Flynn Effect

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The Flynn effect is the name given to the observed rise in average IQ scores since the beginning of measurements. The rise in most industrialized countries is about three IQ points per decade. In 1984, based political scientist James R. Flynn described the phenomenon, which is named after him.

The rise is mostly due to the test scores of those who scored an IQ below 100. The number of those who are classified as mentally handicapped diminishes from year to year. In contrast, the test scores of those who scored more than 100, does not seem to be affected.

IQ tests are re-normalized periodically to hold the average score for an age group at 100. This normalization gave a first indication to Flynn that the IQ was changing over time. The revised versions are standardized on new samples and scored with respect to those samples only. The only way to compare the difficulty of two versions is to have a group of people take both tests. This confirms IQ gains over time.

Today, children go to school for a longer time. They have also become more familiar with testing. It might therefore be expected that the biggest gains occur with school-related content, such as vocabulary, arithmetic or general information. Just the opposite is the case: abilities such as these have experienced relatively small gains and even occasional declines over the years. The largest changes attributed to the Flynn effect appear on general intelligence factor loaded tests.

Flynn originally took the position that the increase indicates that IQ tests do not measure intelligence but only a minor sort of ‘abstract problem-solving ability’ with little practical significance. He argued that if IQ gains do reflect intelligence increases, there would have been consequent changes of our society that have not been observed (a presumed non-occurrence of a ‘cultural renaissance’). Flynn later changed his argument.

Other explanations have included improved nutrition, a trend toward smaller families, better education, greater environmental complexity, and heterosis (the occurrence of genetically superior offspring from mixing the genes of its parents).

Still another theory is that the general environment today is much more complex and stimulating. One of the most striking 20th century changes of the human intellectual environment has come from the increase of exposure to many types of visual media. From pictures on the wall to movies to television to video games to computers, each successive generation has been exposed to richer optical displays than the one before and may have become more adept at visual analysis.

Flynn in his 2007 book ‘What Is Intelligence?’ further expanded on this theory. Environmental changes resulting from modernization — such as more intellectually demanding work, greater use of technology and smaller families — have meant that a much larger proportion of people are more accustomed to manipulating abstract concepts such as hypotheses and categories than a century ago. Substantial portions of IQ tests deal with these abilities. Flynn gives, as an example, the question ‘What do a dog and a rabbit have in common?’ A modern respondent might say they are both mammals (an abstract answer), whereas someone a century ago might have said that humans catch rabbits with dogs (a concrete answer).

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