One of the most fascinating concepts in intelligence research is the Flynn effect. This is the tendency throughout the 20th century for average IQ test performance to improve over time. Philosopher James Flynn published two articles in the 1980s documenting this trend, first in the United States, and later in 13 additional industrialized countries. The increase was substantial: an average of 3 points per decade. This means that every generation, IQ would rise about 15 points. If taken at face value, the implications were hard to believe: the average person from your grandparents’ generation would be as intelligent as someone in the bottom 2% of intelligence today (around the cutoff for an intellectual disability). Projecting back even further, Flynn’s findings implied that the average person 100 years earlier would be unable to learn language or go to the bathroom by themself. Clearly this couldn’t be true. What was going on???
Understanding the Flynn effect
There are a lot of misconceptions about the Flynn effect. So, before explaining it further, it is important to correct common misunderstandings. First, James Flynn did not discover the Flynn effect, nor did he ever claim to. It was first noticed in the 1930s, long before Flynn started his career. He certainly popularized it, but psychologists studying IQ at the time were aware of the phenomenon of increasing performance on IQ tests. The most well known example of the pre-Flynn Flynn effect was the higher performance on IQ tests in World War II, compared to World War I soldiers. Second, Flynn did not name the Flynn effect after himself. Richard Herrnstein and Charles Murray gave it that name in their bestseller book The Bell Curve.
Third, the Flynn effect does represent a real increase in intelligence. It can’t because of the level of disability in the past that it would imply. But it does reflect an increase in IQ test performance. That’s not the same thing as intelligence. Some people (including Flynn originally, though he changed his mind later) believe that this proves that IQ tests don’t really measure intelligence. That is not correct.
While the Flynn effect is fascinating (as shown by the hundreds of studies on the topic), it is not as profound in its implications as James Flynn believed in the 1980s. People are not massively smarter than their grandparents, but they do have a different mix of cognitive strengths and weaknesses. This has implications for the education system and research, but the Flynn effect does not invalidate IQ tests at all.
