Once in Contact, Forever Contaminated! Introducing a Clinically Validated Imagery- and Video-Based Chain of Contagion Task for the Measurement of Disgust and Contamination Change in Experimental Research and Clinical Practice.

Tolin et al. (2004) developed the Chain of Contagion Task (CCT) to experimentally test the law of contagion and looming vulnerability (LV). In the CCT, contaminated pencils are brought into contact with clean pencils. The degree of contamination transferred to further new pencils refers to the level of biased contagious beliefs. Although this could be an important transdiagnostic tool, the usability of the original paradigm has been very laborious. Therefore, an imagery- and video-based CCT is introduced and validated in Study 1 in a nonclinical sample with 85 participants. In Study 2, the imagery-based CCT was validated in a clinical study with 15 participants diagnosed with contamination-related obsessive-compulsive disorder (C-OCD), 15 participants suffering from an anxiety disorder, and 15 nonclinical controls. The number of participants is consistent with those in Tolin's original sample and the statistical evaluation of Study 2 was preregistered. Both CCT could be validated and the results could be replicated. In the imagery-based CCT, the C-OCD group displayed significantly higher contamination ratings, avoidance tendencies and LV than the two control groups. We argue that this open access diagnostic instrument can be applied in research as well as in therapeutic practice (Download CCT videos and imagery: https://doi.org/10.5281/zenodo.7730459).