The Effect of Disgust Sensitivity on Moral Judgements in Obsessive Compulsive Disorder

Charles Darwin coined disgust as a sensation rather more distinct in its nature in which an individual has an aversion to negative stimuli deemed to be revolting primarily in the sense of taste and alternately to anything that evokes feelings akin to disgust (Darwin, 1872). Evolutionarily, disgust is accompanied by a distinct facial expression, the closing of the nares, nausea, and distancing oneself from the aversive stimuli (Haidt, McCauley, & Rozin, 1994). While disgust has traditionally been linked with ingestion and excretion from Tomkins (1963) viewing it as a recognition of competition to our food drive to Angyal (1941) deeming body wastes as the prime negative stimuli to elicit disgust, the emotion of disgust has broadened to include aversions to certain people, places, and things. Disgust has since been broken into four major categories: core disgust, animal-nature disgust, interpersonal disgust, and moral disgust (Rozin, Haidt, & McCauley, n.d.) Yet, there is not resounding confidence for what motivates the emotion of disgust beyond the traditional view of avoidance of harmful pathogens.

Emerging research suggests that there is a link between the emotion of disgust and Obsessive Compulsive Disorder (OCD) (Pittenger, 2017). OCD is a common, chronic disorder characterized by uncontrollable, reoccurring thoughts (obsessions) and behaviors (compulsions) that the individual feels compelled to complete (National Institute of Mental Health, 2016). Obsessive compulsive disorders can be grouped based on the nature of their symptoms with the five most common subtypes being: contamination obsession OCD with washing/cleaning compulsions; harm obsession OCD with checking compulsions, obsessions without visual components (e.g. sexual, religious, aggressive themes); symmetry obsessions with ordering, arranging, and counting compulsions; and, hoarding (Owen, 2018).

It has been suggested that appraisals of disgust could play a major role in obsessive contamination patterns and washing compulsions often exhibited in patients with contamination type OCD (Berle & Phillips, 2006). Researchers have also found that individuals with OCD have a deficiency for recognizing facial expressions of disgust (Pittenger, 2017). Finally, researchers have found similar brain pathways are activated for disgust and OCD pathology (Berle & Phillips, 2006). The frontal-striatal regions of the brain for individuals with OCD symptoms were found to be affected with the emotion of disgust which implies that the discomfort associated with disgust could be connect to the pathogenesis of common OCD behaviors (Sprengelmeyer et al., 1997). This relationship lends to the notion that patients with OCD (specifically contamination-type) will have stricter qualifications for what they deem as disgusting; and, therefore exhibit harsher views on stimuli, people, or situations considered disgusting in their schema.

Additionally, disgust has many similarities to how an individual experiences fear. Both are characterized by withdrawal or avoidance from a certain aversive stimuli. Researchers indicate evaluative conditioning (EC), a version of classical conditioning, as how we are conditioned to be fearful or disgusted by a certain stimuli. Evaluative conditioning proposes that we make hedonic judgements about stimuli, events, etc. to label a formerly neutral stimuli as positive or negative while combining it with an aversive stimuli (Berle & Phillips, 2006). Hence, it only takes one occurrence for this combination aversion to create an engrained state of fear or disgust thereby directly affecting our future behavior. This rationale led our team to question if sufferers from harm obsession OCD would make harsher moral judgements.

Disgust sensitivity describes the extent to which someone feels disgusted about a specific aversion. It is thought that an individual with high levels of disgust sensitivity would more likely be disgusted by other stimuli and situations (Berle & Phillips, 2006). Research has found that individuals with OCD are likely to show high levels of disgust sensitivity. Deacon and Olatunji (2006) studied the effect of disgust sensitivity on predicting contamination anxiety and avoidance, and found that disgust sensitivity was significantly related to anxious and avoidant behavior for all three contamination-related behavioral avoidance tasks (BATs) (Deacon & Olatunji, 2007).

There is additional evidence that moral judgements are correlated with the emotion of disgust. Jonathan Haidt's Moral Foundations Theory lists six foundations of morality: harm, fairness, loyalty, authority, purity, and liberty; with purity having links to disgust sensitivity (Haidt et al., 1994). Leeuwen and colleagues (2016) found that individuals with higher degrees of disgust sensitivity exhibited harsher moral judgments even when controlling for variables like political ideology. This indicates that moral judgements would be driven by an individual's perception of disgust sensitivity in accordance to certain aversive stimuli. Contrastingly, Kurt Gray's Theory of Dyadic Morality suggests that moral judgements are a social construct of a combination of two units: an intentional agent causing damage to a vulnerable patient which when put together causes harm. Hence, moral judgements would be the consequence of harm, with disgust acting as a situational byproduct (Gray, Young, et al., 2012).

