The gap in IQ scores between African-Americans and whites narrowed over the 20th century, agreed experts at a debate held here last week. They disagreed, though, on exactly when that narrowing occurred.
In a paper published in October in Psychological Science, William T. Dickens and James R. Flynn suggest that black Americans began to catch up with whites on a variety of intelligence tests between 1972 and 2002.
The studies are posted by the American Enterprise Institute for Public Policy Research.
But Charles Murray, a scholar at the American Enterprise Institute, the Washington think tank that hosted the Nov. 28 forum, said those researchers got the timing wrong. He cited findings from his own study, published last month in the journal Intelligence, which suggest that any shrinking of the black-white gap that occurred in the last century stalled in the late 1980s.
The timing distinctions go to the heart of the scholars’ differences on the nature of racial gaps in intelligence and society’s prospects for closing them. Mr. Murray, a co-author of The Bell Curve, the 1994 book that touched off a firestorm over its widely disputed contention that genetics are largely to blame for blacks’ lower IQ scores, said interventions aimed at improving black children’s social and economic circumstances are unlikely to narrow the gap any further.
“It is true that environment can have a huge effect,” Mr. Murray said last week. “But once you get to nearly an adequate environment, you’ve probably got most of what you’re going to get from environmental issues.”
Pessimism on NCLB
In contrast, Mr. Flynn, a professor emeritus of psychology at the University of Otago in Dunedin, New Zealand, thinks IQ traits are far more mutable. He cited a study tracking German children fathered by black soldiers and white soldiers after World War II. Scientists found no racial differences in intelligence among those children, who were all raised by white single mothers.
“I think it’s more probable than not that the black-white IQ gap is more environmental than genetic,” said Mr. Flynn, who is known for his discovery of a worldwide rise in IQ scores, called the “Flynn effect.”
“If America could only give all its citizens a decent life,” he said at the debate, “there’d be a lot less interest in this thing called IQ.”
Closing academic-achievement gaps between black students and their better-performing white counterparts is a major aim of the No Child Left Behind Act, which requires schools to improve achievement among student subpopulations as well as for their entire enrollments.
But neither scholar held out hope that the federal law would achieve its goal of proficiency in reading and mathematics for all students by the 2014 target date.
“Improvements in school are good, but they’re not good enough,” said Mr. Flynn.
Mr. Murray took issue with the law’s one-size-fits-all prescription for improving student achievement. “NCLB is a disaster for American education and ought to be repealed forthwith,” he said.
One reason why the researchers found different IQ-gap trends is that they used different tests. Mr. Flynn and Mr. Dickens, a scholar at the Washington-based Brookings Institution, relied on data from different time periods for four tests: the Wechsler Intelligence Scale for Children, the Wechsler Adult Intelligence Scale, the Armed Forces Qualification Test, and the Stanford-Binet Intelligence Scale. (“Black-White Gap in IQ Scores Closing, Study Finds,” June 21, 2006.)
Mr. Murray used Peabody Individual Achievement tests in reading and math and the Peabody Picture Vocabulary Test.
Mr. Flynn said Mr. Murray’s measures were off the mark because the Peabody tests, especially the picture-vocabulary version, are not pure intelligence tests. “Also, I think vocabulary is an unusual problem for black Americans,” he said, citing studies suggesting that parents in lower-class U.S. families tend to talk to their children less than other parents.
Mr. Murray said he chose the Peabody tests because he could link the results to a larger sample of children than were available for the tests that Mr. Flynn used. Mr. Murray gathered testing data from the federal National Longitudinal Survey of Youth, which involves 6,209 children born from the mid-1970s to the mid-1990s and their mothers.
“The vocabulary issue is an interesting chicken-and-egg problem,” Mr. Murray added. “Are the scores low because children do not hear enough vocabulary, or because maternal IQ is low?”
