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The British man whose BMW was left teetering on a Yorkshire cliff edge was an early victim of the phenomenon. Then came the Japanese tourists who drove directly into the ocean in a bid to reach an Australian island and the 67-year old Belgian woman who made the epic journey to Brussels via Zagreb, only wondering if she’d gone off course when the street signs switched to Croatian.
There were already clues that GPS navigation could cause drivers to disengage their common sense. Now scientists have revealed exactly what happens in the brain when people switch from using traditional maps to satnav.
The study found that characteristic brain activity linked to simulating the different possible routes for a journey appears to be entirely absent when a person is following directions rather than independently planning a route.
Hugo Spiers, the neuroscientist who led the work at University College London, explained: “When we have technology telling us which way to go … these parts of the brain simply don’t respond to the street network. In that sense our brain has switched off its interest in the streets around us.”
The findings might explain the disastrous journeys that occasionally result from GPS glitches, a phenomenon that rangers at Death Valley national park in California refer to as “death by GPS”. This mental disengagement might also account for why people who consistently rely on satnav can struggle to remember the directions on a route they have taken many times before.
In the study, 24 volunteers were asked to navigate a simulation of Soho in central London while undergoing brain scans. Some of the time, the volunteers were working out their route manually, while on other trials they were instructed where to go by a satnav.
When volunteers who were navigating manually entered a new street, spikes of activity were seen in the hippocampus, a brain area linked to memory and navigation, and the prefrontal cortex, which is involved in planning and decision-making. As the number of navigational options increased, the brain activity in these region ratcheted up – but no such spikes of activity were detected when people were using a satnav to find their way.
“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,” said 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.”
The study, published in Nature Communications, suggests that we navigate by creating our own internal map of our environment allowing us to calculate the shortest route to our destination.
“Our results fit with models in which the hippocampus simulates journeys on future possible paths while the prefrontal cortex helps us to plan which ones will get us to our destination,” said Spiers.
Based on the new findings on how we navigate, the UCL team also analysed the street networks of major cities around the world to assess how easy they are likely to be to navigate. London, with its irregular network of winding streets and alleyways, appears to be particularly taxing on the hippocampus. By contrast, much less mental effort would be needed to navigate Manhattan in New York, whose grid layout means that at most junctions you can only go straight, left or right.
Dean Burnett, a neuroscientist at Cardiff University, said the findings might help explain previous work showing that London cabbies have bigger and more active hippocampi than the average person, while London bus drivers, who follow pre-set routes rather than working out directions on the fly, do not show these differences.
“Most people manage a normal existence without taxing their navigation skills very much, but the taxi driver data suggests the more you do it, the better you are at it as your brain develops to facilitate it in response,” he said. “If you want to become better at spatial navigation, then you should avoid sat navs where possible. If you just want to get to your destination with as little worry or effort as possible, then they’re fine.”
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All mapped out? Using satnav 'switches off' parts of the brain, study suggestshttps://goo.gl/9kD6hq
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