Every so often a headline announces that humanity is getting dumber. Screens, social media and short attention spans usually get the blame, and the evidence offered is real: in some countries, average IQ scores have stopped rising and started to slip.
But "people are getting dumber" is not quite what the data say. The real story is more specific, more interesting and a good deal less alarming. Here's what the reverse Flynn effect is, where it has shown up, and what researchers think is behind it.
First, the Flynn effect
To understand the reversal, you need the original trend. Across much of the 20th century, average performance on IQ tests rose in many countries by roughly three points per decade. This is the Flynn effect, named after researcher James Flynn, and it was largest on abstract reasoning tasks.
Because tests are re-normed so the average is always 100, these gains were mostly invisible to the public. If you want the full background, our explainer on the Flynn effect covers how it worked and what likely drove it.
What is the reverse Flynn effect?
The reverse Flynn effect, sometimes called the negative Flynn effect, is the finding that in some places those gains have stalled and then turned into modest declines, starting roughly in the 1990s.
The best-known evidence comes from Scandinavia, where many young men historically took cognitive tests as part of military conscription. That created large, consistent datasets stretching across decades. Researchers working with Norwegian, Danish and Finnish data reported that scores peaked for cohorts born around the mid-1970s and then drifted downwards.
Some newer studies have reported similar patterns in other countries, though the evidence is patchier and depends heavily on which tests and samples are used.
How big is the drop?
This is where headlines tend to overreach. The declines reported are real but modest, often a few points per generation rather than a collapse. They also don't appear everywhere, and in some datasets certain abilities have continued to improve while others dipped.
| Claim you might read | What the evidence actually suggests |
|---|---|
| "IQ is falling everywhere" | Declines are reported in some countries and datasets, not universally |
| "We're losing all the 20th-century gains" | The dips are small compared with the earlier rise |
| "All thinking skills are declining" | Results vary by skill; some show declines, others are stable or rising |
| "It's because less intelligent people have more children" | The strongest evidence points to environmental causes instead |
The study that changed the debate
One of the most important studies on the topic was published in 2018 by economists Bernt Bratsberg and Ole Rogeberg, using Norwegian conscription data covering hundreds of thousands of men.
Their key move was to compare brothers. Brothers share parents, so if the decline were caused by changes in who was having children, scores within families should stay steady. Instead, they found the same pattern within families: younger brothers born in later years tended to score lower than older brothers.
That points strongly towards environmental causes, things that changed in the world those children grew up in, rather than shifts in the genetic makeup of the population. It also reinforces a lesson from the original Flynn effect: environment can move IQ scores in either direction.
What might be causing it?
Nobody has a definitive answer yet. Researchers have suggested a range of possible factors, and it's likely several interact.
Changes in education
Teaching styles, curricula and what schools emphasise have shifted. If schooling places less weight on the specific kinds of abstract reasoning that IQ tests reward, scores on those tests may dip even if students are learning other valuable skills.
Reading and media habits
Time spent on sustained reading has fallen for many young people, while time with fast-moving digital media has grown. It's a plausible contributor, but direct causal evidence is limited, so it's worth being cautious about blaming screens for everything.
The tests themselves
Some researchers argue that tests designed decades ago may no longer match how people think and learn today. A test question that once felt neutral can become less familiar over time, so part of the decline may reflect a growing mismatch between test and test-taker rather than lost ability.
Motivation and test-taking
Conscripts and students may approach tests differently than earlier generations did. Even small changes in effort can shift average scores across a large population.
A ceiling on earlier gains
Improvements in nutrition, health and access to schooling drove much of the original rise. Once those gains are largely achieved, they stop pushing scores upwards, and other changes can tip the balance the other way.
So, are people getting dumber?
Not in any simple sense. A more accurate summary would be:
- In some countries, average scores on certain reasoning tests have dipped modestly since the 1990s.
- The best evidence suggests environmental causes rather than genetic ones.
- The size and spread of the decline vary a lot between datasets and abilities.
- IQ tests capture a specific set of skills, so a dip on them doesn't mean people are worse at thinking in every way.
It's also worth remembering that average trends say very little about any individual. Your own reasoning ability is shaped by your experiences, habits and learning, as we explore in can you increase your IQ?.
What this means for you
The reverse Flynn effect is a population-level trend, not a personal forecast. But it does carry a few practical takeaways:
- Environment matters. The habits that support reasoning, such as reading in depth, learning new skills and tackling challenging problems, are worth protecting.
- Norms matter. An IQ score is only as meaningful as the comparison group behind it. Our guide on what counts as a good IQ score explains how to read one.
- Headlines oversimplify. "Getting dumber" makes a better story than "small, uneven declines on certain tests".
If you're curious where your own reasoning sits today, you can take our free IQ test and see how you compare with current norms.
The bottom line
The reverse Flynn effect is real but modest: in some countries, IQ scores that rose throughout the 20th century have dipped slightly since the 1990s. The strongest evidence, including within-family comparisons, points to changes in environment, education and perhaps the tests themselves, not to a genetic decline. People aren't simply getting dumber, but the trend is a reminder that thinking skills respond to the world we build around them.
FAQ
When did the reverse Flynn effect start?
In the best-studied Scandinavian data, scores peaked for people born around the mid-1970s, with declines appearing in later-born groups. Timing varies between countries and datasets.
Is the reverse Flynn effect caused by genetics?
The strongest evidence suggests not. A large Norwegian study found the decline within families, comparing brothers, which points to environmental causes rather than changes in who was having children.
Are screens making us less intelligent?
It's a popular explanation, but direct evidence that screens cause lower IQ scores is limited. Changes in reading habits and education are plausible contributors, and researchers are still testing these ideas.
