Data from: Automatic facial mimicry in response to dynamic emotional stimuli in 5-month-old infants

Human adults automatically mimic others’ emotional expressions, which is believed to contribute to sharing emotions with others. Although this behaviour appears fundamental to social reciprocity, little is known about its developmental process. Therefore, we examined whether infants show automatic facial mimicry in response to others’ emotional expressions. Facial electromyographic activity over the corrugator supercilii (brow) and zygomaticus major (cheek) of 4-to 5-month-old infants was measured while they viewed dynamic clips presenting audio-visual, visual, and auditory emotions. The audio-visual bimodal emotion stimuli were a display of a laughing/crying facial expression with an emotionally congruent vocalisation, whereas the visual/auditory unimodal emotion stimuli displayed those emotional faces/vocalisations paired with a neutral vocalisation/face, respectively. Increased activation of the corrugator supercilii muscle in response to audio-visual cries and the zygomaticus major in response to audio-visual laughter, were observed between 500 and 1000 ms after stimulus onset, which clearly suggests rapid facial mimicry. By contrast, both visual and auditory unimodal emotion stimuli did not activate the infants’ corresponding muscles. These results revealed that automatic facial mimicry is present as early as 5 months of age, when multimodal emotional information is present.