What the Brains of London Taxi Drivers Reveal About the Costs of Technological Convenience
Your brain, like your body, grows weak and sick without exercise.
I RECENTLY SPENT a week on the Greek island of Spetses.
I was there with my wife and kids, and the house where we stayed was on the outskirts of a confusing tangle of winding streets and alleyways.
Spetses is a car-free island—only scooters and commercial vehicles are allowed—and the nearest market was a 20-minute walk from our place. “Vacation” for me means not having to look at screens, so when the time came for a grocery run, I decided to leave my phone behind and find my own way to the market. The friends we were staying with had pointed it out to me, so I knew, approximately, where I needed to go.
I set off with my kids . . . and quickly got turned around. We backtracked, found a familiar street, and, after several more wrong turns and accidental detours, finally ended up at the market. What should have been a 20-minute walk had taken us a good half hour, and the walk home was only a little more direct.
But the next day, when I had to go to the market again, I had little trouble finding my way. Thanks to the previous day’s meandering, I’d built up a mental map in my head filled with landmarks and orientation points. Each day we spent on the island, my mental map grew more detailed. By the end of the week, the tangle of streets and alleyways no longer felt confusing. I could venture out and explore without fear of getting lost.
I didn’t know this term at the time, but apparently I was “friction-maxxing”: opting for effortful cognitive labor over the ease of modern convenience.
The term was coined by Kathryn Jezer-Morton in a 2026 article for New York Magazine. While I only learned about Jezer-Morton’s catchy phrase recently, the big idea behind it—that our brains, like our bodies, may languish for lack of exercise—is something I’ve been thinking about, writing about, and acting on for years.
In my book The Habit Trap, I devote several chapters to the necessity of “cognitive challenge” and the many problems that arise when we spend too much time coasting along in behavioral autopilot. These problems include loss of focus, shallower mental engagement, and other executive-function failures that limit our capabilities, lever us out of the moment, and feed into conditions like anxiety and depression.
Routines encourage this kind of problematic coasting. Habitually offloading difficult cognitive tasks to our devices does something similar.
There’s no question that our digital tools improve life’s ease and efficiency. They’re a boon to many forms of productivity. But while we’re all getting more done with less effort, some critical mental muscles may languish for lack of exercise.
Even those of us who recognize these risks may be low-balling the stakes. Some recent research on GPS and Alzheimer’s disease reveals how offloading cognitive work and embracing tech-enabled convenience may threaten the physical health of our brains.
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At the turn of the century, a groundbreaking study of London taxicab drivers revealed something unusual: they possessed especially large hippocampi.
The hippocampus is a part of the brain involved in navigation and spatial memory. Using structural MRI, the study team found that the taxi drivers—who must pass a notoriously brutal test of local navigational know-how without the aid of GPS—had beefier hippocampi (as measured by gray matter volume) compared to regular people. Furthermore, the taxi drivers who had been in the job the longest had the largest hippocampi.
“This finding indicates . . . that normal activities can induce changes in the relative volume of gray matter in the brain,” the study team wrote.
That may not sound like a big deal, but it is. The researchers had uncovered evidence that how a person uses their brain may change its physical makeup. In the same way training a muscle can increase its size and strength, the study findings seem to show that training the hippocampus with complex navigational tasks can pump up its physical properties.
In the quarter century since that pioneering study, researchers have found that habitual use of GPS leads to a decline in spatial memory, and that those adults who rely heavily on GPS tend to have reduced hippocampal volumes compared to adults who use GPS less.
More work has revealed that, apart from being heavily involved in navigation and spatial memory (and, for that matter, in many other forms of learning and memory), the hippocampus is also strongly linked to the appearance and progression of Alzheimer’s disease.
Loss of hippocampal volume (i.e., shrinkage) is one of the earliest indicators of Alzheimer’s—often showing up even before a person has noticed any symptoms. Research from University College London has also found that the speed of hippocampal shrinkage correlates with the speed of cognitive decline among people with Alzheimer’s. Those who have the lowest hippocampal volume to begin with also tend to lose volume and capability fastest, that research found.
All these links between the size of a person’s hippocampus and their risk for Alzheimer’s disease—coupled with the work on GPS and London taxi drivers—inspired a group of U.S. researchers to look at the rates of Alzheimer’s-related death among people who, thanks to their jobs, are heavily dependent on their brain’s navigation skills and spatial memories.
