Metalinguistic judgments on sentence structure in agrammatism: a matter of task misinterpretation

Judgments of sentence structure were studied in two non-agrammatic and four agrammatic patients. The subjects were required to sort the words from a sentence on the basis of how closely related they felt the words to be in that particular sentence. A hierarchical cluster analysis was then carried out on the data. The non-agrammatic patients produced typical "agrammatic" subjective trees in which function words and adjectives were weakly related to the rest of the sentence. The agrammatic patients produced structures that were fully normal. Two conclusions are drawn. First, this metalinguistic paradigm is inadequate as an indicator of an impairment in the mental representation of constituent structure. Second, the hypothesis that agrammatic speakers do not have such a representation is seriously weakened. Implications are discussed for the methodology of aphasia research as well as for theories on the nature of agrammatism.