Something in contemporary life is reshaping which skills we develop
For most of the twentieth century, the developed world grew measurably sharper at the kinds of abstract reasoning that define modern institutions — a rise so steady it was named a law. Since the mid-1990s, that law has quietly broken, with IQ scores declining across Norway, Denmark, Finland, France, Britain, and Australia for three uninterrupted decades. Norwegian family data has ruled out genetics as the cause, leaving researchers to reckon with something more unsettling: that the shared environment of contemporary life is reshaping the cognitive habits civilization spent a century building.
- A century-long rise in abstract reasoning scores — so reliable that test designers had to keep making tests harder — reversed in the 1990s and has not recovered in any country where it has been measured.
- Norwegian father-son conscription records delivered a stark verdict: younger generations score lower than their own fathers did at the same age, proving the cause is environmental, not genetic.
- An American study of nearly 400,000 responses found verbal reasoning, matrix reasoning, and sequential logic all declining — while three-dimensional spatial reasoning, the skill exercised by video games and digital interfaces, rose.
- Competing explanations — eroding formal instruction, fragmented screen consumption, pollution, sleep loss, declining civic life — remain plausible and unresolved, with no single cause confirmed or ruled out.
- The decline is not a verdict on human potential, but it is a measurable signal that the cognitive domains underpinning law, science, medicine, and policy are being practiced less, not more, across the developed world.
For most of the twentieth century, something quietly extraordinary was unfolding across the industrialized world: average IQ scores rose so consistently that test designers had to periodically rewrite their questions just to keep the baseline at 100. Between the 1930s and the 1990s, scores climbed roughly three points per decade. A modern sample given a 1932 test would score around 30 points higher — placing them in the top 3 percent of that era's population.
Then, in the mid-1990s, the trend reversed. Military conscription records in Norway and Denmark were the first to show it clearly: scores that had climbed for decades began to plateau and then fall. The pattern has since been confirmed in Finland, France, Britain, Estonia, Australia, and the United States. In Norway, the decline has continued for thirty years with no sign of turning.
The original rise was named the Flynn Effect after James Flynn, a New Zealand philosopher who documented it in 1984. Flynn argued the gains were cultural, not biological — that modern life, with its formal schooling and symbol-saturated environments, had trained people in exactly the abstract habits IQ tests reward. Before his death in 2020, he suggested the same logic explained the reversal.
The most decisive evidence came in 2018, when Norwegian economists Bratsberg and Rogeberg examined IQ scores for fathers and sons within the same families, all tested under identical conditions. If the decline were genetic, family members would score similarly regardless of generation. They did not — younger sons consistently scored lower than their fathers had at the same age. The conclusion was unambiguous: the cause is environmental.
A 2023 American study of nearly 400,000 online test responses found declines in verbal reasoning, matrix reasoning, and sequential logic — but a rise in three-dimensional spatial rotation, precisely the skill exercised by video games, navigation apps, and digital interfaces. The pattern suggests not a uniform decline but a redistribution of cognitive practice toward abilities the standard tests were never designed to measure.
Researchers have not converged on a single explanation. Schools moving away from formal reasoning instruction, the shift from deep reading to fragmented digital consumption, environmental pollution, sleep deprivation, and declining social trust are all under investigation. None has been confirmed; none has been ruled out.
What the reversal does not mean is equally important. It is not evidence of biological change — genetics cannot shift at this speed. IQ tests do not measure creativity, emotional intelligence, or practical problem-solving. But they do measure the abstract reasoning that underlies law, science, medicine, journalism, and policy. In every country where the trend has been tracked, the decline has continued.
For nearly a century, something remarkable was happening in the developed world. Year after year, decade after decade, the average person was getting better at the kinds of thinking that IQ tests measure. The gains were consistent enough that test designers had to periodically make their questions harder just to keep the average score at 100. Between the 1930s and the 1990s, IQ scores rose at roughly three points per decade across industrialised countries. A person of ordinary intelligence in 1980 would have scored substantially higher than an ordinary person in 1930 on the same test. If you gave a 1932 IQ test to a modern sample, they would score around 30 points higher on average—high enough to place them in the top 3 percent of the 1932 population.
Then, in the mid-1990s, it stopped. The trend that had seemed as reliable as gravity simply reversed.
The reversal was first noticed in the military conscription records of Norway and Denmark, where every young adult male had been tested on the same instrument under identical conditions for decades. The decline showed up in the data clearly: scores that had climbed steadily through the 1950s, 1960s, 1970s, and 1980s began to plateau in the late 1990s and then started falling. The pattern has since been confirmed in Finland, France, the Netherlands, Britain, Estonia, Australia, and in slightly different form in the United States. The decline has continued for thirty years in Norway with no sign of reversing.
