Fig. 1.

Mean proportion of referents children indicated uniquely in gesture but not in speech (dark columns) and uniquely in speech but not in gesture (light columns) in TD children, children with autism spectrum disorder (ASD) and children with Down syndrome (DS) at child mean age 18 months for TD children and 30 months for children with ASD and with DS; bars represent standard errors. The majority of the unique gestures that conveyed information about objects were requests for objects for children ASD (.59) but not for children with DS (.40), or for TD children (.40).