Intelligence Quotient [IQ]
An intelligence quotient or IQ is a score derived from one of several
different standardized tests attempting to measure intelligence.
IQ tests are used as predictors of educational achievement.
IQ scores are also used by social scientists; in particular, they
study the distribution of IQ scores in populations and the relationships
between IQ score and other variables. IQ correlates with job performance
and income, also with the social status of the parents.
IQ Hereditary Factors
Recent work has demonstrated links between IQ and both morbidity
and mortality. It is as yet unproven as to whether IQ is inherited.
IQ Environmental Factors
Environmental factors play a role in determining IQ. Proper childhood
nutrition appears critical for cognitive development; malnutrition
can lower IQ. Other research indicates environmental factors such
as prenatal exposure to toxins, duration of breastfeeding, and micronutrient
deficiency can affect IQ.
IQ Learned Factors
It is possible to increase one's IQ score by training, for example
by regularly playing puzzle games, or strategy games like Chess.
Early musical training is also thought to increase IQ.
IQ Age Factors
IQ of the same person may vary with age, and the average IQ scores
for many populations are rising at an average rate of three points
per decade, 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 methodological problems with
Most IQ tests are composed of several different subtests. These
tests yield both an overall score and individual subtest scores.
A typical IQ test requires the test subject to solve a number of
problems in a set time under supervision. IQ test items include
various domains, such as:
- short-term memory
- verbal knowledge
- spatial visualization
- perceptual speed.
Some tests have a total time limit, others have a time limit for
each group of problems, and a few are untimed, unsupervised tests,
typically geared to measuring high intelligence.
IQ tests are calibrated in such a way as to yield a normal distribution,
or bell curve. The center value (average IQ) is 100, with a standard
deviation of 15 or occasionally 16.
Each IQ test, however, is designed and valid only for a certain
IQ range. Because so few people score in the extreme ranges, IQ
tests usually cannot accurately measure very low and very high IQs.
Different individuals exhibit different IQ scores, depending on
the individual these may or not be stable over their lifetime.
High IQ Societies
There are several organizations or societies where membership is
limited to those above a certain iQ. The most well known is MENSA
International, which requires members to score in the top 2% of
a standardized IQ test.
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