by Carol A Westbrook
“Drive east 6 blocks and then turn right, and you’ll be there,” I told my son.
He answered, “Forget it. I don’t know which way is east. I’ll just use my GPS.”
I was incredulous. How could any native Chicagoan not know where east is located–toward Lake Michigan, of course! How could he not be able to find his way without GPS directions? After all, Chicago is merely a grid, as you can see on the map below. The streets are straight lines, oriented north-south and east-west, with 8 blocks to a mile. The street numbers increase by 100 every block, with the zero-zero point being downtown, at State and Madison. Give me the coordinates and I can locate you precisely and find my way there using the map in my head (except for those baffling diagonal streets). And if you prefer to use a compass, rest easy, because the compass declination in Chicago is close to zero
I shouldn’t be surprised that my son, like most younger adults, prefers his GPS. A recent survey showed that four out of five 18 to 30-year olds can’t navigate without electronic guidance, whereas more than half of people over 60 were very comfortable with maps. Myself, I prefer a map. If find my GPS is distracting when I’m driving, and if I follow it blindly I lose my place on my mental map.
Yes, I carry a map of Chicago in my head, or any other place I’m staying for more than a few days–including a hotel room. (It’s a handy way to get to the bathroom in the dark.) Most people have mental maps of their immediate vicinity and the areas where they normally travel; how they use those maps is another story.
Think about it. You probably have some sense of location in your head, and if you change your heading that sense will change, too. When you do this you are using your mental map. You didn’t consciously create this mental map, yet you have a sense of where you are in the same way that you know the location of your arms or legs. Most mammals have mental maps, and many other animals do, as well.
Research has shown that this mental map actually exists physically in the hippocampus area of the brain as a group of neurons (brain cells). These neurons are tightly coupled to place and direction, functioning as a grid. The discovery of grid cells was considered so pivotal in understanding brain function that the scientists who did the work, O’Keefe, Moser and Moser, were awarded the Nobel Prize for it in 2014.
Mental maps are well-suited to moving around in the immediate vicinity, but distance travel is another story. Animals who forage long distances, migrate, or travel to a breeding area have an inherent navigational ability. These species use external signals–geomagnetic or solar, for example–combined with their brain maps. Migratory birds use the earth’s magnetic fields, supplementing it with solar or lunar information. Whales also rely on magnetic fields, supplementing it with underwater landmarks detected by sonar. Bees overlay their map with directional information from the sun’s polarized light; migratory monarch butterflies rely on the sun.
I wondered if humans had inherent map skills, too. So I asked a few family members how they found their way along the earth. One son uses his GPS, as you know, while the other prefers maps, like me. My sister uses landmarks (drive past the blue house until you come to the big oak tree and turn right). My husband prefers to orient using the sun–and can get lost on a cloudy day! He attributes his reliance on solar navigation to the fact that he grew up in a town that had no streets oriented to any compass directions, and the compass declination was over 12 degrees!
This small sample would suggest that human navigational skills are learned, but there is more to it than that. You need a sense of direction to make use of your internal map. Brain imaging studies done in human subjects have shown that people do, in fact, have an inherent directional ability, allowing them to face their target, and plan a route to their target. This “internal compass” is also located in the hippocampus, in the same area as the grid cells. An example of how this homing sense is used can be found in our closest related species, the great apes. Chimpanzees in the wild travel great distances every day in search of food, but when it’s time to return home they don’t use landmarks, but instead they head directly there in a straight line, traveling through the tree tops. I imagine it is similar to my always knowing where, exactly, my house is from wherever I am, and what direction is Lake Michigan when I am in Chicago.
So we all have mental maps and a sense of direction, and but how we use them differs from person to person, depending on training, skill, necessity–and possibly gender! It is a longstanding cliché that men and women have different navigation strategies: “men don’t ask for directions, while women navigate using landmarks,” and this has been attributed to inherent differences between male and female brains in spatial perception. And anthropologists have found that gender differences in distance navigation are more pronounced in societies where men had to travel long distances to find mates, whereas women stayed behind to tend to home and family. These cultural differences tend to be learned rather than inherited.
I like this explanation, and I think it helps explain the current preference for GPS to maps in the younger generation. Nowadays, finding a mate does not require crossing a mountain and navigating a dense forest. It merely requires a smart phone and a dating app such as Eharmony.com or Match.com. Meeting those potential mates requires navigating across town, through traffic, finding a parking spot, and locating the restaurant or bar–all done more easily with a smart phone navigator than an internal map. From this perspective, facility with a GPS makes more sense than the ability to make a beeline through the rainforest trees, or locate a street address on a map. Just like the birds and the bees, humans need maps to find their way home, and to find their mates.