It’s no big surprise that young children first learn language by listening to adults talk to them. Nor is it a surprise that reading aloud to kids is important to their success, both in school and work. What might be a bit more surprising: Picture books have, on average, around 70 percent more unique words than conversations directed at kids, according to a new study, suggesting that reading to kids could help improve their vocabularies.
“A large literature indicates that talk directed to the child—rather than adult-adult or background talk—is the core data on which early language learning depends,” Indiana University psychologists Jessica Montag, Michael Jones, and Linda Smith write in Psychological Science, and research on early language learning has focused much attention on conversations between parents and children. At the same time, a few studies have shown a link between parents reading to their children and early vocabulary learning, though no one seems to have investigated exactly why that is.
Across the entire sample, there were 1.72 times as many unique words in picture books than in conversations.
Turns out, there are just a lot of unique words in picture books. Montag, Jones, and Smith discovered that fact first by building a database of 100 picture books, including everything from Judith Viorst’s Alexander and the Terrible, Horrible, No Good, Very Bad Day to Laura Ingalls Wilder’s Winter Days in the Big Woods, for a total of 68,103 words. The researchers’ idea was to compare that to a body of transcribed conversations between parents and children aged zero to five from the Child Language Data Exchange System, known as CHILDES, to see how the vocabularies compared. Because the number of unique words typically increases with the length of a book or conversation, Montag, Jones, and Smith drew random samples from CHILDES conversations to match the lengths of each of the 100 picture books.
Across the entire sample, there were 1.72 times as many unique words in picture books than in conversations. Part of picture books’ greater diversity, the authors note, stems from the fact that each one tells a different story about a different topic. That is, Are You My Mother?, P.D. Eastman’s classic tale of a hatchling bird searching for his mother, isn’t likely to use quite the same words as Oh, the Places You’ll Go (and not just because Dr. Seuss was fond of a nonsensical vocabulary). While individual books had relatively smaller vocabularies, a typical book still contained more unique words than a conversation of equal length.
“Unlike conversations, books are not limited by here-and-now constraints; each book may be different from others in topic or content, opening new domains for discovery and bringing new words into play,” the team writes, though “the primary reason that book reading to infants results in a greater diversity of words … appears to be that different books sample the words in the language more broadly than do different conversations.” In other words, reading the same book over and over isn’t enough.
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