But first, coffee: The roles of arousal and inhibition in the resistance of compulsive cleansing in individuals with high contamination fears

Inhibition plays a crucial role in reducing intrusive thoughts and compulsive behaviors, such as handwashing, in response to the feeling of disgust. The current study examines whether manipulating arousal can facilitate inhibition and the resistance of compulsive cleansing. Forty-seven participants with high contamination fears were recruited for this study. Participants were divided into a caffeine group or a no-caffeine group. Participants touched a potentially contaminated and disgusting stimulus (“dirty” diapers) and were asked to wait as long as they could before washing their hands. Only the caffeine group exhibited greater pre-post stop-signal reaction time improvement in the stop-signal task, indicating improved inhibition. Participants in the caffeine group exhibited significantly lower subjective distress and urges-to-wash their hands both after touching the stimulus and while waiting to engage in the cleansing behavior. Similarly, the caffeine group resisted the urge to compulsively cleanse for about twice as long as those in the no-caffeine group. Time spent washing, subjective distress levels, and urge-to-wash levels after participants washed their hands were similar between groups. The current findings support the notion that increased arousal improves inhibition, which may play a role in improving our ability to resist intrusive disgust and compulsive cleansing behaviors.