Researchers have hypothesized that the emotion of disgust assumes a functional role in numerous aspects of human development (e.g., Rozin & Fallon, 1987). Mounting evidence suggests that disgust is readily acquired, with demonstrations of one-trial learning (e.g., Rozin, 1986), and a slower to extinguish than fear responding (e.g., Olatunji et al., 2007 and Smits et al., 2002). These findings suggest a potentially influential role of disgust in psychological disorders. Specifically, several studies have implicated disgust sensitivity (DS) in the etiology and maintenance of blood-injection-injury (BII) phobia and spider phobia (Davey, 1992, Olatunji et al., 2007 and Tolin et al., 1997).
The phenomenology associated with BII and spider phobia can negatively impact functioning in numerous situations (e.g., medical visits, sleep, etc). In particular, phobic reactions to BII and spider stimuli may result in negative physical, social, or psychological consequences resulting in avoidance or escape of necessary medical attention, experiencing embarrassment (e.g., fainting), or significant distress (e.g., nightmares). Traditional conceptualizations of anxiety disorders have focused on fear mediated avoidance (e.g., Mower, 1960). However, Matchett and Davey (1991) proposed that several specific phobias may function according to a disease avoidance model. Accordingly, one mechanism by which specific fears may manifest is through the fear of contamination and avoidance of disgust-relevant stimuli which may compromise the individual’s physical well-being (e.g., Schienle, Start, Walter, & Vaitl, 2003). In line with the disease avoidance model, several researchers have since suggested that DS may operate as a vulnerability factor for spider (Mulkens, de Jong, & Merckelbach, 1996) and BII (Olatunji, Smits, et al., 2007) fears.
To date, numerous empirical studies have evaluated the disease avoidance model of specific phobias (e.g., Olatunji et al., 2007 and Sawchuk et al., 2000). Specifically, studies have found support for disgust, independent of fear, to predict behavioral avoidance of both BII (e.g., Olatunji, Connolly, & David, 2007) and spider stimuli (Woody, McLean, & Klassen, 2005). Indeed the current literature suggests that DS functions within an etiological and maintenance capacity in psychological disorders. As such, one avenue by which DS may function is through sex differences commonly found in anxiety disorders.
Systematic research on the role of sex differences in DS may broaden our understanding of the development of several anxiety disorders including specific phobias. In a concise review, Craske (2003) detailed current evidence implicating adolescence as a salient developmental period for women to develop anxiety disorders at a relatively greater rate than men. Several environmental factors within adolescence are emphasized as likely etiological factors contributing to the sex differences in anxiety disorders. Specifically discussed are sex-specific socialization effects and psychosocial stressors, among others. Operating from a stress-diathesis framework, it is conceivable that these environmental factors interact with diathesis factors (e.g., trait anxiety, negative affect, DS) to result in increased incidence of anxiety in women, compared to men. Enhanced understanding of DS, independent of alternative general psychological vulnerabilities, may provide additional information directly relevant to developmental models of specific phobia. Additionally, from an applied perspective, sex-specific emotional responding within specific phobias suggests that women and men may differentially benefit from fear-based exposure. As such, treatments tailored to focus on extinguishing disgust in addition to fear may enhance therapeutic outcome and relapse prevention.
Previous studies consistently indicate a higher rate of incidence of specific fears among women compared to men (e.g., Fredrikson, Annas, Fischer, & Wik, 1996). In particular, numerous studies have found that women report elevations in BII fears (e.g., Kleinknecht, 1988 and Schienle et al., 2003) and spider fears (Arrindell, 2000 and Arrindell et al., 1999). Much research has also found that women report elevated levels of generalized disgust sensitivity compared to their male counterparts (e.g., Arrindell, 2000, Davey, 1994 and Haidt et al., 1994). Davey (1994) originally proposed that the biological sex differences found in many specific phobias may be accounted for by the sex differences found in DS. Three studies to date have tested this hypothesis. Arrindell et al. (1999) failed to find evidence for DS as a mediator of the sex differences found in animal fears. However, more recent research has found strong support for DS as a mediator of the sex differences in contamination (Olatunji, Sawchuk, Arrindell, & Lohr, 2005) and BII (Olatunji, Arrindell, & Lohr, 2005) fears. Despite providing strong mediational support, Olatunji, Arrindell, et al. (2005) did not account for the potential impact of several general psychological vulnerabilities. Researchers have argued that the relationship among DS and anxiety may be due to covariation with trait anxiety (Thorpe & Salkovskis, 1998) and/or negative affect (Thompsen, Mehlsen, Viidik, Sommerlund, & Zachariae, 2005). Consequently, the present study was designed to test the ability of DS, above general psychological vulnerabilities, to account for the sex differences commonly found in BII and spider fears. Consistent with prior research, it was hypothesized that DS would mediate the relation between biological sex and specific fears.
