Brain on GPS

Alex Hutchinson’s latest book is The Explorer’s Gene: Why We Seek Big Challenges, New Flavors, and the Blank Spots on the Map, from which this essay has been partly adapted.

“Mummy uses Waze,” a helpful voice piped from the back seat.

We were on our way to my daughters’ playoff hockey game, and I’d just missed a left turn. Now I was scanning the intersections ahead, looking for a road that would take me north without getting snarled in residential cul-de-sacs or blocked by train tracks.

“Don’t worry, we’ve got lots of time,” I lied, clenching the steering wheel and forcing a smile into my voice.

“You wouldn’t have missed that turn if you used Waze,” my younger daughter persisted. “Why don’t you use it?”

I swung left up a promising-looking street. “Wow, I’ve never been up this way before,” I said. “Isn’t this neat? We’re having an adventure!”

No one in the back seat sounded convinced. It sounded pretty thin to me too, but the real reasons I’d sworn off my phone’s turn-by-turn directions were harder to articulate. On a superficial level, I was worried that the navigational centres of my brain were at risk of withering away. But the ubiquity of GPS also felt emblematic of a deeper shift in how we interact with the world and with each other these days: more passive, more automatic, more forgettable. I wanted to chart my own path – and make my own mistakes.

The Global Positioning System, a network of two dozen satellites that can instantly pinpoint your location, originated as a U.S. military project in the 1970s. In 1983, after a Korean airliner accidentally wandered into restricted Soviet airspace and was shot down, Ronald Reagan announced that it would be made available for limited civilian use. In 2000, Bill Clinton lifted the remaining restrictions and kick-started the era of consumer GPS.

I first tried GPS a few years later, borrowing my uncle’s hand-held Garmin unit for a backcountry trip in the Rockies. Then came in-car navigation screens suction-cupped to windshields, replacing map books and sheets of directions printed out from MapQuest. In 2008, Apple added GPS to the iPhone.

Getting GPS on my phone initially seemed like just another incremental step in the long march toward total convenience. But it soon became clear that having an omniscient navigational tool in your pocket at all times represented a dramatic change – not just in how we find our way around, but in how we construct a mental representation of the world around us.

Scientists have long used navigational challenges to probe our inner states. “The history of psychology,” behavioural neuroscientist Paul Dudchenko writes, “is, in part, a history of how rats find their way in mazes.”

One of the most famous rats-in-mazes study was a 1948 paper by Edward Tolman that introduced the concept of “cognitive maps.” At the time, behaviourists argued that rats navigated through mazes by simply memorizing a series of lefts and rights. Tolman showed that if you made shortcuts available, rats would choose the right direction, demonstrating that they had some sort of internal representation of where they were relative to their destination.

In the 1970s, scientists discovered that this idea of a cognitive map wasn’t just a metaphor. We have “place cells” in a region of the brain called the hippocampus, each of which lights up only when we’re in a specific location. We also have specific neurons that keep track of which direction we’re facing and how near we are to the boundaries of a given space. Wire up a rat’s brain, and you can watch neurons fire in succession as the rat wanders through a maze, tracing the contours of a literal map encoded in its brain.

These studies established the hippocampus as the seat of spatial memory in the brain. Famously, a study in 2000 found that London taxi drivers had abnormally large hippocampi thanks to the requirement that they memorize the city’s labyrinthine network of streets.

But plotting your route with a cognitive map encoded in your hippocampus isn’t the only way to get around. In fact, it’s not even the fastest or easiest. You can also use what scientists call stimulus-response navigation, which simply involves following a set of directions and landmarks: Turn right at the gas station, go three blocks, then left after the bridge. Stimulus-response relies on a different brain region called the caudate nucleus, and it takes less mental effort.

The advantage of cognitive mapping is that it’s versatile. If you know how to get from A to B, and from B to C, you can figure out the fastest route from A to C. That’s not possible if you’ve just memorized the routes. Turn-by-turn GPS directions are an ultrapure form of stimulus-response navigation, requiring no awareness whatsoever of your surroundings – and they also eliminate the shortcut problem, because they already know how to get from A to C, or anywhere else you want to go.

