Published online by Cambridge University Press: 15 February 2016
Children with Specific Language Impairment (SLI) have language difficulties of unknown origin. Syntactic profiles are atypical, with poor performance on non-canonical structures, e.g. object relatives, suggesting a localized deficit. However, existing analyses using ANOVAs are problematic because they do not systematically address unequal variance, or fully model random effects. Consequently, a Generalised Linear Model (GLM) was used to analyze data from a Sentence Repetition (SR) task involving relative clauses. seventeen children with SLI (mean age 6;7), twenty-one Language Matched (LM) children (mean age 4;8), and seventeen Age Matched (AM) children (mean age 6;5) repeated 100 canonical and non-canonical sentences. ANOVAs found a significant Group by Canonicity interaction for the SLI versus AM contrast only. However, the GLM found no significant interaction. Consequently, arguments for a localized deficit may depend on statistical methods which are prone to exaggerate profile differences. Nonetheless, a subgroup of SLI exhibited particularly severe structural language difficulties.
I would like to thank the British Academy for funding this project (Award Number PDF/2007/460), and colleagues at the Universities of Reading and Newcastle for their support and advice. In particular I would like to thank Thomas King, David Howard, Christos Salis, and Nils Braakmann for their statistical input. Thanks also to Kerry Davis and Christos Pliatsikas for help with data collection and coding and the three anonymous reviewers. Finally, a massive thank you for those teachers, speech and language therapists, and above all the children who participated.