IQ test
Test that attempts to find innate intellectual power, and not learned ability.
It is now widely believed that a child’s score in an intelligence test can be affected by his or her environment, cultural background, and teaching.
There is widespread scepticism about the accuracy and reliability of i.q. tests, however they are still often used as a diagnostic tool when children display learning difficulties.
The French psychologist Alfred Binet (1857–1911) devised the first intelligence test in 1905.
The IQ (from the German Intelligenz-Quotient), was coined by the German psychologist William Stern in 1912 as a proposed method of scoring early modern children’s intelligence tests.
It is calculated according to the formula: IQ = MA/CA x 100 in which MA is ‘mental age’ (the age at which an average child is able to perform given tasks) and CA is ‘chronological age’, hence an average person has an IQ of 100 ± 10.
Although the term “IQ” is still in common use, the scoring of modern IQ tests such as the Wechsler Adult Intelligence Scale is now based on a projection of the subject’s measured rank on the Gaussian bell curve with a center value (average IQ) of 100, and a standard deviation of 15, although different tests may have different standard deviations.
Intelligence tests were first used on a large scale in the USA in 1917 during World War I for two million drafted men, and their subsequent widespread use for education and employment decisions has provoked protests from minority groups who contend the tests are culturally biased and discriminatory.
IQ scores have been shown to be associated with such factors as morbidity and mortality rate, parental social status, and to a considerable degree, parental IQ. While its hereditary pattern has been inquired for about a century, controversy remains as to how much is inheritable, and the mechanisms of inheritance are still a subject to some argument.
IQ scores are used in many contexts: as predictors of educational accomplishment or special needs, by social scientists who study the statistical distribution of IQ scores in populations and the relationships between IQ score and other variables, and as predictors of job performance and income.
The average IQ scores for many populations have been rising at an average rate of three points per decade since the early 20th century with most of the gain in the lower half of the IQ range: a phenomenon called the Flynn effect. It is disputed whether these changes in scores reflect real changes in intellectual abilities, or merely problems with past or present testing methods.