Associations between the Home Language Environment, Maternal Education, and Naturalistic Response to Joint Attention in Infants at High and Low Familial Risk for ASD
Responding to joint attention (RJA), or the ability to respond to cues from another to share attention to an object, is a pivotal socio-cognitive milestone in infancy. RJA abilities are associated with social and language outcomes later in childhood (e.g., Morales et al., 2000). Moreover, early deficits in RJA are a hallmark of autism spectrum disorder (ASD; Mundy et al., 1986).
Some studies have found that specific caregiver behaviors such as attention-directing styles (Tomasello & Farrar, 1986), persisting tendencies (Saxon & Reilly, 1999), and sensitivity (Hobson et al., 2004) are associated with RJA. However, little is known about the impact of more global aspects of the home environment, like the amount of caregiver speech. Furthermore, despite associations between RJA and language outcomes, it is unclear whether the home environment contributes to both abilities early in development.
To begin to fill these gaps, the current study investigated associations between two aspects of the home environment, language exposure and conversational turns, and RJA in infants at high (HR) and low (LR) risk for ASD. We hypothesized that both language exposure and conversational turns would positively predict RJA for all infants.
We measured RJA using the Dimensional Joint Attention Assessment (DJAA; Elison et al., 2013). This measure characterizes individual differences in infants’ RJA abilities using 4 series of hierarchically ordered joint attention bids varying in cue redundancy. Higher DJAA scores (range 0-4) reflect the ability to respond to subtler, less redundant bids (i.e., gaze shift and head turn cues, vs. gaze shift, head turn, and verbal cue) for joint attention. The DJAA was administered during naturalistic play at 58 assessments of 12- to 15-month-old infants (N=52; 29 HR, 23 LR).
The home language environment was measured at age 15 months using small language recorders worn by the infants in their homes. Adult word counts (AWC) and conversational turn counts (CTC) were quantified using automatic voice detection software and natural log transformed for analyses.
Results: Table 1 contains descriptive statistics. Regression analyses indicated a positive relationship between AWC and mean DJAA scores (t(42)=2.86, p=0.006). Additionally, infants of college-educated mothers received higher DJAA scores than infants whose mothers were not college educated (t(42)=2.01, p=0.051). Lastly, a significant interaction suggested that the relationship between AWC and DJAA scores was strongest for infants of non-college-educated mothers (t(42)=-2.01, p=0.050; Figure 1). Average CTC did not predict mean DJAA scores, and none of these measures differed by ASD risk.
Conclusions: Preliminary results suggest that characteristics of the home environment may relate to RJA. While the number of infant-caregiver conversational turns had no influence, more adult words heard in the home was associated with greater RJA sophistication, particularly for infants whose mothers did not have a college degree. These findings suggest that the influence of more global environmental features may vary by family socio-economic status, acknowledging that shared genetic factors may shape aspects of the home environment. Future work seeks to replicate these findings and examine some of the more proximal factors driving our results.