Complex grammar in Williams syndrome

Abstract

This study investigated knowledge of binding and raising in two groups of children with Williams syndrome (WS), 6–12 and 12–16‐years‐old, compared to typically developing (TD) controls matched on non‐verbal MA, verbal MA, and grammar. In typical development, difficulties interpreting pronouns, but not reflexives, persist until the age of around 6, while raising is not mastered until about the age of 8 or 9. If grammar in WS is delayed, but develops in a fashion parallel to TD population, similar patterns of difficulties may be expected, although it has not been established whether the grammatical development is ever complete in the individuals with this disorder. Knowledge of the principle of binding which states that a reflexive must have a c‐commanding antecedent, was found to be intact in all the participants, in line with previous reports in the literature. In contrast, children with WS younger than 12 showed a poorer performance on personal pronouns, like two groups of younger matched TD controls, suggesting a previously unreported delay in the acquisition of constraints regulating coreferential interpretation of pronouns. Both groups of children with WS showed an extremely limited comprehension of raised, as opposed to unraised structures. The revealed patterns indicate that, like in unimpaired populations, different aspects of grammar mature at distinct stages of language development in WS: reflexive binding is acquired earlier than constraints governing coreference. However, development of raising seems exceptionally delayed, and perhaps even unattainable, as data from several adults with WS studied in Perovic and Wexler () show. If, as hypothesized by Hirsch and Wexler, the late development of raising is related in TD children to lack of maturation of the knowledge of A‐chains or defective phases, it seems reasonable to hypothesize that the even later development of these structures in WS is related to an even later (if ever) maturation of the knowledge of these grammatical forms.

• Williams syndrome
• raising
• binding
• grammar
• A‐chains

Notes

*. An atternative is that certain grammatical operations develop extremely late (compared to cognitive development) in children with WS. What empirical evidence exists, as we point out later, supports the stronger hypothesis that the operations never develop.

1. The six children and young adults with WS studied in Perovic and Wexler (2006) performed worse on psychological passives than controls matched on vocabulary, but better than controls matched on non‐verbal reasoning—a pattern which seems indicative of a general language delay in WS. However, recent data suggest that (aspects of) grammar seem specifically delayed in WS, more delayed than overall mental age: a much larger sample of 26 children and adolescents with WS in Perovic and Wexler (submitted) showed a worse performance on psychological passives than either vocabulary or non‐verbal reasoning matched control children.

2. But cf. Hornstein (2001), Reuland (2001). See Hirsch and Wexler (in press), who show that Hornstein's ideas don't seem to change the results of the Universal Phase Requirement, which is the theoretical idea under which our paper is written.

3. Principle C constrains the distribution of R‐expressions and will not be discussed here.

4. For the discussion of concepts used in these definitions see Chomsky (1981). X binds Y if X c‐commands Y and is coreferential with Y. Y is free if there is no X that binds Y. For present purposes, local can mean “in the same clause as”.

5. The A‐Chain Delay Hypothesis (ACDH) of Borer and Wexler (1987, 1992) also predicts that passives are delayed and that raising (see our discussion coming in a few paragraphs) is delayed. However, Wexler (2004) shows that UPR is empirically superior to ACDH, especially because ACDH with no supplements predicts that young children cannot raise subjects out of the verb phrase, a false prediction.

6. This is an informal definition; see Wexler (2004) for the full definition in terms of “light verbs” v.

7. Hirsch and Wexler show that “theory of mind” considerations cannot explain the data, since children do very well on the think control, which has the same TOM properties.

8. It may still be the case that the acquisition of this module is delayed in WS: reflexives are mastered early in TD, by the age of 3 or 4, thus it is possible that children with WS younger than 6 would have difficulties interpreting reflexives at the age when TD children do not. This is a topic for future research.

9. It remains to be established whether individuals with WS have the knowledge of long‐distance binding. Since young children seem to acquire the restrictions on locality of reflexives relatively slowly (Chien & Wexler, 1990), it is plausible that children with WS will be more delayed on that aspect of binding of reflexives than on the c‐command constraint.