Does Reading Make You Smarter? How It Changes the Way You See the World

You hear it everywhere: reading makes you smarter, or reading is somehow incredibly good for you.

Biographies of famous people are full of stories about books. Sontoku Ninomiya supposedly read while carrying firewood on his back. In China, Zhu Maichen refused to give up his books even while living in poverty. More recently, there is the story that Elon Musk read every book in his local library as a child.

Sure, reading probably is good for you. But how exactly does reading words affect intelligence and intellect? Reading and successful people are paired so often that it makes me wonder: what is really going on here?

Weren't these people simply born with better stats to begin with?
Then again, even naturally gifted people—the kind who seem like geniuses without reading a thing—apparently do, or did, read.

How does reading actually affect intelligence and intellect?
Why is reading said to make us smarter?
Does it really make us smarter at all?
And does this benefit apply to ordinary people too?

I decided to look into it.

Q1. Is it true that reading makes you smarter?

There are two kinds of intelligence

The claim that “reading makes you smarter” is not exactly wrong, but it is far too broad.

Reading is thought to be especially helpful in developing abilities such as:

• Vocabulary
• General knowledge
• Reading comprehension
• Abstraction and reasoning
• Sustained attention
• The ability to imagine another person's perspective

Broadly speaking, intelligence can be divided into crystallized intelligence and fluid intelligence.

Crystallized intelligence is built up through knowledge and experience: vocabulary, accumulated knowledge, and patterns of understanding.
Fluid intelligence is the ability to work through a new problem on the spot, involving things such as processing speed and working memory.

Reading has a stronger effect on crystallized intelligence. Reading a book does not magically boost your processing speed or sharpen your mathematical intuition overnight.

What is crystallized intelligence, exactly?

“Developing crystallized intelligence” can sound as if it merely means becoming more knowledgeable. But the change seems to be larger than that.

Suppose something goes wrong. Without much knowledge, your analysis may end at, “Well, I messed that up...” With more knowledge, you can examine the same failure from several angles:

• Was I affected by a cognitive bias?
• Did environmental factors push me in a certain direction?
• Were my expectations wrong in the first place?
• Was this a problem with the system or structure itself?

If you can face the problem calmly and even come up with ways to solve or improve it, that looks pretty smart to me.

Q2. Why does reading make us smarter?

1. Knowledge reduces the mental load of thinking

Human working memory is surprisingly limited. For someone as easily distracted as I am, mine feels smaller than a six-tatami room.

When you read a text full of unfamiliar ideas, you have to check what each word means and keep track of all its assumptions. That alone can use up your entire processing capacity. In my case, it also sets off a chain of completely unrelated associations.

With enough background knowledge, however, you can compress information into meaningful chunks.

Being “smart” depends not only on the brain's raw processing power, but also on how efficiently you can compress information using the knowledge you already have.

2. More words expand the range of what you can think about

Humans do a great deal of their thinking through language. Complex causal relationships, self-analysis, and abstract concepts are difficult to handle without words.

Reading exposes us to vocabulary and concepts that rarely come up in everyday conversation. As a result, experiences that once felt like only “something is kind of off...” or “I don't know about this...” can be given names.

Once you can name something, you can observe it.
Once you can observe it, you can compare it.
Once you can compare it, you can think about it.

Reading is not only a way to acquire information. It is also a way to acquire more tools for thought.

3. The brain builds circuitry for reading

The ability to read is not something humans are born with. Unlike spoken language, reading is a culturally invented skill that must be learned.

Research by neuroscientist Stanislas Dehaene and his colleagues has shown that learning to read and write changes brain networks involved in vision and language.^[1]

Following written symbols, holding their meaning in mind, connecting them to the surrounding context, and anticipating a conclusion—repeating this sequence is a kind of intellectual strength training.

4. The Matthew effect: the better you read, the more you read

People who read well tend to read more. People who read more gain more vocabulary and knowledge. The more vocabulary and knowledge they have, the more difficult books they can read.

Reading researcher Keith Stanovich called this phenomenon the “Matthew effect.” Early differences in reading ability and experience grow over time into wider differences in vocabulary, knowledge, and comprehension.^[2]

I think this may be the key to all those stories about great people and their books.

Rather than becoming great because they read, perhaps they already had the ability to read well and entered a positive feedback loop early: I can read → I want to know → I read → I understand more → I read even more.

Q3. How can “changing the way you see the world” lead to success?

There is no shortage of stories about voracious reading among the world's super-elite. If we take them all at face value, reading and success begin to look inseparable.

In Q2, I discussed how reading can change “the way you see the world.” Looking at highly accomplished people, it certainly seems as if seeing the world differently could be useful.

So I looked into the idea that it might provide a foundation for success.

Successful people can read reality in finer detail

First, what ability does success require? For the sake of this discussion, I will define it as:

“Reading the situation you are in, finding the resources available to you, noticing gaps that other people overlook, and turning those observations into appropriate action.”

That sounds a lot like reading comprehension.

