The hands and mouth do not always slip together in British sign language: dissociating articulatory channels in the lexicon

In contrast to the single-articulatory system of spoken languages, sign languages employ multiple articulators, including the hands and the mouth. We asked whether manual components and mouthing patterns of lexical signs share a semantic representation, and whether their relationship is affected by the differing language experience of deaf and hearing native signers. We used picture-naming tasks and word-translation tasks to assess whether the same semantic effects occur in manual production and mouthing production. Semantic errors on the hands were more common in the English-translation task than in the picture-naming task, but errors in mouthing patterns showed a different trend. We conclude that mouthing is represented and accessed through a largely separable channel, rather than being bundled with manual components in the sign lexicon. Results were comparable for deaf and hearing signers; differences in language experience did not play a role. These results provide novel insight into coordinating different modalities in language production.