The present study is focused on the effect of contamination obsession OCD and harm obsession OCD and their implications on disgust sensitivity and overall moral judgement. If disgust can be attributed to the judgement of morally disgusting scenarios aligned with Haidt's Moral Foundations Theory, it is predicted that people with contamination OCD will make harsher moral judgements on purity scenarios than people with harm obsession OCD and people without OCD. Patients with contamination OCD tend to have a higher disgust sensitivity which may apply to disgust in a moral context and therefore yield harsher judgements as they will reject the scenarios more strongly. In response to moral scenarios that are not related to purity or disgust, both groups of OCD patients should perform similarly because both groups are concerned with potential harm, more so than the group without OCD.

Alternatively, if moral judgement is mediated by harm instead of disgust as posed by Gray's Theory of Dyadic Morality, both groups of OCD patients, (contamination OCD and harm obsession OCD) will make harsher moral judgements on all types of moral dilemmas than people without OCD because patients with OCD have a higher concern for potentially harmful stimuli and will tend to reject those scenarios more strongly.

Participants were recruited through posters and online advertisements. Participation was limited to individuals currently diagnosed with OCD in between the ages of 18 and 30. A total of ninety individuals ( 5 females and 45 males) participated in this study with thirty individuals in each group (Mage = 25 years, SD = .503 years ) All testing occurred on site and in person. Participation was voluntary, and participants received no compensation for their time.

Obsessive Compulsive Disorder. We used Goodman, Price, and Rasmussen's (1989) Yale-Brown Obsessive Compulsive Scale (Y-BOCS) to first determine what type and how severe each individual's OCD was. Participants indicated the degree to which a series of situations occurred over the past week (e.g. How much control do you have over your obsessive thoughts?, How much time do you spend performing compulsive behaviors?). Our team added addendums to the original questions to differentiate between the different types of obsessive compulsive disorders we were interested in for our study (e.g. How much do you think about harming yourself or others, Do you feel you repeatedly wash your hands to protect for contamination?). Based on the results of this test, the participants were divided into one of three groups: a) contamination obsession OCD; b) harm obsession OCD; and, c) control group with no exhibited OCD tendencies.

Disgust Sensitivity. We used Olatunji and colleagues' (2007) Disgust Scale- Revised (DS-R) to assess the participant's individual differences in disgust sensitivity. Participants indicated how much they agreed with 27 scenarios from the seven domains of disgust elicitors by rating scenarios (e.g. It would bother me tremendously to touch a dead body) on a scale of 0 (strongly disagree, very untrue about me) to 4 (strongly agree, very true about me. The Disgust Sensitivity Scale has been found to have respectable internal consistency (Cronbach's ??? = .80) and test-retest reliability (0.79 for 4-5 month intervals) (Berle & Phillips, 2006). Higher scores on the Disgust Sensitivity Scale indicates that an individual would experience similar levels of disgust to varying situations and stimuli.

Procedure

Moral Dilemmas. After signing the informed consent form, each group was presented with examples of moral dilemmas taken from Gray, Schein, and Ward's (2009) study on how harm can mediate a link between disgusting and immoral acts. Participants were provided with and asked to read a summary of a total of eight moral dilemmas: four purity moral scenarios (e.g. incest, getting a blood transfusion from a child molester) and four harm/non-purity moral scenarios (e.g. domestic violence, adultery) to measure the participant's disgust sensitivity levels. Each group was given an equal number of scenarios (eight) in a randomized order.

The participants were presented with a moral scenario one at a time and were allotted five minutes per moral dilemma to read and reflect. After reading each scenario, the participants rated each moral dilemma on a Likert scale of 1 (completely and morally acceptable) to 7 (completely and morally unacceptable). The purpose of this test was to determine if people with a certain type of OCD (contamination versus harm) would have different reactions to the provided moral dilemmas, thereby indicating harsher moral judgements.

After the participants finished their tasks and supplemental tests, they were debriefed on the purpose of the experiment and provided with contact information for counsel if the subject matter evoked feelings that warranted attention.

