The history of IQ testing is a long one and ranges from the scientifically racist to everyday use in schools.
IQ testing was first developed from the research of Francis Galton. He suspected that using statistical methods and it would be possible to develop a standardised test of intelligence. He believed intelligence to be inherited and correlated with physical characteristics such as head size. His beliefs and theories about intelligence, and their later uses in the eugenics movement, are now thought to be central to the history of scientific racism in Psychology.
This work was developed by Alfred Binet and Théodore Simon who created the Simon-Binet test in 1905. This test in many ways boosted the popularity and interest in intelligence testing. Lewis Terman went on to develop the Stanford-Binet test in 1916, adapting the original test. Terman was an admirer of Galton and was also central to the eugenics movement in the United States.
During the two World Wars such tests were used regularly in order to recruit soldiers. This was especially common in the United States with Robert Yerkes (also see the work of Stephen Jay Gould). Paul Popenoe was in turn influenced by this work within the Military and later developed eugenic ideas around the family after the Second World War.
Charles Spearman also became interested in intelligence and used statistical methods such as factor analysis on the data. He argued that different forms of intelligence were correlated and so there was an underlying factor to intelligence. He called this ‘G’ for general factor. Raymond Cattell went on to develop this theory and argued that there were two types of intelligence.
IQ tests are commonly used and have formed the basis of school testing at different ages within education systems. Many tests are still in use, for example the Stanford-Binet test is currently in its 5th Edition. However, the most common one is the Weschler Adult Intelligence Scale (WAIS) and the version for children, the Weschler Intelligence Scale for Children (WISC) both developed by David Weschler in the 1950s.