Comprehension of wh-questions precedes their production in typical development and autism spectrum disorders

Children with autism spectrum disorders (ASD) rarely produce wh-questions (e.g. "What hit the book?") in naturalistic speech. It is unclear if this is due to social-pragmatic difficulties, or if grammatical deficits are also involved. If grammar is impaired, production of wh-questions by rote memorization might precede comprehension of similar forms. In a longitudinal study, 15 children with ASD and 18 initially language-matched typically developing (TD) toddlers were visited in their homes at 4-month intervals across a 3-year period. The wh-question task was presented via intermodal preferential looking. Silent "hitting" events (e.g. an apple hitting a flower) were followed by test trials in which the apple and flower were juxtaposed on the screen. During test trials, subject-wh- and object-wh-question audios were sequentially presented (e.g. "What hit the flower?" or "What did the apple hit?"). Control audios were also presented (e.g. "Where's the apple/flower?"). Children's eye movements were coded off-line, frame by frame. To show reliable comprehension, children should look longer to the named item (i.e. apple or flower) during the "where" questions but less at the named item during the subject-wh and object-wh-questions. To compare comprehension to production, we coded 30-min spontaneous speech samples drawn from mother-child interactions at each visit. Results indicated that comprehension of subject- and object-wh-questions was delayed in children with ASD compared with age-matched TD children, but not when matched on overall language levels. Additionally, both groups comprehended wh-questions before producing similar forms, indicating that development occurred in a similar manner. This paper discusses the implications of our findings for language acquisition in ASD.