sentiment_satisfied

Happiness

Genuine / Duchenne Smile

Universal2 Action Unitsbilateralsustained duration

A genuine (Duchenne) smile involving both the mouth and the eyes, with cheeks raised.

FACS Breakdown

circle

AU 6Cheek Raiser

Key indicator of genuine (Duchenne) smile - difficult to fake

cheeksmoderate difficultyInvoluntary

Muscle: Orbicularis oculi, pars orbitalis

sentiment_satisfied

AU 12Lip Corner Puller

Primary smiling muscle - can be activated voluntarily

moutheasy difficultyVoluntary

Muscle: Zygomaticus major

A genuine smile is marked by the activation of AU 6. Focus on feeling the muscles around your eyes engage, not just your mouth.

The authenticity of a smile is determined by the eyes - specifically AU 6 (Cheek Raiser).

Eye Involvement

Crow's feet appear (AU 6 + AU 12)

Only mouth moves (AU 12 only)

Cheek Movement

Cheeks raise noticeably

Minimal cheek movement

Voluntary Control

AU 6 is very difficult to fake

AU 12 alone is easy to produce

DISTINGUISHING ACTION UNITS

AU 6

TypeUniversal

Symmetrybilateral

Durationsustained

Action Units2

AU 6AU 12