The Flynn Effect is described as the year-on-year rise of IQ test scores seen in most parts of the world.  This theory was named by Richard Herrstein and Charles Murray after the New Zealand based political scientist, James R. Flynn.  Flynn played a major role in documenting and promoting the awareness of the rise in IQ in society and the implications that it caused.

The average rate of rise in IQ scores seems to be around three points per decade; however, there is evidence from Scandinavian countries that IQ scores rose more than 20 points per generation, following World War II.

Some explications as to why IQ scores continue to rise are factors like improved nutrition, smaller families, better education, and greater environmental complexity. (Mingroni, 2004).  IQ scores are re-normalized periodically, so that the average score for the population is reset to 100.