Fluid intelligence is a kind of cognitive ability based on physiology, such as perception, memory, operation speed and reasoning ability.

Liquid intelligence is a concept corresponding to crystal intelligence, which declines with age. However, crystal intelligence does not decline with age. Crystal intelligence mainly refers to the skills learned, language and writing ability, judgment, association and so on.

Fluid intelligence and crystal intelligence

Raymond Cartel, an American psychologist, divides intelligence into two categories: fluid intelligence and crystal intelligence.

Fluid intelligence is an innate ability to carry out intellectual activities, that is, the ability to learn and solve problems. It depends on innate endowment and improves with the maturity of the nervous system, such as perceptual speed, mechanical memory, graphic relationship recognition, etc., and is not affected by education and culture.