The science of IQ: How it’s measured and what it tells us

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Have you ever wondered how smart you are?

 If you have, well, you’re not alone. All of us probably do that at least every once in a while.

Hence, the invention of IQ tests, which is something we’ve all probably taken at least once in our lives.

Perhaps you’ve taken one for a job application, a mental health assessment, or maybe just for kicks and giggles. 

But how is IQ actually measured and what does it tell us? 

In this article, we will attempt to answer these questions. 

Without further ado, let’s dive in!

What is IQ?

IQ, which is short for intelligence quotient, is a number that signifies a person’s level of intelligence. It is derived from standardized tests created to assess and measure human intelligence and intellectual potential. 

Referred to by psychologists as “fluid and crystallized intelligence”, IQ measures knowledge-based intelligence (crystallized intelligence) and memory-based intelligence (fluid intelligence).

These tests were created to gauge how well a person can solve problems, discern patterns, or make predictions. It measures short and long-term memory and how well people can solve puzzles and problems and how quickly.

Simply put, IQ tests attempt to measure how smart you are.

However, IQ levels are relative and different for different parts of the world. Why is this?

The reason why is actually heavily debated. These differences are widely believed to be caused by genes, environmental factors, social and cultural circumstances, or all of the above.

How IQ is measured

Are you smarter than a fifth grader?

If you have an IQ score of over a hundred, good news! You’re smarter than the average fifth-grade student.

The following is a general overview of IQ scores and what they signify:

  • 1 to 24: Profound mental disability
  • 25 to 39: Severe mental disability
  • 40 to 54: Moderate mental disability
  • 55 to 69: Mild mental disability
  • 70 to 84: Borderline mental disability
  • 85 to 114: Average intelligence
  • 115 to 129: Above average or bright
  • 130 to 144: Moderately gifted
  • 145 to 159: Highly gifted
  • 160 to 179: Exceptionally gifted
  • 180 and up: Profoundly gifted

Most people have an IQ of between 85 and 115. Only a small number of people have an IQ of below 70 (very low) and higher than 130 (very high). 

People with very high IQ include Stephen Hawking and Einstein, who were both estimated to have an IQ of around 160. 

But how, exactly, is IQ measured? How do I know what my IQ is?

As you already know, there are tests you need to take in order to measure IQ. Here are the most commonly used IQ tests:

  • Wechsler Intelligence Scale for Children (WISC-V)
  • Wechsler Intelligence Scale for Adults (WAIS)
  • Stanford-Binet Intelligence Scale
  • Differential Ability Scales (DAS)
  • Peabody Individual Achievement Test

The Wechsler Intelligence Scale for Adults (WAIS) contains 15 subtests, with each subtest measuring a different part of IQ. This includes mathematical skill, language, reasoning, memory, and how quickly you process information. IQ scores are adjusted by age as well.

Usually, these tests are only administered by licensed psychologists. Some of the most common purposes include whether a person is fit for a certain job, assess mental health, or simply to measure your intelligence relative to people who are of a similar age.

What it tells us

“Anybody with [a] very high IQ, they have the ability to manipulate, process and interpret information at a deeper level and a higher speed than the average person,” explained Lisa Van Gemert, a gifted youth specialist from Mensa, the largest and oldest high-IQ society in the world.

But because people aren’t a monolith, IQ is measured in relation to factors such as age, culture, and race.

For example, an American who doesn’t know who George Washington is probably has lower than average IQ in the US, but the same knowledge wouldn’t be significant to a Japanese person’s IQ because it’s largely irrelevant in their society and culture.

Now that we know what IQ measures, what can it not measure?

If you’re street smart, IQ tests won’t be able to measure how smart you are. This is because IQ can’t measure practical intelligence or the ability to make things work. 

If you’re an artist, IQ can’t measure your artistic skills, either. This is because IQ also doesn’t measure your level of creativity or curiosity. 

So if you took an IQ test and found that you have lower than average IQ, don’t fret! It doesn’t necessarily mean you’re stupid.

This is because humans have multiple intelligences, which is not usually measured by IQ tests. 

This means you might be a person with musical and bodily-kinesthetic intelligence, which IQ tests can’t measure. 

