The notion of crystallized intelligence was first proposed by the British psychologist Raymond B. Cattell in a 1943 article in which he outlined his perspective on the structure of intelligence, a perspective born of his efforts to develop a culture-free intelligence measure. Cattell’s theory initially suggested that general intelligence could be conceptually subdivided into two related but distinct components, namely, fluid intelligence (Gf) and crystallized intelligence (Gc). In collaboration with J. L. Horn, Cattell expanded his theory by including additional cognitive abilities; this revised model came to be known as the Cattell-Horn theory. A further extension of the Gf-Gc theory— postulated by John B. Carroll on the basis of a survey of more than 60 years of factor analytic research on uman cognitive abilities and published in 1993— provides one of the most comprehensive and integrated treatments on the subject. Carroll’s three-tiered taxonomy of cognitive abilities, known as the Cattell-HornCarroll model, is a fully hierarchical structure, with the general ability factor (g) at the top, Gf and Gc along with several other factors at an intermediate level, and many more specific factors at the lowest level of the hierarchy. Both the original version of GfGc theory as well as its extensions have proved to be quite influential in the development of modern tests of cognitive abilities.
Cattell believed that psychometric intelligence, as reflected in mental ability tests, is a composite of two major factors. Fluid intelligence comes into play when individuals are confronted with unfamiliar tasks or tasks that require novel solutions. Crystallized intelligence, on the other hand, is displayed on tasks that require the recall of acquired knowledge or the application of well-learned skills. This differentiation is, by Cattell’s own admission, reminiscent of D. O. Hebb’s distinction between biologically determined capacity, or intelligence A, and the capacities that are acquired through experience and education, or intelligence B. It is also similar to the familiar continuum along which tests of ability can be placed—ranging from achievement-oriented to general ability or aptitude measures—depending on the degree of experiential specificity they assume in prospective test takers.
Although the fluid (Gf) and crystallized (Gc) components of intelligence are conceptualized as being interrelated, they tend to become increasingly more independent as development proceeds from infancy through adulthood. Crystallized abilities are derived from fluid abilities, but are developed through education, experience, and practice. As a general rule, fluid intelligence shows a steady decline in adulthood, whereas crystallized intelligence—which reflects the extent of acculturation—can slowly improve over one’s life span.
Another important distinction between crystallized and fluid intelligence is in their susceptibility to brain injury. Performance on measures of fluid intelligence, such as series completion and analogies tests, tends to be more affected by damage to the brain, regardless of where the damage occurs. On the other hand, measures of crystallized intelligence—such as tests of verbal comprehension and content knowledge in specific fields—are more affected by damage to the brain areas associated with those abilities.
At present, the expanded model of Gf-Gc theory is very popular and is widely used in research studies on intelligence because of its ability to account for new empirical data. Variations of the Gf-Gc model have also been explicitly incorporated into the design of assessment instruments developed by Alan and Nadeen Kaufman, such as the Kaufman Adolescent and Adult Intelligence Test (KAIT) and the Kaufman Assessment Battery for Children-Second Edition (KABC-II), as well as other contemporary test batteries, such as the Woodcock-Johnson III. In addition, Flanagan and coworkers have applied their Gf-Gc cross-battery assessment approach to the interpretation of the Wechsler Intelligence Scales (WAIS, WISC, and WPPSI).
- Carroll, B. (1993). Human cognitive abilities: A survey of factor-analytic studies. New York: Cambridge University Press.
- Cattell, B. (1943). The measurement of adult intelligence. Psychological Bulletin, 40, 153–193.
- Cattell, B. (1963). Theory of fluid and crystallized intelligence: A critical experiment. Journal of Educational Psychology, 54, 1–22.
- Flanagan, P., McGrew, K. S., & Ortiz, S. O. (2000). The Wechsler intelligence scales and Gf-Gc theory: A contemporary approach to interpretation. Boston: Allyn & Bacon.
- Horn, L., & Cattell, R. B. (1966). Refinement and test of the theory of fluid and crystallized intelligence. Journal of Educational Psychology, 57, 253–270.