Facial mimicry to infant and adult emotions in mothers and non-mothers

Abstract

A key aspect of parent–infant interaction is parental mirroring of infant emotions through facial mimicry, the automatic imitation of observed facial expressions. Facial mimicry can be measured using facial electromyography (EMG) and has been associated with empathic abilities, such as recognizing others' emotions. Currently, there is no research investigating how such empathy-related processes might change during the transition to parenthood. In this study, we compared first-time mothers of young infants and non-mothers in their physiological responses in two facial muscle areas (corrugator supercilii and zygomaticus major) to dynamic emotional infant and adult faces. In addition, we examined whether the EMG responses are associated with salivary testosterone levels. Participants performed an emotion recognition task with dynamic infant and adult emotional expressions changing between happy and distressed expressions while facial mimicry was measured with EMG. Mothers showed a more pronounced zygomaticus response specifically to smiling infant faces, and a greater corrugator response to faces changing to distress, regardless of stimulus age. Non-mothers' zygomaticus response to infant smiles was inversely associated with testosterone level. No other correlations between testosterone and EMG responses were found. These results indicate that new mothers may show heightened affective empathic reactivity especially to infant emotions.