Forty-year secular trends in cognitive abilities

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