic activity that produces increased salivation and nausea (De Jong et al., 2011), and a specific neural correlate, the insula (Sprengelmeyer, 2007).
It was initially studied as an aversion reaction towards certain foods, thus elicitating disgust, characterized both by physical appearance, and ideational character, which then report the knowledge of the origin of these foods (Rozin & Fallon, 1987; Rozin, Haidt, & McCauley, 2000). The behavioral response consists of distancing oneself from the disgusting object, as it could be harmful or contaminated, maintaining the body’s role of defense (Rozin & Fallon, 1987).
It can be divided into several domains, more sensory or culturally determined, depending on what kind of stimulus elicits them: central disgust, animal nature, interpersonal, and moral (Rozin, 2009). The last three are related to cognitive, rather than sensory, beliefs, and concern, respectively: contagion to mortality and decay, distance from those who are considered disgusting, and preservation of a social order (Rozin, 2009). With regard to Obsessive-Compulsive Disorder, research is more focused on the first domain, namely central disgust. It is characterized by
- rejection of oral intake;
- sense of dangerousness of the disgusting object;
- and potential contamination it may produce.
The primary role of central disgust is food rejection, so the mouth acquires the role of a gateway (Rozin & Fallon, 1987), and the belief that “one becomes what one eats” is reinforced (Rozin & Haidt, 2000). Given this premise, with regard to contamination, more related to touch and sight, Rozin proposes how two magical-sympathetic laws can regulate it: the law of contagion, once you are in contact with something contagious, you will always remain contaminated; and the law of similarity, two objects that appear the same in form, will also be the same in substance (Rozin & Fallon, 1987; Rozin & Haidt, 2000).
Do patients with Obsessive-Compulsive Disorder experience more disgust than others? How can the experience of disgust be measured in terms of individual differences? First, a distinction must be made between disgust propensity (PD), which is an individual’s ease of being disgusted, and disgust sensitivity (SD), which is the intensity of negative appraisal when experiencing disgust (Ludvick, Boshen & Neuman, 2015).
Work will be proposed that addresses disgust propensity in normal samples and those with Obsessive-Compulsive Disorder. For this purpose, in most studies, the instrument used is the Disgust Scale Revised (Olatunji et al., 2009), which assesses the inclination/propensity to feel disgust in multiple domains: animals, body products, death, violations of normal development, food, sex, hygiene, sympathetic laws (unlikely contagion). Although there has been interest in proposing new tools to better explain the variability of responses in patients with Obsessive-Compulsive Disorder (Melli et al., 2015a), the variability appears to be confounding to the conceptualization of the disorder, and consequently to subsequent treatment.
What consequences in the treatment?
The scientific literature, and consequently the treatment proposal, has focused on aspects related to anxiety in Obsessive-Compulsive Disorder, but if we think about the symptom of fear of contagion, a question arises: what is the emotion that you want to avoid? That is, is the problem the fear of the disgusting stimulus, or the ease of feeling the disgust? The answer to this question gives clinicians the ability to intervene with more effective treatments. Both types of avoidance, of threat and disgust, generate compulsions, e.g., cleaning, but resolution of such compensatory behaviors comes through analysis of which emotion generated them.
For example, in a study by Verwoerd and collaborators (2013), it was shown that in a non-clinical sample, divided by low or high contagion avoidance scores, the cognitive error relates the likelihood that a stimulus is threatening to how disgusted the individual feels, corroborating the avoidance itself. Thus, this is the same cognitive error found in anxiety symptomatology: “I feel anxiety, then there is a threat” is equivalent to “I feel disgust, then there is contamination,” with the diference that different emotions come into play (Verwoerd et al., 2013). Thus, the cognitive error underlying avoidance may be common to the two types of emotional experience.
Evidence in Obsessive-Compulsive Disorder in favor of a distinction between avoidance in terms of fear in a situation assessed as threatening, and between avoidance of the situation that generates disgust, will be reported below.
