Space, movement and articulation in a newly emergent sign language: contributions for neural and sociocognitive efficiency

Objective: Here we investigate the involvement of space, movement and nonmanual articulators throughout the evolution of a newborn sign language. We aimed to assess how the development of these constraints might lead to effortless movement and neural economy in social communication. Methods: We analyzed the gestures elicited from 100 sketch cards, produced by 100 deaf and hard of hearing individuals as they came together to develop a new sign language. Results: We found that throughout four two-year time phases, gestures reduced in number, motion amplitude and recruitment of nonmanual articulators. Conclusions: The evolution of a newborn sign language seems to follow the same phases of psychomotor development (experienced, manipulated and represented). Reduction of gesture number and changes in movement and space strategies seem to be linked to more efficient use of energy while enhancing cognition, allowing for the fruition of social communication enabled by sign language.