Intelligence quotient Facts for Kids

IQ scores in a group of people often follow a bell curve. Most people have an average IQ.

An intelligence quotient, or IQ, is a number. This number is the score you get from a special test. These tests are made to measure how intelligent a person is.

IQ helps us compare people. It shows if someone's score is above or below the average. The idea for these tests started in the early 1900s. The tests try to ask questions that don't need specific school knowledge. They aim for questions anyone might be able to answer.

One common IQ test today is the Wechsler Adult Intelligence Scale. It shows where a person's score fits on a bell curve. This curve usually has an average score of 100.

IQ scores can tell us more than just intelligence. This is because intelligence is linked to other parts of life. For example, higher IQ scores can sometimes predict how well someone will do in school. They can also give clues about the kinds of jobs a person might be good at. Scientists also use IQ scores to study groups of people.

People still discuss how much of a person's IQ comes from their parents (inherited). They also debate how much depends on their environment, like their home and school life.

IQ scores are used in different ways:

To guess how well someone might do in school.
To help understand what jobs a person might be good at.
To study how IQ scores change in a population over time.
To see how IQ is connected to other things about people.

The average IQ scores for many groups of people have been going up. They have risen about three points every ten years since the early 1900s. This is called the Flynn effect. Scientists are still debating if this rise means people are actually getting smarter. Or if it means there were problems with how tests were given in the past.

What is the General Factor (g)?
IQ Tests in the United States Military
Problems with IQ Tests
Images for kids
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What is the General Factor (g)?

There are many different kinds of intelligence tests. Some tests use only pictures. Others use only words. Some focus on solving puzzles or simple maths. Other tests look at how well you think about shapes, read, or remember things.

Scores from these different tests often go together. If someone scores high on one type of test, they often score high on others. A psychologist named Charles Spearman noticed this in 1904. He studied how different intelligence test scores were connected.

Spearman found that a single common factor could explain why test scores were related. He called this factor g. The g stands for "general factor" of intelligence. This means that a person's intelligence could be described with one number. Tests that involve solving puzzles or problems are usually best at showing a person's g score.

So, an IQ test tries to measure this g factor. One well-known test for g is Raven's Progressive Matrices. This test uses visual puzzles.

IQ Tests in the United States Military

During World War I, the U.S. military needed to test new recruits. They wanted to figure out what jobs each soldier would be best at. So, they started using IQ tests.

These tests caused some debate at the time. Special tests were made for people who didn't speak English. After the war, the success of these army tests helped make psychology a respected field. More jobs and money became available for psychologists in the United States. Group IQ tests then became common in schools and businesses.

Problems with IQ Tests

People have different concerns about IQ tests. These concerns come from various areas of study. Here are some of the main problems:

What is intelligence? There is no single agreement on what intelligence truly is. So, some people question if IQ tests can really measure it. However, psychologists say the tests don't measure intelligence directly. They see the tests as a way to guess intelligence. This is because people with higher scores usually can do harder tasks.
Combining different skills: Some people think it's wrong to combine many different skills into one single "intelligence" score.
Original purpose: The first IQ tests were made for school children. They helped find kids who needed extra help. Some argue this is different from measuring "intelligence." A child needing more help might not be less intelligent. They might just come from a different background.
Cultural bias: Some tests might be easier for people from certain cultures. People from other cultures might score lower, but they are not necessarily less intelligent.

Do Tests Really Measure Intelligence?

Alfred Binet, a French psychologist, created one of the first IQ tests in 1905. He believed his test could not truly measure intelligence. He used it to find which students needed special help in school.

Binet thought that with good teaching, most students could do well in school. He believed this was true no matter their background. He did not think intelligence was a fixed thing that could be measured with one number.

Some experts completely disagree with using tests to measure mental abilities. For example, paleontologist Stephen Jay Gould argued that IQ tests were based on wrong ideas. He said they were used to support scientific racism. He believed the "general intelligence factor" (g) was just a mathematical idea, not a real thing.

However, IQ tests were very helpful in the military during wartime. This suggests they do measure a useful mental ability. So, IQ scores are not just a made-up idea. They relate to how well people can do certain tasks. Even if experts don't agree on what intelligence is, it doesn't mean the tests are useless. In everyday life, people do notice how intelligent others are.

Can Tests Be Biased?

The American Psychological Association (APA) looked into IQ tests. Their report said that IQ tests predict school success for people of African descent just as well as for people of European descent. This means the tests are not biased against African Americans in this way.

However, IQ tests might be biased in other situations. A study in 2005 found that the WAIS-R test might have cultural influences. This could make it less accurate for Mexican American students. Other studies have also questioned if IQ tests are fair in places like South Africa.

Standard IQ tests, like the Stanford-Binet test, are often not good for children with autism or dyslexia. Using other measures for these children has sometimes led to wrong ideas. For example, some thought many autistic children were mentally delayed.

Historically, claims of low intelligence were used to justify unfair systems. For example, they were used to support the feudal system and unequal treatment of women.

The View of the American Psychological Association

In 1995, the American Psychological Association (APA) created a group of experts. Their job was to write a clear statement about intelligence research.

The APA group found that IQ scores are very good at predicting how well individuals do in school. They also confirmed that IQ predicts adult job status. This is true even when other factors like education are considered. The group also found that differences in intelligence are greatly shaped by genetics. Both genes and environment work together to develop a person's intelligence.

They also stated that there is little proof that a child's diet affects intelligence. This is true unless there is very serious lack of food. The APA group agreed that there are big differences between the average IQ scores of Black and White people. They said these differences are not due to problems in how the tests are made. The group suggested that differences in social status and culture might explain these gaps. They also noted that environmental factors have made average test scores go up in many groups of people.

Images for kids

Psychologist Alfred Binet, who helped create the Stanford–Binet test
Psychologist Raymond Cattell studied different types of intelligence
Physicist Stephen Hawking. When asked his IQ, he said: "I have no idea. People who boast about their IQ are losers."