The role of parental input in the development of a morphological system.

In order to isolate the properties of language whose development can withstand wide variations in learning conditions, we have observed children who have not had access to any conventional linguistic input but who have otherwise experienced normal social environments. The children we study are deaf with hearing losses so severe that they cannot naturally acquire spoken language, and whose hearing parents have chosen not to expose them to a sign language. In previous work, we demonstrated that, despite their lack of conventional linguistic input, the children developed spontaneous gesture systems which were structured at the level of the sentence, with regularities identifiable ACROSS gestures in a sentence, akin to syntactic structure. The present study was undertaken to determine whether one of these deaf children's gesture systems was structured at a second level, the level of the gesture-that is, were there regularities WITHIN a gesture, akin to morphologic structure? We have found that (1) the deaf child's gestures could be characterized by a paradigm of handshape and motion combinations which formed a matrix for virtually all of his spontaneous gestures, and (2) the deaf child's gesture system was considerably more complex than the model provided by his hearing mother. These data emphasize the child's contribution to structural regularity at the intra-word level, and suggest that such structure is a resilient property of language.