T. Nettelbeck et C. Wilson, CHILDHOOD CHANGES IN SPEED OF INFORMATION-PROCESSING AND MENTAL AGE -A BRIEF REPORT, British journal of developmental psychology, 12, 1994, pp. 277-280
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.