Statistical Analyses

The scenario type and OCD diagnosis type were submitted to a two-way 2 (scenario type: disgust, harm) x 3 (OCD diagnosis: contamination OCD, harm OCD, no OCD) mixed analysis of variance (ANOVA). The scenario type (purity vs non-purity) acted as the within-subjects factor and the OCD diagnosis type (contamination OCD, harm OCD, or no OCD) acted as the between-subjects factor. The analysis was followed up with three independent t-tests to identify any significant relationships between the means of the within-subjects' factors and between-subjects' factors.

Results

The two-way 2 x 3 ANOVA yielded a significant difference for the condition of purity vs non-purity moral dilemmas (Figure 1). There was a significant difference between purity moral dilemmas and non-purity moral scenarios between the three groups , F(2, 87) = 15.389, p < .05. For the purity moral scenario condition, there was a significant difference found between both contamination obsession OCD participants and the control group, t(58) = -10.501, p < .05; and, contamination obsession OCD participants and harm obsession OCD participants, t(58) = 6.657, p <.05. Consistent with the hypothesis, participants with contamination obsession OCD recorded harsher moral judgements against the control group and harm obsession OCD group when presented with purity moral scenarios. For the non-purity moral scenario condition, there was a significant difference found between contamination OCD participants and the control group, t(58) = -7.173, p < .05; and, harm obsession OCD patients and the control group, t(58) = -8.740, p <.05. Consistent with the hypothesis, participants in both the contamination obsession and harm obsession participant pools recorded harsher moral judgments against the control group when presented with non-purity moral scenarios. There was an insignificant relationship found between contamination obsession OCD and harm obsession OCD for appraisals of non-purity moral dilemmas, t(58)= -.773, p = .443. Contrary to the original hypothesis, the type of OCD a participant had did not affect their final moral judgement recordings when presented with a non-purity moral scenario. Instead, participants who exhibited any subset of OCD tended to make harsher moral judgements in both conditions.

Discussion

This study provides new evidence to support the relationship between disgust and tendencies of individuals with Obsessive Compulsive Disorders. As hypothesized, Haidt's Moral Foundations Theory was supported by individuals with OCD reporting harsher moral judgements than the control group with no OCD tendencies. Specifically, when confronted with purity moral dilemmas, sufferers of contamination obsession OCD tended to make harsher moral judgements on the scenario over and above individuals with harm obsession OCD and the control group. This association between disgust sensitivity and contamination obsession OCD is aligned with previous researcher's findings (Haidt et al., 1994; Horberg, Oveis, Keltner, & Cohen, 2009; Sprengelmeyer et al., 1997; van Leeuwen, Dukes, Tybur, & Park, 2017). Horberg and colleagues (2009) found that disgust had the power to moralize or amplify the moral significance on matters of purity with the emotion of disgust being a stronger indicator over fear and anger on condemnation of morally impure situations (Horberg et al., 2009).

For the non-purity moral dilemmas, both contamination obsession and harm obsession OCD suffers reported harsher moral judgements when compared to the control group, but there was no indication to support Gray's dyadic view that harm obsession OCD participants would report harsher moral judgements over contamination obsession OCD sufferers. Other findings have found that appraisals of moral dilemmas when considering disgusting stimuli cannot be restricted to purity or bodily norms; rather, disgust should be viewed as dyadic with other components, like physical disgust (e.g. sex crimes), affecting an individual's moral judgements (Chapman & Anderson, 2014). Further supplemental tests for alternate components of disgust, namely studying the dyadic view, could aid in further increasing the internal validity of this study in the future.

It would be intriguing to incorporate the element of sexual disgust to the current study. Leeuwen and colleagues (2017) found that scores of higher sexual disgust were more indicative for purity/sanctity scores over pathogen disgust. It would be interesting to determine whether OCD patients would be more concerned with the threat of sexual reproduction or sexually transmitted disease, and how that would relay to their subsequent moral judgements on similar moral dilemmas. Additionally, the study could be improved by researching the implications of disgust sensitivity across cultures. Spiritual impurity was cited as more distressful over contamination and harm for OCD patients hailing from Iran. This suggests that triggers for OCD in more Western cultures may not have the same gravity or effect for sufferers of OCD globally (Shams, Foroughi, Moretz, & Olatunji, 2013).

A limitation to the present study is the crossover of multiple subtypes of OCD. Seldomly do sufferers with OCD fall directly into one specific subtype of OCD, so our study would need to be updated to include a large population size in order to be more generalizable. In summary, our study's results support previous research that there is a relationship between high levels of disgust sensitivity and appraisals of purity-type moral dilemmas seen in individuals with OCD.

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