Nonmanual

Nonmanual, in the context of sign languages, refers to the set of facial, head, eye, and upper-body movements that accompany manual signs. Nonmanual signals include facial expressions (eyebrows, eyes, cheeks, mouth), head and shoulder movements, gaze direction, and torso orientation. They function together with hand signs as an integrated grammatical system; nonmanuals are not separate words but part of the sign's meaning and syntactic function.

Nonmanuals convey grammatical information such as negation, question type, aspect, and topic marking, as well as evidentiality and intensity. For example, certain facial configurations and head positions modify the sentence's mood or mark yes–no versus wh–questions, while other movements can indicate ongoing action or emphasis. They also signal discourse structure, such as indicating what is the topic under discussion.

Nonmanuals are language-specific in their exact form and use, but they are a common feature of many sign languages worldwide, including American Sign Language, British Sign Language, and others. Variation exists across languages and individuals, with regional or personal differences in emphasis and timing.

Researchers study nonmanuals using video analysis and transcription schemes to capture the timing, simultaneity, and interaction with manual signs. Understanding nonmanuals is essential for fluent sign-language production and comprehension, since misalignment or omission can lead to ambiguity or misunderstandings.