The many faces of mimicry depend on the social context.

One of the richest and most powerful tools in social communication is the face. Facial expressions are a prominent way to convey high-dimensional, dynamic information, such as emotion, motivation, and intentions. Previous research has linked mimicry of facial expressions to positive human interaction (e.g., mutual agreement). In this study, we investigated in a real-world setting whether the mimicry pattern of multiple affective facial expressions depends on the interpersonal attitudinal agreement between interlocutors. We analyzed video clips of Democratic or Republican American politicians being interviewed by either a political ally or an opponent ( N _total = 150 videos). The interviews showed either agreement between two Republicans or two Democrats, or disagreement between members of each affiliation. Using image processing tools, we extracted the intensity of the facial action units for each timepoint. In contrast to the prevalent notion that positive social interaction, such as agreement, fosters mimicry, we found mimicry of all facial expressions in both agreement and disagreement. Moreover, the pattern of the facial expressions mimicry depended on the agreement condition such that an artificial classifier could successfully discriminate between the agreement conditions. Our results suggest that not only positive interpersonal communication is characterized by mimicry but also negative one. This implies that in real-life interactions, mimicry may be a tool to understand others and thus successfully communicate, regardless of the positivity of the social interaction. Whereas the existence of mimicry may be indispensable for social communication, the specific pattern of facial expressions mimicry depends on the social context. (PsycInfo Database Record (c) 2024 APA, all rights reserved).