A statistical analysis of four national intelligence tests indicates that the difference in scores between blacks and whites decreased by about a third between 1972 and 2002. The findings challenge a century-old argument that the racial gap in performance on IQ tests is primarily genetic and therefore invulnerable to social change, say the researchers who performed the new study.
They examined data that have only recently become available to researchers, says William Dickens of the Brookings Institution in Washington, D.C. Using test results from a random distribution of people in the United States, he and James R. Flynn of the University of Otago in New Zealand tallied the increases in IQ scores of blacks and whites over 3 decades. Each of the four tests analyzed included two or three groups of people that took the test at different times.
Previous measures of the intelligence gap, which had used localized populations tested only once, found blacks 15 to 18 IQ points l