Human Journey

The Bigger Brains of London Taxi Drivers

How hard could learning a map of a city be? In London, earning the credentials to drive one of the city’s iconic cabs is equivalent to earning a university degree. It’s so advanced, in fact, that being able to navigate the streets isn’t just considered knowledge, but is formally called “The Knowledge.” The way London’s taxi drivers talk about it, it seems a little like getting a black belt in karate while becoming an Eagle Scout while vying for admission to Mensa.

The reason why is London’s curious urban design, a squirrely mix of streets that were designed over centuries rather than by a one-time urban design grid that you might find in New York or Washington DC. There’s no pattern to learn in London, or a system of mnemonics to remember the order of roads. You simply have to learn every street in the city. And before you can legally drive a taxi, you have to prove to a group of city officials that you can, without fail, navigate between any two points. During the tests, aspiring drivers have to dictate the most efficient route and recall landmarks they’ll pass on the way. The people who are very good at it—and let’s be honest, more than 90 percent are men—can master the system in two years. Most people take four or longer.

Photo by Spencer Millsap / NGM Staff
Photo by Spencer Millsap / NGM Staff

It’s a fun tourist novelty to know that the person driving you has a very detailed spatial map of the city in his head. But for about a decade, a group of researchers at the University College of London have looked into the effect that memorizing such a disorganized system has on your brain. The part of the brain that navigates spatial intelligence is called the hippocampus, a pair of two chestnut sized masses toward the back of your head. The researchers found that London cab drivers have uniquely bigger hippocampi than almost anyone else.

We asked a few London cabbies about this in hopes they could help us understood how their brains worked.

“Oh yeah mate, it’s called the hippocampus,” one cabbie named Simon told us. “Most people don’t use it because of the simplicity of navigating most other places and because of maps and GPS. But with London there’s really no other way.”

What’s it like to map something very complex in your brain, we asked?

“Well, right when the person asks where to go, it’s like an explosion in your brain. You see it instantly.”

An explosion in the brain is a pretty vivid image to understand just how someone’s mind works. Yet it rings true. Each time we got into a cab and stated an obscure street name or small neighborhood, the driver didn’t even respond. He just started driving, seeming to know immediately which streets to take, and what the most direct route would be.

The downside to having a big hippocampus is that when cabbies retire and stop using their spatial mapping so regularly, the hippocampus actually starts to shrink back to normal. It’s like a muscle that shrinks if you don’t use it. What’s more, memorizing such a detailed map of a sprawling city actually took up the place of other grey matter. Researchers found that cabbies were worse at remembering things based on visual information and had worse short term memories. There is, after all, only so much real estate in one’s head.

  • Ronald Reader

    OI! OI!

  • MRadclyffe

    It might take four years to complete and pass The Knowledge, but it would take a lot longer to “master” [sic] the roads in London Town!

  • Wilmenia

    Hello Dan,

    I would like to Congratulate you for your posts in the “Change>>Reaction”. I always read and like it too much. Thanks for share it with us.

    I found very interesting and fun that post about the brain of the drivers in London.
    Few weeks ago I went there for a weekend and was just thinking about the London’s curious urban design. It’s really very confusing to ride there.
    Your post is is very good , and reminds me something my husband wrote about his profession: Conference interpretation. His post “explores some counterintuitive processes that make simultaneous interpreting possible”. Its very interesting too.
    If you feel interested, take a look in that page: (the article is: How do you do that?).
    Again, congratulations. I will continue to read your open minded posts.
    All the best,

  • Memory Man

    Thanks you for this very insightful article. I’ve always been fascinated with these cab drivers as I teach memory improvement myself. I ‘m quite sure though that there is some sort of mnemonic principle that they use.

  • Doug Storton

    What are the safety features for cab drivers in London
    ie were violent passengers are of concern

  • alishabrown

    I also have gone through these tests and with over 26,000 streets to learn, becoming a licensed London taxi driver takes a lot more than just driving skills.

  • Ooty Taxi

    I think we can follow this in India as well so that we too can have well experienced drivers .Seems quite interesting

  • Lisa James

    Each time, I used to read smaller articles or reviews that also clear their motive, and that is also happening with this article which I am reading at this time. When I am in London, I mostly use taxi from stansted airport.

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