What Is an IQ Test?

What Is an IQ Test, Anyway?

Our president loves challenging people to take IQ tests, but that doesn't mean quite what he thinks it does.

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By Avery Thompson

If you like dumb fights about being smart, it's been a good week for you. First came reportsthat Secretary of State Rex Tillerson allegedly called Donald Trump a "f**king moron." In response, Trump did not fire Tillerson but instead, in a recent Forbes interview, challenged the secretary to "compare IQ tests."

Challenging people to compare IQ scores is one of Trump's go-to moves when he feels his brainpower is being insulted. And it shouldn't be surprising the president always falls back on IQ. In the century since it was invented, intelligence quotient has become an all-consuming stand-in for brainpower. It's (a little too) easy to understand the idea of one number that tells you how smart you are—and whether you're smarter than somebody else. In fact, the reality of IQ is much more complex.

While people have been administering intelligence tests for centuries, the first truly standardized intelligence exam was developed by French psychologists Alfred Binet and Théodore Simon in 1905. Their test, called the Binet-Simon test, was designed to evaluate a subject's "mental age" by comparing their answers to several questions to the average for their age group.

Binet-Simon proved successful in France and the test was translated into English. In 1915, it was modified by Stanford psychologist Lewis Terman and gained the new name Stanford-Binet. The Stanford-Binet test became the most common method for testing intelligence in the United States throughout the first half of the 20th century.

Then, in 1955, David Wechsler published the Wechsler Adult Intelligence Scale. Wechsler introduced a number of improvements over the Stanford-Binet, including a better-designed structure and a nonverbal component, which allowed researchers to evaluate test subjects who lacked strong language skills. His method rapidly overtook Stanford-Binet as the most common kind of intelligence test. Even today, what we typically think of as an "IQ test" is almost always the Wechsler test.

Wechsler, like most modern IQ tests, records a subject's ability to answer a broad range of questions and compares them to other test-takers of the same age. Take a quick online version of the test and you'll see what kind of questions appear. Some require mental math—or, at least, being able to think quickly about numbers. Some are the kind of logic puzzles you might remember from the SAT (X is to Y as Z is to _____).

The idea is to measure a person's critical thinking skills—not, say, whether they achieved a Jeopardy!-level of book smarts by memorizing facts. Someone who is more competent than others of the same age will receive a higher score, while someone less competent will receive a lower score. Test-makers try to evolve the test so that the average IQ stays at 100.

Ideally, researchers choose a set of questions that test a person's ability in a number of broad categories like "verbal comprehension," "spatial reasoning," or "working memory." But like any standardized test, IQ is an imperfect way to measure intelligence. It shows how good a person is at answering questions, which—depending on the questions—may or may not have anything to do with the nebulous, difficult-to-define concept of intelligence.

Beyond the grand problems associated with standardized tests and the way we allow them to influence our world and our attitudes toward people, there are some specific issues with the IQ test and using this particular test as our society's stand-in for smarts. Look up "criticism of IQ testing" and you'll find a host of problems with the test, such as:

• There are a number of cultural or environmental factors that can influence the results.
• IQ testing minimizes the role of creativity in intelligence and problem-solving.
• IQ testing is a little too much like phrenology—the 19th century pseudoscience that proposed a person's head and brain shape was tied to their intelligence—in that it provides a scientific-sounding rationale for data that appears to show people of some backgrounds are smarter than others.
• The test is outdated and hasn't been changed enough since the 1950s.

You could spend all day going down a rabbit hole of arguments about IQ, and about which is the best and fairest way to measure human intelligence. At the end of the day, IQ is useful as a research tool, but not for much more than that. New studies back up what is becoming increasingly clear about the brain: Trying to pin down brain power and potential with IQ or any other single test is a hopelessly outmoded and subjective way of thinking about what makes a person intelligent.

Everybody wants a hard, scientific-sounding number that tells them how smart they are. Who wouldn't want to get into Mensa? But IQ is not the easy, definitive statement of a person's intelligence that Trump and many others believe it to be.