In more traditional psychology circles, there are two main types of intelligence: fluid and crystallized. Psychologist Raymond B. Cattell first proposed the two types in the 1970s and developed them further with his student, John Horn.
Fluid intelligence is a person's ability to solve problems, learn new things and use logical thinking in unfamiliar situations. Cattell called the ability to reason fluid intelligence because it "has the 'fluid' quality of being directable to almost any problem," according to Thought Co.
When you use fluid intelligence, you don't rely on any prior knowledge to help you figure things out. Fluid intelligence might come into play when solving puzzles or when you try something creative, like painting or playing a musical instrument for the first time. Fluid intelligence typically peaks in young adulthood and then gradually declines.
Crystallized intelligence, however, is based on prior learning and past experiences, points out Very Well Mind. It's making use of information and skills you've already mastered. You use crystallized intelligence in situations like reading comprehension and vocabulary tests. Because you just keep amassing knowledge, crystallized intelligence increases as you get older.
Both types of intelligence are evaluated on standard IQ tests, which are often criticized by psychologists for being a way-too-simple method of evaluating something so complex. Researchers have recently developed a simpler 10-minute test to evaluate only fluid intelligence. Not available to the public yet, the test has 23 questions and is available free to academics.
Want to do well on the test when it becomes available? Academics sometimes say that it's more difficult to improve fluid intelligence, but Very Well Mind offers some tips on how to try:
"Seek out new challenges. Gains in intelligence don't come from sticking to the same old routines. Keep exploring new things in life and keep learning new things. Tackle learning a new language. Take piano lessons. Visit a new country and learn about the people and culture."