Cattell-Horn-Carroll Theory

The Cattell-Horn-Carroll theory, often abbreviated CHC theory, is a psychometric framework describing the structure of human cognitive abilities, synthesized from the separate work of the psychologists Raymond Cattell, John Horn and John Carroll. It combines Cattell and Horn's model of fluid and crystallized intelligence with Carroll's three-stratum hierarchical model of cognitive abilities, organizing abilities into three levels: a single general ability factor at the top stratum, a set of broad abilities such as fluid reasoning, crystallized knowledge and processing speed at the middle stratum, and a larger number of narrow, more specific abilities at the bottom stratum. The theory holds that the relationships among these many cognitive abilities can be understood by classifying them within this three-level structure, built up from decades of research using the statistical technique of factor analysis. CHC theory is now widely accepted as the most comprehensive and empirically supported account of the structure of cognitive abilities, and it underlies the design and interpretation of most contemporary intelligence tests used in psychological and educational assessment.