Gestural communication in deaf children: the effects and noneffects of parental input on early language development.
We previously reported that deaf children of hearing parents can develop a gestural communication system with some of the observed properties of early child language. In the present study, this phenomenon of gesture creation was replicated in four deaf children aged 1-4 to 3-1 at the time of the first interview. Each child, despite his atypical language-learning conditions (in particular his lack of usable conventional linguistic input, either oral or manual), developed a gesture system comparable in semantic content and structure (specifically, constructional ordering of elements, differential probabilities of production of elements, and recursive concatenation of semantic relations) to the gestural systems of the six deaf children of hearing parents in our original study and comparable as well to the spoken and sign systems of children acquiring conventional languages under typical learning conditions. This phenomenon suggests that the human child has strong biases to communicate in language-like ways. Nevertheless, it is possible that the deaf child's hearing parents, and not the child himself, were responsible for the emergence of the child's structured (yet idiosyncratic) gesture system. To investigate this possibility, we considered three possible parental influences on the child's sentence structures. First, we entertained the hypothesis that the children's sign sentences were merely imitations (perhaps even uncomprehending imitations) of a hearing adult's immediately preceding gestures. Second, we considered the possibility that the regularities underlying the deaf children's structured sign sentences were induced from their hearing parents' gestures taken in toto. Finally, we considered the possibility that the deaf children's sign sentences had been shaped by their parents' responses to those sentences. We found no evidence to support any of these hypotheses. The data reported in this series of studies confirm that deaf children lacking a conventional linguistic input can develop a gestural communication system that shows some of the structural regularities characteristic of early child language. The results suggest that communication with a number of language-like properties can develop in a markedly atypical language-learning environment, even without a tutor's modeling or shaping the structural aspects of the communication. The data are consistent with the hypothesis that the deaf child himself plays a seminal role in the emergence of the structural aspects of these communication systems.