First, clinical studies have established that negative affectivity, anxiety and depression, are not determinants of the link between Propensity to Disgust (PD) and contamination fear symptoms in Obsessive-Compulsive Disorder, whereas it is PD itself that is determinant (Olatunji et al., 2016, Melli at al., 2016, Melli et al., 2015b, Ludvick, Boshen & Neuman, 2015). Thus, anxiety is not one of the factors that statistically explain this link.
In a study by Melli et al. (2015a), the authors developed a scale to distinguish two possible dimensions within fear of contamination: avoidance of harm, and avoidance of disgust, to test whether threat or the emotion of disgust itself generates avoidance in a sample of patients with Obsessive-Compulsive Disorder. The scale was called the Contamination Fear Core Dimensions Scale (CFCDS), consisting of 8 items, 4 for harm avoidance and 4 for disgust avoidance. The individual is then asked to give a Likert scale score from 0 to 5 for each item. The authors found how disgust avoidance was associated with the symptom of contamination and mental contagion, while harm avoidance was more associated with the symptom of responsibility (Melli et al., 2015a).
Thus, they demonstrated how these two dimensions are distinct, though related, and both part of the fear of contamination. Furthermore, the strength of the study concerns the focus on motivational mechanisms of contamination avoidance, i.e., whether it is the motivation to avoid feeling disgust or fear toward a threat (Melli et al., 2015a).
Is it disgust that triggers avoidance or something else? For example, the role of obsessive thoughts as activators was investigated (Melli et al., 2016). The results showed that obsessive thoughts are not in fact mediators, but that there is a direct relationship between PD and fear of contagion. Even more interesting, the authors performed the study with a sample of patients with Obsessive-Compulsive Disorder, predicting how in the general sample only those who presented the symptom of contamination would show this pattern. A result that would have been unsurprising if a sample of only patients with the contamination symptom had been taken into account. Therefore, the authors emphasized that, in general, during the treatment of Obsessive-Compulsive Disorder, when there is the presence of fear of contamination, the patient’s propensity to disgust should be taken into account (Melli et al., 2016).
Thus, it is plausible to wonder about the role of PD in other symptoms. In a paper by Olatunji and collaborators (2016), consisting of three studies, it actually showed that depending on which measures are used, PD can more or less strongly explain symptoms of contamination or all other symptoms. In fact, in the first study that analyzes disgust propensity through the Disgust Scale, Obsessive-Compulsive Disorder symptoms through the Padua Inventory, and anxiety through the Anxiety Sensitivity Index-3, PD would explain more of the contamination symptoms of Obsessive-Compulsive Disorder, but mediated by anxiety. In the second proposed study, the Disgust Scale for PD, the Obsessive-Compulsive Inventory OCI-R for Obsessive-Compulsive Disorder symptoms, and the Depression Anxiety Stress Scale for anxiety, the relationship between PD and contagion symptoms is not significantly different from the relationship between PD and all other symptoms. Whereas in the third study where both PD and disgust sensitivity are considered, and DOC symptomatology measured through the Dimensional Obsessive-Compulsive Scale DOCS, both disgust dimensions are more strongly related to noncontagious symptoms, rather than contamination itself (Olatunji et al., 2016).
Other symptoms of Obsessive-Compulsive Disorder and disgust: what relationships?
Although the study underlined how disgust can be a mediator in Obsessive-Compulsive Disorder in general and not only of contamination, the authors do not distinguish which other symptoms are involved, and to what extent. Indeed, the authors also highlighted how, depending on the type of assessment, the results change. Regardless of this, it is also plausible that other symptoms can be explained in terms of disgust, but through the mediation of other elements.
For example, whether for the symptom of excessive responsibility, PD might be mediated, or go parallel, to the trait of guilt (Melli et al., 2015b). The authors, beyond controlling for both affective dimensions such as anxiety and depression, studied a clinical sample discriminated across the OCDS. Using regression analyses, the authors found how the trait of guilt does not predict Obsessive-Compulsive Disorder symptomatology, while the propensity for disgust is a predictor not only of contamination, but surprisingly also of obsession with symmetry and order. Whereas for symptoms such as responsibility for mistakes and unacceptability of thoughts were predictors of neither PD nor guilt. Thus, it could be hypothesized that, through mediation between PD and obsession with symmetry and order, the OCD patient would feel disgust and thus enact compulsions to appease the feeling of not being complete, and thus disgusting, but not to avoid a future threat (Melli et al., 2015b).
