Genetics, social conditions and culture all may play a part in the rise of human intelligence levels around the world. But the best method of determining why some people are smarter than others is still being debated.
For most of the last century it was widely thought that intelligence was in decline. The idea was that those at the lower end of the intelligence spectrum were having more children, thereby reducing the general intelligence level. Then one day in 1984, James Flynn, a New Zealand-based moral philosopher, had a Eureka moment that turned cognitive science upside down.
He received a package from an academic colleague in Holland. Inside were data from an IQ test known as Raven’s Progressive Matrices. Intelligence quotient, or IQ, is the psychometric system for measuring intelligence. Flynn noticed that 18-year-old Dutch males had made a giant leap in IQ scores from the previous generation. Over the following month, he checked similar data from around the word and the answer was the same: IQ was going up, dramatically.
Flynn found that in both the developed and developing worlds, IQ had improved in the 20th century at the remarkable rate of three points per decade. This development has since become known as the ‘Flynn effect.’
The Flynn effect is noteworthy because it suggests a world-changing increase in intelligence in succeeding generations. IQ measurements are based on the score of 100 being allocated to the median average of a group (e.g., 18-year-old Dutch males). The Flynn effect predicts, for example, that someone with an average IQ today (i.e. of 100) will have grandchildren with a score of 120.
That should make the cognitive gulf between generations huge, Flynn said in a recent publication, but it is not. And thus the Flynn effect has become one of those phenomena that are almost universally accepted but little understood.
Some psychologists have attempted to explain IQ gains in other ways. Some have argued that improved test administration has helped children becoming better at solving the tests. Others credit improved nutrition. Flynn rejects both theories, pointing out that tests are frequently restandardized and that diet has been of marginal importance in the West since the 1950s.
Flynn is convinced that intelligence itself has improved. “But,” he said, “we have to rethink exactly what we mean by intelligence. For what the IQ gains really give us is a cultural history of the 20th century and an insight into the gulf that separates our minds from those of our ancestors. We’ve created tools and the environment to maximize our scores.”
The Flynn effect is coming to an end, at least in western Europe. Recent studies in Scandinavia show intelligence test scores plateauing and arithmetic scores dropping. Far from being surprised, Flynn has been expecting as much. “The Flynn effect is not like the law of gravity,” he says. “Social conditions vary in each country.”
One of the key environmental factors, Flynn says, is the adult-infant ratio: The more adults there are to children, the richer the cognitive environment. He also believes that Scandinavian teaching methods are the best around, and perhaps they, too, have gone as far as they can go. “Everyone needs to relax sometime. And if IQ levels in the West slow down and those in the developing world continue to increase and catch up, then we could be in for some interesting times.”
In any case, the steep rise in IQ would seem to lend weight to the idea that IQ does not evaluate objective intelligence but rather a cultural definition loaded toward the kind of abstract thinking found in postindustrial societies.
Flynn, James R. What is Intelligence?: Beyond the Flynn Effect. August 2007: Cambridge University Press.