There are arguably two types of intelligence. Fluid intelligence is your ability to reason quickly. It relies on the ability to hold attention and benefits from a strong working memory. Crystallized intelligence is your ability to apply knowledge from prior learning that was stored in your long term memory. To illustrate how the two work together, we created a short fairytale – a story of a young man, who wants to save a princess that was captured by an evil witch.
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fluid intelligence

There are arguably two types of intelligence. Fluid intelligence is your ability to reason quickly and independently of your past experiences. It relies on the ability to hold attention and benefits from a strong working memory. While it can be trained, fluid intelligence is mainly determined by your genes.
crystallized intelligence

Crystallized intelligence is your ability to apply knowledge from prior learning that was stored in your long term memory. It increases with experience, and is hence mostly formed by the environment. To solve complex problems, both types of intelligence need to work together.
the full story

To illustrate how fluid and crystallized intelligence work, let us tell you the story of Arthur, a fine young man, who wants to save a young princess that was captured by an evil witch. The witch promised to release the princess only if Arthur brings her a precious jewel from a secret tomb. Arthur agrees, begins his quest, and comes across a deep, dark forest that he must cross.
the quest begin

He navigates through the wilderness with a compass and a map — using the intelligence he crystallized when he spent lots of time studying maps as a boy. At the end of the forest Arthur discovers the entrance to the tomb and sees the prized jewel already sparkling in the distance.
fluid and crystallized cooperation

As he enters the tomb, he steps on a pressure plate. His crystallized intelligence tells him that this is a mechanical trap. — something he learned about earlier in life. He stands still, and thinks of a solution. Since he has never been in this situation before, he cannot draw on past experience. Thankfully, his fluid intelligence takes over and allows him to make a new plan on the fly. Drop the bag! It puts pressure on the plate and you can grab the jewel! — crystalized intelligence takes note for future reference. Arthur then gave the jewel to the witch, freed the princess and brought her safely back home.
intelligence development stage

Suppose Arthur was an average child and we were to plot the development of his intelligence over 90 years. His fluid intelligence would increase sharply until his early twenties and then peak and decline. His crystallized intelligence would peak later and slowly decline at a higher age.
The psychologist Raymond Cattell coined the terms, fluid and crystallized intelligence in 1963.
what do you think?

What are your thoughts? Can you think of a time when you used your fluid and when your crystalized intelligence ? Share your thoughts in the comments below.
Sources
- Fluid and crystallized intelligence – Wikipedia.org
- Research article on improving fluid intelligence with training on working memory – Pnas.org
- Development of the two over our age – Kids.frontiersin.org
- Au, J. et al. (2015). Improving fluid intelligence with training on working memory: a meta-analysis. Psychon Bull Rev, 22(2), 366-77.
- Jaeggi, S. M., et al. (2008). Improving Fluid Intelligence with Training on Working Memory. Proceedings of the National Academy of Sciences of the United States of America, 105(19), 6829-6833.
- Perera, A. (2020) Fluid vs Crystallized Intelligence. Simply Psychology.
- Vinney, C. (2019).Fluid Versus Crystallized Intelligence: What’s the Difference?. ThoughtCo.
- Brain structure is important for both kind of intelligence and changes during the teens – Pubmed.ncbi.nlm.nih.gov
- Fluid intelligence – Sciencedirect.com
Dig deeper!
- Learn about a fluid intelligence test here.
- Scientists have long known that our ability to think quickly, also known as fluid intelligence, peaks around age 20 and then begins a slow decline. However, more recent findings, including a new study from neuroscientists at MIT suggest that the real picture is much more complex.
Classroom exercise
What careers need what type of intelligence?

Idea for exercise in 7 steps:
- Let the students openly discuss what they think is intelligence. To prompt them, you may ask them to name people, animals or machines that they think are intelligent. Write their ideas on a board (spend around 5 minutes on this).
- Introduce the concept of 2 types of intelligence and play our video (10 minutes)
- Show the class an overview of popular professions ranging from airplane pilot and zoo director — you may want to use the image above as a prompt (5 minutes)
- Ask each student to pick one profession and explain which type of intelligence they think that profession will become world class (5 minutes).
- Let the students in breakout groups of two, present their findinding to each other (5 minutes).
- Ask for volunteers to present what they found (10 minutes)
- Summarize and answer question (5 minutes)
Key question you may want to answer:
- Do different professions need different types of intelligence?
- Does it depend on the level of seniority?
- Who needs the most fluidity and who has the most crystallized intelligence?
Collaborators
- Script: Cameron Tan
- Editor: Jonas Koblin
- Fact checking: Ludo Saint Amour di Chanaz
- Artist: Pascal Gaggelli
- Voice: Mithril
- Coloring: Nalin
- Editing: Peera Lertsukittipongsa
- Production: Selina Bador
- Sound Design: Miguel Ojeda