A basic question about bilingual development is how the acquisition of one language affects the acquisition of the other. Previous findings are few and mixed. The present study addressed this question with longitudinal data on the dual-language vocabulary growth of 149 US-born children from Spanish-speaking immigrant families, who were followed…

Over half of US children are enrolled in preschools, where the quantity and quality of language input from teachers are likely to affect children's language development. Leveraging repeated objective measurements, we examined the rate per minute and phonemic diversity of child and teacher speech-related vocalizations in preschool classrooms and…

The toddler and preschool years are a time of significant development in both expressive and receptive communication abilities. However, little is known about the neurobiological underpinnings of language development during this period, likely due to difficulties acquiring functional neuroimaging data. Functional near-infrared spectroscopy (fNIRS)…

While we know that interventions targeting oral language can be effective, little is known about what drives these effects. In this study, we examine whether gains in transfer measures are mediated through the specific words that are trained in a language intervention. Based on a large-scale randomized controlled trial of language intervention in…

Children learn words by listening to caregivers, and the quantity and quality of early language input predict later language development. Recent research suggests that word recognition efficiency may influence the relationship between input and vocabulary growth. We asked whether language input and lexical processing at 28-39 months predicted…

In many low- and middle-income countries, young children learn a mother tongue or indigenous language at home before entering the formal education system where they will need to understand and speak a country's official language(s). Thus, assessments of children before school age, conducted in a nation's official language, may not fully reflect a…

We examined gestural and verbal interactions in 226 mother-infant pairs from Mexican, Dominican, and African American backgrounds when infants were 14 months and 2 years of age, and related these interactions to infants' emerging skills. At both ages, dyads were video-recorded as they shared a wordless number book, a wordless emotion book, and…