Intelligence test
Test that attempts to find innate intellectual power, and not developed ability.
It is nowadays widely believed that a minor’s ability in an intelligence test can be affected by his or her environment, background, and teaching.
There is widespread doubts over the accuracy and reliability of intelligence tests, however they are still widely used as a diagnostic tool when children display learning problems.
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.
‘Sight and sound’ intelligence tests, developed by Christopher Brand in 1981, avoid cultural bias and the pitfalls of improvement by practice. Subjects are shown a series of lines being flashed on a screen at increasing speed, and are asked to identify in each case the shorter of a pair; and when two notes are relayed over headphones, they are asked to identify which is the higher. There is a close correlation between these results and other intelligence test scores.
IQ scores have been shown to be associated with such factors as morbidity and mortality, parental social status, and to a substantive degree, parental IQ. While its hereditary pattern has been looked into for almost a century, controversy remains as to how much is inheritable, and the mechanisms of inheritance are still a matter of some debate.
IQ scores are used in many settings: as predictors of educational achievement 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 mean 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 increase 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.