A man and a child pulling faces
Humanity is not becoming less intelligent across the board, but the evidence suggests that some important skills are weakening. In several developed countries, IQ test scores have stopped rising or have begun to fall. Teenagers are performing worse in mathematics and reading, adult literacy has largely stagnated or declined, and young people are less likely to read for pleasure. Globally, however, IQ scores are still rising, and some abilities are actually improving. Here are five signals that point to a decline in certain abilities, along with the caveats needed to avoid overstating the conclusion.
What you need to know
- In Norway, IQ scores among men born between 1962 and 1991 first rose and then fell. The decline appeared even between brothers from the same family, which points more towards environmental causes.
- An analysis of data from 72 countries covering 1948–2020 found that IQ scores worldwide are still rising, by about 2.2 points per decade.
- In PISA 2022, average scores across OECD countries fell by about 15 points in mathematics and 10 points in reading compared with 2018.
- An OECD survey of about 160,000 adults in 31 countries found that literacy had stagnated or declined almost everywhere. Only Finland and Denmark improved noticeably.
1. IQ scores have fallen in some countries
For much of the 20th century, each new generation performed better on intelligence tests than the one before. This phenomenon is known as the Flynn effect. In developed countries, the gain was about 3 IQ points per decade. In some countries, that growth later stalled.
In Norway, researchers compared men born between 1962 and 1991. Scores rose at first and then began to decline. The drop appeared even among brothers from the same family. This suggests the cause lies more in the environment, such as education, lifestyle and the information environment.
Similar patterns have been found in Denmark and the United States. Among almost 394,000 Americans who took tests between 2006 and 2018, performance declined in logic, number-series tasks and some verbal tasks. Over the same period, the ability to mentally rotate three-dimensional shapes improved.
The global picture is different. A large analysis of data from 72 countries for 1948–2020 indicates that worldwide scores are still rising, by roughly 2.2 points per decade. The gains are especially noticeable in middle-income countries.
2. Teenagers are doing worse in mathematics and reading
The international PISA assessment does not test whether 15-year-olds have memorised rules. It measures whether they can understand texts, reason and solve real-life problems. In 2022, the average score across OECD countries, a group made up mostly of wealthy nations, fell by about 15 points in mathematics and 10 points in reading compared with 2018. The OECD estimates this is equivalent to losing three-quarters of a school year of learning in mathematics and half a year in reading.
The most obvious explanation is the pandemic and school closures. However, the OECD notes that reading and science performance in many countries was already declining before the pandemic. It appears that COVID-19 accelerated a downturn that had begun earlier.
3. Adults are not getting better at understanding texts and numbers
In 2023, the OECD assessed about 160,000 people aged 16 to 65 in 31 countries. The survey measured how well they understand texts, work with numbers and solve problems. Compared with a similar assessment about a decade earlier, literacy stayed at the same level or fell in almost every country. Only Finland and Denmark achieved noticeable improvements.
About one in five adults in these countries struggles with anything more complex than simple texts or basic arithmetic. The gap between the strongest and weakest performers is widening, and the largest declines were among people whose results were already low.
This points to a paradox. On paper, people today have more education than their grandparents did, and the internet gives access to almost any information. Yet this has not translated into better comprehension.
4. Teenagers are reading for pleasure less often
Between 2009 and 2018, the share of teenagers in OECD countries who read for pleasure fell by about 5 percentage points. The share who consider reading a waste of time rose by about the same amount. Meanwhile, the time teenagers spent online outside school increased by more than an hour a day on average between 2012 and 2018.
People have not stopped reading. Messages, posts and news are read constantly. But understanding three lines of text and following a complex argument for 40 minutes are very different tasks for the brain.
According to PISA data, teenagers who read for pleasure understand texts better. The relationship works in both directions: good readers tend to enjoy reading, and regular reading strengthens the skill further.
A teenager lying on a sofa looking at a phone next to a book
5. Memory and thinking are increasingly handed to devices
Navigation apps remember routes, phones store numbers, search engines supply facts, and AI tools write emails and summarise documents. Scientists call this cognitive offloading, which means shifting part of the brain’s work to the outside world. In a well-known experiment, people who believed information would be saved on a computer remembered the information itself less well. However, they were better at remembering where to find it.
A young woman walking down a city street with a map on her phone screen
Problems begin when the thinking process itself is handed to a device. People who habitually rely on satellite navigation remember their surroundings less well. An analysis of 27 experiments found that having a smartphone nearby while studying makes it harder to recall the material later.
Offloading can also be beneficial. The mental effort it frees up can be redirected to more demanding work. Much depends on what exactly we entrust to technology.
The bottom line: losing some skills, not intelligence as a whole
There are plenty of warning signs. IQ scores are falling in some developed countries, school students are solving problems less well, adults have not become more literate, young people are less likely to read long texts, and memory is increasingly delegated to gadgets. For now, however, the world as a whole is not becoming less intelligent. The brain may simply be adapting to a new environment, in which fewer facts need to be memorised but more effort goes into finding and filtering information.
The greater concern is that some long-standing skills are being practised less often. These include sustained concentration, calculating without assistance, careful reading and building an argument independently. The most accessible response is to read long texts from time to time and occasionally manage without prompts from a phone.
