Relating self-other overlap to ingroup bias in emotional mimicry

Humans tend to show congruent facial expressions automatically in reaction to their partners which is defined as emotional mimicry. Although occurring unconsciously, this tendency has been proven to be modulated by social contextual factors such as group membership. Ingroup bias in emotional mimicryhas been well-documented in previous research; however, few studies have investigated the underlying mechanism. Based on the mimicry-as-social-regulator model, this study explored whether the ingroup bias in emotional mimicry arises from the greater self-ingroup overlap. By recording participants' facial electromyographic responses while passively viewing dynamic emotional clips performed by either racial ingroup or outgroup actors, Study 1 validated the presence of ingroup bias in the mimicry of happiness, but not anger. Using asimilar procedure in Study 2, anew sample was employed (N = 37), and a measurement of self-other overlaps via the Inclusion of the Other in the Self Scale was added. The results of Study 2 reproduced the ingroup bias in happy mimicry, and further demonstrated that the effect of group membership on emotional mimicry was mediated by the self-other overlap. In summary, this study provides evidence that the level of interpersonal closeness predicts emotional mimicry.