Abstract Palm-up (PU) is among the most frequent manual forms across signed languages, yet its functional range and form-function mapping remain poorly understood. This study presents a corpus-based analysis of PU in Chinese Sign Language (CSL), drawing on 793 tokens from 15.6 h of naturalistic interaction across three generations of signers. All tokens were coded for function, handshape, movement, clausal position, and non-manual features. PU in CSL is restricted to three functional domains: negation (61 %), discourse marking (28 %), and interrogation (11 %), which together account for 100 % of the corpus with no propositional functions attested. Each domain is associated with a stable bundle of formal features, forming a gradient from context-dependent discourse uses to morphologically bound affixal forms. Age-based analysis shows that the functional inventory is stable across cohorts while internal weighting has shifted, reflecting differential entrenchment consistent with ongoing grammaticalization. These findings support the view that PU is specialized for intersubjective meaning, managing cognitive coordination between signer and addressee, and that this specialization reflects both the iconic, addressee-directed properties of the open-palm form and the conventionalization history of individual signing communities.
Zhang et al. (Thu,) studied this question.