NEW YORK — Betty Hart, whose research documenting how poor, working-class, and professional parents speak to their young children helped establish the critical role that communicating with babies and toddlers has in their later development, died Sept. 28 in Tucson. She was 85.
The cause was lung cancer, said Dale Walker, a colleague and longtime friend.
Dr. Hart was a graduate student at the University of Kansas in the 1960s when she began trying to help poor preschool children overcome speech and vocabulary deficits. But she and her colleagues later concluded that they had started too late in the children’s lives — that the ones they were trying to help could not simply ‘‘catch up’’ with extra intervention.
At the time, a prevalent view was that poor children were essentially beyond help, victims of circumstances and genetics. But Dr. Hart and some of her colleagues suspected otherwise and revisited the issue in the early 1980s, beginning research that would continue for a decade.
‘‘Rather than concede to the unmalleable forces of heredity, we decided that we would undertake research that would allow us to understand the disparate developmental trajectories we saw,’’ she and her former graduate supervisor, Todd R. Risley, wrote in 1995 in ‘‘Meaningful Differences in the Everyday Experience of Young American Children,’’ a book about their findings, which were reported in 1992.
They began a 2½-year study of 42 families of various socioeconomic levels who had very young children. Starting when the children were between 7 and 9 months old, they recorded every word and utterance spoken to them and by them, as well as every parent-child interaction, over the course of one hour every month.
It took many more years to transcribe and analyze the data, and the researchers were astonished by what they eventually found.
“Simply in words heard, the average child on welfare was having half as much experience per hour (616 words per hour) as the average working-class child (1,251 words per hour) and less than one-third that of the average child in a professional family (2,153 words per hour),’’ Hart and Risley wrote.
‘’By age 4, the average child in a welfare family might have 13 million fewer words of cumulative experience than the average child in a working-class family,’’ they added.
They also found disparities in tone, in positive and negative feedback, and in other areas — and that the disparities in speech and vocabulary acquisition persisted into school years and affected overall educational development.
“People kept thinking, ‘Oh, we can catch kids up later,’ and her big message was to start young and make sure the environment for young children is really rich in language,’’ said Walker, an associate research professor at Kansas who worked with Hart and followed many of the children into their school years.
The work has become a touchstone in debates over education policy, including what kind of investments governments should make in early intervention programs. One nonprofit program whose goals are rooted in the findings is Reach Out and Read, which uses pediatric exam rooms to promote literacy for lower-income children beginning at 6 months old.
‘‘Today, much of her research is being applied in many different ways,’’ said Dr. Andrew Garner, the chairman of a work group on early brain and child development for the American Academy of Pediatrics. ‘‘I think you could also argue that the current interest in brain development and epigenetics reinforces at almost a molecular level what she had identified 20 years ago.’’