آزمونهای اجتناب رفتاری و انزجار در ترس آلودگی: تمایزات از اضطراب خصلتی

Much of the existing literature examining the role of disgust is limited to specific phobia. Recent research has begun to examine the role of disgust in contamination fear, a subtype of obsessive–compulsive symptoms. Through the use of behavioral avoidance tasks (BATs), the current study was designed to examine the role of disgust in people with contamination fears, with attention to distinguishing high and low trait anxiety. From a large screening of undergraduate students, three groups were formed based on their level of contamination fear and level of trait anxiety: contamination fearful (n=12), high-trait anxiety (n=11), and low trait anxiety (n=15). Subjects were asked to engage in six different BATs corresponding to six domains of disgust (food, animals, body products, body envelope violations, death, and sympathetic magic). One-way analysis of variance (ANOVA) showed significant differences between the contamination fearful group and the high trait anxiety group on the animal and sympathetic magic BATs. Significant differences on the food, animal, body envelope violations, and death BATs were also found between the contamination fearful group and the low-trait anxious group. The findings modestly support the importance of disgust in contamination fears. Implications for the study of disgust in contamination fear are provided.

One of the most common types of obsessional thoughts in obsessive–compulsive disorder (OCD) is the fear of contaminants (Steketee, Grayson & Foa, 1984). The crux of these obsessions is that there exist contaminants, such as germs and viruses, present throughout the environment that can cause harm. The anxiety caused by contamination fears is commonly alleviated by engaging in excessive washing rituals or by active avoidance of contaminated objects (e.g. handrails; public telephones). This active avoidance behavior has led to comparisons between such contamination fears and specific phobias (Jones and Menzies, 1998 and Steketee, Grayson and Foa, 1984). By comparing contamination fear to specific phobias, changes in treatment delivery have resulted (Steketee, 1993). Until recently, the role of disgust has been largely ignored when considering people with contamination fears. In their seminal article, Rozin and Fallon (1987) characterized disgust as a food-related emotion of oral revulsion with a distinctive physiological expression accompanied by appropriate action. The action associated with disgust is physical distancing oneself form the offensive object, while the distinctive physiological reaction is nausea. Rozin and Fallon (1987) noted that although disgust does have some adaptive function as protection from harmful microbial contaminants, it more frequently results in the rejection of nutritive substances. Woody and Teachman (2000) reviewed the existing literature on the role of disgust and fear and compared the two constructs regarding their “terminology, functional value, behavioral intentions, physiological processes, and acquisition mechanisms” (pp. 292). The authors noted that while appraisals of fear and disgust may overlap, disgust appraisals are more narrowly focused on contamination rather than general threat. Furthermore, they noted that such fears follow some basic rules of disgust appraisal labeled ‘the laws of sympathetic magic’ (Rozin & Nemeroff, 1990). These rules include the law of contagion, which dictates that the properties of one object are transferred by contact to another and remain after contact is broken. Thus, if a disgusting object were to come in contact with a non-disgusting object, the latter would, from that point on, be considered disgusting as well. Such magical ideation fits well with the clinical profile of many people with contamination fears in OCD. Woody and Teachman (2000) thus hypothesized that individuals with contamination fears would have higher disgust sensitivities (i.e. be more easily disgusted). In addition, they encouraged the use of behavioral avoidance tasks in future research in order to gain more objective data than the often-used self-report questionnaire. Until recently, the existing literature examined the role of disgust almost exclusively in animal and blood-injury-injection (BII) phobia. Such work has begun to uncover the importance of considering disgust independently of fear. In a two-part study, Ware, Jain, Burgess and Davey (1994) examined the role of disgust in animal fears. Through factor analysis of previous studies examining animal phobia, they found disgust sensitivity to be significantly correlated with fear-evoking, but physically harmless animals (e.g. rat, spider, slug) and not with predatory animals likely to physically attack humans (e.g. tiger, lion, alligator). In addition, the authors found a significant correlation between the washing subscale of the Maudsley obsessive–compulsive inventory (MOCI) and disgust sensitivity. These results indicate that disgust plays a significant role in the fear of particular animals in that certain fear-relevant animals are avoided because of their disgusting nature and not their perceived physical threat. In another study, Sawchuk, Lohr, Lee and Tolin (1999) investigated the role of disgust in blood-injection-injury phobia. Through the use of a word stem completion task, the authors found that BII phobic participants demonstrated an implicit memory bias for disgust-relevant words. The authors note that this finding is consistent with work conducted on other anxiety disorders. Two recent publications have proposed an increasingly important role of disgust in OCD. Muris et al. (2000) examined the relationship between disgust sensitivity and several types of psychopathology. Specifically, the authors examined the correlation between the disgust sensitivity questionnaire (DSQ) and measures of depression, obsessive–compulsive disorder, agorophobia, blood-injury phobia, social phobia, and eating disorder in a student sample. The authors found that disgust sensitivity was most strongly correlated with the washing subscale of the MOCI, although this correlation was modest (r=0.26). Regardless, these results demonstrate a closer relationship between contamination fears than these other areas of psychopathology. However, it should be noted that in this project disgust sensitivity was assessed using Rozin, Fallon, and Mandell’s (1984) DSQ, which only tapped into food-related disgust. Mancini, Gragnani, and D’Olimpio (2001) also examined the relationship between disgust sensitivity and OCD in a non-clinical sample. The authors recruited 278 volunteers from central Italy to fill out questionnaires assessing disgust sensitivity, obsessive–compulsive symptoms, anxiety, and depression. Using multiple regression analysis, the authors found disgust sensitivity to be a significant predictor of obsessions and compulsions, even after statistically controlling for anxiety and depression. In addition, disgust sensitivity was the best predictor of washing and checking symptoms of OCD while anxiety and/or depression were the best predictors of obsessive rumination and impulses. It should be noted that the authors assessed disgust sensitivity using Haidt, McCauley, and Rozin’s disgust scale (1994) which, unlike the DSQ, assesses disgust across seven specific domains of disgust (food, animals, body products, sex, body envelope violations, death, and hygiene). While both this work and the aforementioned work by Muris et al. (2000) have indicated a greater role of disgust in contamination fears, this work has been conducted through the use of self-report questionnaires alone. Consistent with the aforementioned suggestions by Woody and Teachman (2000), the present investigation seeks to further examine the role of disgust sensitivity in people with contamination fears through behavioral avoidance tasks. We hypothesized that individuals with high levels of contamination fear will show increased avoidance to disgust-relevant stimuli in latency to engage in task and degree of compliance with the task as compared to individuals with low levels of contamination fear, regardless of trait anxiety level. Also, we hypothesized that highly contamination fearful individuals will show a higher degree of outright refusal to engage in tasks as compared to both highly trait-anxious and low trait-anxious individuals with low-contamination fear. Finally, we hypothesized that there will be no significant differences between individuals with low contamination fear who are highly trait-anxious and those who are low trait-anxious regarding disgust sensitivity.