Does early gesture usage contribute alongside oral language to later theory of mind performance and metaphor comprehension? Indications from a longitudinal study with children aged 1-9 years

Longitudinal work has demonstrated both that early gestural skills predict the course of children's language development and, separately, that language skills are important for the development of theory of mind (ToM) and metaphor comprehension. To extend and connect these findings, the current study explores the contributions of gesture (pointing at 1;0 and iconic gesture comprehension at 3;0) and language skills at 3;0 (productive vocabulary, productive and receptive grammar) to the development of later, more complex social pragmatic and socio-cognitive skills at 9;0: ToM and metaphor comprehension. Participants were 35 (18 boys) monolingual German-speaking children who took part within a longitudinal study between the ages of 1-9 years. Results showed that index-finger pointing at 1;0 significantly predicted metaphor comprehension at 9;0 and that both iconic gesture comprehension and language skills at 3;0 mediated the relation between index-finger pointing at 1;0 and ToM performance and metaphor comprehension at 9;0. These findings suggest an early facilitative role of gestures in the ongoing development of children's socio-cognitive and social pragmatic capacities alongside their language skills. Future studies on ToM or metaphor comprehension should thus consider and integrate gesture within their paradigms. Intervention studies with individuals who typically struggle with ToM and other socio-cognitive or social pragmatic skills may also benefit from exploring gesture within their specific contexts.