Children with Down's syndrome: usage of grammatical morphemes

Samenvatting

Children with Down's syndrome are reported to have particular difficulty with grammatical morphology (e.g. Chapman, 1995; Rondal, 1996). This investigation set out to establish if the grammatical morpheme difficulties experienced by this language-disordered group could be explained within the Extended Optional Infinitive (EOI) hypothesis (e.g. Rice et al., 1995), or if children with Down's syndrome present with a general-deficit in grammatical morphology (e.g. Chapman et al., 1998).

Analysis of elicited speech samples revealed that the Down's syndrome participants’ usage of grammatical morphemes met with a number of expectations of the EOI hypothesis e.g. they had obvious difficulties with a range of tense-related grammatical morphemes. However, these participants also generally had difficulty with non-tense-related morphemes when compared to language-matched typically developing controls. Therefore, the Down's syndrome group is reported to have a generalised grammatical morpheme deficit.

Additionally, the typically developing participants had omission of grammatical morphemes in obligatory contexts across-the-board. This finding cannot be explained by a strict interpretation of Wexler’s (1994) Optional Infinitive (OI) stage for grammatical acquisition.