The Flynn Effect is the tendency for intelligence scores of people taking the same IQ test to be better than those of their ancestors. Your grandparents probably did worse on an IQ test than you did on the same test. The effect is been apparent to researchers at least since World War II and World War I military test scores were compared, and Flynn is the scientist credited with generalizing this result.
This is a big deal because it implies that an important part of group averages in intelligence scores are not genetic in origins, providing one of the most powerful refutations of the hypothesis of books like "The Bell Curve" by Murray, that there are inherent genetic intelligence difference detween different ethnic groups. A wide variety of evidence, including studies such as those of twins separated at birth, have shown significant hereditary patterns in performance on intelligence tests, which are also corollated with perofrmance on a wide variety of other academic tasks and socioeconomic success.
James R. Flynn of the University of Otago in New Zealand, the individual after whom the effect is named, has just released a new paper showing that since 1972, that the gap gap in IQ scores between blacks and whites observed by Murray has declined by a quarter to a half.
Wikipedia notes that some scholars believe that the Flynn Effect may be largely a product of improved nutrition for the poor, noting, for example, that "the effect primarily reduced low-end scores, resulting in a pile up of moderately high scores, with no increase in very high scores." Similar causes could be behind the American experience still be observed as the gaps between minority and majority IQ test scores declines.