In the early 2000s, neuroscientist Véronique Bohbot and her colleagues at McGill University began studying the effects of different styles of navigation on the brain. They created virtual mazes that could be navigated equally well with cognitive mapping or stimulus-response. Sure enough, brains scans showed that people who chose to rely on cognitive mapping tended to have bigger hippocampi, while those who relied on stimulus-response had bigger caudate nuclei.

To establish causation, Dr. Bohbot then paid volunteers to come into her lab and play video games like Call of Duty for a total of 90 hours over several months. Those who defaulted to stimulus-response navigation had measurable shrinkage in their hippocampi, while those stuck with cognitive mapping increased their hippocampus size.

This is alarming because having a small hippocampus has been linked to elevated risk of a wide range of neurological conditions including Alzheimer’s disease, depression, schizophrenia, and PTSD. It’s hard to establish that the small hippocampus is what’s causing the problems, but the evidence is suggestive. Schizophrenia patients, for example, tend to already have an unusually small hippocampus when they have their first episode of psychosis.

This is the chain of logic that first grabbed my attention, focused narrowly on the perils of being a slave to my GPS: stimulus-response navigation leads to smaller hippocampus leads to cognitive or neurological problems. But when I interviewed Dr. Bohbot for a magazine article, she sounded a much broader warning: “Society,” she told me, “is geared in many ways toward shrinking the hippocampus.”

I started to think more critically about my own GPS use during a five-day backpacking trip with my wife and kids in Newfoundland’s Long Range Mountains a few years ago. Bad weather and challenging terrain put us far enough behind schedule that I started to worry about our food supplies.

To keep us moving and reduce the risk of wrong turns, I started checking the GPS waypoints I’d downloaded onto my phone as a backup. It was much easier and more accurate than wrestling with the paper map every few minutes, and soon I was hiking with my phone in my hand at all times – and, I realized, staring at its screen watching the route unfurl as we walked, rather than looking at my surroundings.

There’s a rich body of scientific research on the differences between actively acquiring information and passively receiving it. Think of driving a car to a new destination compared to sitting in the passenger seat. You see the same sights, but the driver is far more likely to remember how to retrace their steps. Ask kids to draw maps of their neighbourhoods, and those who are driven to school will tend to draw two dots – home and school – connected by a line, while those who walk or bike will provide a more richly detailed picture.

What finally motivated me to switch off turn-by-turn directions wasn’t so much the fear of Alzheimer’s, although, like Dr. Bohbot, I find the data concerning. Instead, it was an attempt to change the nature of my here-and-how experiences – to climb back into the driver’s seat.

A consistent pattern in Dr. Bohbot’s data is that we gravitate toward stimulus-response navigation as we get older. In one of her virtual-world studies, 84 per cent of children used cognitive mapping, compared to 46 per cent of young adults and just 39 per cent of older adults. This isn’t surprising: The more we know about the world, the easier it becomes to rely on quick cognitive shortcuts instead of laboriously exploring and mapping the world around us.

The same is increasingly true in other domains. Algorithms tell us what to click, and guide our decisions about what to read and watch and listen to. Package tours and travel blogs guide our travel along well-worn and inconvenience-free routes. Review sites ensure that we eat only at those restaurants and purchase only those kitchen gadgets that have been preapproved by the wisdom of the crowd.

All of these innovations are good, and I still rely on them myself. But I can no longer unsee what’s lost along the way. It has never been easier to be a passenger in life, but the experience is almost always paler and less vivid than the visceral jolt of trepidation you feel when, say, you walk through the doors of a restaurant you know absolutely nothing about. Turning off my GPS now and then is a reminder to myself that it’s worth exploring in all these domains – even if that sometimes involves wrong turns.

“When you’re exploring, you’re going to make errors,” Dr. Bohbot told me. “And when you’re making errors, that means you’ll pay attention to your environment in order to find your way, so you’re going to stimulate your hippocampus.”

Did my kids understand any of this? I’m not sure. I did try to explain it to them, and they listened patiently and seemed intrigued. They don’t want my brain to atrophy either. But it was a playoff game, so eventually I fired up Waze just to be safe.