General intelligence consists of two types: fluid and crystallized.

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You use both types of intelligences. If you’ve ever encountered a new problem and solved it by recalling a previous experience, your fluid and crystallized intelligences have teamed up to your advantage.

Fluid intelligence is your ability to learn, assess, and navigate new situations. Crystallized intelligence is accumulated knowledge you can recall as needed. Problem-solving uses both intelligences.

Although they’re different, fluid and crystallized intelligence are both equally important — and in some ways connected.

Fluid intelligence, or general fluid intelligence (Gf), is your ability to:

  • reason
  • recognize patterns
  • solve problems
  • adapt to your environment and the world

You use Gf when you encounter new information and learn.

Gf can sometimes predict a person’s academic and job success. When educators or employers conduct aptitude testing, they’re measuring fluid intelligence.

It’s Gf that allows young people to learn faster and more easily than adults. An analysis from 2018 that included 680 studies found a connection between fluid intelligence and reading and math development.

There was a stronger relation to math and complex skills over reading and foundation skills. Yet, math uses both fluid and crystallized intelligence.

What is an example of fluid intelligence?

When you think of a strategy to solve a complicated math problem, you’re using fluid intelligence.

At what age does fluid intelligence peak?

Fluid intelligence increases until adolescence, then gradually declines.

General crystallized intelligence (Gc), or crystallized intelligence, is information you’ve learned in the past and stored. Gc results from experience, education, and cultural background.

School testing of learned facts and job candidate testing of software knowledge are examples of crystallized knowledge assessments.

What is an example of crystallized intelligence?

When you solve a math problem, your existing knowledge of formulas and symbols is an example of crystallized intelligence.

At what age does crystallized intelligence peak?

Crystallized intelligence increases as you age and gain more life experience. It slows in adulthood but can either stabilize or continue to increase throughout most of your life.

Fluid intelligenceCrystallized intelligence
new informationstored information
short-term memorylong-term memory
increases through childhood, peaks at adolescence, then declinesincreases through childhood, and slows with aging, then stabilizes or continues to increase throughout life
functions include working memory, processing speed, reasoning, cognitive control, inhibition, complex skills, attention tasks, creativityfunctions include procedural (practical), declarative (factual), general and specialized knowledge, wisdom

Although fluid and crystallized intelligences are different, they complement each other.

For example, an emergency room doctor uses both. When a patient arrives, the doctor’s fluid intelligence assesses the situation. Much like when solving a puzzle, the doctor’s fluid intelligence uses clues to arrive at an answer — in this case, a diagnosis.

Then, the doctor’s crystallized intelligence provides the previously acquired procedural knowledge needed for care and treatment.

Fluid and crystallized intelligences are also connected in some ways.

For example, high fluid intelligence allows you to learn faster, which results in more accumulated knowledge and in turn higher crystallized intelligence, as one 2019 study explores.

Changes in fluid intelligence can affect the expression of crystallized intelligence.

If you’re an older adult who has experienced a decline in fluid intelligence, you may not be as skilled at applying crystallized intelligence from your long-term memory to some current or new situations.

Crystallized intelligence testing measures general knowledge. Test types include vocabulary, verbal, and language use assessments. Research from 2015 points to text completion examinations as one measure of crystallized intelligence.

Fluid intelligence includes multiple cognitive qualities, so it requires a more varied testing approach. Assessment options include:

  • Progressive matrices: to test for pattern recognition, as stated in research from 2013
  • Digital span sequencing: to assess working memory, as explained in a 2019 study
  • Trail making test: to measure cognitive flexibility, as described in 2008 research
  • Digital fluency test: to assess creativity, problem solving, and inhibition, as noted in a 2016 study
  • Tower test: to measure planning ability, as explained in another 2016 study
  • Cognitive failures questionnaire: to assess attention, memory, distractibility, and executive function, as suggested in a 2017 study

You can increase both types of intelligences.

To increase your crystallized intelligence, you simply need to acquire new knowledge. Education and experience can help it take root in your long-term memory.

According to 2016 research, improving fluid intelligence requires a more comprehensive approach. It helps to think of fluid intelligence as a reflection of the health and fitness of your brain. So to increase this type of intelligence, you’ll need to nourish it well and exercise it often.

Brain health strategies include:

  • improved diet
  • regular exercise
  • adequate sleep
  • mindfulness training
  • stress reduction

Brain fitness activities include:

General intelligence has two main categories: fluid and crystallized.

Fluid intelligence is your ability to process new information, learn, and solve problems. Crystallized intelligence is your stored knowledge, accumulated over the years.

The two types work together and are equally important. They both increase through childhood. Fluid intelligence decreases with age and crystallized intelligence remains stable or continues to increase with age.

You can increase both types of intelligence. You could improve your fluid intelligence by keeping your brain healthy and fit. Adopting a lifelong learning habit can help you build up more crystallized intelligence.