Complex syntax acquisition: a longitudinal case study of a child with specific language impairment.

Although there is extensive documentation of the morphological limitations of children with specific language impairment (SLI), few studies have reported on complex syntax acquisition in children with SLI. This case study examined the development of complex syntax in a child with SLI between 3 and 7 years. Twelve conversational samples were analysed to describe emergence of complex syntax types, proportional use of complex syntax, and complex syntax production errors. Earliest emerging complex syntax types were catenatives and let's clauses, not always considered true complex syntax, as well as simple infinitives. These three types accounted for 88% of complex syntax tokens through age 4;8 (MLU = 3.12). A diverse range of complex syntax types was produced consistently at age 5;9 (MLU = 4.27), including wh clausal complements, relative clauses, and full propositional clauses. Production errors on complex syntax included omissions of infinitival to, omissions of wh pronouns in wh clausal complements, omissions of obligatory relative markers, and an omission of a complementizer. Production errors continued to be prevalent even in the last language sample at 7;10 (MLU = 5.46). Documentation of complex syntax development in children with SLI is critical to the clarification of linguistic deficiencies that characterize specific language impairment.