Assessment of syntax after adolescent brain injury: effects of memory on test performance

In this study, we investigated the influence of working memory load on performance of a task designed to measure receptive syntax ability. Subjects were 6 brain-injured adolescents and 6 hospitalized control subjects matched for age, sex, and general ability. Each subject was administered the Listening/Grammar subtest of the Test of Adolescent Language (TOAL-3) and a modified version of this subtest with identical syntax and fewer response choices (i.e., a reduced working memory processing and storage load). The syntactic structures tested on these tasks also were measured in spontaneous narratives. The brain-injured subjects' performance was significantly worse than that of controls on both versions of the syntax comprehension subtest. There was a significant group-by-task interaction, as brain-injured subjects' performance was significantly worse on the Listening/Grammar subtest than the modified subtest, whereas Control subjects'performance did not differ across the two tasks. In their spontaneous narratives, subjects in both groups produced the syntactic structures tested on the receptive syntax tasks, with no between-groups difference in syntax production. The results are discussed in terms of test validity and the impact of measurement methods on test performance in disordered groups.