More than just smiling: how positive emotions are expressed on the face

To advance the science of positive emotional expressions, we test how 22 positive emotions are spontaneously displayed on the face, using the participant-negotiated episodic recall method. Respondents (n = 163) narrated emotional events from their lives, and we extracted facial behaviours that reflected peak expressivity (35 410 facial actions). Network models were applied to probe whether specific positive emotions would be conditionally associated with particular facial behaviours. Our results point to three sets of positive emotions: five that do not seem to have specific facial actions related to them (e.g. admiration), nine whose expressions do not significantly involve smiling (e.g. head turn for interest, raised chin for determination), and eight whose facial expressions include smiling as a unique expressive feature (e.g. positive surprise and elation). Notably, nine of these positive emotions had expressive patterns that were distinct from the other emotions in our set (e.g. raised cheeks and closed eyes for sexual desire), while eight emotions were associated with expressive patterns that were shared in pairs (e.g. raised eyebrows for both hope and inspiration). These results provide a tentative map of what specific positive emotions look like when produced on the face in a naturalistic situation. This article is part of the theme issue 'Mechanisms, development, phylogeny and functions of emotional expressions'.