What Is IQ And Is It A Good Measure Of Intelligence?

In short, no. The longer answer is still no.


Jack Dunhill


Jack Dunhill

Social Media Coordinator and Staff Writer

Jack is a Social Media Coordinator and Staff Writer for IFLScience, with a degree in Medical Genetics specializing in Immunology.

Social Media Coordinator and Staff Writer


IQ and EQ (emotional intelligence) supposedly go hand-in-hand. 

Image credit: Brasil Creativo/

The infamous IQ test. Having a high IQ is perhaps the only thing that can make you seem both incredibly smart and incredibly dumb at the same time, depending on who you speak to when bragging. It has a fraught history of questionable science, elitism, and even eugenics, yet it is still used in some of the highest echelons of healthcare and research.  

So, what is IQ, why is it used, and why won’t people stop using it? 


What is IQ?

Intelligence quotient, or IQ, is a test that combines a number of different psychometric tests to form one single metric of human intelligence. It has a dark history tracing back hundreds of years, but French psychologists Alfred Binet and Théodore Simon were among the first to devise a definite test. Called the Binet-Simon test, they designed it as a method of finding children who needed extra help by sending them to special education centers, instead of labeling them as “slow” and sending them to an asylum. 

It centers around the idea that verbal reasoning, visual-spacial skills, and working memory are all components of a larger idea of general intelligence, which can be measured by testing each of the former components. 

The questions were adjusted for age and the score was then divided by the child's age and multiplied by 100 – this was their IQ. Their IQ supposedly measured how well they performed relative to children of a similar age, and could then identify those who would struggle at school and require extra help. 

simon-binet scale
Reproduction of an item from the 1908 Binet-Simon Intelligence Scale, showing three pairs of pictures, about which the tested child was asked, "Which of these two faces is the prettier?"
Image credit: J. E. Wallace Wallin via Wikimedia Commons (public domain)

Intentions were noble when IQ was first conceived, a way to help those who needed it by quantifying something that is essentially unquantifiable. However, as Binet even admitted at the time, the notion of a measurable general intelligence is flawed. Ultimately, their tests were doomed to be misused for nefarious means, which is exactly what happened. 

How IQ has been mishandled throughout history

Throughout history following the creation of a standardized test, IQ has been used by those wishing to feel superior over another class or race of humans, in an effort to segregate or even eradicate those groups. 

IQ testing found a particular home in the surging eugenics movement of Europe and the US, which is the belief that people with desired traits should be selected for and allowed to have children, while those who have undesirable traits should be prevented from doing so. Eugenics was so popular and accepted around the early-mid 1900s that famous faces like Theodore Roosevelt, Alexander Graham Bell, and John D. Rockefeller Jr all subscribed to this horrific ideology. In fact, the original creator of Kellogg’s was such a strong supporter of eugenics, or as he called it “race betterment”, that he attempted to actively prevent the “feeble-minded” from procreating; it may be unsurprising, then, that IQ tests were a powerful weapon in their arsenal against those they wished to remove from society. 

IQ tests were continually used to determine those who were so-called “feeble-minded” during the US eugenics movement. In 1924, the state of Virginia implemented a policy of forced sterilization of people with low IQ scores, a decision that was later upheld by the Supreme Court during a famous case called Buck v Bell, 1927. The idea was that the sterilized woman involved came from a long line of such people and that she must be prevented from continuing it. High-ranking officials even called for the execution of “feeble-minded” people, and it took another 75 years for the US to bar execution of people with mental impairment. 

Throughout these decades of segregation and persecution, the flawed IQ tests were used to claim superiority over those who needed help – the exact opposite of the creators’ intentions. 


From there, most cases of extreme persecution have been at least partially rooted in IQ scores. The Holocaust looked to eradicate low-IQ people, among the many other marginalized groups, while the Civil Rights movement saw Black people beaten with the terribly constructed notion that they had lower IQs on average. Even now, famous studies are still cited by some to demonstrate that people of color, particularly residents of Africa, have lower than average IQs, completely ignoring the poor scientific method, poor metrics of intelligence, and cultural differences that lead to those results being entirely worthless.  

Is IQ a good measure of intelligence?

So IQ has been wielded by the worst hands of human history, that doesn’t necessarily make it a bad measure of intelligence, right? Correct, but the way it is interpreted and used often does. 

In the 1900s, the test was used to marginalize groups based on a single IQ test score. What these tests failed to take into account was that many of those people taking the tests were immigrants, who spoke poor English and so likely didn't perform as well as they should have. It would be like giving the average American a test in Latin and then saying they can no longer reproduce because they failed – those test results mean nothing about the participant’s intelligence. Working class people often scored lower than those educated to a high level, but that does not necessarily indicate overall intelligence, it simply indicates privilege. 

As IQ tests were calibrated for newer generations, scores rose rapidly, at a much faster rate than could be explained by evolution – this is called the Flynn Effect. It’s highly debated why this occurred: it could be education, better food, and healthcare; it could also be that IQ tests simply do not reflect intelligence that well and do not translate into modern cultural settings. 


More recent tests into whether IQ has any clinical relevance haven’t done it any favors, either. A meta-analysis found that correlations between job performance and IQ are flimsy at best, and rife with statistical error at worst. There have been weak correlations found between IQ and success in school, but this may be down to the fact that IQ tests speak the same cognitive language as schoolwork, so a child performing well in academic tasks may feel at home with cognitive tests like IQ. Small links between success and IQ have been found, and some careers even test it, but other predictors of intelligence have just as much – if not more – predictive value. 

Is IQ worthless?

All this is to say that as a measure of total intelligence, IQ does not stack up. However, it is not entirely worthless. IQ tests are an indication of performance for a specific type of cognitive task, ones that can be helpful in academia, careers, and general life. Performing well could bode well for your future, but IQ scores need to be interpreted carefully. 

Human intelligence does not have a single definition – a gifted scientist may not find success in creative fields, and vice versa, but to say one is more intelligent than the other is reductionist. IQ tests are used in research now as a measure of one subset of intelligence, combining towards an overall picture of how smart a person is, but even that is dependent on cultural differences and various other environmental factors. Using it as a metric to compare different groups of people is often poor science, and such investigations are almost impossible with how varied humans truly are. 

All we can do is to stop looking for ways to appear superior and instead look for ways we can help, just like Binet and Simon wished. 


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