Chimpanzees ‘Catch’ Contagious Yawns From Android Mimicking Human Facial Expressions In New Study

Yawns are contagious among humans and many other species, but a new study shows chimpanzees can also “catch” yawns from a humanoid robot.

A new study from researchers at City St Georges, University of London, and colleagues at Spain’s Universitat de Girona reveals that chimpanzees can exhibit contagious yawning in response to an android designed to simulate human facial expressions — suggesting a surprisingly nuanced level of social cognition triggered by artificial agents.

The study, published in Scientific Reports, is the first to demonstrate yawn contagion triggered by an inanimate model. Researchers tested the responses of 14 adult chimpanzees at the Fundació Mona Primate Sanctuary in Spain using an android head that displayed three types of facial movements: full yawning, partial mouth opening (gaping), and a neutral, closed-mouth expression. Each display lasted ten seconds.

Chimpanzees responded most strongly to the yawning animation, showing significantly more yawns and even lying down with bedding after viewing the androids simulated yawn. The gaping expression produced a more limited response, and the neutral face had no effect.

The findings suggest that contagious yawning might go beyond automatic mimicry and act as a behavioral cue related to rest or social bonding.

“Our findings show that chimpanzees exhibit yawn contagion when triggered by a non-biological inanimate agent, a humanoid android, that looks as if it is yawning,” said Ramiro Joly-Mascheroni, lead author and Honorary Research Fellow at City St Georges. “Despite its elusive primary functions — we still dont know exactly why we yawn, let alone why yawning is contagious — yawning may still have an evolutionarily old, non-verbal communicative role, and its contagious aspect may help us find out more about how humans and animals developed ways of communication and social interaction.”

Yawning contagion has been documented in various mammals and even some fish, and in certain cases, humans have been known to catch yawns from other species. But the use of an artificial, non-living agent as the source of this contagion is unprecedented.

“Exploring the yawning responses of primates towards an artificial agent helps us to understand the mechanism of social cognition and interactions beyond humans,” said Beatriz Calvo-Merino, Professor in Cognitive Neuroscience at City St Georges. “This interdisciplinary research enhances the collaboration of disciplines such as psychology, robotics and zoology.”

The team plans to explore whether other actions simulated by robots can trigger similar contagion responses in non-human animals and whether these mechanisms parallel those found in humans. For now, the results offer a surprising insight into the shared behavioral patterns between primates and machines — and the ancient, still-mysterious language of the yawn.