We often hear about this famous IQ – either from legendary geniuses with an IQ of 160 or through pseudo-tests on the internet. But what is it really? Why take an IQ test and what does it involve?

What is an IQ test?

IQ is the Intelligence Quotient, measured by tests. There are several IQ tests, but the Wechsler scales are most commonly used: the WAIS-IV for adults (people over 16 years old) and the WISC-V for children and adolescents (6 to 16 years old). Similarly, there are several models of intelligence, perhaps even several types of intelligence (Gardner’s famous “multiple intelligences”). So what exactly does an IQ test measure?

It measures cognitive efficiency (intellectual performance). The IQ can thus evaluate through different tests: categorization abilities, vocabulary, general culture, mental and concrete manipulation, memory, reasoning abilities, speed of information processing…

We will obtain a Total IQ score, as well as scores for the different families of the test (we will speak of indices: Verbal Comprehension Index, Perceptual Reasoning Index, etc.).

But what is the purpose of these measures? The Wechsler scales make it possible to situate the cognitive efficiency of a person in relation to an average of people of his age. In simple terms, they show whether the person tested is above or below average. But IQ is not just a number!

Why take an IQ test?

First of all, an IQ test must be taken by a psychologist trained in this field (and especially not on the Internet). It can take several hours to complete the test. And it is not trivial! It is the result of a questioning, of a situation that poses a problem – for example school difficulties, a gap compared to people of the same age, an atypical way of functioning… It is also a reflection with the psychologist: is it relevant to take this test?

This can allow :

  • To better understand the origin of certain difficulties
  • To better understand his intellectual functioning
  • To orientate towards a treatment that is adapted to the person: a change of school, sessions with a psychologist…
  • Identify a potential learning disability and refer to specialized professionals: speech therapist, psychomotor therapist, etc.


An IQ test will, for example, reveal dyslexia, dysphasia, dyspraxia, mental retardation, or even a high potential.

The role of the psychologist

An IQ test alone does not mean much. It is an overview of one facet of a person at a given time in his or her life and an indicator of his or her strengths and weaknesses. But the other facets – personality, life history, behaviors… – are not assessed. However, a person cannot be reduced to a simple number!

This is why it is important to be accompanied by a psychologist, through a psychological assessment. The psychologist will be able to :

  • Interpret the results in relation to the person (for example, qualify a lower score due to high stress)
  • Advise on what to do next (which other professionals to consult, how to react?)
  • Suggest additional tests (personality tests)
  • To simply help with psychological difficulties (for example: to work on self-esteem in the case of dyslexia)