"Since the intelligence test was invented more than 100 years ago, our IQ scores have been steadily increasing," said BBC Future. But, in recent years, that trend has been slowing or even reversing – suggesting that we may well have "passed the summit of human intellectual potential".
And the outlook seems similar for human "cognitive capacity" – our ability to apply our intelligence to real-world uses. There has been "remarkably little" long-running research, said the Financial Times, but, from the data we do have, evidence is mounting that our capacity to reason, concentrate and solve problems "peaked in the early 2010s, and has been declining ever since".
What's driving cognitive decline?
The timing of this "inflection point" is "noteworthy", said the FT's chief data reporter John Burn-Murdoch, because it coincides with "our changing relationship with information", now concentrated online. "Decreasing performance" in maths and literacy skills worldwide is probably the result of the "transition away from text and towards visual media". But we're also seeing a "broader erosion" in capacity for "mental focus and application" as we passively consume an increasing "torrent of content" on "constantly refreshed feeds".
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In fact, the "mere presence" of smartphones reduces our "available cognitive capacity", University of Texas researchers have concluded. In a study published in 2017, they found that volunteers were significantly better able to retain and process information if their phone was in another room. Simply turning off or hiding the phone didn't work: people still suffered "brain drain" when their device was nearby.
There's every reason to believe that "underlying human intellectual capacity" is "undimmed", said the FT, "but outcomes are a function of both potential and execution". And, "for too many of us, the digital environment is hampering the latter".
What else might be going on?
It's already known that air pollution can have a "huge" negative effect on cognitive ability. In a groundbreaking study published in 2018, scientists at Yale University and Peking University analysed verbal and maths tests given to 20,000 people in China over four years, and compared them with air-quality data from the same period. They found that higher air-pollution levels significantly impeded cognitive performance – and the longer the exposure, the worse the damage.
"Polluted air can cause everyone to reduce their level of education by one year, which is huge," Xi Chen, one of the study authors, told The Guardian. He stressed that the pollution was "most likely to be the cause of the loss of intelligence, rather than simply being a correlation".
Has the pandemic made things worse?
There is evidence that the Covid-19 pandemic did have an effect on our minds. In 2023, about a million more US adults self-reported serious cognitive problems – difficulty remembering, concentrating or making decisions – than before the pandemic, according to analysis of census data by The New York Times. Researchers attributed the "sharp increase" to the effects of long Covid, which has been linked to brain fog and "serious cognitive problems". A 2024 study, published in the New England Journal of Medicine, compared the cognitive performance of people who had recovered from Covid-19, with that of a similar group who had never contracted the virus. "The Covid-19 group did worse," said Time, "equivalent to a deficit of about three IQ points."
Is AI affecting our IQ?
The rapid rise of artificial intelligence is revolutionising the world's industries but a "less-discussed consequence" is its contribution to the "decline of human cognitive skills", said Forbes. Earlier tools, such as calculators, simplified tasks but "did not erode our ability to think critically": the user still had to "understand the basics of the task at hand". But AI is already "reshaping the way we process information", often "diminishing our reliance on our own cognitive abilities". Effectively, it is "'thinking' for us".
The effects are already being seen in schools and workplaces. In a University of Pennsylvania study, published last year, researchers found that US high-school students who regularly used Chat GPT to help with their assignments performed worse on tests than those who didn't.
