Non-Manual Markers

Facial expressions, head movements, eye gaze, mouth movements, and body postures that convey grammatical information in sign languages. Unlike facial expressions in spoken languages which primarily convey emotion, non-manual markers in sign languages serve linguistic functions: raised eyebrows indicate yes/no questions, furrowed brows mark wh-questions, head shakes express negation, and specific mouth movements modify verb meanings. Accurate rendering of non-manual markers is one of the greatest challenges in sign language animation, as current animation technology often produces facial expressions that appear less natural than human signers.