Complementizers and subordination in typical language acquisition and SLI

This study aims to report on the pattern of use of complementizers by Greek SLI children as well as describe differences and/or similarities with patterns of emergence in typical language development. The complementizers na (corresponding to the English infinitival marker to), oti and pos (corresponding to the English that) and pu (introducing factive complements and relative clauses) were investigated in spontaneous speech samples of 8 children with SLI and two control groups: 8 language-matched and 8 age-matched children. The theoretical frameworks adopted are that of the Interpretability Hypothesis, according to which LF-interpretability plays a determining role in the acquisition of formal features by SLI children, and Roussouʹs account of the C domain in Greek. In line with these accounts, the child data was analysed with respect to feature specification, posing a distinction between pu on the one hand, specified for the interpretable feature of definiteness, and oti and pos on the other, while na holds a unique status, functioning as marker of mood/modality and a clause-typing element. Additionally, the selectional restrictions these complementizers impose on inflection were also investigated. The results indicate that complementizers with low specification for LF- interpretability are more sensitive in SLI, while their selectional properties are active, revealing a problem in the morpho-phonological operation of spell-out rather than their lexical representation in the childrenʹs underlying grammar.