Naturalistic Language Recordings Reveal "Hypervocal" Infants at High Familial Risk for Autism

Abstract

Children's early language environments are related to later development. Little is known about this association in siblings of children with autism spectrum disorder (ASD), who often experience language delays or have ASD. Fifty-nine 9-month-old infants at high or low familial risk for ASD contributed full-day in-home language recordings. High-risk infants produced more vocalizations than low-risk peers; conversational turns and adult words did not differ by group. Vocalization differences were driven by a subgroup of "hypervocal" infants. Despite more vocalizations overall, these infants engaged in less social babbling during a standardized clinic assessment, and they experienced fewer conversational turns relative to their rate of vocalizations. Two ways in which these individual and environmental differences may relate to subsequent development are discussed.

Figure 1

Panel A, significant group differences in 9-month infant vocalizations. Panel B, adult word count by risk status. Panel C, conversational turn count by risk status. Red diamonds indicate Hyper-Vocal group. High-Risk-Average-Vocal infants are indicated with blue dots, Low-Risk-Average-Vocal infants with green triangles.

Figure 2

Vocalization group differences on AOSI social babbling scores. Higher AOSI social babbling scores indicate less social babbling directed to the examiner. * p < .001, + p < .05