Solving the “thirty-million-word gap” is not as simple as pouring more language into a child’s ears until she catches up with her peers. New research from a team at MIT points to “conversational turns”—defined as an adult utterance followed by a child utterance, or vice versa, with no more than a five-second pause between the two—as the best predictor of scores on standardized tests of vocabulary, grammar, and verbal reasoning. These findings were independent of parental education levels, socioeconomic status (SES), and the amount of language to which children were exposed in the home. The senior researcher on the team described conversational turns as “almost magical” in their ability to build language competence in children.
The study involved thirty-six children between the ages of four and six and their parents. All were native English speakers, and the children were typically developing, with no history of premature birth, neurological disorders, developmental delay, speech/language therapy, or grade repetition. All participants passed a pre-test hearing screening. The children participated in a functional MRI task (fMRI) that monitored neural activity in Broca’s area, the part of the brain most associated with language production and processing. The task involved passively listening to short, simple stories geared to their age and with incidents deemed familiar to most children (e.g., playing games, getting hurt, etc.). Children completed standardized behavioral assessments to characterize verbal and nonverbal cognitive skills. Each family was also given a recording device—worn on the child’s clothing—that recorded up to sixteen hours of audio from the child’s perspective. The recordings were processed to determine the total number of adult words spoken, the total number of child utterances, and the total number of adult-child “conversational turns.”
As other research has shown, higher parental education and SES are significantly correlated with more language exposure for children—both in number of adult words heard and more conversational turns experienced. But socioeconomic status only explained a moderate share of the differences in language exposure, indicating that there was wide variability within families of similar SES. When looking at the adjusted assessment scores, conversational turns came to the fore as the strongest predictive variable. And fMRI results on the children’s passive listening test reinforced the test score analysis. The more conversational turns a child experienced, the greater the activation in Broca’s area during language processing, independent of the child’s SES, cognitive ability, or sheer numbers of adult words and child utterances. The neural pattern observed explained 48 percent of the relation between children’s conversational turns and their verbal scores.
The researchers connect their findings with prior research on younger children showing similar importance of qualitative aspects of children’s language experiences over sheer quantity of language experienced, with the additional support of test scores and neural imaging data. They speculate on the value of context and feedback during the turn-taking process in bolstering language processing and word understanding.
Limitations to the study relate to the exclusion of all but typically-developing children, a lack of detail on the nature of the conversational turns taken (sense versus nonsense, proper English versus “baby talk,” etc.), and a concern that low SES and language “deprivation” might have registered among potential subjects as having a non-typical development. However, these findings seem to be an important addition to the research into how language is processed in the developing brain. If the suspected external elements of the word gap, such as family socioeconomic status and parental education level, can be mitigated or corrected as this research suggests, we ought to strongly encourage parents to have more conversations with their kids. Further research should attempt to account for the limitations noted here and to drill further into the mechanism by which the most meaningful language processing occurs.
SOURCE: Rachel R. Romeo, et al, “Beyond the 30-Million-Word Gap: Children’s Conversational Exposure Is Associated With Language-Related Brain Function,” Psychological Science (February 2018).
