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IQ and Intelligence: Everything You Wanted to Know About IQ Tests


Update 02.02.2024

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8 min

IQ and Intelligence: Everything You Wanted to Know About IQ Tests

You’ve probably seen something like this on the news: “A nine-year-old child with an IQ of 155 completes his bachelor’s degree.” But have you ever wondered what IQ actually means? If a 9-year-old graduates from college, they are obviously intelligent, but are they smarter than you? If so, how much smarter? Does it even matter if you have an average IQ in a world with so many diverse pathways to success? What is an average IQ anyway?

If you have asked yourself at least one of these questions, this article is for you. Allow me to answer your questions so you can finally understand why IQ is mentioned so often in popular culture. First, let’s define what IQ means.

What is IQ and how is it measured?

IQ stands for intelligence quotient and measures a person’s ability to reason and solve problems. “A quotient of what?” you might ask. Well, we need to take a short journey into the history of intelligence tests to answer this question.

Scientists have tried to design generalized intelligence tests since the late 1800s, but in 1905, a Frenchman named Alfred Binet created the first modern-day IQ test.

Binet wanted to evaluate children’s cognitive abilities by comparing their mental and biological age. How did he figure out their mental age? Ask them general knowledge questions and have them perform reasoning tasks that an average child their age could perform correctly.

If a 6-year-old child succeeded on all questions that most 7-year-olds answered correctly and then got stumped, the child’s mental age was 7. If a 7-year-old succeeded on all questions, most 8-year-olds answered correctly, their mental age was 8.

To derive an IQ score, he subtracted the age indicated by the children’s cognitive abilities (mental age) from the child’s biological age. Psychologist William Stern agreed with many of Binet’s ideas but thought that dividing mental age by biological age would be a more accurate comparison. 

This calculation meant that if a 7-year-old could solve tasks as well as the average 7-year-old, they scored 7/7, which was an IQ score of 1. On the other hand, a 7-year-old who performed at a level of the average 8-year-old had a score of 8/7, or an IQ of 1.1, which is a little higher than average IQ.

Psychologist Lewis Terman, who worked at Stanford University, further improved the test and suggested multiplying the result of the division by 100 to eliminate the decimal point. Hence, an IQ score of 1 became 100 (which sounds much cooler), and an IQ of 1.1 became an IQ of 110. The test became known as the Stanford-Binet test and is still one of the most popular for measuring IQ.

Now you see what quotient means in IQ and know one method to calculate it:

IQ= Mental age/Biological age x 100

However, this test was designed with questions to test children and doesn’t work for adults. For example, if someone says a 50-year-old performs like an 80-year-old, they won’t take it as a compliment. New tests with more challenging tasks had to be devised to see how adults performed at different ages, on average, and how it declined with advanced aging. 

How is IQ measured in adults?

The most common adult IQ test today relies on a method developed by David Wechsler. Wechsler tested adults across different age groups and designed the test so the average adult in each age group would score 100, or a normal IQ. There’s a range of average IQs, with some people scoring above 100 and some scoring below it. But I’ll talk about that in more detail later.

First, I want to emphasize what exactly this IQ test measures: cognitive abilities only. This means that when taking an IQ test, you only evaluate a few parameters:

  • Skills and knowledge acquired throughout life
  • Verbal and nonverbal abilities
  • Ability to reason to perform new tasks that can’t be performed automatically (fluid reasoning)
  • Ability to analyze and interpret real-world quantitative information (quantitative reasoning)
  • Ability to make sense of surrounding and abstract information and solve problems

An IQ test doesn’t consider emotional or creative intelligence, which can sometimes be even more important than “academic” intellect in an era of fast communication.

Pro tip: Take EQ test from Breeze to find out more about how you understand your emotions.

IQ test scores depend on many factors, from test-taking skills to how licensed psychologists interpret the results. Yes, only licensed psychologists should administer IQ tests, so if you decide to take an online IQ test, don’t rely too much on the score because it’s most likely inaccurate.

But what does average IQ even mean? What is the average IQ in America? Does average IQ differ across countries? Let’s answer these questions one by one.

What is the average person’s IQ?

David Wechsler established that, for his test, the average score of people in a given age group was 100. You must also know that one standard deviation from this score is 15. This means you have an average IQ if you score within 15 points of 100 in either direction (in a range between 85 and 115).

What about scores that are higher or lower than the standard deviation? What is a normal IQ? Is an IQ of 80 low? No, it is in a second range of deviation. Everything from 70 to 85 is also considered an average but low average. And everything from 115 to 130 is a high average. 

What is a high IQ and a low IQ, then? And what do they mean?

  • A score over 130 is in the top 2% of the population. It’s considered high and means you may be gifted or even a genius.
  • A score under 70 is considered low and can indicate a developmental disability.

But remember, only a licensed professional can interpret IQ tests, so don’t try to diagnose yourself based on the results of an online test.

Do average IQ scores differ across countries?

Let’s move on to another question. Do average IQ scores differ across countries? The short answer is yes, but not enough to produce any conclusions about why.

According to research by the Ulster Institute in 2019, the three countries with the highest average IQ are Japan (106.48), Taiwan (106.67), and Singapore (105.89). The average IQ in China is 104.1, placing it in the top five countries with high IQs, together with Hong Kong in fourth place.

Meanwhile, the average IQ in the US is 97.43, which means it’s not in the top 10 countries. Still, you can see that people in most countries have an average human IQ in the range of 70 to 107. 

Do these average scores prove anything about the intelligence of people from different countries? No. It only shows that one approach to measuring intelligence can’t be applied to everyone, as social, economic, and political factors affect people’s performance. In fact, if we look at other types of intelligence tests by country, we can see that the same countries rarely made it to different top 10 lists.

