Acquisition of Nouns in Young Children with ASD: Insight into Learning Processes from Item Analyses
Objectives: We asked: (1) do toddlers with ASD, like TD toddlers, understand and produce more nouns on the “shape side” (solid+shape+count; e.g., cup, block) than on the “material side” (nonsolid+material+mass; e.g., rain, milk)? and (2) are “shape side” nouns acquired first such that they represent a higher proportion of nouns in children with small vocabularies?
Methods: TD toddlers (n=46; M age=19 months) and toddlers with ASD (n=39; M age=32 months) were drawn from a longitudinal study. Expressive and receptive vocabulary were assessed using parent report (MacArthur-Bates Communicative Development Inventories [CDI]: Word and Gestures; Fenson et al., 2007). Groups did not differ on number of nouns produced,p=.700, d=0.08.
Nouns from the CDI (n=209) were coded following Samuelson and Smith (1999) for each toddler’s lexicon. The proportion of nouns characterized by solid+shape, nonsolid+material, solid+count, and nonsolid+mass was calculated.
Results: Like the TD children, those with ASD understood and produced many more solid+shape than nonsolid+material nouns, ps<.001, and many more solid+count than nonsolid+mass nouns, ps<.001. See Figures 1 and 2. The proportion of noun types was not correlated with vocabulary size in either group after controlling Type I error.
Conclusions: Overall, these findings suggest that the regularities proposed to support learning biases are present in the vocabularies of children with ASD: “shape side” nouns dominate the vocabularies of children in both groups regardless of vocabulary size. Despite this, their performance reveals no consistent shape bias during word learning (Potrzeba et al., 2015). It is possible that children with ASD, rather than lacking the data (vocabulary) are instead lacking the processes by which the data could be analyzed. That is, the process of lexical learning may develop distinctly in children with ASD due to the ways in which or the extent to which these regularities and their organization are utilized over time (Ellawadi, Fein, & Naigles, 2016; Tek et al., 2008). The current study has implications for theories of lexical acquisition in ASD, including shared mechanisms with typically developing children and the role of prior knowledge.