Using publicly available data collected from millions of Americans, the researchers discovered that, out of more than 400 different occupations, people who worked as taxi or ambulance drivers—jobs that require on-the-fly navigation and lots of spatial memory activation—enjoyed the lowest risk of death due to Alzheimer’s disease. And it wasn’t close: The taxi and ambulance drivers’ risk at any age was 56% lower than the general population’s. (Their risks for other common diseases—and even for other causes of dementia—were average, which suggests these were not inordinately healthy people.)
“We couldn’t address every source of potential confounding, but the correlation between these jobs and a reduction in Alzheimer’s death was so striking,” said Christopher Worsham, an assistant professor of medicine at Harvard Medical School and co-author of the book Random Acts of Medicine, when I spoke with him about his group’s work. “When you take into account the existing research on the hippocampus and how it relates to dementia, it becomes even more compelling.”
While there’s plenty of evidence that our cognitive capabilities follow a use-it-or-lose-it principle—meaning the less we exercise our mental muscles, the weaker they become—Worsham’s findings suggest it’s not just our cognitive skills that suffer when we lean too heavily on our devices; the physical health of our brain might be at risk when we offload certain effortful activities to new technologies.
“We know that some forms of cognitive struggle are really important to us when it comes to learning and skill development,” Worsham said. “If we’re all farming out that struggle to computers and AI agents, our findings may be an early indication of what this could mean for us, and it’s worrying.”
Like a good scientist, he’s careful to add that there’s a lot left to be sorted out. “We understand so much about how the body works, but the brain is still such a black box,” he said. “But right now we have a situation where the researchers who study these things are very cautious and hesitant to extrapolate, while AI companies and their lobbyists are the opposite—they’re free to over-promise and play down any risks to cognitive health.” The unfortunate consequence of this mismatch is the rapid adoption of these technologies without a balancing regard for what we all may be giving up in the bargain.
“You even see some of the computer scientists who have helped develop these technologies warning that there may be risks, but we don’t seem to be listening to them,” he added.
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After reading Kathryn Jezer-Morton’s piece on “friction-maxxing” and the downsides of convenience, I read some online rebuttals to her arguments.
The most common—and, in my opinion, the laziest—was the assertion that the history of human innovation and progress has basically been one long march toward greater ease and convenience. Since we’re all still here and doing okay, freaking out about the state of AI-powered convenience is silly, that line of criticism goes.
I think these critics need to exercise their own mental muscles a bit more, because their argument ignores the mountain of work on the risks of a sedentary lifestyle.
We know beyond all doubt that if we don’t move our bodies, we lose range of motion, strength, and capability. Ultimately, we end up sick—or worse. As the convenience of modern life has rendered movement increasingly optional, we’ve had to set aside more time for intentional, effortful movement—a.k.a., exercise—which is something few people devoted much time to prior to the 1970s. The “fitness boom” that has seized America in recent decades can be viewed as a byproduct of technological progress and the health problems it created for us.
I think we’re going to need another boom—this time to protect our brains from technology-enabled inactivity. And doing the occasional Sudoku or playing with a “brain training” app is not going to cut it. “These things sound good, but the evidence supporting them is terrible,” Worsham told me.
It’s been a month since I walked around Spetses with my kids, but I still have that mental map in my head. I can still wander those pretty streets in my mind, recalling conversations I had with my kids, places my friends pointed out to me, and even thoughts that came to me as I explored the unfamiliar island. I feel like my memories are much richer than they would have been if I’d had to devote half my attention to Google Maps.
Navigating without GPS is the kind of intrinsic, engaging cognitive work that has been a part of the human experience since our species’ inception. It’s one of many age-old cognitive tasks—tasks like critical thinking, deliberative problem solving, persistent focus, creative brainstorming, and attentive social interaction—that used to be inescapable (and rewarding!) aspects of daily life for every human. But now, thanks in large part to AI, these tasks are increasingly optional.
There’s a lot left to be sorted out. Good science and the evidence it produces takes time. But based on what we already know, the health and capability of our minds may depend on us setting aside our devices—at least occasionally—and putting our brains back to work.