"Go, go, go!" Mothers' verbs align with infants' locomotion.

Caregivers often tailor their language to infants' ongoing actions (e.g., "are you stacking the blocks?"). When infants develop new motor skills, do caregivers show concomitant changes in their language input? We tested whether the use of verbs that refer to locomotor actions (e.g., "come," "bring," "walk") differed for mothers of 13-month-old crawling (N = 16) and walking infants (N = 16), and mothers of 18-month-old experienced walkers (N = 16). Mothers directed twice as many locomotor verbs to walkers compared to same-age crawlers, but mothers' locomotor verbs were similar for younger and older walkers. In real-time, mothers' use of locomotor verbs was dense when infants were locomoting, and sparse when infants were stationary, regardless of infants' crawler/walker status. Consequently, infants who spent more time in motion received more locomotor verbs compared to infants who moved less frequently. Findings indicate that infants' motor skills guide their in-the-moment behaviors, which in turn shape the language they receive from caregivers. RESEARCH HIGHLIGHTS: Infants' motor skills guide their in-the-moment behaviors, which in turn shape the language they receive from caregivers. Mothers directed more frequent and diverse verbs that referenced locomotion (e.g., "come," "go," "bring") to walking infants compared to same-aged crawling infants. Mothers' locomotor verbs were temporally dense when infants locomoted and sparse when infants were stationary, regardless of whether infants could walk or only crawl.