“The year in which IQ is tested can make the difference between life and death for a death row inmate. It also can determine the eligibility of children for special services, adults’ Social Security benefits and recruits’ suitability for certain military careers, according to a new study by Cornell University researchers.

That’s because IQ scores tend to rise 5 to 25 points in a single generation. This so-called ‘Flynn effect’ is corrected by toughening up the test every 15 to 20 years to reset the mean score to 100. A score from a test taken at the end of one cycle can vary widely from a score derived from a test taken at the beginning of the next cycle, when the test is more difficult, says Stephen J. Ceci, professor of human development at Cornell.” A .pdf of Kanaya, Scullin and Ceci’s paper

is here.