History of IQ Tests

First recorded tests for identifying the intellectual skills were the Imperial Examination System that started in 605 to select best officials for the administrative service of imperial China. The system lasted for 13 centuries till 1905 because of the effectiveness of the system. Father of the modern intelligence tests was Sir Francis Galton. His intelligence tests were non verbal sensory tests. They were described in the article, “An inquiry into Human Faculty” that was published in 1883. These tests were designed for the adults and were initially popular. But the test results did not have a correlation with college grades and were abandoned later.

Mental Age and the Intelligence Quotient

Some other mental tests developed by Cattell, Munsterberg and Jastrow during the period 1889-1893 were also were for the use with adults. Professor Stanford E. Chaille of Tulane University had developed developmental standards for infants from birth to three years as early as 1887. He used the concepts of mental testing and mental age in the article published to present the results of his research. His ideas and studies were not noticed by the psychologists because the article was published in an inconspicuous medical journal.

Binet’s IQ Tests

Concept of mental age was the basis of Alfred Binet’s mental tests. The terms “mental age” and “intelligence quotient” were first used by Alfred Binet with the publication of Binet’s IQ test in 1908. Binet’s IQ tests were developed for identifying the gifted children and those children having learning difficulties due to low levels of intelligence. Binet-Simon scale published in 1905 and revised twice in 1908 and 1911 is the first widely used standardized IQ test.

H.H. Goddard translated Binet-Simon scale and introduced it to U.S. This IQ test was standardized using a large sample from US subjects by Lewis Terman from Stanford University. The standardized test was called the Stanford-Binet scale. This IQ test became widely known and widely accepted for a long time. Many revised versions are still in use for many applications.

Modern IQ Tests

Binet’s IQ tests and the later versions use the concept of mental age and it does not work well for adults. This made many psychologists to find other ways of accurately measuring the intelligence of adults. After realizing the limitations of Binet’s methods American psychologist David Wechsler developed and published a new intelligence test known as Wechsler Adult Intelligence Scale in 1955. The current versions of Wechsler’s tests are:
• Wechsler Adult Intelligence Scale (WAIS III)
• Wechsler Intelligence Scale for Children (WISC)
• Wechsler Preschool and Primary Scale of Intelligence (WPPSI)

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