Theories of intelligence

Ask ten psychologists what intelligence is and you'll get ten answers — which is exactly why examiners love this topic. The trick isn't defining intelligence; it's matching each theorist to the shape of their model.

Start with Charles Spearman, who used factor analysis and noticed that people good at one mental task tended to be good at others. He argued for a single general intelligence factor he called "g" — the shared engine behind all cognitive performance — plus specific "s" factors for particular tasks. When a question mentions g or a single underlying intelligence, think Spearman.

Next, Raymond Cattell split that general ability in two. Fluid intelligence (Gf) is your on-the-fly reasoning and problem-solving with novel material — it peaks in young adulthood and declines with age. Crystallized intelligence (Gc) is accumulated knowledge, vocabulary, and learned skill — it holds steady or rises across the lifespan. A handy hook: fluid = flexible/new, crystallized = crystallized/stored. This Gf-Gc pairing (later expanded into the Cattell-Horn-Carroll model) is the most testable piece here.

Then come the pluralists who rejected a single number. Howard Gardner's theory of multiple intelligences proposes several relatively independent intelligences — linguistic, logical-mathematical, spatial, musical, bodily-kinesthetic, interpersonal, intrapersonal, and naturalist — arguing a person can be strong in one and weak in another. Critics note his "intelligences" look a lot like talents and lack strong psychometric support, but the name and the plurality are what get tested.

Briefly, Robert Sternberg's triarchic theory rounds out the pluralist camp with three parts: analytical, creative, and practical intelligence.

Clinical Pearl: Match the theorist to the structure — Spearman = one factor (g); Cattell = two (fluid vs. crystallized); Gardner = many (multiple intelligences); Sternberg = three (analytical/creative/practical). Remember fluid declines with age while crystallized endures.