Cultural facial expressions dynamically convey emotion category and intensity information.

Communicating emotional intensity plays a vital ecological role because it provides valuable information about the nature and likelihood of the sender's behavior. 1,2,3 For example, attack often follows signals of intense aggression if receivers fail to retreat. 4,5 Humans regularly use facial expressions to communicate such information. 6,7,8,9,10,11 Yet how this complex signaling task is achieved remains unknown. We addressed this question using a perception-based, data-driven method to mathematically model the specific facial movements that receivers use to classify the six basic emotions—"happy," "surprise," "fear," "disgust," "anger," and "sad"—and judge their intensity in two distinct cultures (East Asian, Western European; total n = 120). In both cultures, receivers expected facial expressions to dynamically represent emotion category and intensity information over time, using a multi-component compositional signaling structure. Specifically, emotion intensifiers peaked earlier or later than emotion classifiers and represented intensity using amplitude variations. Emotion intensifiers are also more similar across emotions than classifiers are, suggesting a latent broad-plus-specific signaling structure. Cross-cultural analysis further revealed similarities and differences in expectations that could impact cross-cultural communication. Specifically, East Asian and Western European receivers have similar expectations about which facial movements represent high intensity for threat-related emotions, such as "anger," "disgust," and "fear," but differ on those that represent low threat emotions, such as happiness and sadness. Together, our results provide new insights into the intricate processes by which facial expressions can achieve complex dynamic signaling tasks by revealing the rich information embedded in facial expressions. [Display omitted] • Emotion categories and intensity are represented by specific facial movements • Emotion classifier facial movements are highly distinct; intensifiers are not • Emotion classifiers and intensifiers have distinct temporal signatures • Cultural variance in facial signals may impact cross-cultural communication Chen et al. examine how facial expressions dynamically represent emotion category and intensity information. Using a perception-based data-driven method and information-theoretic analyses, they reveal, in two distinct cultures, that facial expressions represent emotion and intensity information using a specific compositional dynamic structure. [ABSTRACT FROM AUTHOR]