What Is Crystallized Intelligence And Its Importance?

Medically reviewed by Julie Dodson, MA
Updated April 2, 2024by BetterHelp Editorial Team

The subject of human intelligence has generally been under investigation by cognitive psychology experts for well over a century. The first intelligence test used in America, "The Binet and Simon Tests of Intellectual Capacity," is believed to have begun its rise to popularity in 1908. Since that time, intelligence testing has evolved drastically, often incorporating concepts such as fluid and crystallized intelligence. Fluid intelligence generally refers to problem-solving skills, while crystallized intelligence can be thought of as your accumulated knowledge. It can be possible to continue improving your crystallized knowledge throughout your lifetime, and an online therapist may help you reach this goal.

A note on intelligence

It can be important to note that "intelligent" is not necessarily synonymous with "smart" or other positive descriptions of a person's aptitude. In years prior, researchers attempted to reduce a person's potential to a single score, the intelligence quotient (IQ). That effort has been mostly unsuccessful

Today's researchers and psychologists usually recognize the complexity of intelligence and cognition. They generally break down a person's cognitive skills into three broad categories. Crystallized intelligence typically refers to accumulated knowledge, fluid intelligence normally refers to problem-solving and adapting to new situations, and working memory usually refers to the capacity to hold onto information temporarily.

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Crystallized intelligence

Crystallized intelligence generally refers to the accumulated knowledge a person can retain. When psychologists and researchers speak about crystallized intelligence, they are usually referring to a person's ability to apply previously acquired knowledge or prior learning to a problem in front of them. The phrase "long-term memory" is often associated with crystallized intelligence. Although crystallized intelligence and long-term memory are not necessarily synonymous, they can be considered very similar concepts.

Crystallized intelligence is basically a person's "encyclopedia." It can represent the bundled knowledge they have gained over the years, including everything from advanced concepts taught in school to basic knowledge like "birds have feathers." Because people normally continue to learn throughout their entire lives, crystallized intelligence tends to increase the longer a person has been alive, usually resulting in higher crystallized intelligence.

When people solve a problem using crystallized intelligence, they tend to look up facts and information in their personal encyclopedia. As an example, consider a doctor who specializes in a particular disease. After years of treating that disease, the doctor likely relies more on their own intuition than medical texts and resources. They may have transferred the knowledge of that disease from medical literature to their personal encyclopedia, likely increasing their crystallized intelligence.

Fluid intelligence

Fluid intelligence typically involves a person's ability to solve new and unfamiliar problems, which is normally distinct from crystallized intelligence. 

Imagine a person is asked to sort a bucket of marbles. The marbles are a variety of colors and shapes, and for the sake of this example, this person has never sorted marbles before. We could give this person instructions on how to sort the marbles, but that may force the person to rely on existing knowledge, a component of crystallized intelligence.

In our example, the person is given no additional information besides the direction to "sort the marbles." Deciding how the marbles should be categorized and the best method to sort them usually relies heavily on fluid intelligence. The person must generally examine the similarities and differences between the marbles and engage in problem-solving and critical thinking to figure out where they should be placed.

Fluid intelligence and crystallized intelligence are nearly always used together. Even though we didn't give the person instructions on how to complete the task, crystallized intelligence was likely still involved. The person probably knew a little bit about how sorting works (putting similar items together, etc.), and even knowing the definition of the word "sorting" generally relies on crystallized intelligence.

Unlike crystallized intelligence, which usually improves steadily over time, the fluid intelligence peak is typically in early adulthood, around age 20. In general, fluid reasoning slowly declines through adulthood, mainly due to changes in the brain due to aging.

Raven’s Progressive Matrices Test is commonly used to assess fluid intelligence. Based on differences in fluid and crystallized intelligence, the same test can not be used diagnostically for both types of cognitive abilities.

A note on working memory


Working memory isn't normally a category of intelligence in the same way as crystallized and fluid intelligence, but it can still be an essential component of general intelligence. Working memory can refer to a person's ability to hold on to information temporarily. 

You might think of a person's working memory as their problem-solving workbench. The bigger the workbench, the more productive the person can work. A person with a high working memory can usually process more information than a person with a low working memory in the same span of time.

Working memory can be closely related to fluid intelligence. In the past, researchers usually considered working memory a part of fluid intelligence. Today, it is usually represented as its own category within the theory of fluid and crystallized intelligence types. The term "short-term memory" is often used interchangeably with “working memory” and can illustrate the concept well. While crystallized intelligence (long-term memory) normally requires information to be retained indefinitely, short-term memory can be more like a scratchpad the brain can use to process information that does not need to be stored for later use.

