Lots of people who are interested in traditional methods of navigation - myself included - have long suspected that habitual GPS use weakens our ability to find our way around without the help of those little glowing screens.

As I observe in Incredible Journeys, using GPS relieves us of the need to pay attention to our surroundings and keep track of our position as we travel around. So it’s reasonable to suppose that people who rely most heavily on GPS will have more difficulty navigating without its help than those who keep their wits about them and their eyes open.

Now a new study has confirmed these suspicions.

There are two basic ways of navigating a new environment and they rely on quite different parts of the brain.

One is the ‘spatial memory strategy’. This means learning the relative positions of a series of landmarks and it allows us to form a ‘cognitive map’ of our surroundings. It depends heavily on a region in the middle of the brain called the hippocampus - which is crucial to our ability to recall events.

The other approach is based simply on learning a sequence of manoeuvres - turn left at the end of the street, then go 50 yards and then turn right, and so. Known as ‘stimulus-response learning’, it involves a different part of the brain called the caudate nucleus - which is also the key to learned skills like riding a bicycle.

Louisa Dahmani and Véronique Bohbot wanted to find out whether individuals who were dependent on GPS relied more on stimulus-response strategies than on spatial memory when they had to find their way without its help.

So they asked 50 healthy young adults (18 women and 32 men) between the ages of 19 and 35 who lived in Montreal, Canada, to perform a series of navigation tasks in computer-based ‘virtual’ mazes. The subjects also completed questionnaires that explored - among other things - how confident they were in their navigational abilities and the degree to which they relied on GPS in their every day lives. 13 of the original subjects took part in a follow-up study three years later designed to find out what the long-term effects of GPS use might be.

As expected, Dahmani and Bohbot found that the more people relied on GPS to navigate, the less likely they were to deploy a spatial memory-based strategy when they had to navigate without its help.

The follow-up study also suggested that there was a causal relationship between GPS habits and poor spatial memory. And it looks as if this relationship is ‘dose-dependent’ - in other words, the more you use GPS, the weaker your spatial memory is likely to become.

There is of course the possibility that people rely on GPS more and more because their spatial memory is declining. But Dahmani and Bohbot found no relationship between GPS usage and subjective reports of a weakening sense of direction. So this explanation seems implausible.

Higher GPS dependence was specifically associated with a reduced ability to remember and make use of landmarks. This probably explains why the heavy GPS users had more trouble forming cognitive maps than the other subjects.

The authors speculate that increased dependence on stimulus-response learning (based in the caudate nucleus) may actually weaken spatial memory (based in the hippocampus).

Dahmani and Bohbot refer to other studies that compare GPS use with the employment of other, more traditional aids like maps. These plausibly suggest that our level of engagement is an important factor in spatial learning.

GPS of course requires far less mental effort than following a route with the help of landmarks, or navigating with a map and compass.

The authors reach a simple conclusion: ‘the greater the use of GPS, the greater [the] decline in spatial memory over time’.

This has important implications for all of us, but especially for those - like the Inuit hunters of Arctic Canada - who have traditionally relied on their senses and wits to navigate perilous environments. Over-reliance on GPS in places where the direct route between two points may be unsafe (it might for example take you over a precipice!) can cost you your life.

Dahmani and Bohbot end with an interesting suggestion: perhaps GPS manufacturers could include landmarks in the automatic guidance instructions ‘as a way to re-engage users with their surroundings’. That might help, but we also need to put our gadgets aside whenever possible and exercise our little grey cells!