What is the IQ or Intellectual Quotient?

What is the IQ or Intellectual Quotient?

The IQ or IQ (English IQ) It is a value that results from performing a standardized test to measure the cognitive abilities and intellectual capacity of a person in relation to their age group.


  • 1 How to obtain the IC number
  • 2 Origin of the intelligence tests
  • 3 Factors that influence the Intellectual Quotient
  • 4 Age and CI
  • 5 Criticisms of the concept of CI

How the IC number is obtained

Many times we will have seen or heard that IC is the intelligence quotient, but in reality that would not be the correct term, although it is considered valid, since the figure obtained to measure the CI derives from the arithmetic operation that is obtained by dividing one quantity (dividend) by another (divisor), so the result is the quotient.

The IQ is obtained by dividing the mental age of an individual (which are the results offered by the intelligence tests) and its chronological age, multiplied by one hundred.

The average IQ of an age group has been set at 100 points, and all those scores that are between 90 and 110 are considered within the normal parameters. The tests are designed so that the distribution of the results is a Gaussian distribution, that is, to follow the curve of the Gaussian Bell.

Origin of the intelligence tests

In 1905, the French psychologist Alfred Binet published the first modern intelligence test: the Binet-Simon intelligence scale. Its main objective was to identify students who needed special help to meet school requirements. With the collaboration of Theodore Simon, Alfred Binet published reviews of his intelligence scale between 1908 and 1911, and the last one appeared just before his death.

In 1916, the first adaptation of the Binet-Simon scale was published by Lewis M. Terman of Stanford University. Terman's test, which is called "Stanford-Binet Intelligence Scale"formed the basis of one of the modern intelligence tests commonly used today. They are colloquially known as IC test.

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For children under 16 years of age, the most commonly used test in IC measurement is the Wechsler Intelligence Scale for Children (WISC), a scale that measures the intellectual quotient in children aged 6 to 16 years from the results of the fifteen blocks that make up this test, created by David Wechsler in 1949 and with successive reissues (the last one, the WISC- IV, dated 2003).

It is one of the most used instruments in school psychology to detect learning disorders that can lead to school failure, but has been criticized for reducing intelligence to various parameters and not taking into account the extreme variability that can arise in individuals of these ages when undergoing psychometric tests. There is also the equivalent of the WAIS test for adults.

WAIS test tests measure

  • Linguistic competence: word definitions, synonyms, reading comprehension, general culture questions or guessing words from clues
  • Perception: follow shapes patterns, match drawings, complete figures
  • The memory: repeat sequences of numbers and letters, mental calculation
  • Mental processing capacity: mark the figures that respond to a certain characteristic in a limited time, locate drawings among other figures

Ranges of scores established to measure IQ

140 or more: geniuses or almost geniuses
120 - 139: gifted intelligence
110-119: bright intelligence
90-109: normal intelligence
80-89: unintelligent
70 - 79: border area with cognitive deficit
60-69: mild cognitive deficit
50-59: moderate cognitive deficit
25 - 45: severe cognitive deficit
0 - 24: deep cognitive deficit

Gauss bell

Factors that influence the Intellectual Quotient

Historically there has been a great controversy about the role of genetics in intelligence and the influence of the environment, especially education. Most studies state that there are some innate abilities, but that can be stimulated or repressed according to the environment in which the person develops and the learning experiences he has. There are also physical factors that affect intelligence, such as proper nutrition in childhood or not using certain drugs that damage the brain.

No evidence has been found that relates sex or ethnicity to a given IQ, although there is more dispersion among men than among women. What seems to differ in this regard are the specific skills: men stand out visually and spatially and women often use more details to help memory. As for the cultural role, they tend to be more present in sectors where verbal skills predominate and they in the mathematics, but these biases appear not to be the result of IC deviations, but of gender stereotypes.

The IQ scores in a population have evolved upward throughout history (the call Flynn effect), so these tests require continuous adaptation if you want the standards to remain reliable.

Age and CI

Apparently the IC can vary throughout our lives, especially during the childhood stage. In general, there are small variations in the score (within some margins) until adulthood, where it begins to slowly decrease.

It has been observed that the fluid intelligence varies more over time and the crystallized one that remains more stable.

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Criticisms of the concept of CI

Many scientists claim that the intellectual quotient, and even the intelligence measurement systems themselves, are not valid for a number of reasons. On the one hand, they indicate that intelligence tests do not really measure intelligence, but the proximity to an established canon of knowledge with an eminently cultural and social content, without a real relationship with cognitive abilities. On the other hand, they claim that intelligence is not a measurable quality, but a relationship between the individual, the community and the environment.

Currently the IQ cannot be used as a synonym for intelligence, but it is an estimator of it. And it has been shown that human intelligence is related to various factors such as the social status of parents (for access to better education, food and health) as well as genetic inheritance. Although intelligence inheritance mechanisms have been investigated for almost a century, there is still controversy about the extent to which intelligence is hereditary or environmental.

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