Syntactic Problems in German Individuals with Down Syndrome: Evidence from the Production of Wh-Questions

Individuals with Down syndrome (DS) have difficulties to produce complex syntactic structures. It has been proposed that these problems specifically affect A-movement. This study aimed to investigate if A'-movement is affected as well by studying the production of wh-questions. We conducted an experimental task eliciting wh-questions of 23 German speaking children/adolescents with DS (mean age: 11;4 years) and a control group of 15 typically developing (TD) children (mean age: 4;1 years) matched for nonverbal mental age. To evaluate the syntactic development over the lifespan, we also tested wh-question production in 20 adults with DS (mean age 28;7 years). The majority of subjects in both groups with DS showed severe difficulties in producing wh-questions correctly in contrast to performance close to ceiling in the TD group. A detailed error analysis suggests that some of these problems are not due to difficulties with the wh-movement (A'-movement) operation proper. Moreover, auditory-verbal short-term memory skills correlated significantly with the productive outcome in the group of children and adolescents with DS. The implications of these findings that contribute to the debates on the nature of syntactic problems in DS will be discussed.