An IQ test is an examination that attempts to measure your innate intelligence, or "how you think," as opposed to your accumulated knowledge, or "what you know." The name "IQ" stands for "intelligence quotient," because the first such tests were scored by a process of mathematical division, and the result of division is known as a quotient. While tests are no longer scored this way, the name has stuck.
History
French psychologist Alfred Binet developed the the first IQ-style tests at the beginning of the 20th century. The first tests were designed only to assess the intelligence of children. The U.S. military relied on intelligence testing to assess and place recruits during World Wars I and II. Psychologist David Wechsler used the military IQ tests as a model in devising his own test in 1949. Today, a group of tests derived from Wechsler's work are the most widely used IQ tests.
Tests
The fourth version of the Wechsler Intelligence Scale for Children, the WISC-IV, was released in 2009. A companion test, the Wechsler Adult Intelligence Scale, targets people 16 and older. Other frequently used IQ tests include the Stanford-Binet Intelligence Scale, the Das-Naglieri Cognitive Assessment System and the Kaufman Assessment Battery for Children.
Elements
IQ tests commonly assess the taker's logical reasoning, math ability, spatial-relations skills, short-term memory and problem-solving skills.
Scoring
IQ tests originally were scored by dividing the subject's "mental age," as determined by which questions she answered correctly on the test, by her "chronological age," her actual age in years, then multiplying that quotient by 100. For example, an 8-year-old child with a mental age of 12 would have an IQ of 125, with the calculation being 12/8 = 1.25, and 1.25 x 100 = 125. A person whose mental age precisely matched his actual age would have an IQ of 100, so a 100 IQ was defined as "average."
Modern IQ tests no longer use such a formula. They simply compare a person's test results with those of everyone else in the same age group, on a scale where 100 is defined as average intelligence.
Criticism
Criticism of IQ tests focuses on the content of the tests--that is, the type of questions they ask--and their application. Such areas as vocabulary and "logic" can be strongly influenced by culture and socioeconomics. For example, consider a test that asks what word goes best with "cup": saucer, plate or bowl. The test may intend "saucer" to be the correct answer. However, a test-taker who grew up in a home where tables weren't set in a formal fashion might not know what a saucer is. He may be just as "intelligent" as the next person, but his score will suffer because of cultural factors. Authors of IQ tests are continually refining tests to address such concerns; some tests have removed verbal elements entirely.
Even test creators argue that the results are only one tool for assessing a person's abilities, and that "intelligence" in a person is not a fixed quality, but changeable--even from day to day. In reality, however, people and institutions tend to put great weight on IQ scores. Students have been labeled "learning disabled" based on the outcome of IQ tests alone. As authors revise their tests, they also are revising their instructions to stress the tests' limited application.
