Gesture acts as a forerunner of language development in typically developing children. Children take their initial steps into sentences, and later, into extended speech (narratives, explanations) using gesture-speech combinations before expressing the same meanings entirely in speech. This project aims to determine whether gesture also serves as a reliable index of burgeoning spoken language abilities of children with autism spectrum disorder (ASD), who exhibit delays and/or deviations in attaining similar milestones. This project approaches this question by studying gesture and speech use at two crucial milestones of language development, namely onset of sentences to request and comment (study 1) and onset of extended speech in narratives and explanations (study 2) using longitudinal observations. Study 1, focusing on first sentences, examines changes in gestures and speech of 18 children with ASD and 18 typically developing children, as they transition from producing single words to simple sentences in two language contexts: commenting on objects and requesting objects. Study 2, focusing on extended speech, examines changes in gestures and speech of 25 children with ASD and 25 typically developing children in two language contexts: producing narratives and providing explanations. Given the reported difficulties children with ASD exhibit in gesture production at the early ages--followed by delays in later speech production--the project asks whether the pattern of gesture-speech combinations leading the way to early sentences and later narratives/explanations is disrupted, or whether this language-learning process is so robust that children with ASD, like typically developing children, initially rely on gesture and speech together to convey their emerging spoken language abilities.
This research will make an important contribution in two major respects: First, the findings will inform theories of language development about the robustness of the gesture-speech system across different learners. Compared to typically developing children, the language-learning trajectory of children with ASD shows variability, with weaknesses in early commenting and later narrative contexts, accompanied by relative strengths in early requesting and later explanation contexts. Children with ASD also show unique deficits in early pointing gestures, but relative strengths in later iconic gestures, making them an ideal group to understand whether and how gesture is part of the developmental process that supports language-learning across stages and contexts of language acquisition. Second, the findings have potential clinical implications. Gesture, when considered in relation to the accompanying speech, can be used to identify when a child is in a transitional state with respect to a language milestone. More specifically, children whose gestures convey different information from their speech show more readiness to learn, and in turn, are also more likely to benefit from instruction. As such, gestures might serve as a good index of emerging language abilities, which, in turn, may help educators and clinicians to identify the best time to introduce task-specific strategies for language learning for children whose development is delayed or deviant. These strategies could range from providing more targeted spoken language input to explicitly encouraging children to use particular gestures when talking about the concepts that they are at the cusp of learning--both of which have been shown to be effective strategies in teaching new concepts to typically developing children.