Is intelligence the same as IQ?
When it was believed that there was only one intelligence, it was postulated that it could be measured, that results could be compared, and that the most intelligent person would be the one who scored highest on these tests. Their origins were associated with the creation of an instrument that would allow for predicting which students would have the worst prognosis in school.
In France, the Minister of Public Education created a commission in 1904 to study the problem of mental retardation in public schools. The objective was to develop an instrument that could predict future academic performance and identify students who, given their intellectual limitations, were likely to have lower academic performance in the future. As a result of this work, the first intelligence tests were created by Alfred Binet and his disciple Theodore Simon.
This work was carried out during the first decade of the last century. The development of the new tests took into account that intellectual processes had an evolutionary and cumulative nature, and therefore, to determine a person's mental age, the intellectual processes they could address were considered. Thus, someone who could only adequately solve the problems of 8-year-old children, for example, had a mental age of 8 years, regardless of their chronological age.
The Binet test, with subsequent revisions, and especially Terman's revision in the 1930s, is still the most widely used test for determining people's intellectual abilities. Its conceptual basis is a theory of intelligence formulated by Binet himself.
The creation of intelligence tests marked a milestone in the history of psychology by providing psychologists and educators with an instrument to assess a process as complex as intelligence, and for a time, it proved to be adequately predictive of academic performance. For a long time, it was estimated that about half of a student's academic performance was determined by their intellectual ability. Currently, it is estimated that 20% of the variation in academic performance and 10% of the variation in job performance among workers could be attributed to IQ level (Sternberg, 1999).
Consequently, intelligence tests reflect the concept of intelligence held a century ago and are therefore not useful for assessing socio-affective or practical intelligence, given that, at the beginning of the last century, these were not concepts taken into account when discussing intelligence.
IQ tests only assess analytical intelligence; and they only assess a portion of it, leaving aside more complex processes such as metacomponents, processes that also could not have been predicted a century ago, given that they were formulated just a few decades ago by Flavell and reformulated years later by Sternberg (1997).
IQ tests cannot assess socio-affective or practical intelligence, as they were not designed for that purpose. Consequently, the validity of a test and its corresponding IQ score is much more limited than was believed a few years ago.
To go deeper: Do gifted children exist?