What is the Intelligence Quotient (IQ)?

Measure intelligence. We can measure the length of something, its volume or its weight with relative ease, since they are directly observable physical attributes.

But, What happens when we try to obtain a measure of something subjective, such as intelligence or any aspect of an individual's personality? It is necessary to develop mechanisms and techniques that allow us to observe this attribute and obtain a score from which to work. In the case of cognitive ability, the intellectual quotient or IQ is used.

• Related article: "Is Intelligence Quotient (IQ) the same as intelligence?"

Intelligence: a complex concept

Intelligence is understood as that capacity or set of capacities through 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 judge the information correctly, develop strategies, adjust our behavior according to our goals and resources and solve problems, among other capabilities.

Although the concept of intelligence itself is difficult to define (aspects of what it includes, whether it is modifiable or not, its link with aspects such as personality or if it is a single ability, several hierarchical or different independent skills by example),

it is one of the most valued skills in the world.

Due to its usefulness in allowing us to adapt efficiently and to the observation that not everyone manifests the same level of efficiency in the different tasks we undertake, the need arose to assess the capacity intellectual. This would, for example, make it possible to adjust teaching and learning to the capacities of students (from In fact, this was what prompted Binet to be asked to develop the first test to measure the intelligence).

The IQ

The Intellectual Quotient or IQ, is, in itself, a measure of intelligence. It is the product of dividing the mental age by the chronological and multiplying it by one hundred. That is, the approximate age at which most subjects are capable of solving a certain problem is calculated and is related to the subject's real age. Multiplication by one hundred is intended to eliminate decimals.

The result obtained from this operation is what is called the intellectual quotient. But the number itself is only significant compared to the results obtained by the mean of the source population. Thus, when we speak of IQ we are actually making a comparison between our own performance with that of the majority of individuals of the same age.

The intelligence quotient is measured through very diverse and different tests depending on the characteristics of the subjects, the objective of said measurement, their age or if it is intended to assess a specific aspect or intelligence at the general.

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. The intellectual quotient or total IQ, the verbal IQ and the manipulative IQ can be measured separately (the first being the one that refers to memory and understanding while the second is linked to more perceptual and organizational aspects), in addition to different indices such as processing speed, verbal comprehension, perceptual reasoning and memory of job.

The normal distribution of intelligence from IQ

The scores obtained in different intelligence tests have to be standardized and passed to a type of distribution that allows observing in what relation the own capacities adjust to the mean population. In the case of the IQ, the normal distribution is used for this.

It is considered that a value of 100 or values ​​close to this would be in the mean, with more than half of the population of the same age having similar scores. Above this measure we would speak of a capacity above the average, and below it we would be dealing with intellectual capacities below.

But it is necessary to bear in mind that we are talking about an average. There is a range within which the scores of people with an equivalent level of cognitive ability can range. That is why in the normal distribution we apply the standard deviation, which can be understood as the dispersion range of the scores within the same range. Scores that are that distance from the mean or will still be within the same range.

The different ranges of intelligence according to the IQ

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

People who go more than two standard deviations (that is, with an IQ below 70 or above 130) of the average have capacities that are significantly different from those of the majority of the population.

Intellectual disability

Subjects with an IQ below 70 are considered to have intellectual disability. Depending on the manifested IQ, said disability will be of greater or lesser severity. If it is between 70 and 50, the degree of disability is considered mild (this being the range in which the majority of the population with intellectual disabilities is found). If we find an IQ between 50 and 35, the disability would be moderate, which would imply the need for supervision and special education.

Between 35 and 20 would indicate the existence of a serious intellectual disability, depending on supervision and considering them legally incapacitated. An IQ below 20 is considered the existence of profound intellectual disability, which generally occurs with neurological damage that greatly limits the performance and interaction with the half.

Intellectual giftedness

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

Subjects with an IQ between one and two standard deviations below the mean are considered borderline intelligence, while those who know somewhere between one and two standard deviations have superior 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 due in the first place 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 final result by the in general we measure the attribute of intelligence follows unitary result and makes reference to factor G (or general). Another controversial aspect is that the tests carried out to measure it, as a general rule, focus on certain skills that leave out others such as musical intelligence.

A third aspect to take into account is that there may be cultural biases in the measurement instruments used, despite the fact that in general they try to be as objective as possible. The skills necessary to adapt to the environment will vary according to its characteristics.

Similarly, not everyone has the same concept of intelligence.. Thus, an indigenous person living in an Amazon tribe may obtain very low results simply because the tasks assigned to him They ask do not conform to their usual reality, despite the fact that they can perform better than most people in the jungle.

Something similar happens with illiterate people, or those who have suffered deprivation of stimuli. They are compared with people of the same age, but who have been able to have resources such as a formal education. However, the different tests used to measure intelligence try to reduce these biases as much as possible.