Maternal Responses to Vocal Bids of Infants at High Versus Low Risk for Autism

Background: Maternal responsiveness to infant vocal behavior is associated with language development (Tamis-LeMonda, Bornstein, & Baumwell, 2001). In addition, research suggests that maternal responses to infants’ vocalizations vary based on developmental status (e.g., vocalizations vs. words; Gros-Louis, West, Goldstein, & King, 2006).  While relations between caregiver input and infant communication development have been well-documented in typically-developing infants, relatively little is known about caregivers’ responses to children at-risk for autism. By examining the communicative relationship between mothers and their infants at high-risk (HR infants: later-born sibling of child with autism), we may be able to identify consistent patterns of maternal responsiveness that play a role in the process of language acquisition. 

Objectives: To examine how mothers of HR infants and mothers of low-risk infants (LR infants: later-born siblings of typically-developing children) respond to their 18 month-old infants’ vocalizations and words.

Methods: 12 HR (5 males) and 13 LR (6 males) infants and their mothers (HR mothers, LR mothers) were filmed at home for 45 minutes. The visit consisted of 15 minutes of naturalistic observation, 15 minutes of semi-structured toy play, and 15 additional minutes of naturalistic observation. For the purposes of this study, only spontaneous vocal communication produced by the infant that was directed toward the mother was coded (e.g., child made eye contact with mother while vocalizing).  Infant vocal productions were then classified as either non-word vocalizations (i.e., vowel strings, reduplicated and variegated babbling) or words (i.e., actual English words or word approximations). Maternal responses produced at any time following the onset and within two seconds of the offset of the infant’s bids were coded (Gros-Louis et al, 2006). 

Results: HR mothers showed lower responsiveness to infant vocalization (M = .591, SD = .083) as compared to LR mothers (M = .839, SD = .076), but the groups did not differ in their responsiveness to words (M = .742, SD = .062; M = .768, SD = .057, respectively).  This was reflected in a significant interaction (F = 4.55, p = .044) between infant risk status (HR vs. LR) and type of infant vocal communication (non-word vocalization vs. word) illustrating that HR mothers responded differently to non-word vocalizations than to words, while mothers of LR infants did not.

Conclusions: The finding of an interaction effect suggests that the HR mothers’ rates of responsivity vary according to the quality of their infant’s vocal communication more so than for LR mothers. HR mothers may be more focused on their infants’ developmentally-advanced vocalizations (words) at the expense of less developmentally-advanced vocalizations whereas the LR mothers respond to all infant vocal bids at a similar rate.  Future studies might include longitudinal observations from a younger age and develop measures that explore the developmental impact of variation in caregiver responses on communicative development of infants at-risk for autism.