AU12 — Lip Corner Puller
The Action Unit produced by the zygomaticus major muscle, which pulls the corners of the mouth obliquely upward — the basic mechanical smile.
AU12 is the lower-face Action Unit at the core of every smile, genuine or social. On its own it indicates a polite or controlled smile; in combination with AU6 (cheek raiser) it forms a Duchenne smile of authentic enjoyment.
Tracking AU12 intensity and co-activation patterns over time is a foundational signal in coaching, sales-coaching, and clinical applications of FACS analytics.
Related terms: action unit, duchenne smile, au6 cheek raiser, facial action coding system
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