Family income is a “far more powerful’’ determinant of I.Q. at age 5 than whether a child lives with a single parent or how well educated the mother is, a new study suggests.
The study, led by Greg J. Duncan, the director of the Survey Research Center at the University of Michigan, found that among a sample of 900 children who were born at low birthweight, those who lived in “persistent poverty’’ for their first five years had I.Q.'s 9.1 points lower than those who were not poor during that time.
The children in persistent poverty also scored 4 points worse than the never-poor children on a scale measuring behavior problems linked with fearfulness, anxiousness, and depression, and 3.3 points worse on one measuring problems linked with aggression and temper tantrums. But the behavior problems were linked with family structure as well as income.
The findings are based on longitudinal data from the Infant Health and Development Program, an eight-site study launched in the 1980’s. That study was designed to gauge the effectiveness of a set of educational, family-support, and health interventions in stemming the incidence of developmental delay in low-birthweight babies.
While poverty has long been linked with a host of adverse outcomes for children, Mr. Duncan said, what distinguishes his study from others is its attempt to “tease out’’ income’s relative effect compared with other social factors.
The analysis, which Mr. Duncan presented in New Orleans last month at a meeting of the Society for Research in Child Development, states that “family income is a far more powerful correlate of age-5 I.Q. than more conventional [socioeconomic] measures such as maternal education, ethnicity, and female headship.’'
“There is little doubt that child poverty, which is much higher in the United States than in other Western countries, as well as higher now than two decades ago, is scarring the development of our nation’s children,’' the paper concludes.
Weighing Income, Values
The study is “consistent with an enormous and growing body of knowledge about the harm poverty does to children,’' Arloc Sherman, a program associate with the Children’s Defense Fund, said last week.
The data, which also square with other studies showing that “poverty matters’’ for families regardless of their structure, education, or race, “should motivate everyone who cares about children and this country’s educational future to look again at the problems of inadequate family income,’' he said.
Mary Larner, the director of the early-childhood program at the National Center for Children in Poverty, suggested the data could help steer public debate over the consequences of single-parenting away from a “blame-the-victim mentality.’'
Robert Rector, a senior policy analyst for family issues with the Heritage Foundation, disputed the study’s conclusions, however. Arguing that poverty alone is a poor predictor of intelligence, he said that an increase in family income since the 1920’s--when more than half the population would have fallen below current federal poverty guidelines adjusted for inflation--"has not been correlated with an increase in intelligence.’'
Rather than material wealth, Mr. Rector said, the presence or absence of “middle-class norms and values’’ are the “operative variable’’ in how well children do. Such values, he said, include factors such as whether and how often parents read to children.
He also argued that the “types of solutions’’ to poverty that focus on increasing federal benefits to the poor tend to “undermine and destroy middle-class standards’’ rather than promote them.
While the study found that income is a stronger predictor of both I.Q. and behavior than is family structure, it notes that the behavior problems of children living in persistently poor families appeared more closely linked to family status than to income in two cases. The first was when a family was headed for a long period of time by a single mother who never married; the second was when a family headed by two parents split up, leaving the child with a single mother.
Ms. Larner suggested, however, that one reason the study’s emphasis on the role poverty plays is significant is that family income is more amenable to policy solutions than family structure and other “social and interpersonal influences.’'
Mr. Duncan said in an interview that he is “encouraged by the discussions that are taking place’’ among policymakers on such options as increasing welfare and food-stamp benefits, reforming the welfare system, increasing job opportunities and training, raising the minimum wage, and expanding the federal earned-income tax credit, which is aimed at helping the working poor.
A plan to expand the tax credit proposed by President Clinton last week would raise the maximum benefit for families with two or more children from the current level of $1,998 to $3,371 in 1995.
Race and Neighborhoods
Another part of the analysis, based on data from the Panel Study of Income Dynamics that Mr. Duncan heads, identified a “dramatic racial difference’’ in black and white children’s experiences with poverty.
In a sample of 1,364 children studied over a six-year period, nearly half of the black children, but fewer than one-tenth of the white children, who did not live in poor families lived in neighborhoods where more than 10 percent of their neighbors were poor. While 51 percent of the white children did not live in either a poor family or a poor neighborhood, only about 5 percent of the black children escaped both family- and neighborhood-level poverty.
