A facial expression is a particular configuration of the face or a modification of facial features, associated or not with a look or change of gaze. A facial expression can be paired with the execution of a manual gesture, of the head, or some other, such as nodding of the head while smiling, or raising of the eyebrows, a raised index finger, while an important word is pronounced.
Every facial expression can be described as a particular configuration of facial muscles (with the help of the FACS or Facial Action Coding System), or as a whole or a form with an iconic value: a joyous or angry face, the features of doubt, reflection, etc.
Facial expression thus has an iconic use: just like for conventional gesture, a linguistic translation is possible, and facial mimicry can be substituted for a verbal one. But just like for coverbal/nonverbal gesture, facial expression is used jointly with speech and contributes to multimodal messages (see multimodality).
Like gestures, facial expressions have multiple functions: the expression of emotions or feelings, the expression of mental states, the realization of coverbal/nonverbal linguistic acts, connotations in the verbal message, indexicalization of referents in physical contexts, marking the progression of speech and discourse, signaling immediate intentions in ongoing interactions, etc.
Contents validated by the Groupe de Travail 4 (multimodality and visual-gestural modality)