The relationship between early verb comprehension and developing motor skills in 9- to 20-month-olds

We investigated infants’ understanding of words that refer to action events. Based on the argument that changes in motor abilities may have important influences on language development (Iverson, 2010), we hypothesize that differences in comprehension ability might be related to infants’ experiences with different kinds of motor actions. New motor abilities provide new opportunities for infants to explore their physical world (Smith et al., 2007). Direct experience with an action might enable infants to expand their comprehension abilities (Huttenlocher et al., 1983). Motor abilities also provide new opportunities for infants to engage with social partners and might prompt more talk about actions (Karasik et al. 2008; Reid et al., 2010). If motor experience influences vocabulary development, then infants might show better comprehension for actions with which they have more experience. We tested for comprehension of two types of action events in a split-screen preferential looking paradigm: seated posture with manual actions [splash-shake, wave-laugh, blow(bubbles)-eat(with a spoon)] and upright posture with gross motor actions [kick-throw, jump-run, walk-dance]. The participants were infants from rural small towns in Central Pennsylvania. The Ages and Stages survey was used to gather parent reports of the infants’ motor development. The MacArthur Bates Communicative Development Inventory (MCDI) was used to estimate vocabulary. A parent report survey of how frequently the family used the target words was included to gather an estimate of exposure to these words. We assigned infants to a Younger or Older subject group based on the Ages and Stages standard that independent walking is typically developed by 15 months of age. Then, infants were assigned to either the "seated-manual" action condition or the "upright-gross motor" action condition. Each infant saw all three sets in each condition in a blocked presentation. Order of presentation and side of presentation were counterbalanced between subjects. Looking times were scored frame by frame from digital video recordings. Final analyses are in progress.