Summary: Certain types of interactions between parents and babies result in greater infant vocabulary.
Analysis of recordings from infants’ homes reveals that certain types of vocal interactions between adults and infants are associated with a larger infant vocabulary. Lukas Lopez of University of California, Merced, and colleagues present these findings in the open-access journal PLOS ONE on November 25.
Previous research has shown that, in the home, one-on-one vocal interactions with caregivers who engage in infant-directed speech promotes infants’ vocabulary development. Laboratory studies suggest that different types of infant vocalizations and caregiver responses may have different effects on vocabulary, but few investigations have attempted to translate these findings to a realistic in-home setting.
To address this knowledge gap, Lopez and colleagues closely analyzed portions of day-long audio recordings from the homes of 53 13-month-old infants. The recordings were captured by wearable LENA recording devices, which are widely used to measure vocal interactions with children. The researchers also asked the infants’ caregivers to report the size of their vocabulary.
Statistical analysis revealed relationships between vocabulary size and different types of interactions captured in the recordings. Most notably, infants tended to have a larger vocabulary if they produced a greater number of speech-like babbling sounds and, in return, received a greater amount of adult responses that incorporated sounds similar to their babbling. The authors speculate this may be because adults find it easier to respond meaningfully to babbling that sounds closer to real words; adult imitation of infant babbling (with reuse and expansion into whole sentences on the part of the adult) may also help infants develop a larger vocabulary.
These new findings are in line with earlier findings from similar studies performed in laboratory settings, and might help inform development of new strategies to assist children who struggle with vocabulary development.
Future investigations could expand on this study by incorporating measures of vocabulary that do not rely on caregiver reports, or by following children over time to observe the long-term impact of different types of vocal interactions.
The authors add: “Over merely talking to your infant, we found that parents who respond to their infants’ babbles with word and sentence corrections have infants who say more words.”
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Source:PLOS Contact: Lukas Lopez – PLOS Image: The image is in the public domain
Adult responses to infant prelinguistic vocalizations are associated with infant vocabulary: A home observation study
This study used LENA recording devices to capture infants’ home language environments and examine how qualitative differences in adult responding to infant vocalizations related to infant vocabulary. Infant-directed speech and infant vocalizations were coded in samples taken from daylong home audio recordings of 13-month-old infants. Infant speech-related vocalizations were identified and coded as either canonical or non-canonical. Infant-directed adult speech was identified and classified into different pragmatic types. Multiple regressions examined the relation between adult responsiveness, imitating, recasting, and expanding and infant canonical and non-canonical vocalizations with caregiver-reported infant receptive and productive vocabulary. An interaction between adult like-sound responding (i.e., the total number of imitations, recasts, and expansions) and infant canonical vocalizations indicated that infants who produced more canonical vocalizations and received more adult like-sound responses had higher productive vocabularies. When sequences were analyzed, infant canonical vocalizations that preceded and followed adult recasts and expansions were positively associated with infant productive vocabulary. These findings provide insights into how infant-adult vocal exchanges are related to early vocabulary development.