Crested macaque facial movements are more intense and stereotyped in potentially risky social interactions

Peter Robert Clark, Bridget Waller, Muhammad Agil, Jerome Micheletta

Research output: Contribution to journalArticlepeer-review

17 Downloads (Pure)


Ambiguity in communicative signals may lead to misunderstandings and thus reduce the effectiveness of communication, especially in unpredictable interactions such as between closely matched rivals or those with a weak social bond. Therefore, signals used in these circumstances should be less ambiguous, more stereotyped and more intense. To test this prediction, we measured facial movements of crested macaques (Macaca nigra) during spontaneous social interaction, using the Facial Action Coding System for macaques (MaqFACS). We used linear mixed models to assess whether facial movement intensity and variability varied according to the interaction outcome, the individuals' dominance relationship and their social bond. Movements were least intense and most variable in affiliative contexts, and more intense in interactions between individuals who were closely matched in terms of dominance rating. We found no effect of social bond strength. Our findings provide evidence for a reduction in ambiguity of facial behaviour in risky social situations but do not demonstrate any mitigating effect of social relationship quality. The results indicate that the ability to modify communicative signals may play an important role in navigating complex primate social interactions.
Original languageEnglish
Article number20210307
Number of pages11
JournalPhilosophical Transactions of the Royal Society B
Issue number1860
Early online date8 Aug 2022
Publication statusPublished - 26 Sept 2022


  • primates
  • facial expressions
  • communication
  • FACS


Dive into the research topics of 'Crested macaque facial movements are more intense and stereotyped in potentially risky social interactions'. Together they form a unique fingerprint.

Cite this