Humans perceive emotional expressions displayed by non-human primates and spontaneously mimic these expressions, according to a study published March 11, 2026, in the open-access journal PLOS One by Ursula Hess from Humboldt University of Berlin, Germany, and colleagues.
The matching or mimicry of the emotional behavior of others is prevalent in many species, including humans and non-human primates. Emotional mimicry is considered to be an important facet of human empathy. Previous studies have shown that infant and juvenile non-human primates spontaneously mimic human facial gestures, such as tongue protrusion and lip smacking. In addition, humans and chimpanzees voluntarily imitate each other’s behavior. However, it has not been clear whether humans spontaneously mimic the perceived emotional expressions of non-human primates.
To fill this knowledge gap, Hess and colleagues conducted an online experiment in which 212 participants saw videos that showed monkeys and apes displaying different expressions. The expressions consisted of a play face, a threat display, and a neutral expression. While the participants were watching the videos, their own facial expressions were filmed using webcams. The researchers assessed their emotional mimicry using an open-source tool that tracks facial activity. After each video, the participants rated the degree of positivity or negativity of the expression and the levels of different emotions (i.e., anger, disgust, fear, happiness, sadness, surprise, to assess how participants interpreted the expressions), as well as the perceived psychological closeness and liking toward the non-human primate.
The results revealed that humans can recognize positive and negative expressions of non-human primates and attach discrete emotion labels to the expressions. The participants also spontaneously mimicked these expressions. The strength of the mimicry depended on both their perception of the primate expression and their perceived closeness to the primate. Specifically, the participants reported that they liked and felt closer to primates showing positive expressions, and their mimicry of positive expressions was more pronounced when these feelings of closeness were higher.
The videos were only five to seven seconds long and showed not only the faces of the primates but also their body postures, which may have affected their interpretation. Additionally, the study explicitly takes an observer-focused perspective regarding terms such as "emotional mimicry" and "emotional expression”; it is not possible to determine what another organism is subjectively experiencing based on their facial expression. Nonetheless, the findings may shed new light on the deep-rooted, cross-species nature of emotional connection, suggesting that the human ability to empathize and mirror emotions extends beyond humankind.
The authors add: “The research suggests that humans are capable of perceiving and resonating with the emotional states of non-human animals. This finding challenges long-standing anthropocentric paradigms and fosters a reconceptualization of the human-animal relationship.”
Author interview: https://plos.io/4r3RsI7
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Citation: Hess U, Kastendieck T, Erkol MG, Mauersberger H, Davila-Ross M, Liebal K, et al. (2026) Evolutionary echoes of emotion: Humans mimic other primate expressions. PLoS One 21(3): e0342196. https://doi.org/10.1371/journal.pone.0342196
Author countries: Germany, U.K., Italy
Funding: The author(s) received no specific funding for this work.
PLOS One
Experimental study
People
Evolutionary echoes of emotion: Humans mimic other primate expressions
11-Mar-2026
The authors have declared that no competing interests exist.