| Theorist | Theory Summary |
|---|
| Spearman | Intelligence is mainly a function of a general intelligence (g) factor |
| Thurstone | Intelligence is a function of seven primary mental abilities—verbal comprehension, number facility, spatial relations, perceptual speed, word fluency, associative memory, and reasoning |
| Cattell and Horn | There are two types of intelligence—crystallized intelligence, which refers to accumulated knowledge and verbal and numerical skills, and fluid intelligence, which refers to abilities independent of acquired knowledge, such as abstract reasoning, logical problem solving, and speed of information processing |
| Gardner | Intelligence is defined as eight independent intelligences—linguistic, logical-mathematical, spatial, musical, bodily-kinesthetic, intrapersonal, interpersonal, and naturalist |
| Sternberg | Intelligence is defined as three types of abilities—analytical, creative, and practical |
| Stanovich | Intelligence is not sufficient for good thinking; rationality, which is independent of intelligence, is also necessary |