Maternal Lexical Diversity and the Language Development of Children with ASD and DLD

Background: Quantity and diversity of maternal linguistic input are related to child language outcomes. However, less is known about maternal and child characteristics that may impact this relationship in children with ASD. Current research suggests that in children with ASD, quantity and diversity of maternal linguistic input impact child language skills (Fusaroli et al., 2018). In typically developing children, maternal socioeconomic status (SES) relates to maternal language input, which impacts child language outcomes (Hart & Risley, 1995). The impact of SES on maternal linguistic input in children with ASD is not well studied. Child characteristics, such as social communication deficits inherent to ASD, may be an important factor to consider (Arunachalam & Luyster, 2018). By comparing children with ASD to children with developmental language disorder (DLD) we are able to examine the unique impact that social communication difficulties, above and beyond language delays, may have on maternal language input.

Objectives: The current study aims to (1) examine the relationship between mother’s use of language type (number of unique words), token (frequency of words) and type/token ratio (TTR) and child’s use of language type, token, and type/token ratio (2) investigate differences in maternal linguistic input based on SES (3) to examine the extent to which ASD status moderates the relationship between maternal input and child language.

Methods: The current study included 184 mother-child dyads: 111 children with ASD (M=2.77 years, SD= .53) and 73 children with DLD (M=2.66 years, SD=.50). 10 minute mother-child interactions using a standardized set of toys were transcribed and analyzed using SALT (Systematic Analysis of Language Transcripts; Miller & Iglesias, 2008). From the transcription, type, token and TTR of total words, adjectives, nouns, prepositions, and verbs were analyzed for both the mother and child. Mothers completed a questionnaire indicating their household income. Income status was defined as follows: low income $0-$25,000, middle income $25,001-$100,000, high income greater than $100,000.

Results: We computed pearson correlations to determine the relationship between maternal input and children’s lexical diversity across both populations (see Table 1). We used two-sample t-test to examine the differences in maternal input based on household income (Table 2). Linear regressions revealed that ASD status moderates the relationship between maternal language measures and children’s language measures for preposition token (F(1, 180) = 4.745, p <.05) and preposition TTR (F(1, 180) = 7.284 p <.05).

Conclusions: This research highlights the importance of investigating maternal and child characteristics that may impact the relationship between maternal linguistic input and language development in children with ASD. Future research should include longitudinal approaches to investigate the relationship between maternal linguistic input and later child language outcomes to examine the extent to which types of linguistic input change based on the child’s developmental level. Further research is necessary to characterize the differences in maternal linguistic input based on SES in children with communication disorders. It is essential to continue to investigate the extent to which social communication deficits may moderate the relationship between input and children language levels.