Few numbers in education are as famous as the “30 million word gap”. It has shaped policy, school programs and parenting advice. But where did it come from, and does it still hold up?
Where the number came from
In the 1980s, researchers Betty Hart and Todd Risley recorded talk at home in 42 families once a month for about two and a half years, starting when the children were babies. They found big differences in how much the children were spoken to. Extrapolating to all of a child’s waking hours, their 1995 book estimated a gap of about 30 million words heard by age 3 between children in the most and least talkative homes.
What later studies found
- Smaller in a bigger sample: a 2017 study using LENA all-day recorders with 329 families found a gap of about 4 million words by age 4. Only the extremes (the most talkative 2% of families compared with the quietest 2%) came close to Hart and Risley’s figure.
- Communities differ: other researchers recorded children in several working-class and low-income communities and found the amount of talk varied widely from place to place, and was often much higher than the original study suggested.
- Small original sample: critics point out that the headline figure rested on a small number of families.
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Conversation beats word counts
In 2018, Rachel Romeo and colleagues at MIT recorded 36 children aged 4 to 6 for two days and scanned their brains while they listened to stories. The number of conversational turns (a child says something, an adult responds, or the other way round) was linked with stronger activity in Broca’s area and with better language scores, more than the total number of adult words. Lead author Rachel Romeo described turns as a measure of engagement.
What to do with this
- Talk with your child: narrate, ask, wait, respond.
- Read books together and chat about them. Books add words that everyday talk rarely uses (see why picture books build big vocabularies).
- Don’t worry about counting. Warm, back-and-forth moments are what the research points to.
Sources
- Hart, B. & Risley, T. R. (1995). Meaningful Differences in the Everyday Experience of Young American Children. Paul H. Brookes
- Gilkerson, J. et al. (2017). Mapping the early language environment using all-day recordings. American Journal of Speech-Language Pathology
- Shanahan on Literacy: Is there really a 30 million-word gap?
- NPR (2018): Let’s stop talking about the 30 million word gap
- MIT News (2018): Back-and-forth exchanges boost children’s brain response to language
Turn screen time into story time: free books and audiobooks to talk about together.