If you find that you have a deep, profound understanding of others, IQ can’t measure that, either, because emotional intelligence also can’t be gauged by IQ tests.

However, even if you get a very high IQ score, studies show that being smart is simply not enough to determine if you’re going to be successful. 

This is because a lot of smart people don’t really know how to tap into their fullest potential. 

So how do you turn potential into achievement?

Study shows that successful people are actually more gritty than they were intelligent. 

According to this study, grit has two components: passion and perseverance. 

Passion is defined as the ability to have lasting interest in something, while perseverance is the ability to complete a project all the way to the end despite the challenges along the way.

The study explained that grit improves with age and increases with education. People who graduated college, for example, were found to have more grit than people who didn’t. 

Take that with a grain of salt, however. The authors didn’t really explore the possibility that it might actually be the opposite: people who graduated college might naturally have more grit in the first place, which might have enabled them to finish school. 

But the point still stands: having a high IQ is not enough to be successful. Among many other factors, you still have to put in the leg work in order to succeed. 

Debates and controversies

The concept of IQ is highly controversial.

Some people assume that people of certain sexes, ethnicities, and other backgrounds have lower IQ in order to fuel racist and sexist agenda. 

But this is simply not true.

The American Psychological Association has not found any evidence that supports the claim that certain sexes and races naturally have lower IQs than others.

It also must be noted that IQ is developed by western europeans under their own unique, cultural standards. 

This makes it unclear whether IQ can accurately measure intelligence of non-western or non-European people. 

So if you’re a person of non-European descent, know that IQ tests might not be able to accurately gauge your intelligence.

 There are also several environmental factors that can develop your IQ. This includes, but are not limited to the following:

  • good nutrition
  • regular schooling of good quality
  • laws requiring fortification of certain food products
  • laws establishing safe levels of pollutants, like lead
  • musical training in childhood
  • higher socioeconomic status
  • lower incidence of infectious diseases

We have also already discussed that IQ can’t measure other types of intelligence. A 2012 study actually debunked certain IQ myths. 

The study, which is the largest recorded online intelligence study, analyzed variations in performance under 3 categories: short-term memory, reasoning, and a verbal component. 

Results showed that no one component or IQ could explain the whole of human intelligence.

It also showed that regular brain training did not help cognitive abilities, although aging is a factor that negatively affected reasoning and memory.

Other findings include the following: 1) people who play computer games have better short term memory and reasoning; 2) Smokers had bad short term memory and verbal factors; and 3) People suffering from anxiety had bad short term memory. 

Key takeaways

In essence, IQ is a number that attempts to measure how intelligent you are. The average IQ is around 85-115. Anything lower or higher signifies low or high IQ. 

IQ can be measured using different tests, such as the Wechsler Intelligence Scale for Adults (WAIS), which measures your intelligence through your mathematical skill, language, reasoning, memory, and how quickly you process information. 

However, IQ tests are not one-size-fits-all. IQ is measured relative to age, ethnicity, social and cultural factors, and many others. 

Other types of intelligence can’t be measured by IQ tests. Creativity, curiosity, musical skill, and emotional intelligence are among the many types of intelligence that can’t be measured by IQ. 

This means having low IQ doesn’t necessarily mean you’re stupid, as you might possess other skills that can’t be measured by IQ tests.

Having a high IQ also doesn’t automatically mean you’re going to be successful. While intelligence might be one of the keys to success, a better indicator is grit. Intelligence plus grit equals better, much higher chances to be successful. 

As a concept, IQ is also highly controversial. Some people justify racist and sexist agenda by arguing that certain races and sexes naturally have lower IQ, but this has never been scientifically proven. 

In the end, human intelligence is much too complex to be measured by something as restrictive as IQ. As humans, we’re too multifaceted to be defined by a number. 

So if you’re too fixated by IQ scores, chill out! At the end of the day, we’re too complicated creatures to be defined by just a number. 

Joyce Ann Isidro

Joyce is a writer who believes in the power of storytelling and changing lives by writing stories about love, relationships, and spirituality. A bookworm and art enthusiast, she considers herself a creative-at-heart who likes to satisfy her childish wonder through new hobbies and experiences.

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