Once is not enough: Standards of well-formedness in manual communication created over three different timespans

Natural languages are characterized by standards of well-formedness. These internal standards are likely to be, at least in part, a product of a consensus achieved among the users of a language over time. Nevertheless, it is possible that an individual, attempting to invent symbols to communicate de novo, might generate a system of symbols that is similarly characterized by internal standards of well-formedness. In these studies, we explore this possibility by comparing (1) a conventional sign language used by a community of signers and passed down from generation to generation with (2) gestures invented by a deaf child over a period of years and (3) gestures invented by nonsigning hearing individuals on the spot. Thus, we compare communication in the manual modality created over three different timespans—historical, ontogenetic, and microgenetic—focusing on the extent to which the gestures become codified and adhere to internal standards in each of these timespans. Our findings suggest that an individual can introduce standards of well-formedness into a self-generated gesture system, but that gradual development over a period of time is necessary for such standards to be constructed.