Introduction:
Facial expressions are central to political communication, particularly for women leaders navigating the double bind between authority and warmth. This study investigates how President Claudia Sheinbaum's smiles function as multimodal resources in the construction of her political ethos across debates, speeches, and official messages.
Purpose:
To develop a bio-behavioral inventory of political smiles and analyze their emotional, rhetorical, and perceptual roles in Mexico's first female presidency.
Method:
A multimodal mixed-methods design integrated (1) automatic facial coding with FaceReader™ based on FACS, (2) inferential modeling of smile frequencies across communicative contexts, (3) text mining and sentiment analysis of speech transcripts, and (4) perceptual validation with 103 university students who rated authenticity, warmth, intensity, and threat.
Results:
Across 2,000+ video segments, five facial configurations were identified: open, isolated, Duchenne (+25), controlled, and special smiles. Open smiles dominated institutional and celebratory contexts (≈ 90%), whereas Duchenne smiles appeared more frequently in late-cycle debates, signaling authenticity and affective intensity. Regression models confirmed contextual modulation: isolated smiles increased toward the end of campaigns, and controlled smiles appeared mainly in recorded messages. Sentiment analyses revealed emotional shifts mobilization in mayoral debates (fear + trust), confrontation in presidential debates (anticipation + anger), celebration in public speeches (joy + trust), and solemnity in recorded messages (sadness + confidence). Perceptual ratings showed that Duchenne smiles were judged most authentic and warm, while controlled smiles elicited higher perceived threat.
Conclusions:
Smiles act as strategic performances balancing courtesy and authenticity within gendered expectations of leadership. By coupling facial coding, computational linguistics, and perceptual validation, this study provides an integrative model for understanding affective communication and symbolic power in contemporary political leadership.