IQ - Intelligence Quotient
Intelligence is the mental ability to respond to new and changing situations in a purposeful way that demonstrates comprehension, learning, abstract thinking, and problem solving capabilities. An IQ is a number that attempts to measure a person's intelligence.
IQ tests are calibrated to give people with average intelligence a score of 100, with numbers above and below this following a Gaussian curve (see chart). As a result, most people will have an IQ that clusters around the middle of the graph, with a few people lying at the edges.
Correlation with Success
IQ is often measured because it correlates well with success in a variety of life events. People with high IQs generally finish a higher level of education, have bigger incomes, do better at their jobs, have lower violent crime rates and have better health. It should be noted that IQ seems to be independent of self-assessed levels of happiness.
There are a number of standardized tests that attempt to measure a person's IQ, however there is some debate about the accuracy and validity of many of these tests. Several popular tests have been shown to be culturally biased. For example, someone who grew up in Asia and then took an English based IQ test might receive an inaccurate score. Some tests claim to correct for this problem.
The first IQ test was developed by a psychologist named Alfred Binet to help identify students who might need extra help in school. This test was later refined by Stanford Professor Lewis Terman into the "Stanford-Binet" test, which is still used today to identify gifted students.
The first test to measure intelligence in adults was designed by Dr. David Wechsler and was called the "Wechsler Adult Intelligence Scale" (WAIS). He also created a test for children called the "Wechsler Intelligence Scale for Children" (WISC). The unique thing about these tests is that they report separate scores for verbal and performance IQ. This gives the ability to judge intelligence independent of verbal ability. These tests are still in use today.
Some scientists argue that intelligence is such a complicated concept that comes in so many different flavors, that it is impossible to condense it all into a single number. One common theory, proposed by psychologist Howard Gardner, is that there are eight different types of intelligence: interpersonal, intrapersonal, kinesthetic, linguistic, logical, musical, naturalistic, and spatial.
Traditional IQ tests do a good job of measuring linguistic and logical intelligence, but they fail to measure intelligence in the other areas. For example, a virtuoso piano player or a gifted athlete may score low on a written IQ test, even though they may have a high intelligence in their area of expertise.
Good aptitude tests that demonstrate that these different types of intelligence are independent of each other have yet to be made.
The most accurate way to get your IQ tested is to take an official IQ test given by a qualified professional. Many psychologists are trained to administer the test and it shouldn't be too difficult to locate one in your area.
There are a number of books, that you can find at a bookstore or library, with self-tests that you can take and score at home. While these are not official tests, they can give you a good idea of your IQ score. The Amazon.com box to the right may contain some useful books about IQ and IQ tests.
It is also possible to estimate your IQ from certain standardized test scores. Braingle's IQ calculator can estimate your IQ from SAT or GRE test scores.
It is also possible to estimate your IQ by taking Braingle's IQ test. This is not an official test, but it can give you a good idea of what you may score on an offical IQ test.