Horses (Equus caballus) facial micro-expressions: insight into discreet social information.

ABSTRACT: Facial micro-expressions are facial expressions expressed briefly (less than 500 ms) and involuntarily. Described only in humans, we investigated whether micro-expressions could also be expressed by non-human animal species. Using the Equine Facial action coding system (EquiFACS), an objective tool based on facial muscles actions, we demonstrated that a non-human species, Equus caballus, is expressing facial micro-expressions in a social context. The AU17, AD38 and AD1 were selectively modulated as micro-expression-but not as standard facial expression (all durations included)-in presence of a human experimenter. As standard facial expressions, they have been associated with pain or stress but our results didn't support this association for micro-expressions which may convey other informat

SUBMITTER: Tomberg C 

PROVIDER: S-EPMC10224940 | biostudies-literature | 2023 May

REPOSITORIES: biostudies-literature