An Experimental Investigation of the Factors Supporting the Emergence of Spatial Agreement in Nicaraguan Sign Language

Studies of natural language emergence provide unique opportunities for examining the learner-internal and environmental factors underlying language development, but lack the control of factors necessary to test hypotheses about language development. By ‘language development,’ I intend to encompass both language acquisition and modern-day language change/emergence, which I argue are driven by many of the same factors. Researchers of Nicaraguan Sign Language, an emerging language, have proposed that intergenerational transfer and particularly child language-learning mechanisms (e.g. the propensity to ‘reanalyze’ and systematize inconsistent input) shape the development of the language. We observe this potential pattern in the emergence of the systematic use of space to express argument structure from the first to the second cohort, but are unable to confirm it using only naturalistic data. I used an experimental semiotics approach to ask whether interaction between individuals in the same “generation” of adult hearing gesturers was sufficient to encourage the emergence of spatial devices to express argument structure like those of established sign languages. Pairs of adult, hearing non-signers participated in an interactive gesture communication task designed to elicit the use of space to express argument structure. No pairs spontaneously generated linguistic spatial devices for expressing argument structure as complex as those in established sign languages, but their strategies resembled such devices in some ways. For instance, hearing gesturers did represent the actions of different characters in distinct spatial locations, and some hearing gesturers generated separate gestures for identifying characters independently of their spatial location (similar to ‘lexical items’). I conclude that while interaction promotes a degree of systematicity in this communicative task, it is not solely responsible for the emergence of complex linguistic devices like the use of space to express argument structure. I further discuss how this work informs the cross-disciplinary discussion on how (or whether) to distinguish gesture from language, our classification of spatial devices for argument structure in established sign languages as gestural or linguistic, and hypotheses regarding learner-internal versus learner-external contributions to language development