Investigating Knowledge of Complex
Syntax: Insights From Experimental
Studies of Williams Syndrome
University of Maryland
It is relatively easy to quantify performance on tests of language. A more difficult task is translating a pattern of performance into conclusions regarding the linguistic abilities/mechanisms that underlie that performance. For example, poor performance can be caused by many things: deviant or missing knowledge, parsing difficulty, memory overload, and so on. In the adult processing literature, it is taken for granted that adults who are unable to interpret triple-embedded clauses or who misinterpret relative clauses of some types in speeded tasks do not do so because of impaired grammatical knowledge. However, when some population of interest has a cognitive or linguistic disorder, they cannot be granted the same benefit of the doubt because the integrity of their linguistic knowledge may itself be the object of study.
Despite the difficulty of translating performance on language measures into conclusions regarding grammatical knowledge, there are good reasons to at least try. One reason is that poor performance by disordered groups is sometimes equated with impaired competence, and premature conclusions are drawn about the relevance of those disorders to theories of language acquisition. Another important reason to try to understand the causes of poor performance is that a deeper understanding may elucidate cross-etiology comparisons. For example, at the level of performance,