Selective impairment of italian grammatical morphology in the congenially deaf: A case study

Abstract

Z is a congenitally deaf woman who has acquired an extraordinarily high level of competence in Italian, a spoken language with a rich system of inflectional morphology. Examples of Z's spoken and written language are compared with equivalent samples for an educated native speaker (NC) and a second control subject (BC) who acquired Italian as a second language. Like NC and BC, Z produces complex and well-formed syntactic constructions. Unlike BC, Z also demonstrates near-normal levels of lexical competence (in word selection, spelling, derivational morphology). By contrast, Z displays severe impairments in grammatical morphology. Her pattern of morphological impairment is also qualitatively different from that of our bilingual control: violations of bound morphology are restricted almost entirely to long-distance agreement; most errors involve omission, addition, or substitution of free-standing function words. Results are discussed in terms of a possible causal link between phonetic/phonological deprivation and problems with grammatical morphology. Some models proposed to account for loss of morphology in aphasia are discussed, and we conclude that these models cannot account for the unique profile of grammatical impairment displayed by the deaf.