Intelligence HomeContact Us

Intelligence Test (IQ)

IQ, an abbreviation for "intelligence quotient", is a score derived from a set of standardized tests that were developed with the purpose of measuring a person's cognitive abilities in relation to one's age group. It is expressed as a number normalized so that the average IQ in an age group is 100 – in other words an individual scoring 115 is above-average when compared to similarly aged people. It is usual, but not invariable, practice to standardise so that the standard deviation (£m) of scores is 15. Tests are designed so that the distribution of IQ scores is more-or-less Gaussian, that is to say that it follows the bell curve. Scores on a given test in a given population have tended to rise across time throughout the history of IQ testing (the Flynn effect), so that tests need repeated renormalisation if these standards are to be maintained.

IQ scores are generally taken as an objective measure of intelligence. Because intelligence is difficult to define, the definition "Intelligence is what the IQ test measures" has been seriously proposed.

Modern ability tests produce scores for different areas (e.g., language fluency, three-dimensional thinking, etc.), with the summary score calculated as a some general measure, whose significance is disputed. Significantly, individual subtest scores correlate highly with one another and with between different tests.

While it might be argued that IQ tests encode their creator's beliefs about what constitutes intelligence, analyses of an individual's scores on a wide variety of tests will reveal that they all measure a single common factor and various factors that are specific to each test. This kind of analysis has led to the theory that underlying these disparate cognitive tasks is a single factor, termed the g factor, that represents the common-sense concept of intelligence.

Opponents argue that it is much more useful to know which are the strengths and weaknesses of a person than to know that he or she holds a measureable superlative on n percent of the populace in some "general intelligence" measure. Such opponents often cite the example of two people with the same overall IQ score but very different ability profiles. However, most people have highly balanced ability profiles. Differences in subscores are greatest among the most intelligent, which may lead them to this misconception.

Others argue that IQ testing is unnecessarily narrow and have proposed wider testing that covers emotional/social intelligence, creativity, artistic intelligence, etc. An extreme argument along these lines states that "one's IQ is merely a measure of how good one is at doing IQ tests." While this is inherently almost a truism it conveys the impression that either there is no correlation with actual IQ, or that the concept of IQ is meaningless.

The modern field of intelligence testing began with the Stanford-Binet test. It is worth noting that Alfred Binet, who created the IQ test in 1904, was aiming to identify students who could benefit from extra help in school: his assumption was that lower IQ indicated the need for more teaching, not an inability to learn. Indeed, this interpretation is still held by modern experts. A popular modern IQ test is the Raven's progressive matrices test

(The following numbers apply to IQ scales with a standard deviation £m = 15.) Scores between 90 and 110 are considered average—so a person scoring 95 is simply average, not below-average. For children scoring below 80 special schooling is encouraged, children above 135 are "highly gifted". In previous years, scores below 70 (regarded as evidence of "feeble-mindedness") were divided into ranges labelled moron, imbecile and idiot, while scores above 150 were labelled genius. Some writers say that such scores outside the range 55 to 145 are essentially meaningless because there are not enough people to make statistically sound statements. Moreover, at such extreme values, the normal distribution is a less accurate estimate of the IQ distribution.

Race and IQ
The Bell Curve (cf), published in 1994 by R. J. Herrnstein and Charles Murray, created great controversy among the scientific community and the public by suggesting that the average IQ of races differ. They claim that the mean IQ scores of African Americans are one standard deviation (15 points) lower than those of European Americans, and they attribute between 40 - 80% to genetic factors. Critics publically claimed that their evidence for a 'genetic' factor was exacerbated by the lack of account for some of the social factors believed to determine IQ, such as economic status, stress in environment, and access to education. As a result of the book's controversial claims, Murray received bomb threats and was denounced as a racist by a number of public figures, including Jesse Jackson. In contrast, the majority of intelligence researchers support the conclusions made in the Bell Curve (see the Wall Street Journal: "Mainstream Science on Intelligence" below). The book also argues that East Asians and Jews generally have higher IQ than all other races.

Arthur Jensen was one of the earliest researchers to propose that the IQ gap between blacks and whites is best explained by a hypothesis that attributes at least some of the cause to genetic factors. His 1969 paper in "Harvard Education Review" also stated that compensatory education was not very effective and that "genetic differences were more important than cultural or socioeconomic differences in explaining individual differences in IQ within the white population."

Opposition to IQ testing
Many scientists disagree with the practice of psychometrics in general. In The Mismeasure of Man, Professor Stephen Jay Gould strongly disputes the basis of psychometrics as a form of scientific racism, objecting that it is:

...the abstraction of intelligence as a single entity, its location within the brain, its quantification as one number for each individual, and the use of these numbers to rank people in a single series of worthiness, invariably to find that oppressed and disadvantaged groups--races, classes, or sexes--are innately inferior and deserve their status. (pp. 24-25).

Later editions of the book include a refutation of The Bell Curve.

While public discourse on IQ testing is generally deflamatory, IQ tests are used ubiquitously in research and education. In general, there is a disparity between the public perception of IQ testing and the opinion of intelligence researchers.

Some proponents of IQ have pointed to a number of studies showing a fairly close correlation between IQ and various life outcomes, particularly income. Research in Scotland has shown that a 15-point lower IQ meant people had a fifth less chance of seeing their 76th birthday, while those with a 30-point disadvantage were 37% less likely than those with a higher IQ to live that long. Research by Charles Murray on siblings has shown that there is a strong correlation between IQ and earned income. The controversial study IQ and the Wealth of Nations claims to show that the wealth of a nation correlates closely to its IQ score.

The SAT is an IQ Test
A recent study determined that the SAT is a de facto IQ test and that SAT scores can be used in lieu of IQ scores for the purpose of psychological investigations. This finding is consistent with the observation that both IQ and SAT scores show a performance gap between races.

Online IQ tests
Although such tests have become wildly popular with the explosion of the internet in recent years, there is great reason to believe that these IQ tests are highly inaccurate in their estimation of one's IQ. For example, by inputting random answers on one particular IQ test, an IQ of roughly 80 is obtained. Comparing results among a large set of people shows a common factor—most scores are above 110. Most of these websites attempt to sell certificates showing test results. It is therefore recommended not to take online IQ tests as a true judge of one's IQ, even when considering that people who take these tests voluntarily are likely to be above average anyway.

Many other books on emotional intelligence have appeared in the train of Goleman's work.

See also

Other resources
Scientific American: Intelligence Considered
Scientific American: The General Intelligence Factor
Wall Street Journal: Mainstream Science on Intelligence
Number of highly gifted relatives of high IQ-subjects
Estimated IQs of the greatest geniuses
Uncommonly difficult IQ tests

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia.


Copyright © 2004-2007 All Rights Reserved
Information provided with no warranties. Use it at your own risk