study by Betty Hart and Todd Risley showed this most starkly.Hart and Risley had been studying early education for many years, even before Head Start was created. No matter how many creative ways they developed to bolster language in their programs, they were perplexed by the persistent difference in vocabulary growth between middle-class children and poorer children. Field trips, directed experiences, and discussions, all of it was ineffective.
âWe began to ask what went on before we ever saw these children, because they started in preschool at age four,â Risley once explained in an interview. A little basic math revealed that if children were in preschool for a total of sixteen hours from Monday to Friday, they were awake for at least another sixty to seventy hours in a week. That begged the question of what happened at home. Hart and Risley decided to look at âwhatâs going on in children before we ever see them in preschool, before theyâre four, while theyâre learning to talk,â as Risley put it. Over two and a half years, beginning when the children were nine months old, they sent observers into forty-two families in Kansas City for one hour every month to record every word that was said between parent and child. The families represented the entire socioeconomic spectrum from white-collar educated professionals through to parents on welfare.
What they found was so surprising Risley called it a âdiscovery,â not just a result. They had expected that the content of the language was most important. Instead, the most significant and fundamental factor was a massive difference in the amount of talking, the sheer volume of words that some children heard compared to others. The children of educated professional parents tended to hear as many as 2,100 words per hour. Those with uneducated parents on welfare heard 600. The average child heard 1,500 words an hour. Extrapolating those numbers to a yearâs worth of listening, Hart and Risley calculated that children with the most talkative parents had heard forty-eight million words by the time they were four. Those at the other end of the spectrum had heard a fraction of that, only thirteen million wordsâa gap of thirty-five million words.
Secondly, Hart and Risley did find what they expected: There were qualitative differences in the language the children heard, and those did matter. All parents used a certain amount of similar baseline vocabulary to instruct and inform children: âStop that,â âHold out your hands,â etc. Subtracting that kind of talk, which Risley calls âthe business languageâ of parenthood, left very little conversation in the quietest homes. But talkative parents engaged in what Risley called âlanguage dancing.â âThe talkative parents are taking extra turns, responding to what the child just said and did, and elaborating on it, caring.â
Together, the amount of words and the quality of the âextra talkâ had a direct, strong effect on the child. By the time they were three, children who had heard more words and more interesting talk had higher IQs and larger vocabularies. When Hart and Risley tested the children again at nine, the effect was still clear: The difference in early language exposure accounted for differences in vocabulary size and IQ. In fact, early language exposure canceled out socioeconomics or race. In the cases where a poorer parent talked a lot to a child, the child did fine; and if a professional parent did not talk to a child, the child struggled. As the children moved through elementary school, the differences had academic repercussions.
Clearly, experience matters. Even today, psychologists and linguists continue to recalibrate their assessment of the balance of power between what is innate in language and what is learned. There isa lively, ongoing debate, for instance, on whether itâs the ability to use language specifically