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The Intelligence Quotient (IQ)

The first intelligence tests used in the field of psychology

The scales designed by Binet and Simon were the first intelligent tests that became widely accepted at the beginning of the 20th century. The Alpha and Beta army tests, that were used in World war I to assess military personnel, became very popular.

In recent years, the Wechsler scales are the most widely used instruments in the field of psychology for measuring intelligence. The designer of these tests, Wechsler, published his first scale in the 1930s. He used material from the Binet Alpha and Beta tests to make his test. An important feature of his test was, that when calculating the IQ, this test took age into account. In other words, in the computation of the IQ, an age-correction takes place. Because of this feature, the IQ stays constant over the life span.

What does IQ mean?

An IQ tells you what your score is on a particular intelligence test, compared to your age-group. The test has a mean score of 100 points and a standard deviation of 15 points. What does this standard deviation mean? It means that 68 percent of the population score an IQ within the interval 85-115. And that 95 percent of the population scores within the interval 70-130.

Some examples:
What does it mean when your IQ is 100? That means that half of the population scores higher than you. The other half scores lower than you.
And what does it mean when you have an IQ of 130? That means that 97,5 percent of your age group scores lower than you. Only 2,5 percent scores higher.

An easy way to interpret an IQ is to use the following rules:
A score that is no more than one standard deviation (=15) away from 100, can be interpreted as a normal score.
A score that is between one and two standard deviations away from 100 can be interpreted as low (70-85) or high (115-130).
A score that is more than two standard deviations away from 100, can be interpreted as very low (lower than 70) or very high (higher than 130).

English websites about IQ

Majon. A small, but nice site. There are 4 IQ tests on it. The questions that are asked during the tests are good.


IQ Test. Also more information about IQ and the history of IQ.

2h. This site is comparable with 123 Test (on the dutch IQ-link-page), but in english. Lots of banners.

The Spark. When you're done with serious IQ tests, you can pick funny or 'unintelligence tests' here. Original questions.

You can also take a look at our link page for more psychology related tests.

Dutch websites about IQ

Click here to view our dutch page with links to other, dutch IQ sites.



The IQ of Albert Einstein is 160