Cattell–Horn–Carroll theory

The Cattell–Horn–Carroll theory (commonly abbreviated to CHC), is a prominent psychological theory on the structure of human cognitive abilities. Based on the work of three psychologists, Raymond B. Cattell, John L. Horn and John B. Carroll, the Cattell–Horn–Carroll theory is widely regarded as the most influential theory in the study of human intelligence. Based on a large body of research, spanning over 70 years, the theory was developed using the psychometric approach, the objective measurement of individual differences in abilities, and the application of factor analysis, a statistical technique which uncovers relationships between variables and the underlying structure of concepts such as 'intelligence' (Keith & Reynolds, 2010). The psychometric approach has consistently facilitated the development of reliable and valid measurement tools and continues to dominate the field of intelligence research (Neisser, 1996). The Cattell–Horn–Carroll theory (commonly abbreviated to CHC), is a prominent psychological theory on the structure of human cognitive abilities. Based on the work of three psychologists, Raymond B. Cattell, John L. Horn and John B. Carroll, the Cattell–Horn–Carroll theory is widely regarded as the most influential theory in the study of human intelligence. Based on a large body of research, spanning over 70 years, the theory was developed using the psychometric approach, the objective measurement of individual differences in abilities, and the application of factor analysis, a statistical technique which uncovers relationships between variables and the underlying structure of concepts such as 'intelligence' (Keith & Reynolds, 2010). The psychometric approach has consistently facilitated the development of reliable and valid measurement tools and continues to dominate the field of intelligence research (Neisser, 1996). The Cattell–Horn–Carroll theory is an integration of two previously established theoretical models of intelligence: the Gf-Gc theory of fluid and crystallised intelligence (Cattell, 1941; Horn 1965), and Carroll's three-stratum theory (1993), a hierarchical, three-stratum model of intelligence. Due to substantial similarities between the two theories they were successfully amalgamated to form the Cattell–Horn–Carroll theory (Willis, 2011, p. 45). In the late 1990s the CHC model was expanded by McGrew, later revised with the help of Flanagan. Later extensions of the model are detailed in McGrew (2011) and Schneider and McGrew (2012) There are a fairly large number of distinct individual differences in cognitive ability, and CHC theory holds that the relationships among them can be derived by classifying them into three different strata: stratum I, 'narrow' abilities; stratum II, 'broad abilities'; and stratum III, consisting of a single 'general ability' (or g). Today, the Cattell–Horn–Carroll theory is considered by some to be the most comprehensive and empirically supported theory of cognitive abilities, informing a substantial body of research and the ongoing development of IQ (Intelligence Quotient) tests (Kaufmann, 2009. p. 91). However, independent attempts by Stefan Dombrowski and colleagues to empirically verify the linkage of CHC theory with the Woodcock-Johnson Tests of Cognitive Abilities and Achievemnt were found to be unsuccessful. Put simply, Dombrowski and colleagues concluded that that instrument does not meaure all of the CHC abilities posited in the instrument's technical manual. Thus, Dombrowski and colleagues called to question the linkage of CHC theory with the Woodcock-Johnson battery of tests (both the prior and present editions). Paradoxically, the Woodcock-Johnson, Third Edition Battery was the main instrument used to establish the empirical basis of CHC theory and yet independent research using this instrument has failed to locate all of the CHC abilities the instrument purports to measure. CHC theory has struggled to align with other IQ tests including the Wechsler Intelligence Scales for Children, Fifth Edition and the Stanford-Binet, Fifth Edition. However, the Differential Abilities Scales, Second Edition appears to measure all of the CHC abilities posited in the instrument's technical manual. This independent body of research should give researchers and clinicians pause. It is not that CHC theory is necessarily incorrect or wrong; it is that the theory may not fit well our presently available IQ tests. The Cattell–Horn–Carroll theory of intelligence is a synthesis of Cattell and Horn's Gf-Gc model of fluid and crystallised intelligence and Carroll's Three Stratum Hierarchy (Sternberg & Kauffman, 1998). Awareness of the similarities between Cattel and Horn's Gf-Gc expanded model abilities and Carroll's Broad Stratum II abilities were highlighted at a meeting in 1985 concerning the revision of the Woodcock-Johnson Psycho-Educational Battery (Woodcock & Johnson, 1989). At this meeting Horn presented the Gf-Gc theory to several prominent figures in intelligence testing, including John B. Carroll (McGrew, 2005). Carroll was already a vocal proponent of the Cattell-Horn theory, stating in 1993 that the Gf-Gc model 'appears to offer the most well-founded and reasonable approach to an acceptable theory of the structure of cognitive abilities' (Carroll, 1993, p. 62). This fortuitous meeting was the starting point for the integration of the two theories. The integration of the two theories evolved through a series of bridging events that occurred over two decades. Although there are many similarities between the two models, Horn consistently and unyieldingly argued against a single general ability g factor (McGrew, 2005, p. 174). Charles Spearman first proposed the existence of the g-factor (also known as general intelligence) in the early 20th century after discovering significant positive correlations between children's scores in seemingly unrelated academic subjects (Spearman, 1904). Unlike Horn, Carroll argued that evidence for a single 'general' ability was overwhelming, and insisted that g was essential to a theory of human intelligence (Carroll, 1997). Raymond B. Cattell (20 March 1905 – 2 February 1998) was the first to propose a distinction between 'fluid intelligence' (Gf) and 'crystallised intelligence' (Gc). Charles Spearman's s factors are considered a prequel to this idea (Spearman, 1927), along with Thurstone's theory of Primary Mental Abilities (Thurstone, 1947). By 1991, John Horn, a student of Cattell's, had expanded the Gf-Gc model to include 8 or 9 broad abilities (Horn, 1994). Fluid intelligence refers to quantitative reasoning, processing ability, adaptability to new environments and novel problem solving. Crystallised intelligence (Gc) refers to the accumulation of knowledge (general, procedural and declarative). Gc tasks include problem solving with familiar materials and culture-fair tests of general knowledge and vocabulary (Horn & Cattell, 1966). Gf and Gc are both factors of g (general intelligence). Though distinct, there is interaction, as fluid intelligence is a determining factor in the speed with which crystallised knowledge is accumulated (Cattell, 1963). Crystallised intelligence is known to increase with age as we accumulate knowledge throughout the lifespan. Fluid processing ability reaches a peak around late adolescence, then declines steadily (Horn, 1981). Recent research has explored the idea that training on working memory tasks can transfer to improvements in fluid intelligence (Jaeggi, 2015). This idea did not hold under further scrutiny (Melby-Lervåg, Redick, & Hulme, 2016). The American psychologist John B. Carroll (June 5, 1916 – July 1, 2003) made substantial contributions to psychology, psychometrics and educational linguistics. In 1993, Carroll published Human Cognitive Abilities: A Survey of Factor-Analytic Studies, in which he presented 'A Theory of Cognitive Abilities: The Three-Stratum Theory'. Carroll had re-analysed data-sets from 461 classic factor analytic studies of human cognition, distilling the results into 800 pages, thus providing a solid foundation for future research in human intelligence (Carroll, 1993, p. 78-91).