The role of verbal and nonverbal behaviors in children's later language processing: Data from low-SES Latino families in the US
International Congress of Infant Studies Virtual Congress
Caregivers are children's first teachers, engaging children in rich interactions that help them learn about the world. Early disparities in the quantity and quality of caregiver interactions, particularly verbal engagement, have been shown to begin early and to contribute to children's academic outcomes (Hart & Risley, 1995; Walker et al.,1994). This work has inspired decades of research devoted to understanding why individual differences in early language environments link to later language outcomes (e.g., Gilkerson et al., 2018; Pan et al., 2005). Weisleder and Fernald (2013) proposed that language processing skills mediate the link between caregivers' verbal engagement at 19 months and children's vocabulary development at 24 months. How does caregiver engagement support children's language processing? One hypothesis is that language processing skills develop as a function of children's ability to identify referents in broader communicative interactions, which include verbal and nonverbal behaviors. Research has shown that the nonverbal dimensions of caregivers' referential input (timing, gesture, gaze) positively relate to children's later vocabulary knowledge (Cartmill et al., 2013; Trueswell et al., 2016). However, it is unclear how verbal and nonverbal behaviors work together. Here, we compare 5 models (differing in the predictors they include) which represent ways in which the amount of verbal and nonverbal behaviors could contribute to children's later language processing skills and vocabulary size: 1) labels only 2) gestures only 3) labels and gestures (additive), 4) labels and gestures (interaction), or 5) labels overlapping with gestures. Participants were lower-SES Spanish-speaking families in the US. We videorecorded a 5-min free play session at 18 months and coded the number of labels and gestures (i.e., pointing, holding, giving, or touching objects) used by caregivers as well as the number of times caregivers paired a label with a gesture (overlap). At 25 months, children's speed of language processing was assessed in the Looking-while-Listening task (Fernald et al., 2008) and vocabulary size was approximated using the MacArthur-Bates Communicative Developmental Inventories (CDI) (Fenson et al., 2007). We preregistered the sample size, coding procedures and analysis plan. The five models were fit as Bayesian linear regression models (Table 1). For language processing, a model including the number of labels as a predictor (Model 1) provides a better fit to the data compared to a baseline model which includes only control predictors (processing at 18 months, SES). For vocabulary size, Model 1 also provides the best fit, yet labels paired with gestures (Model 5) also explains the data better than the baseline model. This research replicates and extends previous findings showing that verbal engagement predicts the development of children's later language skills, even when pitted directly against the frequency of gesture use, measured either alone or in combination with labels. Nevertheless, different combinations of labels and gestures also explain variance for both language processing and vocabulary size. Ongoing analyses are exploring possible explanations for these patterns. Investigating verbal and nonverbal communicative behaviors in relation to child language outcomes can offer new insights into how caregivers can support children's later language development.
Child and Adolescent Development
Manuel Bohn, Janet Bang, Joel Ramírez, Virginia Marchman, and Anne Fernald. "The role of verbal and nonverbal behaviors in children's later language processing: Data from low-SES Latino families in the US" International Congress of Infant Studies Virtual Congress (2020).