Article drop in child language can be explained by grammatical
factors. Inspired by Chierchia et al. (2001) we assume that missing articles
result from a mis-mapping between the semantic property ‘argumenthood’ and
its syntactic counterpart (noun, or article+noun). Misanalyzing predicative
nouns (cat) as argumental results in non-adultlike bare nouns.
On the other hand, the observation that young normally developing children often use a definite article where an adult would have used an indefinite (Maratsos, 1974; Schaeffer, 1997; 1999) has been explained by the lack of a pragmatic concept until about age 3;6. Lacking this concept causes the child to attribute her own knowledge to the hearer. Since definite articles denote familiarity of the noun’s referent to both speaker and hearer, it follows that children overgenerate the definite article: they use it when the referent is familiar to the speaker, i.e. themselves, and the hearer (adultlike), but also when the referent is familiar only to the speaker, i.e. themselves (non-adultlike).
Hypothesizing that children with SLI are impaired in their grammar, but not in their pragmatics (cf. Leonard, 1998), we predict that 4-year old English-speaking children with SLI drop articles (similar to MLU controls, but unlike normally developing age-mates), but do not overgenerate the definite article the (similar to normally developing 4-year olds).
An investigation of the speech of 14 English-speaking children with SLI between the ages of 3;11 and 4;10 (mean age 4;05) and an MLU range of 2.0-5.1 (mean MLU 3.8) and two control groups (MLU and age) of 14 children each confirms this prediction: 4-year olds with SLI drop articles at a rate of 13%, similar to their MLU controls (8%), but unlike their age controls (3%). On the other hand, they do not show problems with the correct use of the definite article: similar to both their MLU and their age controls they do not overgenerate the. (For comparison, normally developing 2/3 year old English-speaking children overgenerate the 16% (Schaeffer, 1999).) These results suggest that 4-year-old children with SLI have the pragmatic concept that regulates the correct use of the, just like their normally developing age mates, but that they are impaired in a grammatical aspect of DP, as shown by their article drop.
Interestingly, the same children produce errors on two other syntactic mechanisms: 34% on subject-verb agreement (similar to their MLU controls 23%, but unlike their age controls 5%), and 13% on subject Case (unlike either their MLU controls 3%, or their age controls 0%). These results further emphasize their grammatical impairment.
In summary, by examining two aspects of the D-system we provide support for the hypothesis that children with SLI have a grammatical, but not a pragmatic impairment, and furthermore, for the modularity of grammar and pragmatics.