Does IQ Really Measure How Smart You Are?

When people talk about smarts, Intelligence
Quotient or IQ always seems to come up. People love to bring up how Einstein had a
genius-level IQ of 160. And to join Mensa, you need to have an IQ
of at least 130. But is IQ even a good way to measure intelligence? Well, that depends on how you define intelligence. IQ scores may be a useful shorthand to talk
about education strategies for big groups of people, like when discussing public policy. But IQ can be affected by a lot of factors,
even things as subjective as your motivation while taking the test. The first sort of IQ test was invented by
the French psychologist Alfred Binet in the early 1900s. A law in 1882, aimed at egalitarianism, said
that any healthy child had to go to school and learn the basics, like: reading, writing,
arithmetic, history, public policy, and the natural sciences. The law even included special consideration
for children with disabilities, like deafness or blindness. But the French government acknowledged that
not every kid would able to keep up with the normal curriculum, for lots of possible reasons. So, Binet and other psychologists were commissioned
to create a standardized test to measure how different kids handled their schoolwork. Along with Théodore Simon, Binet developed
the Binet-Simon test – in which children would answer a series of questions until they
couldn’t anymore. That way, kids could be grouped in classes
with students with similar scores, instead of relying on their age or the subjective
judgments of teachers. In the next decade or so, this scale was revised
for use with both kids and adults and renamed the Stanford-Binet Intelligence Scales. This popular IQ test is still used today,
along with other standardized tests that are meant to measure learning ability – sometimes
defined as how quickly and easily we learn new things. On early versions of the test, IQ was calculated
by taking a person’s score on a standardized test, dividing it by their chronological age,
and then multiplying the result by 100. In more modern versions, you’re basically
ranked against other test takers. The scores of a group of people are scaled
so that 100 is the average, and your IQ score is determined based on where you are in relation
to that average. But here’s the thing: whether or not IQ
tests actually measure your intelligence depends on how you’re defining intelligence. In simple definitions, intelligence is the
ability to learn new things or adapt to new situations. But the definition can also include the ability
to use logic or reason, or to think abstractly. These definitions are all focused on intellectual
capacity, which is how intelligence is defined by the American Psychological Association. And they don’t include other kinds of intelligence,
like social or emotional intelligence, or things like creativity, or self-awareness. The Stanford-Binet test, for instance, focuses
on testing five main categories of information: baseline knowledge, basic mathematics, visualizing
objects in space, working memory, and fluid reasoning – or the ability to solve new
problems. So, depending on what you’re trying to understand
about someone, IQ tests might be useful, or they might be a waste of time. It also turns out that your IQ score can be
affected by a lot of different things – and because intelligence is so complex, we’re
not sure how strongly different factors might affect it. There’s some evidence that says cognitive
abilities are somewhat heritable, meaning there might be some kind of genetic component
to IQ. But it’s not that simple! Recent studies have shown that IQ tests are
affected by motivation. For example, one 2011 meta-analysis found
that people who are offered cash if they do well on an IQ test scored higher than people
who weren’t offered anything. Like, up to 20 points higher for just a 10
dollar reward. That’s a huge effect! And we know that motivation can play a role
in other things, like your grades and your career path, that could be wrongly chalked
up to just an IQ score. IQ also seems to be affected by environmental
factors. Cultural values can influence your IQ scores. For example, a kid who grows up in a community
that prizes storytelling might do better on verbal sections of the test, or problems that
require you to remember and reuse information. How much education you get – and the quality
of that education – may have an effect, too. Kids who miss school because it’s hard for
them to get there, or who attend schools without many resources, tend to score lower than their
peers. Even your family environment can affect your
IQ, like whether you grow up in a low-income household or whether you experience a lot
of trauma as a kid. So, like a lot of things, IQ seems to result
from a mix of nature and nurture. There are just so many factors that affect
your learning ability as you grow up – from the environment you develop in before you’re
born, to things like education opportunities and family dynamics. But psychologists seem to agree that one thing
that seems to help people with learning and academic achievement is thinking about intelligence
as a thing that can change. So IQ tests aren’t anywhere near perfect
or comprehensive, but they can help us predict how people might learn in the near future,
which can make a difference in the support they receive. For instance, IQ scores can affect diagnosis
of intellectual disability, which can inform public policy about education programs to
support different students. It’s understandable why it’s valuable
to have a standard way to sort-of measure intelligence, like when it comes to making
these general policy decisions. But it’s also easy to see why IQ tests have
been surrounded in controversy, too. There’s a lot we don’t understand about
intelligence, and a lot that an IQ score can’t tell us about a person or groups of people. So while IQ can be a useful shorthand in some
cases, it is not something would set in stone and do not let a number define you. Thanks for watching this episode of SciShow
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