The stability of some dimensions of ability between the ages of 12 and 15 years was investigated for 225 boys and 242 girls in Sweden. Testing in grades 6, 8, and 9 indicated high stability for the general intelligence factor and for the residual of the General Visual factor. (SLD)

A written intelligence test with verbal, reasoning, and spatial subscales was administered to two comparable national samples of 1,000 thirteen-year olds in Sweden, tested in 1961 and in 1966. The increases were greater for girls than for boys, and the changes occurred simultaneously with several changes in social and educational conditions. To…