Our IQ is steadily declining
Should you be worried?
Are we scoring lower on IQ tests because of the food we eat? Are schools and teachers the cause? Or maybe computers and mobile phones?
Or is the trend due to something completely different?
The phenomenon of declining IQ scores was detected early in Norway.
Now researchers are seeing the same trend in other countries.
The researchers don’t know what’s behind it. Proposals vary widely. Jon Martin Sundet (81) is a psychology professor and arguably Norway's leading IQ researcher over many years. When we ask him why, he answers calmly:
“Does it really matter?”
We’ll come back to Sundet later.
- IQ is short for intelligence quotient.
- An IQ test is intended to give a numerical expression of a person's abilities, as measured through intelligence testing.
- The average IQ for each age group is set to 100.
The Norwegian soldiers
Two other Norwegian researchers published a study in 2018, in which they established that starting with the cohort born in 1975, the IQ of young Norwegian men entering military service has fallen steadily. Social economists Ole Røgeberg and Bernt Bratsberg at the University of Oslo’s Frisch Centre were behind the study.
The two researchers also discovered something else about the Norwegian soldiers that they believed to be even more important:
“Our main finding was that the decreasing IQs have nothing to do with genetics.”
“The development is due to environmental factors – in other words something in our surroundings,” says Røgeberg.
“But we don’t know what these factors are.”
Have you heard of the Flynn effect?
Before going any further, we need to take a look at the Flynn effect.
The Flynn effect is a phenomenon that for a long time could be observed to varying degrees all over the world.
The effect had to do with the fact that for decades and decades new generations of people scored better on intelligence tests than their predecessors.
James Flynn, a New Zealand political scientist, made this discovery at the end of the 1970s.
We need to take into account that IQ is not an objective scale like metres or kilograms. Instead, the tests have been developed so that the average test score of all participants in the same cohort should be 100 points.
IQ tests were recalibrated as people's IQs changed over time. This ensured that the average person would always score 100 points.
Discovering the phenomenon that Flynn and some other researchers realized had been going on for a long time was thus not that easy.
Massive increase in IQ
In the United States, Flynn and colleagues found that the average American’s IQ had, amazingly, increased from around 70 points in the year 1900 to 100 points in the year 2000.
That is, if the measurements had not been calibrated along the way.
This means that an average person who lived in the year 1900, taking an IQ test in the year 2000, would have received a score that health professionals could have diagnosed as mild intellectual disability.
During the hundred years from 1900 to 2000, the increase in the average IQ of people thus came to 30 points – around 3 points per decade.
This steady increase in IQ in modern humans became known as the Flynn Effect.
No simple genetic explanation
Flynn was clear that such a large increase in our mental abilities could certainly not just be due to genetic factors.
He believed that the finding had to do with changes in the environment around us.
Røgeberg and Bratsberg were able to confirm Flynn’s belief in their study of Norwegian male brothers who had served in the military.
“I think we have good reason to believe that better schools and education were behind a lot of the positive Flynn effect we saw earlier,” says Røgeberg.
He points to a collective study that summarizes a lot of research on the impact of schooling: People's IQ scores have increased by somewhere between one and five points for every year of additional schooling.
“The level of education of the men who showed up in the Norwegian military increased sharply throughout the 20th century.”
“This trend happened in tandem with the expansion of compulsory education. More and more people completed upper secondary education and went on to study at colleges and universities,” Røgeberg says.
New study on 400 000 Americans
Researchers discovered a few years ago that the Flynn effect had stopped.
And not only that – it had actually reversed direction – in pretty well the entire developed part of the world.
Røgeberg points out that Sundet and two Norwegian colleagues may have been the first to notice this in a study published in 2004.
The most recent major study to find a decline in IQ looked at the test results for nearly 400 000 American adults between 2006 and 2018.
The American researchers found the greatest decline in IQ in the youngest participants – of both sexes – ages 18 to 22.
The ability to solve problems has declined in mathematics and vocabulary.
Only the participants' ability for certain types of reasoning has increased.
The researchers in the USA point out that similar findings have been made in Finland, France, Great Britain, Norway, Denmark, Australia, the Netherlands and Sweden in recent years.
The researchers in this American study posed some possible explanations, including poorer schools, the food we eat or perhaps the increased use of computer technology at the expense of book reading.
Still good at logical and abstract thinking
The test that Norwegian soldiers have to take when they show up for military service is technically not an IQ test, but it is designed in the same way.
The test is divided into three sections.
One section involves mathematical skills. Another section is vocabulary based. And the third section has to do with logical and abstract thinking skills.
