Movements and Holds in Fluent Sentence Production of American Sign Language: The Action-Based Approach

The importance of bodily movements in the production and perception of communicative actions has been shown for the spoken language modality and accounted for by a theory of communicative actions (Cogn. Process. 2010;11:187-205). In this study, the theory of communicative actions was adapted to the sign language modality; we tested the hypothesis that in the fluent production of short sign language sentences, strong-hand manual sign actions are continuously ongoing without holds, while co-manual oral expression actions (i.e. sign-related actions of the lips, jaw, and tip of the tongue) and co-manual facial expression actions (i.e. actions of the eyebrows, eyelids, etc.), as well as weak-hand actions, show considerable holds. An American Sign Language (ASL) corpus of 100 sentences was analyzed by visually inspecting each frame-to-frame difference (30 frames/s) for separating movement and hold phases for each manual, oral, and facial action. Excluding fingerspelling and signs in sentence-final position, no manual holds were found for the strong hand (0%; the weak hand is not considered), while oral holds occurred in 22% of all oral expression actions and facial holds occurred for all facial expression actions analyzed (100%). These results support the idea that in each language modality, the dominant articulatory system (vocal tract or manual system) determines the timing of actions. In signed languages, in which manual actions are dominant, holds occur mainly in co-manual oral and co-manual facial actions. Conversely, in spoken language, vocal tract actions (i.e. actions of the lips, tongue, jaw, velum, and vocal folds) are dominant; holds occur primarily in co-verbal manual and co-verbal facial actions.