IQ does not remain the same throughout life

A meta-study shows that an intelligence quotient measured once is not necessarily meaningful later on

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If you were able to achieve a well above-average IQ in an intelligence test as a child, you do not necessarily have to be highly intelligent as an adult. Conversely, children with a lower or average IQ can also perform significantly better in intelligence tests in later years. As researchers from the University of Trier and the University of Texas found out, intelligence measurements in young children only represent a snapshot. Even at kindergarten age, they are only meaningful for a limited period of time. After that, the half-life of intelligence measurements increases continuously. Researchers describe an intelligence quotient measured in adults as "highly stable". This means that a measurement is very valid for around five years, but also has substantial stability and validity beyond that.

"It has long been known that intelligence test results are not highly stable over a person's entire life. With our study, however, we have now been able to provide a uniquely precise assessment of what stability looks like in detail and, in particular, how age at testing is related to stability," says Dr. Moritz Breit, giftedness researcher in the Department of Psychology at Trier University.

Together with Dr. Vsevolod Scherrer, Prof. Dr. Elliot M. Tucker Drob and Prof. Dr. Franzis Preckel, he analyzed data from 205 longitudinal studies with a total of 87,408 participants. The team summarized their findings in an article that was recently published in the journal "Psychological Bulletin".

"Intelligence tests in children are often used to make decisions about placement in the education system or support environments. For example, they help determine whether a child should attend a special school or start school early, which can have a major impact on their future life," explains Dr. Moritz Breit. "Our results suggest that intelligence tests in children should be repeated at certain intervals to check whether the child is still in the right support environment. In early childhood and even at primary school age, you cannot rely on a single test in the long term."

But why are intelligence measurements in children only meaningful for a limited period of time? Intelligence is made up of many different abilities, which increase significantly, especially in childhood and adolescence. Not only do the different abilities develop at different rates, but also the different children. This means that a wide range of developments take place at a young age, which can proceed differently in different children. For example, children develop their motor or language skills at different rates. Even if intelligence tests are specifically tailored to the respective age group, a test result can be influenced by a delayed stage of development compared to other children at the time of testing, which is then made up for in further development.

In adulthood, many abilities appear to have reached a plateau. Therefore, cognitive developments at different speeds no longer play a major role here. On the other hand, most adults also live in rather constant environments or choose environments that suit their abilities, so that a certain stability is also given here due to the influence of the environment.

Moritz Breit: "Our results show that intelligence test results can be subject to major changes, particularly in childhood, and are only sufficiently stable and valid in the longer term from adolescence or adulthood. This reflects the now established finding that intelligence and intelligence development are not only determined by genetic factors, but also by environmental influences and the complex interaction between the two."

Note: This article has been translated using a computer system without human intervention. LUMITOS offers these automatic translations to present a wider range of current news. Since this article has been translated with automatic translation, it is possible that it contains errors in vocabulary, syntax or grammar. The original article in German can be found here.

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