CHILDHOOD CHANGES IN SPEED OF INFORMATION-PROCESSING AND MENTAL AGE -A BRIEF REPORT

Measures of inspection time (IT) and raw Peabody (PPVT) scores obtaine d by Nettelbeck & Wilson (1985) from 70 children aged from 6 to 13 yea rs were used to test predictions that, if mental age (MA) growth is me diated by speed of information processing, then controlling for IT (sp eed index) would reduce correlation between chronological age (CA) and PPVT (MA index) to zero; but the correlation between IT and PPVT woul d be unaffected by controlling for CA effects. The opposite outcome wa s found, suggesting that increasing CA mediates both MA growth and imp rovement in processing speed. Implications for theories about the natu re of intelligence are discussed.