What to Know About IQ Tests

Medically Reviewed by Jabeen Begum, MD on November 25, 2022
5 min read

IQ tests have had a somewhat controversial history. Despite that, they’re still a popular way for people to judge their intelligence against others. But how do IQ tests judge intelligence, and are these tests accurate? 

Intelligence quotient, usually shortened to IQ, is a measure of how well someone uses information, logic, and reasoning compared to their peers.

The first test for measuring IQ was developed by psychologist Alfred Binet in 1904. He believed intelligence primarily meant common sense but that it was a combination of many different skills that could be heavily shaped by the individual’s environment. He originally developed his test to measure the intellect of French schoolchildren, with the hope that his research would be used by teachers to adjust their teaching methods to help individual students.

When the idea of IQ tests came to America, things shifted. While some researchers believed, as Binet did, that intelligence was learned and was a combination of skills, others believed it was a single trait passed on through genetics. This led to proponents of eugenics co-opting IQ and IQ tests for their movement. IQ was used to justify the sterilization of people in the state’s care, like those in mental hospitals, care homes, and prisons. By 1935, 20,000 people had been forcibly sterilized in the U.S.

In 1922, Harry Laughlin, the superintendent of the Eugenics Record Office, argued that while IQ was a start, the U.S. should work to eliminate what he called “the most worthless one-tenth of our present population,” which included the blind and visually impaired, deaf, and those dependent on the government, including orphans and homeless people. While most states didn’t take these suggestions to heart, the German government did. Its Hereditary Health Court, Erbgesundhetsrecht, sterilized nearly 380,000 people before the start of World War II.

While the use of IQ tests to promote eugenics was often racially motivated, it wasn’t always. One of the most well-known court cases of this era is Buck v. Bell, which appeared in front of the Supreme Court in 1927. The state of Virginia had passed its compulsory sterilization law in 1924, and Carrie Buck, an 18-year-old white woman, was the first person the state selected for sterilization. 

At the time, Carrie was involuntarily committed to the State Colony for Epileptics and Feeble-Minded. Harry Laughlin provided a deposition in the case, stating that IQ tests showed that Carrie had a mental age of 9 years and her mother, Emma, had a mental age of 8 years. Clearly, their feeble-mindedness was inherited, Laughlin claimed. This was supported by a social worker who claimed that Carrie’s daughter, Vivian, suffered from the same mental deficiency. Vivian was 6 months old. Carrie did not win her case. 

As research into IQ has continued over the years, science has come to agree with Binet’s original belief: that intelligence is not genetic but learned and multifaceted. In 1984, researcher James Flynn discovered that IQ scores had been steadily rising over the last several decades. Dubbed the “Flynn Effect,” he theorized that there are a few reasons for this, including:

  • Higher-quality education
  • Nearly unlimited access to information
  • More frequent exposure to cognitively demanding tasks
  • Better health and nutrition 

As research continues, IQ tests become more varied. Psychologist Howard Gardner created a multifaceted IQ test that measures not just verbal and mathematical skills but also mechanical, musical, physical, and social skills. Psychologist Robert Sternberg has developed an IQ test that measures analytical, creative, and practical intelligence. He believes that practical intelligence, or common sense, isn’t well measured by traditional IQ tests but that it’s a better indicator of future job success than traditional IQ tests are.

There are many different types of IQ tests, but they all ask questions designed to get an idea of someone’s general intelligence. The type of IQ test you take will depend on your age, your culture, and even the IQ test’s purpose. 

Some IQ tests are designed for children at specific ages, while others are designed for adults. Some workplaces will give IQ tests to understand how their workers think and what to look for in new hires. Even the SAT was developed based on the army’s IQ test.

Some IQ tests test crystallized intelligence, which is essentially your knowledge. Others test fluid intelligence, or your logic and reasoning skills. Some tests may measure both. Depending on the way your brain thinks, you may score higher on one type of test than another.

You can take an IQ test in person or online, depending on which you prefer. There are a number of places and websites that offer IQ tests.

Once you’ve scheduled your test, there isn’t much you need to do to get ready. Some places offer practice tests to try, or you can find practice tests online. Otherwise, make sure you get enough rest and eat a good breakfast before your test. 

The results you get will vary with the type of test you take. To get an idea of how well you scored, look at your test’s IQ test result scale.

It’s been over a century since Binet developed the first IQ test, and the accuracy and usefulness of these tests are still being debated today. This makes sense when you consider that the original use of the test, to help teachers adapt to their students’ learning styles, is very different from the way they're used today and have been used in the past.

In his 1987 article “Massive IQ gains in 14 nations: What IQ tests really measure” for Psychological Bulletin, James Flynn concluded, “IQ tests do not measure intelligence but rather a correlate with a weak causal link to intelligence". If intelligence is truly multifaceted, as Binet, Gardner, and Sternberg believed and as research seems to indicate, how can one test truly give an accurate assessment of overall intelligence?

The American Psychological Association doesn’t believe we should do away with IQ assessments completely. Instead, they call for more research into IQ testing so it can be used to maximize learning opportunities rather than create an additional barrier.