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 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.

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.

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.

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.

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 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.

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