The promise of preschool

Once upon a time there were 123 poor, African-American children living in a Michigan town called Ypsilanti.

When they were just 3 and 4 years old, some grown-ups divided them into two groups: one would go to a super-duper preschool, and one would not. Then, beginning in the 1960s, the grown-ups checked in on the children, year after year for decades.

They found that the children who went to preschool lived much more happily ever after than the others. They were much less likely to get arrested for drug-dealing, much more likely to graduate from high school, earn good money, and own their homes. The preschool girls were five times as likely to be married at age 27 as the no-preschool girls.

That, in brief, is the tale of a landmark research project called The High/Scope Perry Preschool Study. But the story of preschools does not end there.

Although support for preschool has been mounting in both brain and social science, the broader questions are not quite as simple to answer. Should your child go to one? Should you help pay for everyone's child to go?

These questions are coming to the fore in Massachusetts. Thomas M. Finneran, the powerful speaker of the House of Representatives, is pushing the idea of universal preschool. He has appointed a special task force to examine early childhood education, and its hearings have begun, including one scheduled for tomorrow at the Morse School in Cambridge. Strategies for Children, a Boston nonprofit that backs the idea, has estimated that universal early education would ultimately cost about $1 billion a year.

Several states have approved the concept, including Georgia and Oklahoma, and last month, Los Angeles County approved its own $100-million-a-year plan to expand public preschool for 4-year-olds, using money from cigarette taxes.

Most social science researchers agree that, as the Ypsilanti experience showed, intensive, high-quality preschool offers significant benefits for poor children. For many, that is reason enough to support public preschool.

But beyond that, researchers say, the science gets a bit murkier. If the children are middle class, or the preschool is not so fabulous, the impact is less clear-cut.

For example, a recent study of Oklahoma's statewide program to provide preschool for 4-year-olds found large benefits for children poor enough to qualify for a subsidized or free school lunch, and almost none for children who could afford to pay full price.

It also found that among Hispanic children, test scores a year after enrolling in the preschool improved by 54 percent; black children improved their test scores by 17 percent; but white children's scores were not different enough to be statistically significant, though the researchers noted that the tests may not have been sophisticated enough to pick up changes in already "high-performing white students."

Most of the benchmark studies -- including the Perry Preschool and another classic, gold-standard study called the Carolina Abecedarian Project -- have included only poor children. W. Steven Barnett, director of the National Institute for Early Education Research, a New Jersey think tank, said that while the research does show greater preschool benefits for poor children, studies indicate that better-off children benefit as well. "There is no sharp cut-off," he said.

Much of the social science research on the effects of preschool is plagued by methodology problems.

The problem with the research, said David Blau, a professor of economics at the University of North Carolina and author of "The Child Care Problem," is that it focuses on very high-cost, high-quality programs unlikely to be duplicated in a broad public system. "What we don't know," he said, "is whether, if you scale it down, you get proportionally smaller but similar kinds of benefits. If you cut the costs in half, do you get half the benefits? Or is there some threshold before you get benefits?"

There are also naysayers who question the Perry Preschool results as well as the weaker research on children from higher-income families.

The Cato Institute, a libertarian think tank in Washington, D.C., published a sort of manifesto against universal preschool in 1999, titled "Universal Preschool is No Golden Ticket," arguing that even among poor children, "benefits to the children have been few and fleeting."

Among other things, it emphasized that some studies of Head Start, the federally subsidized program for hundreds of thousands of poor children, have indicated that the program's benefits do not seem to last into later years the way the Perry Preschool's did.

But the mainstream viewpoint sounds more like Dr. Jack Shonkoff, dean of Brandeis University's Heller School, who oversaw an important National Academy of Sciences report on early childhood development, published in 2000.

The push for preschool, Shonkoff said, can be traced to two growing bodies of research: social science like the Perry study, and the science of brain development.

Neuroscience has shown in recent years how "early experience influences the emerging architecture of the brain," he said. So the brains of poor children may be at a disadvantage from the get-go because of poor nutrition, toxins, and family stress.

While the brain science work shores up the idea that early education is important, it has been conducted mainly on animals. Scientists caution against trying to apply these theories too directly to humans at this point.

From the social science, Shonkoff added, "It's crystal clear that if universal education makes sense, it should start earlier than age 5. The preschool years are foundational, and if we're interested in promoting learning, it makes no sense to jump in when the train had already left the station for a couple of years."

These days, more and better research is underway about preschool. Improved studies of the Head Start program are in progress, and so is a massive study run by the National Institute on Child Health and Development that has been following about 1,000 children since 1989.

Kathleen McCartney, a professor at Harvard's Graduate School of Education, is part of the network of researchers on that study; she has also testified in favor of the preschool proposal in the Massachusetts Legislature.

For her, she said, the bottom line is that "We do know that there are already gaps between the haves and the have-nots in kindergarten, and that suggests we need to start earlier."

Meanwhile, the Perry Preschool Study continues, with work underway on follow-up interviews done with the participants at age 40. Findings are expected to be published this summer.

"With any luck," said Barnett of the National Institute for Early Education Research, "we'll find they're better able to pay for a nursing home."

Carey Goldberg is reachable at goldberg@globe.com.