What is IQ, and how predictable is it?
Albert Einstein and Stephen Hawking are perhaps the most famous geniuses in modern history. Although there is no evidence that either man underwent an IQ test, it is estimated that both scored around 160 on the IQ. While this is an impressive score, it's not even close to being the highest IQ or IQ in the world, and this raises several questions: What is IQ? If you're working with the goal of becoming smarter, what does your IQ score mean, and does that matter? Can he predict whether you will live an ordinary life or make pioneering contributions to society?
Show key points
- Albert Einstein and Stephen Hawking are believed to have IQs around 160, yet even such high scores don't represent the peak of recorded human intelligence.
- IQ, or intelligence quotient, is calculated through standardized tests that aim to measure various cognitive functions and has evolved from its original purpose of comparing mental and chronological age.
- Modern IQ tests assess a wide spectrum of abilities like verbal reasoning, math skills, visual-spatial analysis, processing speed, and memory.
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- While IQ can indicate general intellectual potential, it doesn't encompass traits like common sense, emotional intelligence, or practical decision-making skills.
- Contrary to popular belief, intelligence as perceived in daily life or school performance doesn't always align with measured IQ scores.
- IQ remains relatively stable throughout a person's life, though certain abilities such as processing speed may vary with age and are considered in age-adjusted scoring.
- Levels of IQ are categorized on a bell curve, with average intelligence centered at 100, and scores above or below illustrating standard deviations from the mean.
While you can improve your cognitive ability using brain-enhancing methods, such as finding new hobbies, learning something new, or mastering a new language, your IQ tends to be stable. We spoke with experts to better understand the meaning of IQ and its implications. Here's what they had to say.
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What is IQ?
IQ means IQ. It is a numerical result that results from performing one of the many standardized tests that measure specific cognitive abilities.
When IQ tests were first developed in 1912, the score was intended to reflect a person's "mental age" ratio divided by chronological age and then multiplied by 100, according to Minsa International, an association of people who score in the top 2% of total IQ applicants. (Here's a practice test for Mensa's IQ test in order to see if you're eligible to join.) According to this criterion, a person who was 10 years old and who also experienced a 10-year-old mentality would have an IQ equal to 100.
Today, after testing so many people for more than a century, the same score of 100 is considered average.
How is IQ determined?
IQ tests look at different cognitive abilities to identify overall mental or logical abilities," says René Lexo, a PsyD and supervisory psychologist at American Mensa, who acknowledges the existence of different types of intelligence. Simply put, IQ tests measure an individual's ability to think, apply skills, and solve problems."
Several IQ tests are available. Here are some of the most widely used:
Wechsler Adult Intelligence Scale (WAIS IV)
Wechsler Children's Intelligence Scale (WISC)
Woodcock Johnson Cognitive Abilities Tests
Stanford-Binet Intelligence Scale
Progressive Raven Matrices
IQ tests use a range of formats and shapes; some involve multiple-choice questions, while others require a short answer or puzzle solving. These tests can take up to 15 minutes or up to four hours to complete, depending on the test.
What do IQ tests measure?
John DeLuca, Ph.D. in neuropsychology and senior vice president of research at the Kessler Foundation, says, "IQ tests attempt to measure the overall intellectual factor, referred to as a 'g.'" There are a lot of things that go into this factor, but 'g' represents the idea of this global intelligence."
In an effort to assess "g", each IQ test measures a slightly different set of cognitive skills. Lexo says some examples include oral argumentation, mathematical skills, visual-spatial argumentation, processing speed, and working memory. Together, DeLuca says, try to evaluate the verbal and nonverbal aspects of intelligence.
But contrary to popular belief, IQ tests don't determine how smart you are.
"The IQ test will tell you if you have some level of overall intellectual ability," says DeLuca. "Does that mean you have common sense? No, it means that you have the ability to process information at a high level, which doesn't mean you're smart in everything you do. Einstein may have had a high IQ, but that doesn't mean he was able, for example, to make good decisions about his financial life."
Lexo agrees: "Mental intelligence and academic achievement are not the same kind of intelligence." Terms like "intelligent" tend to be subjective and subjective, she adds, anyway. For example, parents may describe their children as smart because they can memorize or perform certain actions, but when measured objectively, these children can only be of average intelligence – sorry parents!
Conversely, a person with a reading disorder, such as dyslexia, may get poor grades in school but perform well in the non-verbal and verbal components of the IQ test, thus showing high intelligence.
What do IQ scores mean
IQ tests are scored on the bell curve, with a score of 100 – the top of the bell shape on the graph – reflecting average intelligence. DeLuca says that with this scale, 50 percent of people would get 100 points. Scores above or below that score are located on either side of the bell and reflect standard deviations from the mean.
IQ scores also take into account age, because it's normal for certain aspects of intelligence to change over time. For example, your processing speed at age 20 is likely to be faster than at age 50, explains Deloka, so the results reflect the average for your age group. So, even if you take the same test 30 years apart, your IQ score should remain roughly the same.
Just as each IQ test measures slightly different aspects of intelligence, each test also divides the range of scores slightly differently. With that in mind, this is how one of the most common IQ tests ranks the results:
Stanford-Binet
Above 140: genius or semi-genius
From 120 to 140: Very Superior Intelligence
From 110 to 119: Superior Intelligence
90 to 109: Average or normal intelligence
From 80 to 89: dullness
70 to 79: Borderline Lack of Intelligence
Under 70: impaired mind
