History and Development of IQ Tests
Interest in intelligence and subsequently a method of defining it and quantifying it led to the development of IQ tests or Intelligence tests. An English scientist by the name of Sir Francis Galton was amongst the pioneers in the development of intelligence testing.
He believed that intelligence, like some human traits, was passed down genetically from generation to generation. He then set out to develop an intelligence test. His tests were revolved around sensory perception and reaction in order to determine the level of intelligence. One major setback faced by Galton's test was that scoring well on his test did not indicate that a student would perform well academically, which at that time was considered practical proof of good mental ability.
Another person who was deeply interested in intelligence testing was Alfred Binet, a French pyschologist. He had been conducting research on mentally handicapped children together with a young physician named Theodore Simon. During that time, the French education ministry conducted a study on the education of mentally handicapped children. As a result, Simon and Binet were hired to develop an assessment method. This led to the development of the first IQ test. The test focused on a range of mental functions, such as attention, memory discrimination, imagination, and verbal fluency. The test also resulted in the Simon-Binet Intelligence Scale.
A revision of the test was done a couple of years later when certain problems were noticed by an American pyschologist, Lewis Terman. The revised test and scale became known the Stanford-Binet Scale, which has been the standard against which all subsequent tests have been measured. Lewis Terman was also the man who introduced the word IQ, or Intelligence Quotient.
The Stanford-Binet Scale itself had certain limitations especially when applied to adults due to the equation used in the scale. Modern IQ tests for adults compare an individual's test score against others in the same age, with the average test score result being assigned as 100. The word IQ is still widely used in reference to the score of an intelligence test.
What is an IQ score?
An IQ score an individual's intelligence quotient score. Originally this number was calculated from this formula.
" 100 x mental age/chronological age "
This formula is a simplification of the actual scale known as the Stanford-Binet Intelligence Scale. Aged based scales have a limitation as they do not work well for adults. Almost all modern IQ tests adopt the normal distribution method of scoring, which was first developed by David Wechsler. In his intelligence test, known as the Wechsler Adult Intelligence Scale, the individual's test score is compared against others in the same age, with the average test score result being assigned as 100. In a graphical representation, it takes the form of a Gaussian bell curve with the center value of 100.
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