Effects of experienced disgust on habituation during repeated exposure to threat-relevant stimuli in blood-injection-injury phobia

Despite growing evidence implicating disgust in the etiology of blood-injection-injury (BII) phobia, the relevance of disgust for exposure-based treatment of BII phobia remains largely unknown. Individuals with BII phobia were randomly assigned to a disgust (view vomit videos) or neutral activation (view waterfall videos) condition. They were then exposed to 14 videotaped blood draws, during which fear and disgust levels were repeatedly assessed. Participants then engaged in a behavioral avoidance test (BAT) consisting of exposure to threat-relevant stimuli. Examination of outcome comparing the identical first and last blood-draw clips revealed that fear and disgust toward blood draws was significantly reduced in both groups. Disgust levels were also found to be more intense for the video stimuli relative to fear levels whereas the opposite was true for BAT stimuli. Contrary to predictions, the disgust induction did not enhance reductions in negative responses to the target video or reduce behavioral avoidance. Growth curve analyses did show that individuals with BII phobia exposed to the disgust induction showed greater initial fear levels during repeated exposure than those in the neutral condition. However, this effect was not consistently observed across different analytic approaches. Changes in fear during exposure were also found to be independent of changes in disgust but not vice versa, and greater initial fear levels during repeated exposure to threat was associated with fear and disgust levels during the BAT. The implications of these findings for conceptualizing the role of disgust in etiology and treatment of BII phobia are discussed.