But this hypothesis has not yet been tested. The strength of this article relates to the importance that disgust may also elicit compulsive behaviors to quell contamination, but potentially for other OCD symptoms as well.
Thus, once it is established that the propensity to disgust is in close association with contamination, and perhaps with other symptoms of Obsessive-Compulsive Disorder, it is fair to ask whether there are, and what might be, cognitive mediators within this relationship. Indeed, it has been seen that, in a non-clinical sample, a cognitive fallacy is to assume that one can be contaminated in innocuous situations (Verwoerd et al., 2013).
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.
Types of avoidance and therapy
From a therapeutic point of view, detecting, and distinguishing, which avoidance the patient enacts is crucial: on the one hand through the extinction of those behaviors learned in terms of Pavlovian conditioning, suitable for those symptoms generated by anxiety, but not very useful for the fear of contamination mediated by disgust, treatable in terms of counterconditioning (Ludvick, Boshen & Neuman, 2015).
In fact, it has been hypothesized that disgust reactions might be maintained through evaluative conditioning, i.e., the change in valence of a stimulus, given by pairing it with another stimulus, through an abstract, hence thinking, relationship. Such abstract relations could be magic-sympathetic laws, disgust-based reasoning, and mental contamination (Ludvick, Boshen & Neuman, 2015).
If we think about the last one, the generation of high disgust propensity could be given by a referential type of learning, where the unconditioned stimulus does not go to predict the conditioned one, but is only its reference, i.e., the mere presence of the unconditioned stimulus generates an evaluation of the conditioned one, without it actually being present (Ludvick, Boshen & Neuman, 2015). Thus, treatment will not rely on extinction, but on counterconditioning: the pairing of the old unconditioned stimulus with a new conditioned stimulus with positive valence, to break the previous link (Ludvick, Boshen & Neuman, 2015).
Thus, although there is evied evidence of a relationship between disgust propensity and Obsessive-Compulsive Disorder, it should be further investigated:
- whether the propensity to disgust belongs only to the fear of contagion, or whether, in part, to other symptoms as well;
- what could be other cognitive distortions that reinforce the link, besides mental contamination and reasoning based on disgust;
- what might be the eliciting contexts, i.e., whether neutral non-disgusting situations can activate the propensity to disgust in patients with Obsessive-Compulsive Disorder;
- and whether there is a direct link between these distortions and compulsive acts to resolve them. Indeed, clarifying the relationship may provide insight into what treatment may be most effective for disgust (Melli et al., 2014), for example, if we interpret treatment in terms of counterconditioning evaluative learning (Ludvick, Boshen & Neuman, 2015).
In addition, there has been more focus in the literature on the central disgust dimension in Obsessive-Compulsive Disorder, a key logical step if we take into account the model of disgust, and the evidence reported on OCD.
Although it may be interesting to investigate another component of disgust, the interpersonal one. That is, interpersonal disgust would be about creating a distance of who is potentially, or is, considered disgusting (Rozin & Haidt, 2000). If we think about the stimuli that normally generate it, it could be plusible that the evaluation of interpersonal disgust in Obsessive-Compulsive Disorder is generated in terms of self-referentiality: it is the envy itself that is the disgusting stimulus, as well as others. The stimuli that normally elicit interpersonal disgust can be divided into four domains: strangeness (refers to contact with something unfamiliar or whose origin is unknown), moral stigma (rejection of those individuals who have unacceptable conducts), disease (aversive reactions towards the sick that remind us of our vulnerability), misfortune (repulsion for those individuals who have suffered a misfortune), and in these cases the contagion concerns the rejection of the acquisition of the characteristics of those individuals to be rejected (Rozin & Haidt, 2000).
