Pavlovian fear conditioning provides a model for anxiety-related
disorders, including obsessive-compulsive disorder (OCD). However, disgust is
the predominant emotional response to contamination, which is a common theme in
OCD. The present study sought to identify disgust conditioning abnormalities
that may underlie excessive contamination concerns relevant to OCD. Individuals
high and low in contamination concern (HCC, n = 32;
LCC, n = 30) completed an associative learning task in
which one neutral face (conditioned stimulus; CS+) was followed by a
disgusting image (unconditioned stimulus; US) and another neutral face
(CS−) was unreinforced. Following this acquisition procedure, there was
an extinction procedure in which both CSs were presented unreinforced. The
groups did not show significant differences in discriminant responding to the
CSs following acquisition. However, following extinction, the HCC group reported
less reduction in their expectancy of the US following the CS+, and also
reported greater disgust to the CS+, compared to the LCC group.
Increased disgust to the CS+ following both acquisition and extinction
was correlated with increased symptoms of contamination-based OCD and increased
disgust sensitivity. Additionally, disgust sensitivity mediated group
differences in disgust responding to the CS+ at acquisition and
extinction. Also, failure to adjust US expectancy in response to extinction
partially mediated group differences in disgust to the CS+ following
extinction. Together, these findings suggest that excessive contamination
concerns observed in OCD may be related to difficulty inhibiting acquired
disgust, possibly due to elevated disgust sensitivity that characterizes the
disorder.