<Table> External video <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Td_colspan="2"> James Flynn: Why our IQ levels are higher than our grandparents', (18: 41), TED talks </Td> </Tr> </Table> <Tr> <Td_colspan="2"> James Flynn: Why our IQ levels are higher than our grandparents', (18: 41), TED talks </Td> </Tr> <P> The Flynn effect is named for James R. Flynn, who did much to document it and promote awareness of its implications . The term itself was coined by Richard Herrnstein and Charles Murray, authors of The Bell Curve (1994). Although the general term for the phenomenon referring to no researcher in particular continues to be "secular rise in IQ scores", many textbooks on psychology and IQ testing have now followed the lead of Herrnstein and Murray in calling the phenomenon the Flynn effect . </P> <P> IQ tests are updated periodically . For example, the Wechsler Intelligence Scale for Children (WISC), originally developed in 1949, was updated in 1974, in 1991, 2003 and again in 2014 . The revised versions are standardized based on the performance of test - takers in standardization samples . A standard score of IQ 100 is defined as the median performance of the standardization sample . Thus one way to see changes in norms over time is to conduct a study in which the same test - takers take both an old and new version of the same test . Doing so confirms IQ gains over time . Some IQ tests, for example tests used for military draftees in NATO countries in Europe, report raw scores, and those also confirm a trend of rising scores over time . The average rate of increase seems to be about three IQ points per decade in the United States, as scaled by the Wechsler tests . The increasing test performance over time appears on every major test, in every age range, at every ability level, and in every modern industrialized country, although not necessarily at the same rate as in the United States . The increase was continuous and roughly linear from the earliest days of testing to the late 1990s . Though the effect is most associated with IQ increases, a similar effect has been found with increases in attention and of semantic and episodic memory . </P>

The flynn effect refers to the increase in iq scores over the years and it may be due to