The Plastic Brain

Why everything you just read about saboteurs is fixable, and what the cab drivers of London can teach you about your own.

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To drive a black taxi in London, the kind with the iconic shape and the rear-facing jump seats, you have to pass an exam called "The Knowledge." The exam was introduced in 1865, and it has been refined, but not fundamentally changed, for over 150 years. To pass it, an aspiring driver must memorize, in detail, every street, alley, square, hotel, hospital, theater, museum, church, embassy, restaurant, school, and government building inside a six-mile radius of Charing Cross station. That works out to roughly 25,000 streets and 20,000 landmarks, plus the optimal routes between any two of them in real time, accounting for one-way streets, time-of-day traffic patterns, and current roadworks.

It takes the average aspirant three to four years of full-time study, on top of working a regular job. Most candidates spend the first year just riding a moped around London with a clipboard, tracing routes. The drop-out rate is approximately 70%. Only about half of the people who actually sit for the exam pass it on their first attempt.

In 2000, a neuroscientist at University College London named Eleanor Maguire put a group of London taxi drivers into an MRI scanner. She compared their brains to a control group of bus drivers (matched for age, sex, education, and time spent driving in London, but who drove fixed routes and therefore did not need to memorize the city's layout). What she found set off a quiet revolution in modern neuroscience.