Nonmanual signals of the head, face, and upper torso have been previously reported to serve prosodic, lexical, and syntactic functions in American Sign Language (and other sign languages). We report here the systematic use of body lean forward and body lean back to convey the notion of 'contrast' at several levels. Prosodically, they mark 'stress' in opposition to 'unstressed'. Lexically, they reinforce the notions of actor 'involvement/non-involvement' on specific verbs. Semantically, they mark two broad categories of meaning that are fundamental to distinctions in all realms of discourse: 'inclusion' (lean forward) and 'exclusion' (lean back). These markers may occur with traditional focus particles such as even and only, or significantly, they may also occur independently, marking inclusive and exclusive domains on a variety of other structures (pronouns, quantifiers, and NP contrast). Pragmatically, leans are used to indicate the fundamental opposition between 'affirmation' and 'negation/denial' of the truth of propositions. The independent functioning of these leans provides support for considering them as nonmanual morphemes of contrasting categories.
