Fluid and crystallized intelligence

In psychometrics, fluid and crystallized intelligence (abbreviated gf and gc respectively) are factors of intelligence test scores originally described by Raymond Cattell. Crystallized intelligence is usually described as being dependent on learning, while fluid intelligence is independent of past experience.

Cattell's work on gf and gc
In his 1936 book Guide to Mental Testing, Cattell defined intelligence as follows:

"…abilities may be conceived as (1) a general ability entering into almost all performances, but far more into complex relation education than other performances; (2) certain group factors each covering an area such as verbal, number, spatial, musical, etc., performance; and (3) certain abilities which are absolutely specific to one performance."

Cattell discusses fluid and crystalized intelligence in Intelligence: Its Structure, Growth, and Action:

"It is apparent that one of these powers… has the “fluid” quality of being directable to almost any problem. By contrast, the other is invested in particular areas of crystallized skills which can be upset individually without affecting the others." (Cattell, 1987)

In other words, fluid intelligence is a simple, innate, general ability, which stays fairly constant throughout life. It includes such abilities as problem-solving, memory, learning, and pattern recognition. As evidence for its continuity, Cattell documents that what he notes as gf abilities are rarely affected by brain injuries. gf is highly similar to Spearman’s original concept of g (see general intelligence factor). For instance, the known fact of IQ decline in seniors at age 50 and higher (Schaie 1983;Hertzog & Schaie;) can be attributed to decline in Gf but not in Gc.

Crystallized intelligence, on the other hand, is more dynamic. It consists primarily of specific, acquired knowledge. For example, a child who has just learned how to recite the fifty states of America now owns a new piece of crystallized intelligence; but their general ability to learn and understand (gf) has not been altered. Not surprisingly, people with a high capacity of gf tend to acquire more gc knowledge and at faster rates.

Examples of gf and ''gc
Examples of gc, the abilities that depend on knowledge and experience, include:


 * Vocabulary
 * Ability to see similarities between objects and situations
 * General information

Examples of gf, which is basically abtract reasoning, include:


 * Solving puzzles
 * Classifying figures into categories
 * Changing problem solving strategies easily with each new problem

Factor loadings of gf and gc
According to Paul Kline's 1998 The New Psychometrics, Cattell's 1971 study identified a number of factors that shared at least 60% correlation with gf and gc.

Factors with median loadings of greater than 0.6 on gf:


 * induction (I)
 * visualization (Vx)
 * quantitative reasoning (RQ)
 * ideational fluency (FI)

Factors with median loadings of greater than 0.6 on gc:


 * verbal ability
 * language development
 * reading comprehension
 * sequential reasoning
 * general information