Crystalized vs. fluid: Which is better?

Determining whether fluid intelligence is superior to crystallized intelligence, or whether the reverse is true, depends entirely on context. Some problems require more accumulated knowledge in a certain subject to solve (crystallized intelligence). In contrast, others rely heavily on in-the-moment critical thinking (fluid reasoning). While some problems certainly rely more on one type of intelligence than the other, in practice, both kinds of intelligence tend to be required for every problem, potentially making it essential to consider both types of intelligence equally.

To an outside observer, it may appear that one type of intelligence is superior to the other. For example, those with more crystallized intelligence tend to do better academically, often leading to an increase in confidence that can propel the person to higher levels of achievement.

Fluid reasoning, while often just as important, tends to be less visible than crystallized intelligence. Consider a high school student with average fluid reasoning abilities who is enrolled in five classes: math, history, literature, science, and geography. Of those, just one subject relies heavily on fluid reasoning, math. The other subjects listed usually require much more rote memorization of facts and concepts. If the student has a strong ability to crystalize new knowledge, they will likely do better in all subjects. If the student has a lower ability to crystalize new knowledge, they may need help to perform well in school, regardless of their problem-solving ability.

Because academic achievement tends to be linked so highly to intelligence, there often exists a common misconception that a high ability to crystalize knowledge is what makes a person intellectually capable. However, there can be a large gap between what society considers to be examples of intelligence and what researchers believe to be true. In general, every person needs crystallized and fluid intelligence, and they can both play a role in success, academic or otherwise.

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Can crystallized intelligence and fluid intelligence be improved?

Through the study of psychology, cognitive abilities and general intelligence have been explored. The theory of fluid and crystallized intelligence suggests that human intelligence can be improved throughout a person’s life, particularly intelligence crystallized.

Almost anyone, through effort, can increase their intelligence. However, this process usually relies on improving crystallized intelligence. A person's crystallized intelligence generally improves every time they learn and retain something new. All a person may need to do to improve their crystallized intelligence is continue to learn and grow. Often, the main barrier to improving crystallized intelligence isn't a person's intellect, but whether they feel confident enough to engage in the learning process.

Fluid intelligence tends to be more complex. It typically relies on cognitive processes that decline as the brain ages. For many years, researchers generally assumed that fluid intelligence was fixed and that any attempt at improving it would be futile. However, tests and recent research suggest the opposite. In a controlled study published in a psychological review, scientists were able to improve fluid intelligence scores after administering a course of specially designed training.

The training developed by the researchers didn't necessarily improve fluid reasoning directly. Instead, the training mainly focused on enhancing the participant's working memory. Working memory, or a person's ability to hold on to information temporarily, is usually closely linked to fluid reasoning. In essence, a person can improve their fluid reasoning by processing larger amounts of information in the same amount of time. While it may not be possible to make the same gains in working memory and fluid reasoning as in more crystallized intelligence, a significant degree of improvement is likely possible.

The working memory training investigated by scientists may still be under development, and more research likely needs to be conducted before empirically supported tools for improving fluid intelligence are widely available. For now, the best ways to improve intelligence overall rely on improving crystallized intelligence.

How can online therapy improve my crystallized intelligence?

Online therapy can help you find the confidence you need to achieve your crystallized intelligence goals, such as learning a new language or tackling complex tasks. Improving crystallized intelligence, as intelligence refers to the ability to retain and apply information, usually requires not only retention skills but also motivation and confidence. Completing therapy sessions online can be convenient, as there’s generally no need to leave home or seek out a therapist in your local area.

The process may appear challenging for someone who doesn't consider themselves a natural learner, but all people may be able to improve their intelligence, regardless of their ability. Using empirically supported techniques like Motivation Enhancement Therapy, a therapist can help you find the drive to improve your crystallized intelligence. 

As this study explains, online therapy is normally just as effective as traditional in-office therapy.


Although it may seem like intelligence is innate and fixed, crystallized intelligence can be continually improved throughout the lifespan. It can be vital to develop confidence and a desire for learning when improving intelligence. In general, the more time a person spends learning new things, the higher their crystallized intelligence becomes. There may be tools to strengthen fluid reasoning in the future, but for now, the best and most reliable way to increase intelligence may be to become a lifelong learner and consistently add to your crystallized intelligence progress. An online therapist may assist you in this process.
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