Thus, it is conceivable that individuals with Obsessive-Compulsive Disorder may also have a high propensity for interpersonal disgust, given in turn by a likely mechanism of mental contagion or self-referral, which generates avoidance, or attempted control, of disgust.
However, these latter speculations go beyond what was presented in this article, proposed to investigate factors that may increase vulnerability in experiencing disgust. The analysis reported evidence in favor of a link between disgust and Obsessive-Compulsive Disorder, and highlighted its peculiarity, which is important for the use of new treatments, to complement standard ones.
- De Jong, P. J., Van Overveld, M., & Peters, M. L. (2011). Sympathetic and parasympathetic responses to a core disgust video clip as a function of disgust propensity and disgust sensitivity. Biological Psychology, 88: 174 – 179.
- Ekman, P. (1993). Facial Expression and Emotion. American Psychologist, 49(4): 176 – 379.
- Ludvick, D., Boschen, M. J., & Neumann, D. L. (2015). Effective behavioural strategies for reducing disgust in contamination-related OCD: A review. Clinical Psychology Review, 42: 116 – 129.
- Melli, G., Bulli, F., Carraresi, C., Tarantino, F., Gelli, S., Poli, A. (2017). The differential relationship between mental contamination and the core dimensions of contact contamination fear. Journal of Anxiety Disorders, 45: 9 – 16.
- Melli, G., Bulli, F., Carraresi, C., Stopani, E. (2014). Disgust propensity and contamination-related OCD symptoms: The mediating role of mental contamination. Journal of Obsessive-Compulsive and Related Disorders, 3: 77 – 82.
- Melli, G., Chiorri, C., Carraresi, C., Stopani, E., Bulli, F. (2015a). The two dimensions of contamination fear in obsessive-compulsive disorder: Harm avoidance and disgust avoidance. Journal of Obsessive-Compulsive and Related Disorders, 6: 124 – 131.
- Melli, G., Chiorri, C., Carraresi, C., Stopani, E., Bulli, F. (2015b). The role of disgust propensity and trait guilt in OCD symptoms: A multiple regression model in a clinical sample. Journal of Obsessive-Compulsive and Related Disorders, 5: 43 – 48.
- Melli, G., Moulding, R., & Poli, A. (2016). Is it more disgusting if I think about it? Examining the interaction of obsessive beliefs and disgust propensity in clinical obsessive- compulsive disorder. Journal of Obsessive-Compulsive and Related Disorders, 11: 74 – 81.
- Olatunji, B. O., & Sawchuk, C. N. (2005). Disgust: Characteristic features, social implications, and clinical manifestations. Journal of Social and Clinical Psychology, 24: 932 – 962.
- Olatunji, B. O., Ebesutanib, C., & Kim, E. H. (2016). Does the measure matter? On the association between disgustproneness and OCD symptoms. Journal of Anxiety Disorders, 44: 63 – 72.
- Olatunji, B. O., Moretz, M. W., McKay, D., Bjorklund, F., de Jong, P. J., Haidt, J., Hursti, T. J., Imada, S., Koller, S., Mancini, F., Page, A. C., Schienle, A. (2009). Confirming the Three-Factor Structure of the Disgust Scale–Revised in Eight Countries. Journal of Cross-Cultural Psychology. 40(2): 234 – 255.
- Rozin, P. & Fallon, A. E. (1987). A perspective on disgust. Psychological Review. 94(1): 23-41.
- Rozin, P., Haidt, J., Fincher, K. (2009). From Oral to Moral. Science, 323, 1179 – 1180.
- Rozin, P., Haidt, J., McCauley, C. (2000). Disgust. In M. Lewis & J. M. Haviland-Jones (Eds.). Handbook of Emotions, 2nd edition. (pp. 637-653). New York: Guilford Press.
- Sprengelmeyer, R. (2007). A neurology of disgust. Brain, 130, 1715 – 1717.
- Verwoerd, J., de Jong, P. J., Wessel, I., van Hout, W. J. P. J. (2013). “If I feel disgusted, I must be getting ill”: Emotional reasoning in the context of contamination fear. Behav Res Ther; 51(3):122-7.