Intelligence is the ability to acquire and apply knowledge and skills. This ability becomes more obvious when the person has the chance to learn and practice those skills. Intelligence is rooted in genetics, but environmental factors also play a role in its development (or lack thereof). For example, lead poisoning in childhood is known to reduce intelligence.
Can intelligence be measured?
Spearman’s g
In the early 20th century, a British psychologist named Charles Spearman noticed that children who scored high in one school subject also tended to get high scores in seemingly unrelated school subjects (e.g., writing, mathematics, and music). The correlations between scores in different subjects were always positive. (This finding is called a positive manifold.) This finding also meant that the children who scored poorly on one test tended to score poorly on the others, as well. Spearman concluded that the positive manifold was due to some general mental ability (g) along with various task-related abilities.
Binet-Simon Intelligence Test
The original purpose of intelligence testing was to keep underperforming children in school, as opposed to sending them away to institutions. In the early 20th century, French law required all healthy children between the ages of 6 and 13 to be in school. Thus, the question arose about what to do about children who seemed to lack the mental ability to do schoolwork. Some psychiatrists argued that these children were sick and should be sent away to an asylum. In contrast, the psychologist Alfred Binet argued that these children were merely slow (arriéré [retarded]), not sick. Thus, they should be kept in school.
In 1905, Binet and the psychiatrist Théodore Simon developed a test of verbal abilities. The test was intended to show whether a child was able to do the things that a child of that age was expected to do. This test was translated into English. In 1910, Lewis Terman at Stanford University revised the test, creating the Stanford Revision of the Binet-Simon Intelligence Scale. This became the most popular intelligence test in the United States.
IQ score
The German-American psychologist William Stern coined the term Intelligenzquotient (intelligence quotient) to refer to his method of scoring the results of an intelligence test. Like many traits that are the result of many contributing factors, IQ scores for a population tend to form a bell-shaped curve: most people are close to average, while there a lot fewer people at either tail of the curve. IQ tests are designed so that the average score will be 100, and the standard deviation (a measure of spread) will be about 15.
IQ test scores are normed so that the average is around 100, and the standard deviation (a measure of spread) is about 15. For this reason, most people have an IQ score between 85 and 115. Mensa membership is open to people who score in the top 2%.
Dmcq, CC BY-SA 3.0 , via Wikimedia Commons
What do IQ tests measure?
These observations raise important questions:
- What underlying phenomenon do IQ tests measure?
- What is the best way to measure it?
- How should the tests be designed, and how should the results of the tests be interpreted and applied?
Does IQ matter?
Nobody doubts that having low IQ would make your life difficult and that low-IQ children need special care and specialized services. Fortunately, American society has come a long way in respecting the rights and dignity of people with intellectual disabilities. However, Americans don’t seem to know how to relate to people on the other end of the IQ spectrum, especially the gifted children.
American society has not yet overcome its longstanding anti-intellectualism. Richard Hofstadter explained in Anti-intellectualism in American Life (1963), that widespread contempt for intelligent and educated people (“eggheads”) was a way for middle-class people to express their anger at the educated people who held power over them. This attitude has led to a dangerous disrespect for science as well as for the wisdom of the past, as well as contempt for smart people.
Having a high IQ makes a lot of things easy for you, such as schoolwork. However, high intelligence can also make a person’s life difficult in surprising ways:
- Schools are set up for typical students, not for extremely bright ones. As a result, bright children may not fulfill their potential.
- People with above-average intelligence typically have above-average social skills—because they tend to have better skills in many different domains. However, having extremely high IQ can make one’s social life difficult.
People who are somewhat above average in IQ can use their intelligence to understand other people better—but they are still basically like typical people. In contrast, people with really high intelligence will think so differently than others that it creates a social gulf that is hard to bridge. Yet there is a simple solution to this problem: find other brilliant people to socialize with. That’s why so many Mensa members say that Mensa is “where everybody gets your jokes!”
Mensa’s mission
Mensa’s constitution states a threefold mission:
- Identify and foster human intelligence for the benefit of humanity.
- Encourage research in the nature, characteristics, and uses of intelligence.
- Provide a stimulating intellectual and social environment for members.
Further reading
To learn more about intelligence, check out the following:
