information:filtering, structural:summarization, stylistic:tone, quality:correction
Non-manual elements

Sign languages convey much of their prosody through non-manual elements. Postures or movements of the body, head, eyebrows, eyes, cheeks, and mouth are used in various combinations to show several categories of information, including lexical distinction, grammatical structure, adjectival or adverbial content, and discourse functions.

At the lexical level, signs can be lexically specified for non-manual elements in addition to the manual articulation. For instance, facial expressions may accompany verbs of emotion, as in the sign for angry in Czech Sign Language. Non-manual elements may also be lexically contrastive. For example, in ASL (American Sign Language), facial components distinguish some signs from other signs. An example is the sign translated as not yet, which requires that the tongue touch the lower lip and that the head rotate from side to side, in addition to the manual part of the sign. Without these features the sign would be interpreted as late. Mouthings, which are (parts of) spoken words accompanying lexical signs, can also be contrastive, as in the manually identical signs for doctor and battery in Sign Language of the Netherlands.

While the content of a signed sentence is produced manually, many grammatical functions are produced non-manually (i.e., with the face and the torso). Such functions include questions, negation, relative clauses and topicalization. ASL and BSL use similar non-manual marking for yes/no questions, for example. They are shown through raised eyebrows and a forward head tilt.

Some adjectival and adverbial information is conveyed through non-manual elements, but what these elements are varies from language to language. For instance, in ASL a slightly open mouth with the tongue relaxed and visible in the corner of the mouth means "carelessly", but a similar non-manual in BSL means "boring" or "unpleasant".

Discourse functions such as turn taking are largely regulated through head movement and eye gaze. Since the addressee in a signed conversation must be watching the signer, a signer can avoid letting the other person have a turn by not looking at them, or can indicate that the other person may have a turn by making eye contact.