This article originally appeared on Usable Knowledge from the Harvard Graduate School of Education.
To help your baby develop a large vocabulary — to give her the tools she’ll need to read, comprehend, and make sense of the world — it’s not just talk that’s important. It’s conversation.
To be sure, parental talk of any kind is a good thing; the number of words that a child hears in infancy and toddlerhood is strongly predictive of future vocabulary growth. (Educators and policymakers have tuned in, launching initiatives that encourage parents to spend more time talking with their babies.)
But for Associate Professor Meredith Rowe, an educational psychologist at the Harvard Graduate School of Education, the amount of words a child hears is just one factor, and not the most significant, in predicting future vocabulary growth.
In an important 2012 paper and in follow-on research published just this year, Rowe found that diversity of words is more predictive of future language skills, especially as a baby grows through toddlerhood. And it’s not just using a wide assortment of words that’s important — it’s using complex words, interactive words, and words to tell stories, explain, and imagine.
We asked Rowe to share some takeaways.
It seems pretty well established that the quantity of parental words influences children’s rate of vocabulary growth. What was your interest in moving the conversation beyond quantity to look at quality?
We’ve known for a while that the quantity of input matters. I think the shift to a focus on quality rather than quantity was a natural next step in the field. Many researchers, including myself, got to a point where we wanted to know more about the mechanisms underlying language learning. Knowing that quantity of input matters is a start, but knowing more about which types of input are most useful at different ages is more informative about how children grow their vocabularies. And I think pitting the quantity and quality against each other is an important step in the conversation, and what I was trying to accomplish in that 2012 paper in Child Development. It is much easier to send a message about quantity, but if we know that quality trumps quantity, statistically, then perhaps we can really try and change the message to be more about having high-quality conversations with children rather than just “talking a lot.”
Tell us about the kinds of “quality” talk you say you’re most interested in — the use of rare words and decontextualized words.
I’m actually interested in a really wide range of what we call input quality measures, and I think one of the biggest challenges for the field is to pinpoint the specific features of input that are most beneficial for children’s language learning at different points in early childhood. Some of my work has focused on the importance of non-verbal input, specifically pointing a lot and at a lot of different things while you talk with your young children (ages 9 through 18 months).
Then, some of the work I’ve done looking at input to toddlers and preschoolers has built off of [Professor] Catherine Snow’s previous research with the Home School Study of Language and Literacy Development to show that using rare or sophisticated vocabulary words and using talk that is abstract or beyond the here and now is very helpful at these ages.
Can you give us an example of the “rare” and the “abstract”?
Often these things go hand-in-hand. So a parent might have a conversation with a three-year-old about their recent trip to the children’s museum, and they might reminisce about how much fun they had putting balls through a chute and trying to line them up at the right angle so that it worked properly. This could lead to a discussion about gravity or many other related topics. [Ed: Italics signify rare words, within the context of a “beyond-the-here-and-now” conversation.]
In that 2012 paper and in the paper that just came out in Developmental Psychology, we found that this type of decontextualized talk about the non-present predicted not only vocabulary but also children’s syntax and narrative development. And this particular type of talk with children in the toddler/preschool age range was more predictive of child language outcomes than the quantity of talk or other types of talk, and it wiped out the effect of quantity in the statistical models.
You looked at parental input in a diverse group of 50 caregiver-child pairs, assessing data collected when the child was 18 months, 30 months, and 42 months of age. Did you find wide variance?
Parents varied widely in the quantity and quality of words they spoke to their children. For example, in a 90-minute interaction, the number of words that parents spoke to their children at 18 months ranged from 360 to over 9,200. Similarly, at 30 months, some parents did not produce any narrative utterances, whereas others produced over 250.
What factors add to the variance?
Primary caregiver education is positively related to both quantity and quality measures. On average, more highly educated parents use more words and more diverse vocabulary at each child age than less educated parents.
But there were some areas where we did not see average social class differences in input. For example, with that beneficial narrative talk about the trip to the museum, the more educated parents did not use it more, on average, than the less educated parents.
I think this is important. Different parents communicate with their children in different ways. Our goal is to inform parents and caregivers of the types of input that are most beneficial for young children’s language development. If parents are already communicating in these helpful ways, then it will be easier for them to continue to do so.
As you look at the body of work you’ve done so far, what are the broad takeaways for parents and early educators?
In a broad sense, our findings show that parents can scaffold their children’s vocabulary growth at different points in their development by providing them with exposure to different types of communication. The results suggest that beyond the quantity of their talk, parents should focus on the quality:
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