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Whatcha guvnor: inside the mind of a London cabbie

By Clare S Ryan, on 28 November 2013

London’s black taxis – or cabs – are as iconic as Big Ben, red buses and the London Eye, so it was no surprise to arrive to a packed audience at Dr Hugo Spiers’s (UCL Cognitive, Perceptual & Brain Sciences) Lunch Hour Lecture on 21 November.

The lecture was a whistle stop tour of the brains of a London cabbie, famously studied by UCL neuroscientists for more than 15 years.

London cabbies – what’s the big deal?
The Great Exhibition of 1851 gave birth to the London cabbie as we know it: the deficiency of the taxi service at the time became widely publicised and, in response, the first test for London’s taxi drivers was devised, called the London Knowledge.

Today, drivers who can complete ‘the Knowledge’ are able to perform amazing feats of memory multiple times a day. To pass the test, they must memorise more than 25,000 streets and one thousand sites of interest so that they can mentally map the route from any point in London to any other.

Learning the knowledge takes three years (similar to a UCL undergraduate degree) and the exam is rarely passed first time.

As a result of this gruelling training, the brains of cabbies are of particular interest to neuroscientists, as they can be used to study lots of interesting questions, such as does special memory change the shape of cabbies’ brains? How does the brain navigate space? And, fundamentally, how does memory work?

The science bit – some early findings
Most of the work on the brains of taxi drivers is associated with Professor Eleanor Mcguire, who conducted the first study, back in 2007, to look at the brains of cabbies.

In her experiment, she persuaded drivers to call out the quickest route from Grosvenor Street to Elephant and Castle while in a PET scanner. This yielded their first key finding: the part of the brain that ‘lighted up’ when they performed this task was the hippocampus – a primitive part of the brain that has been shown to be very important in memory and spatial awareness.

Her next study was to look at whether or not the structure of the hippocampus was different in cabbies compared to you and me.

Using an MRI scanner this time, they found that the structure of a cabbie’s hippocampus is different – they have a bigger posterior hippocampus and a small anterior hippocampus. The effect seemed to be stronger the longer that someone had been a taxi driver. You can read the 2000 study in PNAS.

So, cabbies use their hippocampus to navigate London and it turns out that this part of their brains is different from the average person’s. But can you see the change happening in an individual – or were they born with this ability and different brain shape?

By scanning the brains of drivers before they started the knowledge and then again if they had passed the test, the researchers were able to answer this question.

They found that the density of the cells in the grey matter is greater in qualified taxi drivers who have passed the knowledge compared to drivers before they started the training, or those who never managed to pass the test.

This finding points to the startling, and perhaps reassuring, fact that people can change the structure of their own brain and improve their memory through rigorous training.

Neuroscientists bring out their Playstations
But what scientists really want to know – which brings us back to the title of the lecture – is what is going on in the minds of cabbies when they’re driving. What are they thinking?

However, studying this presents a problem for scientists. How do you get cabbies to experience driving while they’re inside a scanner? It would take creating an exact simulation of the entire of London, probably costing millions of pounds.

Luckily for them, Sony had done just that for a computer game, spending more than £15m. Although apparently not a very good game, it was invaluable for Dr Spiers and his colleagues.

With minor tweaking (the design of the world’s first metal-free Playstation controller, for instance) they were able to design routes through London for their cabbies to ‘drive’ while having their brains scanned. Imagine the cabbie version of Grand Theft Auto.

In the experiment, after they’d driven the routes in the scanner, Dr Spiers replayed the video simulation to them and asked each participant questions about how they’d felt during the experience.

He found that most of the time cabbies are coasting, rather than planning their route. Perhaps not surprisingly, a lot of them felt pretty angry and anxious, and, all but one, showed very low levels of happiness throughout.

He also found that taxi drivers seem to have a homing system in place in their brains. In a region called the entorhinal cortex, activity seemed to decrease the closer that they got to their goal location.

That’s all folks
So that’s it. Dr Spiers delivered a brilliant lecture, full of anecdotes to explain the subject – perhaps a bit like the lecture form of being in the back of a cab.

Black taxis may be icons of London, but what’s going on inside their drivers brains is perhaps even more of a surprise.

You can watch the lecture below:

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