Facial mimicry is independent of stimulus format: Evidence for facial mimicry of stick figures and photographs

The present research investigated facial mimicry of the basic emotions joy, anger, and sadness in response to stimuli in different formats. Specifically, in an electromyography study, 120 participants rated the expressions of joyful, angry, and sad faces presented as photographs or stick figures while facial muscle activity was measured. Using both frequentist and Bayesian approaches to hypothesis testing, we found strong support for a facial mimicry effect: Participants showed higher zygomaticus major and orbicularis oculi activity (smiling) towards joyful faces, while they showed higher corrugator supercilii activity (frowning) towards angry and sad faces. Although participants rated the stick figures as more abstract and less interesting stimuli, the mimicry effect was equally strong and independent of the format in which the faces were presented (photographs or stick figures). Additionally, participants showed enhanced emotion recognition for stick figures compared to photographs, which, however, was unrelated to mimicry. The findings suggest that facial mimicry occurs in response to stimuli varying in their abstractness and might be more robust to social-cognitive influences than previously assumed.