In the mid-1980s, James Flynn made a groundbreaking discovery in human intelligence. The political scientist at the University of Otago in New Zealand found that over the last century, in every nation in the developing world where intelligence-test results are on record, IQ test scores had significantly risen from one generation to the next.
“Psychologists faced a paradox: either the people of today were far brighter than their parents or, at least in some circumstances, IQ tests were not good measures of intelligence,” writes Flynn.
Now, in a new book, Are We Getting Smarter? Rising IQ in the Twenty-First Century, Flynn unpacks his original finding, explaining the causes for this widespread increase in IQ scores, and reveals some new ones, regarding teenagers’ vocabularies and the mental decline of the extremely bright in old age. Ultimately, Flynn concludes that human beings are not smarter—just more modern.
Malcolm Gladwell explains why the “Flynn effect,” as the trend is now called, is so surprising. “If we work in the opposite direction, the typical teenager of today, with an IQ of 100, would have grandparents with average IQs of 82—seemingly below the threshold necessary to graduate from high school,” he wrote in a New Yorker article in 2007. “And, if we go back even farther, the Flynn effect puts the average IQs of the schoolchildren of 1900 at around 70, which is to suggest, bizarrely, that a century ago the United States was populated largely by people who today would be considered mentally retarded.”
In the last half-century, what have the IQ gains been in America?
The overall gain is about 3 points every 10 years, which would be 9 points in a generation. That is highly significant.
Now, on these tests [two that Flynn looks at are the Wechsler Intelligence Scale for Children, or WISC, and the Wechsler Adult Intelligence Scale, or WAIS], the gains vary by subtest. For example, there is a subtest called “similarities,” which asks questions like, what do dogs and rabbits have in common? Or what do truth and beauty have in common? On this subtest, the gains over those 50 years have been quite extraordinary, something like 25 points. The arithmetic subtest essentially tests arithmetical reasoning, and on that, the gains have been extremely small.
How do these gains compare to those in other nations?
If you look at the Wechsler gains abroad, they are pretty close to U.S. gains. There was a period of high historic gains in Scandinavia; these seem to have tailed off as the century waned. I thought that might be true of other countries as well. Maybe the engine that powers IQ gains was running out of fuel? But the latest data from South Korea, America, Germany and Britain show the gains still humming along at that same rate into the 21st century.
So, what has caused IQ scores to increase from one generation to another?