Satnav switches off drivers’ brains

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Do London cabbies have extra-large brains? Yes, they do.
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It’s official: satnav makes you stupid.

A study by researchers at University College London (UCL) has found that relying on satellite navigation while driving through city streets switches off those parts of the brain that would otherwise be dedicated to computing alternative routes.

The work, led by Hugo Spiers from the university’s School of Experimental Psychology, builds on earlier research by another team from UCL that mapped the brain activity of London cab drivers as they underwent the gruelling process of learning the city’s streets – a rite known in the trade as “the Knowledge”.

The cabbie study found that becoming familiar with London’s labyrinthine routes, a process that takes four years, resulted in the bulking up of each driver’s hippocampus, an area in the brain’s medial temporal lobe strongly associated with the conversion of short-term into long-term memory.

In a paper published in Current Biology the researchers, led by Katherine Woollett of UCL’s Wellcome Trust Centre for Neuroimaging, reported that doing the Knowledge produced “enduring, structural brain changes”. No such changes were found in non-cabbie controls, or drivers who failed the test.

Similarly, Spiers’ team used 24 volunteers, who were asked to find their way through a simulation of London’s Soho while having their brains scanned. When asked to do so without assistance, the volunteers all recorded activity spikes in the hippocampus and prefrontal cortex every time they entered a new street. The intensity of the brainwaves correlated with the number of further options each new street presented.

“Entering a junction such as Seven Dials in London, where seven streets meet, would enhance activity in the hippocampus, whereas a dead-end would drive down its activity,” says Spiers. “If you are having a hard time navigating the mass of streets in a city, you are likely putting high demands on your hippocampus and prefrontal cortex.”

When the volunteers were then asked to navigate a route relying on satnav instructions, their hippocampi and prefrontal cortexes were quiet.

“When we have technology telling us which way to go, however, these parts of the brain simply don’t respond to the street network,” says Spiers. “In that sense our brain has switched off its interest in the streets around us.”

And while that means that using Siri to get from A to B might be less stressful than using your wits, it also means that the route will not be imprinted into long-term memory. Making the journey a second time will be no more familiar than the first.

And that, as any London taxi driver will tell you, is the whole purpose of the Knowledge.

The study is published in Nature Communications.

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