The original rise was named after James Flynn, a New Zealand philosopher and political scientist who documented it in 1984. Flynn was not an intelligence researcher by training; he came to the question from political philosophy, looking for evidence about whether abstract reasoning capacity was evenly distributed across populations. What he discovered by gathering historical test data was that scores had risen so dramatically that test designers had been continuously rewriting their tests without anyone noticing the pattern. Flynn's own explanation, laid out in his 2012 book, was that the gains reflected not biological changes in human brains but rather cultural changes in how people practiced abstract thinking. Modern life—with its symbol-heavy environments, its formal schooling, its demand for categorical and hypothetical reasoning—had trained people from childhood in exactly the mental habits the tests reward. The tests measured cultural exposure to a particular mode of thinking, not raw intelligence. Before his death in 2020, Flynn noted that the same logic could explain why the trend had reversed.
In 2018, Norwegian economists Bernt Bratsberg and Ole Rogeberg published a study that did something most previous research had not: they examined the data within families. The Norwegian conscription records included IQ scores for fathers and sons across multiple generations, all measured under identical conditions on the same test. If the decline were genetic, parents and children would score at similar levels regardless of when they were tested. If it were environmental, younger generations would score lower than their fathers did at the same age, even within the same family. The data showed the latter unambiguously. The conclusion was direct: the Flynn Effect and its reversal are both environmentally caused. The decline cannot be explained by genetic drift, by changes in fertility patterns, by selective immigration, or by any of the other biological hypotheses that had been proposed. Whatever is making younger Norwegians score lower than their fathers did, the cause lies in the shared environment of contemporary life.
An American study published in 2023 by researchers at Northwestern University and the University of Oregon examined nearly 400,000 online IQ test responses collected between 2006 and 2018. Three of the four cognitive domains tested showed declines: verbal reasoning fell by about 4.35 points, matrix reasoning by about 2.85 points, and letter-and-number series by about 1.65 points. The fourth domain—three-dimensional spatial rotation—rose. This last finding may be the most revealing. Three-dimensional spatial reasoning is precisely the kind of cognitive task that contemporary digital environments exercise continuously: video games, navigation apps, computer interfaces, and 3D rendering tools all demand it. It is also the only major domain on which contemporary Americans appear to be improving.
The peer-reviewed literature has not converged on a single explanation. Several hypotheses are under active investigation. The educational hypothesis argues that schools have moved away from the rote memorisation and explicit instruction in formal reasoning that built up the abstract habits the original Flynn Effect rewarded. The screen-time hypothesis argues that the shift from sustained deep reading to fragmented digital consumption has reduced the cognitive practice the tests reward. The environmental hypothesis in the broader sense points to a combination of nutrition, pollution, sleep deprivation, declining social trust, and reduced civic engagement. The test-itself hypothesis suggests that IQ tests designed in the early twentieth century are increasingly poorly calibrated to the cognitive abilities contemporary humans actually develop. Each hypothesis is plausible and supported by some evidence. None is conclusive. None has been ruled out.
What the reversal does not mean is important to state clearly. It is not evidence that contemporary humans are biologically less intelligent than their parents. Genetic change does not happen at that speed. It is not evidence that humans are less capable in some broader sense. IQ tests measure specific cognitive abilities under specific conditions. They do not measure creativity, social intelligence, emotional regulation, practical problem-solving, or many other capacities humans use daily. But the reversal is evidence that something in the shared environment of contemporary developed-world life is changing how humans practice and develop the kinds of abstract reasoning that accumulated across the twentieth century. The 3D rotation finding suggests the change is not a uniform decline but a redistribution of cognitive practice toward different abilities than those the standard tests were designed to detect. Whether that redistribution represents a net gain, a net loss, or simply a sideways shift remains unknown. What is at stake is whether the societies in which this is happening have measurably less cognitive capacity across the intellectual domains—law, science, journalism, education, medicine, policy-making—that depend on the skills these tests measure. The trajectory has not reversed. The decline has continued in every country in which it has been measured.
Citações Notáveis
The Flynn Effect and its reversal are both environmentally caused. The decline cannot be explained by genetic drift, by dysgenic fertility, by selective immigration, or by any of the other prominent hypotheses.— Bernt Bratsberg and Ole Rogeberg, Norwegian economists
The tests had not measured raw intelligence. They had measured cultural exposure to a particular mode of thinking.— James Flynn, on the original IQ gains
A Conversa do Hearth Outra perspectiva sobre a história
So for a hundred years, people got smarter at the things IQ tests measure, and then it just stopped?
Not just stopped. It reversed. The scores started falling in the mid-1990s and haven't recovered. It's been three decades now.
But that doesn't mean people are actually dumber, right? You said that in the piece.
Right. It means something about how we live now is changing which cognitive skills we develop. The one thing that's improving is 3D spatial reasoning—the exact skill video games and digital tools exercise all day.
So we're trading one skill for another?
Possibly. Or we're losing something without gaining an equivalent replacement. The research doesn't know yet. But the skills that are declining—abstract reasoning, verbal reasoning—those are the foundation of most intellectual work. Law, medicine, science, policy. If fewer people are developing those skills, that matters.
What changed in the 1990s that could cause this?
That's the question nobody can answer definitively. Schools changed, screens became ubiquitous, how we read changed, nutrition changed, sleep patterns changed. The Norwegian study proved it's environmental, not genetic. But which environmental factor is the culprit? Still unknown.
And we can't just reverse it by going back to how things were?
We don't even know what to reverse yet. You can't fix a problem you don't understand.