CHC Theory

Recent advances in current theory and research on the structure of human cognitive abilities have resulted in a new empirically derived model commonly referred to as the Cattell-Horn-Carroll theory of cognitive abilities (CHC theory). CHC theory of cognitive abilities is an amalgamation of two similar theories about the content and structure of human cognitive abilities. The first of these two theories is Gf-Gc theory (Cattell, 1941; Horn 1965), and the second is Carroll's (1993) Three-Stratum theory.

The CHC model was expanded by McGrew (1997) and later revised with the help of Flanagan (1998). There are 10 broad stratum abilities and over 70 narrow abilities below these. The broad abilities are: crystallized intelligence (Gc), fluid intelligence (Gf), quantitatve reasoning (Gq), reading & writing ability (Grw), short-term memory (Gsm), long-term storage and retrieval (Glr), visual processing (Gv), auditory processing (Ga), processing speed (Gs), decision/reaction time/speed (Gt). (G) from Carroll's model has been omitted, but fluid and crystallized intelligence from the Cattell-horn model remained.

Many tests of cognitive ability have been classified using the CHC model and are described in The Intelligence Test Desk Reference (ITDR) (McGrew & Flanagan, 1998). CHC theory is particularly relevant to school psychologists for psychoeducational assessment. 5 of the 7 major tests of intelligence have changed to incorporate CHC theory as their foundation for specifying and operationalizing cognitive abilities/processes. Since even all modern intellectual test instruments fail to effectively measure all 10 broad stratum abilities an alternative method of cognitive assessment and interpretation called Cross Battery Assessment (XBA; Flanagan, Ortiz, Alfonso, & Dynda, 2008) was developed.

Recently (March 11th, 2009) McGrew released a draft of the revised broad and narrow ability definitions.