Cobra Effect · The brain
The taxi drivers whose brains changed
How London's taxi drivers showed that intense learning can reshape the adult brain.
7 cards, read aloud in 2:47, with a test and sources.
To drive a black cab in London, you must pass a test called the Knowledge.
Trainees learn around twenty five thousand streets, and thousands of landmarks. It takes years of study, and only about half of those who start go on to qualify. The neuroscientist Eleanor Maguire wondered what all that learning does to the brain.
In 2000, her team published scans of sixteen licensed taxi drivers’ brains.
They compared them with men who did not drive taxis. They looked closely at the hippocampus, a structure important for memory and for finding your way. All of the drivers in the study were men.
The back part of the drivers’ hippocampus was larger, and the front part smaller.
The total size was about the same. The longer someone had driven a taxi, the larger the back part tended to be. But the study could not show which came first, the driving or the difference in the brain.
In 2006, the team compared taxi drivers with London bus drivers.
Bus drivers spend as long driving the same busy streets, but they follow fixed routes. The taxi drivers again had more grey matter toward the back of the hippocampus, and less at the front. So driving and traffic alone could not explain it. The taxi drivers were also worse at remembering a complicated new drawing.
Then the team followed trainees for years, from the start of their training.
In 2011 they reported on seventy nine trainees, and a group of men who were not training. At the start, there were no differences between them in brain structure or memory. Those who qualified grew more grey matter in the back of the hippocampus. Those who failed, and those who never trained, showed no such change.
The brain, it seems, can change with intense learning, even in adults.
The change was in a specific region, linked to the skill being learned. And it came with a trade off, since qualified drivers did worse at some other memory tasks. Eleanor Maguire died in 2025, aged fifty four.
So when two things go together, ask whether a study followed people over time.
The first taxi study found a difference, but not its cause. Comparing bus drivers ruled out one explanation. Following trainees before and after came closest to showing that learning changed the brain. Each study answered a question the last one had left open.
Sources
- Navigation-related structural change in the hippocampi of taxi drivers, Maguire and colleagues, PNAS, 2000. The first taxi driver study.
- London taxi drivers and bus drivers: a structural MRI and neuropsychological analysis, Maguire, Woollett and Spiers, Hippocampus, 2006. The comparison with bus drivers.
- Acquiring the Knowledge of London’s layout drives structural brain changes, Woollett and Maguire, Current Biology, 2011. Following trainees before and after.
Nearby ideas
- The man who could not make new memories. How one man's lost memory showed that remembering and learning skills are separate.
- The cells that see edges. How an accident with a glass slide revealed brain cells that detect edges.
- Is the brain one net or many cells?. How a black stain and a famous feud revealed that the brain is made of separate cells.
- The patient who could only say tan. How one patient's lost speech pointed to a part of the brain with a special job.
- The patients with a divided brain. What patients with a divided brain revealed, and the myth it was stretched into.