General Ability Level Moderates Cognitive-Achievement Relations for Mathematics

Spearman's Law of Diminishing Returns (SLODR) suggests general intelligence would be a stronger predictor of academic skills at lower general ability levels, and broad cognitive abilities would be stronger predictors of academic skills at higher general ability levels. Few studies have examined how cognitive-mathematics relations may vary for people with different levels of general cognitive ability. Multi-group structural equation modeling tested whether cognitive-mathematics relations differed by general ability levels for school-aged children (grades 1-5 and grades 6-12) using the Woodcock-Johnson Third Edition (n = 4470) and Fourth Edition (n = 3891) standardization samples. Results suggested that relationships between cognitive abilities and mathematics varied across general ability groups. General intelligence showed a stronger relative effect on mathematics for those with lower general ability compared to those with average or high general ability, and broad cognitive abilities showed a stronger relative effect on mathematics for those with average or high general ability compared to those with lower general ability. These findings provide a more nuanced understanding of cognitive-mathematics relations.