The first intelligence test
To indicate the intelligence of humans several tests have been developed. We will explain some of them.
The first intelligence test was developed by Sir Francis Galton, a cousin of the famous Charles Darwin.
Galton was interested in the differences in intelligence between human beings, and he believed that certain families were more intelligent than others. Galton administered a battery of tests measuring qualities such as reaction time, breathing capacity and head size.
The present-day intelligence tests
|"The IQ is a ratio of intelligence of a person and that of an
The intelligence test as we know it was formulated by the French psychologist Binet. He assumed that intelligence should be measured by tasks requiring reasoning and problem solving abilities.
Binet thought that a slow learning child was like a normal child but retarded in metal growth. So he concluded that a slow learning child would perform the same as a younger child in intelligence tests. he devised a scale of mental age. Average mental age (MA) scores correspond to chronological mental age (CA). A bright child's MA is above his CA, and a slow learning child's MA is below his CA.
An advantage of the mental aged scale is that it can easily be interpreted.
The American psychologist Lewis Terman used Binet's method to develop a scale for intelligence. This index is called Intelligence Quotient (IQ), and this scale expresses intelligence as a ratio of mental age (MA) to chronological age (CA):
IQ = MA/CA × 100
The 100 is used to make the result better to compare. Numbers like 101, 125 and 89 are easier to handle than 1.01, 1.25 and .89. It is easy to conclude that when a child is smarter than the average (his MA is higher than his CA), his IQ will be above 100, and otherwise.
Tests following the pattern originated by Binet, use a great variety of items to test intelligence. Failure on one kind of item is scored the same way as a failure on another item. So this test does not show any particular strenghts or weaknesses.
To distinguish between various aspects of intelligence, the Wechsler Intelligence scale is developed. This test is almost identical to Binet's test, but it is divided in two parts, a verbal scale and a performance scale.
Another failure of the tests is that performance increases with practice. There are books containing intelligence tests, and when you pratice them a couple of time, you know how to handle every problem so you will score pretty high on an IQ-test.
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