DAVID EPSTEIN: The Flynn effect is this startling finding that IQ scores, scores on IQ tests around the world, in the 20th century have been rising at a pretty steady rate of about three points per decade. And not only have they been rising at three points per decade, but the scores are rising on the most abstract tests and the most abstract parts of tests.

So, for example, the test that has the fastest rising score Is called Raven's Progressive Matrices. This has nothing to do with anything you've learned in school. It's just patterns, abstract patterns, in a sequence and one is missing, and you have to figure out how to fill in the missing patterns -- pure abstraction. This test was created so that you wouldn't have to bring anything to it that you've learned in life. If Martians landed on Earth, this was supposed to be the test that could determine how clever they were. And yet, it's the place where we've seen the fastest rise in scores, in this abstract thinking skills that aren't really specifically taught anywhere.

When James Flynn, the professor who first noticed this trend, for whom the Flynn effect is named, started wondering what was going on, he went back to some famous studies by a Soviet psychologist named Alexander Luria. And Luria found an incredible natural experiment. In the 1930s when the Soviet Union was nationalizing, essentially, some of the remote territories -- villages that had not been developed for agriculture and they wanted to develop industry in those places -- Luria wondered if taking people who were living in what he called a pre-modern environment where they were subsistence farmers and quickly moving them into modern work, where they had to work together and coordinate schedules and coordinate tasks for agriculture, even have some schooling in some cases, how would that change the way that they think? And so he saw this natural experiment where he came in the middle of this revolution, where dome of these pre-modern villagers -- again using his terminology -- were still in their original environment as subsistence farmers and others were getting connected to the modern world, getting a little bit of schooling; some were being trained to be teachers, others were being appointed to head collective farms and had to start managing people and thinking ahead and setting long-term complicated goals. And what he found was that this actually had a profound effect on the very way that they think. When the pre-modern villagers were given skeins of wool or silk of different colors and hues and asked to organize them into groups, they basically said, 'It can't be done. None of them are similar.' Whereas when some of the villagers who had been touched by modernity were given the same task, they pretty easily grouped them into colors, even if they didn't really have names for those colors, they started to recognize the abstraction of a color for use in grouping.

And the same thing was true with shapes. So for example, a 26-year-old remote villager named Alieva was asked to group certain shapes together. But to her, a square with a solid line was obviously a map and the same square with a dotted line was obviously a watch. She could only see them as these concrete objects, whereas the villagers who had started to interact with the modern world were used to abstract classifications. And even if they didn't know the names of the shapes, they recognized that the concept was the same and they could group them together. And so that's just one example. But in all of these tests what Luria noticed was that the pre-modern villagers were grounded in the concrete, in their own direct experience. They could only answer questions based on concrete objects that they had directly experienced. Where the greater the dose of modernity the villagers had had, the more they had to engage in complex interconnected work, the more they were able to group things with abstract concepts, to use classification schemes, or what James Flynn came to call scientific spectacles. He'd say they see the world through scientific spectacles.

Some of the ways that modern work changed the very thinking of pre-modern villagers are sort of miraculous. On the screen is a famous example called the Ebbinghaus illusion. And if you're watching this, then you're clearly engaged in modern work and in the modern world, and I want you to tell me which one of the central circles looks larger? And again, since you're engaged in modern work, the circle on the right probably looks larger -- the big one surrounded by smaller circles. But pre-modern villagers actually saw correctly that both central circles are actually the same exact size. And scientists who study this think that this has to do with how we differently perceive these circles in relation to one another. So for the pre-modern villagers, they see each individual circle; they're not as drawn to the holistic context. And so they can accurately see the size of the central circles. Whereas people who are more used to abstraction and thinking of things and classification in relation to one another are more drawn to the holistic context. So the contrast between the circles affects your perception.

Now, we in our modern work world have to use abstraction constantly. We have to apply our knowledge to situations that we've never actually seen before. And we get by on that. It's called transfer. We have to take knowledge from one place and use the concepts and apply them to something we've never seen before. And there's evidence that the act of doing that has continued to make us better and better at this abstract thinking that shows up on the Raven's Progressive Matrices. So modernity has essentially changed the way we think, to make us better at using broad abstract concepts and applying them to situations that are unfamiliar to us. And it's not to say that one type of thinking is better than the other. That's certainly not the case. They're just adapted to different conditions. So, whereas the pre-modern villagers would, to use familiar terms, often miss the forest for the trees, they don't see the holistic concept of these groupings, whereas we in the industrialized world will often miss the trees for the forest. We see these broader concepts but sometimes not the individual concrete details that they do.