The Impact of Disgusting Sounds on Pupil Diameter of Misophonic and Non-Misophonic Listeners

Everyday sounds can elicit a range of emotional and physiological responses. For individuals with misophonia, some sounds can produce strong feelings of disgust, annoyance, and anger, often accompanied by increased perspiration and heart rate. Presently, methods of diagnosing misophonia rely on clinical interviews and self-assessment scales. Coupling these subjective measures with an objective, physiological method like pupillometry may lead to improved understanding of misophonia and inform efficacy of treatments. Previous studies show that both unpleasant and pleasant sounds increase pupil diameter (Partala and Surakka 2003; Nakakoga et al. 2020); however, these have not compared pupil responses to disgust versus other emotions. Thus, we asked whether the pupil dilation to auditorily disgusting stimuli would be differentiable from other emotional sounds. In our listening task, we monitored pupil size changes while participants listened to positive and negative emotional sounds from the IADS database (Bradley and Lang 2007) along with "triggers" known to be especially aversive to misophonics. Participants reported the intensity of their emotional reactions (e.g., disgust, annoyance, happiness, fear) as well as valence and arousal. Misophonic listeners reported greater intensity of emotions associated with triggers (disgust, anger, and annoyance) as well as for fear. For all listeners, there was a positive association between changes in pupil diameter and emotion intensity. Overall, misophonics had greater pupil dilation than non-misophonics, but after equating for emotion category of the sounds, misophonic pupil dilation was larger only for trigger sounds. Thus, pupillometry can differentiate misophonic and non-misophonic listeners based on responses to everyday sounds evoking disgust.