Background: A limited range of evidence suggests that children with specific language impairment (SLI) have difficulties with higher order thinking and reasoning skills (executive functioning, EF). This study involved a comprehensive investigation of EF in this population taking into account the contributions of age, nonverbal IQ and verbal ability.
Methods: Ten separate measures of EF were assessed in 160 children: 41 had SLI; 31 had low language/cognitive functioning but did not fulfil the criteria for SLI (low language functioning or LLF); and 88 were typically developing with no language difficulties. Group differences in performance were assessed after controlling for age, nonverbal IQ and verbal ability in a series of regression analyses.
Results: Children with SLI and LLF had significantly lower performance than typical children on 6 of the 10 EF tasks once age and nonverbal IQ had been controlled (verbal and nonverbal executive-loaded working memory, verbal and nonverbal fluency, nonverbal inhibition and nonverbal planning). Performance on these EF tasks remained lower for those in the SLI group even when verbal IQ was entered in the regressions.
Conclusions: Children with language impairments showed marked difficulties on a range of EF tasks. These difficulties were present even when adjustments were made for their verbal abilities.