General Intelligence Contributions to Cognitive Performance Across Ability Levels and Age: An IPD Meta-Analysis of Child and Adolescent Norming Data

Cognitive differentiation effects describe differences in the strength of the correlations among cognitive performances depending on general ability level and age. In this context, variations in the contribution of general intelligence (g) to specific cognitive performances have attracted significant interest, yet have not been investigated meta-analytically. The present study provides an examination of moderated g-factor loadings through a two-stage individual participant data (IPD) meta-analysis of 29 samples from 20 German test standardizations in children and adolescents (N = 42,207). Standardization samples ensured population representativeness, sufficient sample size, and representation of different cognitive tests. Using nonlinear factor analysis, we examined the moderation of g-loadings by age, ability, and their interaction. Subsequent multi-level meta-regressions revealed decreasing g-loadings with increasing ability levels (meta-analytic λ2 = –.046 [95% CI -.064, -.028]). Age moderation effects were inconsistent and nonsignificant (meta-analytic λ3 = .003 [95% CI -.024, .030]). A negative age × ability interaction was present in some samples but not significant meta-analytically (meta-analytic λ4 = –.005 [95% CI -.012, .002]). Moderator analyses indicated that effects differed between test families but rarely between CHC abilities. The results highlight ability level as a key source of differences in the contribution of general intelligence to specific cognitive performances, underscoring the need for conditional reliability estimates in cognitive assessment and for cognitive theories on the nature and development of general intelligence to account for this effect. Age differences in g-factor loadings were less consequential, suggesting limited relevance. The study was funded by the German Research Foundation. OSF registration: https://osf.io/fqdbx/?view_only=e8db0c938c8541f5ac81e69ea5c20fab.