Parental Verbal Responsiveness during Prelinguistic Vocal Development: Variability and Association with Language Outcomes

The current study explored infants’ prelinguistic vocalizations with mothers and fathers, in addition to how parents responded to infants’ vocalizations. In particular, we were interested in determining if mothers and fathers differed in their level of responsivity, or in specific types of responses. In addition, we examined the relation between parents’ responsiveness and language development. To test this, we observed seven infants once per month from age 8-12 months with their mothers and fathers separately during free play to compare parental verbal and behavioral responses to infants’ vocalizations. The main findings of this study are that: 1) infants did not differ in their vocal production when playing with mothers and fathers; 2) mothers and fathers did not differ in overall responsiveness or responsiveness to vowel-like (V) or consonant-vowel (CV) vocalizations. Interestingly, we found that parents tended to respond to proportionally more V vocalizations than CV vocalizations, and previous studies have found no differences in responses to V vs. CV vocalizations. Importantly, both mothers and fathers produced sensitive responses significantly more than redirective responses. This means that parents are more likely to respond to their infant’s vocalizations semantically and verbally rather than semantically behaviorally. Given that parents’ most frequent responses were sensitive vocal responses, we classified mothers’ and father’s responses as ten specific speech acts. Overall, the most frequent speech acts by parents were questioning, naming, imitating and descriptives, whereas the least frequent speech acts by parents were prohibiting, exclamation, and affirmation. However, parents varied slightly depending on whether infants produced V or CV vocalizations. Play vocalizations were more frequent than prohibitions, affirmations, and exclamations when parents responded to V vocalizations, whereas when parents responded to CV vocalizations, imitations and questions were most frequent responses. In addition, parents imitated CV more than V vocalizations. A novel aspect of our study is that we not only examined maternal responsiveness but also paternal responsiveness to compare mothers and fathers and to investigate fathers’ impact on infants’ language growth. Fathers were similar to mothers in their production of sensitive verbal and behavioral responses; however, there was a trend that fathers produced fewer specific speech acts compared to mothers. Further studies are required to investigate how specific speech acts specifically relate to infants’ language outcomes.