Autonomic correlates of physical and moral disgust

Given that the hypothesis of a common origin of physical and moral disgust has received sparse empirical support, this study aimed to shed light on the subjective and autonomic signatures of these two facets of the same emotional response. Participants (20 men, 20 women) were randomly assigned to physical or moral disgust induction by the use of audio scripts while their electrocardiogram was continuously recorded. Affect ratings were obtained before and after the induction. Time and frequency domain heart rate variability (HRV) measures were obtained. After controlling for disgust sensitivity (DS-R) and obsessive–compulsive (OCI-R) tendencies, both scripts elicited disgust but whereas the physical script elicited a feeling of dirtiness, the moral script evoked more indignation and contempt. The disgust-induced subjective responses were associated with opposite patterns of autonomic reactivity: enhanced activity of the parasympathetic nervous system without concurrent changes in heart rate (HR) for physical disgust and decreased vagal tone and increased HR and autonomic imbalance for moral disgust. Results suggest that immorality relies on the same biological root of physical disgust only in subjects with obsessive compulsive tendencies. Disgust appears to be a heterogeneous response that varies based on the individuals’ contamination-based appraisal.