Relative clauses are barriers to wh-movement for young children.

Two studies are described which investigate preschool children's sensitivity to relative clauses as barriers to the movement of wh-questions. The children were presented with short stories followed by questions in which the wh-word had two possible sites of interpretation, the ungrammatical option being inside a relative clause. A cross-sectional study with 23 children aged 3;1 to 6;1, and a longitudinal study over the course of one year with 12 children aged 3;1 to 4;1 at the start, found young children refused to extract wh-questions from the ungrammatical site inside a relative clause. This confirms other findings that children's early grammars are sensitive to universal constraints on movement. In addition, the children differentiated between wh-complements and relative clauses in their tendency to mistakenly answer the medial wh-complementizer but not the wh-relative pronoun. Explanations for the latter are framed in terms of children's initial assumptions about the attachment of complements.