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Thirty Million Words Aren't Enough

Quality and quantity matter for low-income kids' language skills, researchers say.
(Photo: Dylan Cantwell/Flickr)

(Photo: Dylan Cantwell/Flickr)

Thirty million words. That's the gap between what kids from high- and low-income families hear by the time they're three, and it's widely thought to explain socioeconomic disparities in language skills and, later on, academic success. But a recent study puts an age-old twist on that: Quality may matter more than quantity.

There's a lot riding on the idea that learning a language is primarily a matter of quantity. Language proficiency is perhaps the most important factor in predicting a kid's future success in school, and many argue the sheer quantity of speech a child hears growing up is the best predictor of language proficiency. As developmental psychologists Betty Hart and Todd Risley wrote in 2002, "the most important aspect to evaluate in childcare settings for very young children is the amount of talk actually going on, moment by moment, between children and their caregivers."

Meanwhile, there's an enormous gap in the amount of talk in low-income versus middle- and upper-income households, something that's been confirmed in a number of subsequent studies. That research inspired several initiatives aimed simply at increasing the amount of time parents talk with their kids.

"With the right scaffolds, low-income toddlers can and do become successful language learners."

"Yet the quantity of language input is insufficient to account for variations in language development," argues a team of psychologists led by Kathy Hirsh-Pasek. Both quantity and quality affect kids' language skills, the team writes in Psychological Science, and "[b]etween the two, quality, measured in part as diversity and complexity of words and grammar, might be the more potent predictor."

To test their theory, Hirsh-Pasek and her colleagues analyzed 60 videos of mothers talking with their two-month-old kids, collected as part of a National Institute of Child Health and Human Health project. In those interactions, the researchers looked for signs of quality communication, including mutual engagement in play, fluent and connected speech, and routines (think: taking turns with a toy). They also tracked how many words mothers spoke per minute, and followed up a year later to assess kids' speaking skills—what's called expressive language—using a standard scoring system.

Expressive language skills, the team found, had more to do with the quality of communication between parent and child than sheer quantity. While the quantity of mothers' speech seemed to underly some of the differences in expressive language between kids, communication quality explained much more. What's more, whatever explanatory power quantity seemed to have on its own, it essentially vanished when the team first controlled for quality, and then considered quantity’s effects.

"Hearing a sufficient number of words ... [is] indisputably important to language success. However, focusing primarily on word quantity neglects how words are integrated into early caregiver-child interactions," Hirsh-Pasek and her team write, noting that extending this and other studies of quality communication will help researchers better understand language development. "With the right scaffolds, low-income toddlers can and do become successful language learners," they write.

Quick Studies is an award-winning series that sheds light on new research and discoveries that change the way we look at the world.