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bioRxiv · 10.1101/2024.09.02.610622

Spatiotemporal structure and substates in emotional facial expressions

Cuve, H. C. J.·Sowden-Carvalho, S.·Cook, J. L.
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Abstract

From overt emotional displays to a subtle eyebrow raise during speech, facial expressions are key cues for social interaction. How these inherently dynamic facial signals encode emotion across non-verbal expression and speech remains only partially understood. In Study 1 we recorded participants facial movements signalling happy, sad and angry emotions in Expression-only and Emotive-speech conditions. We employed a data-driven pipeline integrating facial motion quantification, spatiotemporal classification and clustering to investigate the structure and function of facial dynamics in signalling emotion. Results reveal that a few spatiotemporal patterns reliably differentiated emotion in non-verbal expressions and emotive speech facial signals. Furthermore, we identified transient substates - or dynamic phases - that are diagnostic of emotion intent and conditions. A perceptual validation with naive observers (Study 2) showed that the low-dimensional spatiotemporal structure captures meaningful cues that closely predict human emotion categorisations. We discuss theoretical implications of a low-dimensional spatiotemporal structure for optimal transmission and perception of dynamic facial emotion signals and face-to-face interaction. This work also provides a framework for modelling dynamic social cues and insights for the design of expressive emotive capabilities in social agents.

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Cuve, H. C. J., Sowden-Carvalho, S., Cook, J. L.. 2024-09-03. Spatiotemporal structure and substates in emotional facial expressions. https://doi.org/10.1101/2024.09.02.610622

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