Who proposed the concept of separate fluid and crystallized intelligences?

The concept of separate fluid and crystallized intelligences was proposed by James Cattell. Fluid intelligence refers to the ability to solve new problems, use logic, and identify patterns, independent of acquired knowledge. Crystallized intelligence, on the other hand, involves the knowledge and skills that one has accumulated over time, which includes vocabulary and general knowledge based on experience. Cattell's distinction enhances understanding of how different types of intelligence operate, providing a more nuanced view of human cognitive ability. This theory also laid the groundwork for further research into the different domains of intelligence and their implications for education and psychological assessment.