Forty-Year Secular Trends in Cognitive Abilties

Changes are shown in the distribution of scores on a set of tests used by the Danish draft board since the late 1950s until the present day. Whereas there were marked gains in earlier decades, especially in the lower end of the distribution, the last 10 years have only seen very modest gains. Such gains as have occurred appear primarily to manifest themselves in a test of visuo-spatial abilities.