When we read a text, we look at the words on the surface, interpret the context, fill in unstated assumptions, infer the author's intent, and notice contradictions. The same skills can be applied when we try to read reality.

What reading trains may not be limited to the ability to read words. It may also train the ability to read the structures beneath what is visible.

Knowledge becomes a lens for seeing opportunities

Opportunities do not come with signs saying, “This is an opportunity.”

Imagine seeing a long line outside a shop. One person may think only, “That place is popular.” Another may notice its location, price range, signage, customer base, turnover rate, and even how photogenic it looks on social media. They are looking at the same scene but seeing different worlds.

Some people can see it. To everyone else, it is merely another event.

The knowledge and concepts we gain from reading become lenses through which we can examine reality. The more lenses we have, the more patterns we can detect in things we once passed by without a second thought.

Abstraction lets us apply knowledge across fields

The value of reading is not limited to learning specific facts.

When you read history, business, psychology, and fiction, you begin to see shared patterns in subjects that once seemed unrelated.

• People hate losing things
• Stories move people
• Groups are easily swept along by the prevailing mood
• Public explanations and real motives are often different

Once you can abstract patterns like these, you can use history to think about marketing or draw a design concept from psychology.

You no longer merely “know a lot.” You can connect one piece of knowledge to another.

Q4. What about speed-reading and video summaries?

Speed-reading and video summaries are not pointless. They are useful for grasping the big picture, choosing which books to read, or learning the outline of a subject. But they reduce the friction involved in reaching understanding.

According to work by Maryanne Wolf and others, deep reading involves advanced cognitive processes such as inference, deduction, analogy, critical analysis, reflection, and insight.^[3]

While reading, the brain is not merely looking at words. It is running through complicated internal questions: “What does this mean?” “Why did this person do that?” “What would I do?” “Is this assumption actually true?”

A video summary gives you material that someone else has already organized, so there is less friction on the way to understanding. Speed-reading may help you skim the surface of information quickly, but it can also leave less time to stop and reconstruct the ideas in your own mind. Besides, I cannot read that fast. At some point I am just looking at the page.

The result may be a stronger sense that you “know” something, without necessarily reaching the point where the structure of your own understanding changes.

Perhaps the true substance of reading lies not in the information itself, but in the internal change that takes place along the way.

Q5. What about fiction?

Fiction is thought to have a somewhat different set of effects.

When you read a novel, you follow the characters' motives, misunderstandings, emotions, and differences in perspective. In that sense, it resembles practice in “reading other people's minds.”

For a while, a study suggesting that literary fiction improves theory of mind—the ability to infer other people's mental states—received a great deal of attention. Later replication studies, however, found that the effect was small and varied widely between studies.^[4]

At present, we cannot go so far as to say that reading fiction will definitely make you more empathetic.

What does seem clear is that fiction offers an experience of simulating multiple perspectives from the inside. If nonfiction expands our concepts, perhaps fiction is reading that expands the ways in which we can see other people.

Q6. Does getting smarter mean your IQ goes up too?

According to the National Reading Panel, children who read more tend to show greater fluency, vocabulary, and comprehension. However, it also cautions that the relationship between how much people read and how well they comprehend is correlational; it cannot be reduced to a simple causal claim.^[5]

A longitudinal study that followed 1,890 pairs of identical twins from ages seven to sixteen also found that early differences in reading ability were associated with later differences in intelligence—and that the effect was not limited to verbal ability.^[6]

This does not mean that anyone can become universally brilliant simply by reading a lot of books. Still, reading and intelligence do appear to be related.

Perhaps because the subject is sensitive, nearly every source becomes cautious and qualified at this point. Reading ability, a home environment where books are affordable, personal interests, and pre-existing cognitive traits all interact. There is an element of the genetic and environmental lottery here, so it is probably impossible to draw an easy conclusion.

Reading is likely to develop certain aspects of intelligence.
Its effects appear especially strong in vocabulary, knowledge, comprehension, and reasoning.
But the amount you read does not automatically raise every aspect of intelligence.

That seems to be the safest answer for now.

Conclusion: Maybe “because it's interesting” is reason enough to read

The claim that reading makes you smarter does not appear to be wrong.

But it does not mean that books magically upgrade the brain's hardware. It means gradually building abilities such as:

• Expanding your vocabulary
• Increasing your knowledge
• Compressing information
• Following causal relationships
• Imagining other people's perspectives
• Staying with a long context
• Examining your own thinking

As these abilities accumulate, the way you see the same reality changes.

You may begin to see opportunities, read other people's motives, or free yourself from assumptions you once took for granted.

Perhaps so many great people have stories about reading because books expanded the way they saw the world and improved the accuracy of their actions, which in turn helped them accomplish extraordinary things.

Reading may be a way of adding new senses for perceiving reality.

We cannot change the IQ or family circumstances we were born with. But reading is intellectual capital that we can accumulate later, which may make it especially valuable for ordinary people.

Then again, reading while overthinking all of this sounds exhausting. Maybe it is enough to read simply because a book is interesting.

And with that, I think I will go reread World Trigger.

Notes