What is IQ?

Measure intelligence. One can measure the length of a bit, its volume or its weight with relative ease, because they are directly observable physical attributes.

But, What happens when we look for a measure of something subjective, like intelligence or any other aspect of an individual’s personality? We need to develop mechanisms and techniques that allow us to observe this attribute and get a score from which to work. In the case of cognitive ability, IQ or CI is used.

    Intelligence: a complex concept

    Intelligence is understood as that capacity or set of capacities thanks to which we are able to adapt correctly and in the most efficient way to the environment, so that thanks to it we are able to analyze, interpret and to correctly judge information, to develop behavior towards our goals and resources, and to solve problems, among other abilities.

    Although the very notion of intelligence is difficult to define (aspects on which it includes, whether it is modifiable or not, its link with aspects such as personality or if it is a single capacity, several hierarchies or different independent skills for example), it is one of the most valued skills in the world.

    Because of its usefulness in allowing us to adapt effectively and the observation that everyone does not show the same level of efficiency in the different tasks that we undertake, it appeared necessary to assess intellectual capacity. This would make it possible, for example, to adjust teaching and learning to the capacities of the pupils (this is what led Binet to be asked to develop the first test to measure intelligence).


    IQ, or IQ, is, in itself, a measure of intelligence. It is the product of dividing mental age by chronological age and multiplying it by percentage. In other words, the approximate age at which most subjects are able to solve a given problem is calculated and is related to the subject’s actual age. Percent multiplication is intended to eliminate decimal places.

    The result obtained from this operation is what is called an IQ. But the number itself is significant only in relation to the results obtained by the mean of the source population. So when we talk about CI, we are actually making a comparison between our own performance and that of most individuals of the same age.

    IQ is measured through very diverse and different tests depending on the characteristics of the subjects, the purpose of this measurement, their age or whether it aims to assess a particular aspect or an intelligence at the general level.

    One of the best known tests in this regard are the Wechsler scales, the Wechsler Adult Intelligence Scale or WAIS. in the case of adult subjects and the Wechsler intelligence scale for children or WISC in the case of children. Total IQ or IQ, verbal IQ, and manipulative IQ can be measured separately (the former being that which refers to memory and comprehension while the latter relates to more perceptual and organizational aspects), in addition to different cues such as processing speed, verbal comprehension, perceptual reasoning and working memory.

    The normal distribution of intelligence of IC

    The scores obtained in the various intelligence tests must be standardized and passed to a type of distribution which makes it possible to observe in which relation the own capacities adjust to the average of the population. In the case of IQ, the normal distribution is used for this.

    We consider that a value of 100 or values ​​close to it would be on average, With more than half of the population of the same age having similar scores. Above this measurement, we would speak of an above average capacity, and below that we would be confronted with below average intellectual capacity.

    But keep in mind that we are talking about an average. There is a range between which the scores of people with an equivalent level of cognitive ability can vary. That is why in the normal distribution we apply the standard deviation, which can be understood as the range of dissemination of scores in the same range. Scores that are this distance from the average or will stay in the same range.

    The different ranks of intelligence according to IQ

    In the case of intelligence, the average would be 100 and we have a standard deviation of 15. This indicates that people with an CI between 85 and 115 would still have an average intellectual capacity.

    People who are more than two standard deviations (i.e., with an IC less than 70 or greater than 130) from the mean have abilities that are significantly different from the majority of the population.

    Intellectual disability

    Subjects with an IQ below 70 are considered to have an intellectual disability. According to the manifested CI, this handicap will be more or less severe. If it is between 70 and 50, the degree of disability is considered mild (this is the range in which most of the population with an intellectual disability is found). If we find ourselves with a CI between 50 and 35, the handicap would be moderate, which would mean the need for supervision and special education.

    Between 35 and 20 years, this would indicate the existence of a severe intellectual disability, dependent on supervision and considering them as legally incapable. An IQ below 20 is considered to be the existence of a profound intellectual disability, which usually occurs with neurological damage that significantly limits performance and interaction with the environment.

    intellectual giftedness

    For subjects above the average, those with an IQ above 130 are considered gifted (Although this requires the presence of other attributes such as creativity and that the subject excels in all or most areas, in addition to a CI above this level).

    Subjects with an IQ between one and two standard deviations below the mean are considered borderline intelligence, while those between one and two standard deviations have higher intelligence.

    Criticisms of the idea of ​​IQ

    The use of IQ as a measure of intelligence has been controversial and controversial since its inception.. This is mainly because the concept of IQ is based on the conception of intelligence as a general ability.

    This means that although today there is a tendency to think that there is more than one type of intelligence, the end result for the generally we measure the intelligence attribute follows the unit result. and refers to the G (or general) factor. Another controversial aspect is that the tests carried out to measure it focus, as a rule, on certain skills which exclude others such as musical intelligence.

    A third aspect to consider is that there may be cultural biases in the measuring instruments used, although they generally try to be as objective as possible. The skills needed to adapt to the environment will vary depending on its characteristics.

    Likewise, not everyone has the same concept of intelligence. So, an Indian living in an Amazonian tribe may score very low simply because the tasks asked of him do not correspond to his usual reality, although he may perform better than most of the inhabitants of the Amazon jungle.

    Something similar happens with illiterate people or those who have suffered from deprivation of stimuli. They are compared to people of the same age, but who may have had resources such as formal education. However, the various tests used to measure intelligence attempt to reduce these biases as much as possible.

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