Developmental researchers typically focus on only one domain of expertise. However, children's development typically does not adhere to researchers' siloed expertise. Instead, multiple psychological domains develop simultaneously and changes in one domain can cascade into developmental changes in domains far afield from the original accomplishment. The proposed training plan and research project focus on the developmental relations between walking and talking. Learning to walk allows infants to explore the environment in new ways. Compared with crawling, walking infants go more places, see more of the surrounds, and access more distal toys for play. The proposed research project will test whether the changes instigated by walking have a cascading effect on infants' language experiences and language learning. The central hypothesis is that walking prompts a developmental cascade, wherein: (1) walkers explore a wider variety of places and objects than crawlers; (2) enhanced exploration elicits different forms of language input from caregivers; and (3) differences in language input are related to infants' receptive and productive vocabularies.
Three specific aims will test the developmental cascade hypothesis.
Aim 1 is to compare effects of crawling versus walking on infants' real-time exploration of places and toys and the amount and variety of content of caregiver language input in a controlled experiment in the laboratory.
Aim 2 is to extend this investigation to an hour-long naturalistic observation of the same infants and caregivers in their homes, thus capturing an ecologically valid portrayal of everyday activity. The critical data from both studies is the amount and variety of places and objects accessed by crawlers versus walkers, and the amount and variety of language input from caregivers. Finally, Aim 3 is to test whether individual differences in the real-time observations in Aims 1 and 2 account for the size and composition of infants' vocabularies. The long-term objective is to understand the cascading effects of infants' motor skill acquisition on other psychological domains such as language learning. Findings also have promise to inform clinical interventions because language impairments frequently co-occur with delays in motor development (e.g., in autism spectrum disorder and developmental coordination disorder).
This research aims to understand how locomotor development?the transition from crawling to walking? affects infants? exploration of places and toys, the language infants elicit from caregivers, and consequently infants? language learning. Despite the fact that motor delays are frequently observed in infants with social- communication or language deficits (e.g., in autism spectrum disorder), the processes linking these motor and linguistic domains are poorly understood. The proposed project will explicate these processes and therefore has potential to inform comprehensive clinical strategies that integrate motor- and communication-focused interventions.