Facial disgust in response to touches, smells, and tastes

Disgust serves to defend the body from the entry of toxins and disease. Central to this function is a strong relationship with the proximate senses of smell, taste, and touch. Theory suggests that distinct and reflexive facial movements should be evoked by gustatory and olfactory disgusts, serving to impede bodily entry. While this hypothesis has received some support from facial recognition studies, whether smell and taste disgusts actually produce distinct facial responses, is unknown. Moreover, there has been no assessment of the facial response evoked by contact with disgusting objects. To address these issues, this study compared facial responses to touch, smell, and taste disgusts. Sixty-four participants were asked to touch, smell, and taste disgust-evoking and neutral control stimuli, and rate them on disgust, on two occasions—first, while they were video recorded and second, with facial electromyography (EMG) applied (measuring levator labii and corrugator supercilii activity). Videos were coded for facial expressions by humans and for facial action units (FAUs) by machines. Self-report data confirmed the disgust stimuli as highly disgusting. Comparison of the overall pattern of FAUs evoked by touch, smell, and taste disgusts, indicated two distinct facial disgusts for the proximate senses—a chemosensory and a tactile-disgust face. The nose wrinkle and upper lip raise were central to all facial disgusts, indicating their centrality to the disgust face. Several facial disgusts appear to exist, each with different functional goals.