By the age of three, typically developing children can draw conceptual distinctions between "kinds of individual" and "kinds of stuff" on the basis of syntactic structures. They differ from adults only in the extent to which syntactic knowledge can be over-ridden by semantic properties of the referent. However, the relative roles of syntax and semantics in determining the nature of the count-mass distinction in language acquisition are still not well-understood. This paper contributes to this debate by studying novel noun acquisition in a subgroup of children, aged 8-15 years, with specific language impairment, whose core deficits are limited to within the grammatical system (G-SLI), We conducted two experiments: a production task and a word extension task. Such children might be expected to rely to a greater extent than their age-matched peers on semantic properties of referents in order to assign noun interpretations, since by hypothesis they have greater difficulty in accessing and utilizing syntactic category distinctions than typically developing children. In the production task, the Children with G-SLI demonstrated rigid over-application of a pluralization rule which masked even basic knowledge of semantic information about individuated objects versus non-individuated substances. Age-matched control children only performed in this way when all syntactic and conceptual/perceptual cues were neutralized. In the word extension task, which required a non-verbal response, the Children with G-SLI showed evidence of only very limited abilities to use syntactic or semantic information for word-learning. Thus, developmental deficits in the grammatical system can be seen to impact on lexical acquisition as well as syntactic development.
Learning outcomes: As a result of this activity, the reader will be able to: (1) describe how syntactic (grammatical) impairment affects the ability to use syntactic cues for lexical acquisition, resulting in difficulties representing the structure of even simple phrases; (2) discuss the interaction between language components throughout development, and the cumulative impact of impairment in one or more aspect of language, which results in secondary impairments in other parts of the system; (3) consider the effects of an impairment in the ability to use syntactic cues for narrowing down word meanings, and how this can result in a much bigger problem affecting the subtle semantics of words and word classes.