September 3, 2009
A new book asks the question, Why do we get lost? I think the more interesting question is, how do we know where we are?
When I was growing up in Munhall I remember being so confused about the layout of the neighborhood that I gave up trying to make sense of it. If I turned left out of my driveway, I could take a certain route through a certain part of town and end up at school. But if I went down my street the complete opposite direction, and passed through a different part of town, I’d end up at the same place.
(Years later, I found out why: my street was shaped like a squiggly horseshoe. When I walked my dog around the block, the block was not square or triangular but rather shaped like an “S”. No wonder I was confused.)
But even without a mental map, I got around just fine by recognizing landmarks and street names. Now, several groups of scientists are suggesting that humans navigate by landmarks, while other animals use geometry.
Hamsters, toads, and spiders can all navigate like homing pigeons: take the critter away from home by any route you please, and she’ll fly, or crawl, straight back. According to Jack Loomis at UC Santa Barbara, people do badly on a simplified version of this test; and William Warren at Brown found that people could navigate by landmarks through a maze that, geometrically, couldn’t possibly exist. (The maze was a virtual world with invisible “wormholes”).
But are we really so bad at geometric navigation? A recent study looked at the question of whether people who are lost end up walking in circles. The answer: only if they are blindfolded or have no other cues. Test subjects walking around the Sahara, with only shadows from the sun for guidance, did a decent job of walking in a straight line – even though the sun moved during their long hike.
Meanwhile, blindfolded people, asked to walk through a field, wandered wildly but didn’t always prefer circular directions. (You wouldn’t know it, though, from all the headlines of “We really do walk in circles.” Only sometimes! Not even most of us!) The authors figured that “sensory noise” – basically, errors in where we think our body is – accounts for the wiggly path.
But some people are bad at navigating even by landmarks. Giuseppe Iaria and Jason Barton, are studying what happens in the brains of people who have a broken sense of direction. You can take their tests at the catchily named GettingLost.ca (which, um, I had trouble finding again after my first visit).
The series of tests takes about an hour, but it’s interesting to see what they think a sense of direction is made of. (They especially encourage people who have trouble navigating to take the tests.) The tasks include recognizing objects from different angles, recognizing faces (people with face blindness, called prosopagnosia, often have trouble navigating), recognizing landmarks after you’ve seen them in situ, and a variety of sleep-inducing walks through an almost featureless landscape, reminiscent of an empty Doom set, or a prison yard, where you’re asked whether you were led along two identical or different routes. In the most tedious test, the prison yard gets a couple of storefronts, and you’re asked to repeatedly locate them on a map. Despite my childhood difficulties, I did pretty well on the tests. It seems that landmark-based navigation works pretty well after all.