Intelligence (psychology)
In psychology, intelligence is the capacity to learn from experience, reason, solve problems, and adapt to new situations. Major theories differ on whether it is a single general ability (g) or a collection of distinct abilities.
Psychologists define intelligence as the ability to learn from experience, reason abstractly, solve problems, and adapt to the environment. The field's central debate is whether intelligence is one thing or many. Charles Spearman argued for a single general intelligence (g) underlying performance across all mental tasks, based on the observation that scores on different cognitive tests correlate positively.
Later theorists split intelligence apart. Raymond Cattell distinguished fluid intelligence — novel reasoning and problem-solving, which tends to decline with age — from crystallized intelligence, the accumulated knowledge and vocabulary that remains stable or grows across the lifespan. Howard Gardner proposed multiple independent intelligences (linguistic, logical-mathematical, spatial, musical, bodily-kinesthetic, interpersonal, intrapersonal, naturalist), and Robert Sternberg's triarchic theory identified analytical, creative, and practical intelligence.
Intelligence is measured with standardized tests such as the Wechsler scales and Stanford-Binet, which yield an intelligence quotient (IQ) normed to a mean of 100 with a standard deviation of 15. Good tests must be standardized, reliable, and valid. Scores reflect both heredity and environment, and the Flynn effect — the generational rise in average IQ scores through the 20th century — points to strong environmental influences. Separately, business courses use "intelligence" in a different sense: business intelligence refers to systems that turn data into decisions, not to cognitive ability.
The MCAT tests theories of intelligence in its psychological foundations section, and AP Psychology devotes part of its cognition unit to intelligence and achievement testing — expect questions matching theorists to theories and interpreting IQ score distributions.
Key takeaways
- Intelligence is the capacity to learn, reason, solve problems, and adapt to new situations.
- Spearman's g holds that one general ability underlies all cognitive performance; Gardner and Sternberg propose multiple intelligences.
- Fluid intelligence (novel reasoning) declines with age, while crystallized intelligence (accumulated knowledge) persists.
- IQ tests are normed to a mean of 100 and standard deviation of 15, and must be standardized, reliable, and valid.
- The MCAT and AP Psychology exams test intelligence theories, theorists, and score interpretation.