So, yes, IQ tests aren’t entirely accurate because they don’t take into account the different factors affecting a person’s score. Many sources cite the Ulster report, but it remains controversial since it doesn’t account for participants’ socioeconomic status, education, culture, sociopolitical situation, etc. This is important as various factors can influence IQ.

Girl is reading about whats is IQ, What is average IQ score

What can change my IQ level?

There are three ways your IQ can change.

Different psychologists may interpret your results in different ways

As I’ve already mentioned, the results of IQ tests depend on interpretation, and there’s a lot of research pointing to controversies over interpretation. For example, researchers have found that women perform slightly better on some verbal tasks, and men perform better on some spatial ability tests. If a specialist who interprets results believes that spatial ability is more important for IQ or is biased against women, they may give men a higher score. The same goes for racial differences and other biases, which is frustrating, but it happens.

Education and lifestyle changes

In this context, a lifestyle change doesn’t mean taking up running or going to fancy places. Those changes won’t improve your IQ. But if you can improve your cognitive skills and make them more efficient, you can score higher on some IQ tests.

Similarly, negative lifestyle changes can lead to a lower IQ score. If you abuse substances like alcohol or drugs, you’re literally killing brain cells, which interferes with your cognitive skills and with acquiring new skills and knowledge. Hence, IQ scores will decrease as a result.


Age is one of the most studied factors that influence IQ.

On the one hand, your IQ can improve as you acquire more skills and knowledge over time, and your brain actively develops until your mid-20s or 30s. One of the most significant differences was reported in research conducted in 2011, which is still quite relevant. Scientists found that teenagers who passed IQ tests in early adolescence improved their scores by 20 points on average four years later!

But age can also negatively affect IQ level, meaning the older you become, the higher the chance of getting a lower score if you don’t train your mental skills. Moreover, older adults are more vulnerable to dementia, which profoundly affects their mental abilities.

Can your intelligence change?

Most scientists agree that it’s possible to improve IQ. Still, mixed opinions exist about enhancing the ability to learn and comprehend information quickly.

An average kid doubtfully can be an adult genius if they study hard. Sure, they’ll learn a lot of facts, develop good learning skills, and be well-educated to excel in their area of expertise. Some people might call them genius, considering their knowledge base and achievements. But this isn’t the same as being a kid who’s a genius from a young age and graduated college at ten.

Hard work can help someone with an average IQ learn new information more efficiently, for example, if they maximize the skill of connecting new information with things they already know. But being an intelligent person who works hard and a genius isn’t the same.

A genius has some innate qualities, or intelligence, that help them perform well on IQ tests from an early age. A person who works hard could be someone with average intelligence who has learned skills and strategies to learn more efficiently.

The same goes for lower IQ. Except in cases of head injury, severe substance abuse, dementia, or other disease processes, you can’t lose your ability to reason even if your IQ score decreases. IQ results and intelligence aren’t the same, although they are often closely intertwined.

The real question is, “Do IQ scores have meaning in real life?” And the answer is no, IQ doesn’t primarily affect your chance of success. Here’s why.

IQ isn’t everything

There’s a good chance you fall into the average IQ segment—95% of the population scores between 70 and 130. But IQ scores are just numbers that supposedly show how good you are at solving specific puzzles.

Meanwhile, there are many different intelligence tests. They don’t all measure the same kind of intelligence, and comparisons may be invalid, especially if they don’t consider different social, economic, and cultural factors.

You might score differently on different tests, but your scores probably still fall in the average IQ range, whether on the low or high spectrum.

More specifically, you likely have an average IQ in the USA or whichever country you live in, meaning you scored the same as most people where you live.

So, why is the concept of IQ so popular? Because standardized tests make IQ relatively easy to measure, as opposed to emotional intelligence or creativity. People love comparing numbers, especially when arguing about who’s the smartest, and showing off good IQ scores is an easy way to do that.

IQ tests measure specific types of intelligence but don’t evaluate other essential skills that lead to success in life. I mean, it’s terrific if a person can solve a complex math problem.

But if they don’t have social intelligence, someone else who needs a calculator to add numbers but who has high social intelligence may be a better leader because they can manage interactions and resolve conflicts.

Also, rational thinking may not give you any advantage when it comes to fine art, music, and other creative pursuits, where you need to feel your surroundings and develop an artistic vision.


Your IQ score doesn’t really matter since, like the other 95% of the population, you’ll live perfectly well with an average level of intellect. Should you even be concerned with your IQ score? No, because it doesn’t necessarily reflect your real-life problem-solving skills. And I’m sure you have other strengths to brag about.

So, what will you do next time when a test titled “What is your IQ?” pops up online? Correct! You skip it to save your time and whatever price it charges to send you the results.

Should you take an IQ test if a professional psychologist or other healthcare provider offers one? If you’re curious, go ahead. But remember that IQ isn’t everything, and you have many other talents and traits to focus on.

Better take a stand for your emotional well-being. You can get a personal mental health plan from Breeze after taking accurate and fun mental health tests to learn more about yourself.

Joy Ismail, PhD, shares her opinion on why IQ isn’t everything: Intelligence is a measure of overall cognitive function, including memory, language, problem-solving, planning, and attention. IQ tests only measure a very restricted set of cognitive processes and, therefore, are poor indicators of intelligence. In the recent decade, we have understood—as scientists and as people—that there are many types of intelligence and learning styles. Some individuals excel at problem-solving tasks, while others possess remarkable memory capacities, and still others exhibit savant-like musical abilities. None of these is superior to the other, and IQ is no longer a satisfactory measuring stick for intelligence or ability.
Joy Ismail, PhD photo

Reviewed by Joy Ismail, PhD

Joy is a neuroscientist, researcher, scientific consultant, and science writer. She holds a PhD in Biomedical Sciences (Neuroscien...