What concept did Raymond Cattell differentiate in intelligence testing?

Raymond Cattell is best known for his theory of intelligence, which he divided into two distinct types: fluid intelligence and crystallized intelligence. Fluid intelligence refers to the capacity to think logically and solve new problems independently of acquired knowledge, essentially representing a person's ability to reason and adapt to unfamiliar situations. It typically peaks in early adulthood and then gradually declines with age.

Crystallized intelligence, on the other hand, involves the knowledge that comes from prior learning and past experiences. It encompasses skills such as vocabulary and general knowledge that have been acquired throughout a person's life. Unlike fluid intelligence, crystallized intelligence tends to remain stable or even improve as one ages, reflecting the accumulation of knowledge and experience.

Cattell's differentiation of these two types of intelligence has had significant implications for how intelligence is assessed and understood, influencing various fields including psychology, education, and cognitive science. This distinction aids in recognizing that intelligence is not a singular construct but rather comprises multiple facets that can manifest differently across individuals and contexts.