Through Thick and Thin: Gesture and Speech Remain as an Integrated System in Atypical Development.

Gesture and speech are tightly linked and form a single system in typical development. In this review, we ask whether and how the role of gesture and relations between speech and gesture vary in atypical development by focusing on two groups of children: those with peri- or prenatal unilateral brain injury (children with BI) and preterm born (PT) children. We describe the gestures of children with BI and PT children and the relations between gesture and speech, as well as highlight various cognitive and motor antecedents of the speech-gesture link observed in these populations. We then examine possible factors contributing to the variability in gesture production of these atypically developing children. Last, we discuss the potential role of seeing others' gestures, particularly those of parents, in mediating the predictive relationships between early gestures and upcoming changes in speech. We end the review by charting new areas for future research that will help us better understand the robust roles of gestures for typical and atypically-developing child populations.