ABSTRACT
During the early part of the 20th century, researchers sought to describe intelligence as a singular, general mental ability--G. During the 1930s and 1940s, researchers rejected the idea of a single intellectual ability in favor of primary mental abilities (see chapters 5 and 6 that describe two separate conceptions of these abilities). Raymond Cattell (1940, 1941, 1945) called into question both approaches. He believed that research would reject the idea of a unitary structure defining intelligence, but he also believed that the numerous primary mental abilities identified by the factor-analytic studies could be combined into more comprehensive structures. The results of his factor analysis of the primary mental abilities produced the theory of fluid and crystallized intelligence (Cattell, 1957, 1963; Horn & Cattell, 1966, 1967), which contends that, rather than being organized into a single general ability, primary mental abilities are organized into two principal classes of abilities and achievements.