“In our 2018 project that looked at the changes in Norwegian soldiers, we only had access to the total scores based on these three tests,” says Røgeberg.
“But analyses by Sundet, which are based on the results from each subtest, show that the ability for logical and abstract thinking has remained at a high level among young Norwegian men.”
Fixed intelligence and fluid intelligence
Mathematical abilities and vocabulary are often called fixed intelligence, or knowledge that is accumulated and learned over time.
Fluid intelligence is often described as the ability for abstract thinking and analysis. These skills involve the ability to solve problems and quickly see things in new ways.
Røgeberg finds it interesting that the most abstract skills have remained at a high level.
He does not find it that strange to imagine that pen and paper calculation skills could have become weaker in recent generations of young people. Many of them have grown up using calculators at school, and now all young people walk around with an advanced calculator in their pocket.
The foreign words that new generations of Norwegian soldiers continue to be tested on were often more common in the 1950s than today.
“So maybe we shouldn’t be surprised that these scores have declined as well.”
Røgeberg emphasizes that he is speculating. But it could be that these parts of the IQ tests are simply poorly adapted to today's young people.
What about TV and mobile use?
At the same time, Røgeberg does not rule out that something has changed within schools. Or maybe with the food we eat.
We also know that people are reading fewer books and that they would rather sit and watch TV or a mobile screen.
“I’m an economist, not a psychologist,” he says.
“But if I allow myself to speculate a little more, I think another hypothesis could be that today we’re interested in developing different qualities in our children than what parents emphasized in the past,” says Røgeberg.
“Maybe we need other cognitive abilities more than math skills now.”
Marrying cousins in remote locations
Sundet has 30 years of Norwegian IQ research behind him.
“In Norway, over a million soldiers were IQ tested between 1957 and 2002. We’ve found out a lot with the help of this data,” he says.
Sundet and colleagues, for example, investigated the significance of the fact that in the past consanguinity was much more common in remote places in Norway. This means that quite a few Norwegians had children with close relatives.
“We found that this had little or no effect on people's IQ,” he says.
Discovered the reverse Flynn effect
The past few decades of Sundet's research career have dealt largely with the Flynn effect.
And eventually, the reverse Flynn effect.
The researcher first came across the reverse Flynn effect when new Norwegian conscript cohorts appeared for their military service assessment from the mid-1990s on.
Sundet makes the same point as Røgeberg when we ask him for a possible explanation:
“Remember that these tests often remained unchanged for all those years. And words change meaning over time,” he says.
“So it may not be so strange that young people today score poorly on words that were common in the 1950s.”
Young people don't have much use for extensive math skills any longer, either,” says Sundet.
The psychology professor also points out that we live in a society where everyone is becoming increasingly specialised.
“When so many of us become specialists in something, the general skill requirements we face may not be as great anymore – it’s at least a possible hypothesis,” he says.
Doesn’t think people are getting any dumber
Sundet does not believe that declining results on IQ tests have anything to do with people becoming dumber.
Rather, it could be that intelligence in our time is becoming something different from what it was in the past.
“We have to remember that IQ tests don’t really measure people's intelligence,” he says.
“They measure people's skills in certain areas, which is different than intelligence.”
High IQ and high intelligence are not the same thing
- IQ tests have been widely criticized because they only measure people's intelligence to a limited extent.
- IQ tests only measure a small sampling of a person's skills. Social intelligence is not measured at all.
Young people today are good at other things
If you’re applying for a new job, you may be asked to take an IQ test or something similar to one.
Whoever asks you to take such a test might be assuming that it could reveal some underlying or deeper information about you.
“It’s important to remember that young people today have become extremely good at completely different things than what we have often been able to measure with IQ tests,” says Sundet.
“When I ask my grandchildren about some difficult topic, they just tap a few buttons on their mobile phone,” says the 81-year-old.
“And whoosh, they come up with an answer about the most difficult things.”
“How do they do it so quickly?”
Data has changed people's lives dramatically.
Psychology professor Jon Martin Sundet is far from convinced that this trend is for the worse.
Jon Martin Sundet et.al.: The end of the Flynn effect?: A study of secular trends in mean intelligence test scores of Norwegian conscripts during half a century. Intelligence, 2004. (Summary)
Bernt Bratsberg and Ole Røgeberg: Flynn effect and its reversal are both environmentally caused. PNAS, 2018.
Elizabeth Dworak et.al: Looking for Flynn effects in a recent online U.S. adult sample: Examining shifts within the SAPA Project. Intelligence, 2023.
Translated by: Ingrid P. Nuse
Read the Norwegian version of this article at forskning.no