Non-Manual Signals

Linguistic information conveyed through parts of the body other than the hands in sign languages, including facial expressions, mouth movements, eye gaze, head tilts, head shakes, and body shifts. In American Sign Language and other sign languages, non-manual signals serve essential grammatical functions: they can indicate questions (raised eyebrows for yes/no questions, furrowed brows for wh-questions), negation (head shaking), topicalisation (raised eyebrows with head tilt), and modify the meaning of signs (e.g., changing adjective intensity or adding adverbial information). The same sequence of hand signs can have completely different meanings depending on accompanying non-manual signals, making them critical for accurate sign language communication and a key challenge for sign language animation technology.