Scores from intelligence tests are estimates of intelligence. Unlike, for example, distance and mass, a concrete measure of intelligence cannot be achieved given the abstract nature of the diagnostics of emotional sphere of the child 3 years methodology of “intelligence”.
IQ scores are used for educational placement, assessment of intellectual disability, and evaluating job applicants. Even when students improve their scores on standardized tests, they do not always improve their cognitive abilities, such as memory, attention and speed. Historically, even before IQ tests were devised, there were attempts to classify people into intelligence categories by observing their behavior in daily life. The English statistician Francis Galton made the first attempt at creating a standardized test for rating a person’s intelligence. French psychologist Alfred Binet, together with Victor Henri and Théodore Simon had more success in 1905, when they published the Binet-Simon test, which focused on verbal abilities. Goddard published a translation of it in 1910. The many different kinds of IQ tests include a wide variety of item content.
Some test items are visual, while many are verbal. Test items vary from being based on abstract-reasoning problems to concentrating on arithmetic, vocabulary, or general knowledge. The British psychologist Charles Spearman in 1904 made the first formal factor analysis of correlations between the tests. Spearman’s argument proposing a general factor of human intelligence is still accepted in principle by many psychometricians. During World War I, a way was needed to evaluate and assign Army recruits to appropriate tasks. This led to the development of several mental tests by Robert Yerkes, who worked with major hereditarians of American psychometrics—including Terman, Goddard—to write the test.
At the start of the war, the army and national guard maintained nine thousand officers. By the end, two hundred thousand officers presided, and two- thirds of them had started their careers in training camps where the tests were applied. In some camps, no man scoring below C could be considered for officer training. 75 million men were tested in total, making the results the first mass-produced written tests of intelligence, though considered dubious and non-usable, for reasons including high variability of test implementation throughout different camps and questions testing for familiarity with American culture rather than intelligence.
The results of these tests, which at the time reaffirmed contemporary racism and nationalism, are considered controversial and dubious, having rested on certain contested assumptions: that intelligence was heritable, innate, and could be relegated to a single number, the tests were enacted systematically, and test questions actually tested for innate intelligence rather than subsuming environmental factors. While not widely used, Thurstone’s model influenced later theories. David Wechsler produced the first version of his test in 1939. It gradually became more popular and overtook the Stanford-Binet in the 1960s.
It has been revised several times, as is common for IQ tests, to incorporate new research. One explanation is that psychologists and educators wanted more information than the single score from the Binet. Wechsler’s ten or more subtests provided this. Eugenics refers to the principles of heredity used to improve the human race. Francis Galton first used the term in the late 1800s.
The eugenics movement was popular in the US in the 1920s and 1930s. Different from Galton, who promoted eugenics through selective breeding for positive traits, Goddard went with the US eugenics movement to eliminate “undesirable” traits. Goddard coined the word “feeblemindedness” to refer to people who did not perform well in the test and thus were intellectually inferior. Noteworthily, California’s sterilization program was so effective that the Nazi turned to the government for advice to eliminate the birth of the “unfit”. The US eugenics movement lost its momentum in 1940s and was halted by the horrors of Nazi Germany. Psychologist Raymond Cattell defined fluid and crystallized intelligence and authored the Cattell Culture Fair III IQ test. The second stratum consists of broad abilities.