The Contribution of Reciprocal Social Interaction to the Acquisition of Verbs and Spatial Terms In 2-Year-Olds with ASD and Siblings-at-Risk

Background: Accumulating evidence suggests that for children with ASD, vocabulary growth is highly dependent on social skills. Understudied, however, is the nature of vocabulary that is acquired. Extensive research with typical children suggests that not all words are created equal; rather, some kinds of words are more difficult to learn than others (Hirsh-Pasek & Golinkoff, 2006). The so-called “hard words” label static and dynamic relationships between objects or entities, and include verbs like “run” and prepositions like “on”.  These words are more difficult to learn in part because their meaning is less perceptually obvious than a concrete noun like “ball”. Thus, figuring out the meaning of a relational word often requires children to utilize more than just perceptual cues – they must also integrate knowledge gleaned from social cues. The relationship between social understanding and verb vocabulary in children with ASD has been established (Lopez & Lord, 2009), but the theoretically similar link between social understanding and a different type of relational words – prepositions or spatial terms – has yet to be explored.

Objectives: Explore the link between social understanding and relational vocabulary in children with ASD and siblings-at-risk who did not receive a diagnosis. It was hypothesized that social skills would predict both types of relational words (verbs and prepositions) in children with ASD, but not in unaffected siblings.

Methods: Ten 2-year-olds with ASD were matched to 10 2-year-old siblings of children with ASD on the non-verbal portion of the Mullen Scales of Early Learning (Mullen, 1995). These children were seen as part of the Infant Brain Imaging Study; a multi-site longitudinal study of brain and cognitive development in infants at risk for ASD. Parents completed the MacArthur-Bates Communicative Development Inventory – Words and Sentences questionnaire (Bates et al., 2007). All children were administered the ADOS-G (DiLavore, Lord, Risi & Rutter, 1999).

Results: Consistent with Lopez and Lord’s (2009) finding that expressive verb vocabulary is affected by social affect, linear regressions run separately for each group revealed an effect of reciprocal social interaction scores on verb vocabulary size after controlling for non-verbal cognitive ability in the ASD group (p<.05), but not the sibling group (all ps=n.s.). Our hypothesis that words labeling non-dynamic relations would also be sensitive to social skills was likewise confirmed, as reciprocal social interaction scores predicted preposition vocabulary in the ASD group only (p<.05) after controlling for non-verbal cognitive ability.

Conclusions: Social understanding has been linked to verb development in ASD (Lopez & Lord, 2009), and the present research extends this finding in an important way: rather than arguing that social understanding in children with ASD is important for any particular word class, our findings suggest that social cues are crucial to acquiring relational words in general, including spatial terms. Data for this study continues to be collected, and future analyses will include participants who are not at genetic risk of developing ASD, thus creating a three-group design.