False belief and sentence complement performance in children with specific language impairment.

Abstract

Children with specific language impairment (SLI) have language abilities not commensurate with other cognitive abilities. This pattern makes the SLI population of interest when investigating the relationship between language and theory of mind. One view regarding this relationship is that theory of mind develops independently of language, but certain language skills are required to meet the demands of tasks used to measure theory of mind, such as false belief. Another view is that language development facilitates theory of mind development, and specifically, that mastery of sentence complement structures is necessary for false belief. The study asked (1) if children with SLI can succeed on false belief, despite their language deficits, when the linguistic demands of the false belief task are low, and (2) if performance on sentence complement structures predicts false belief performance. Fifteen children with SLI, 15 children matched for age and 15 children matched for language comprehension level participated in a false belief task with four conditions of differing linguistic complexity, and a test of sentence complementation understanding. Spontaneous production of sentence complements was also measured. Group differences for false belief and sentence complementation, and condition differences for false belief, were tested non-parametrically. Partial correlation analysis, log-linear analysis, and Wilcoxon-Mann-Whitney tests were used to explore relationships among the complementation and false belief measures for all children and for each group. Children with SLI performed similarly to age-matched peers on false belief when linguistic complexity of the task was low, and performed more poorly than age-matched peers on understanding of sentence complements. For all children, sentence complement performance was correlated with false belief (controlling for age), and those who performed well on sentence complements had higher mean rates of false belief success. Log-linear analysis showed the sentence complement-false belief relationship to hold for a condition with relatively low linguistic demands. The study provides evidence that children with SLI can perform at age-appropriate levels when false belief tasks are less demanding, and that mastery of sentence complementation is a predictor of false belief ability.