Baxter's sense of direction never ceases to amaze me. Of course, I'm one of those direction-impaired people who can't find my car in the mall parking lot half the time, so when animals achieve great feats of geographic memory and accuracy (for example the swallows returning to Capistrano or salmon swimming in the Pacific for a half-dozen years and then finding their way back to tiny tributaries in Idaho where they hatched), I'm in awe. It's humbling to realize that most creatures on the planet have a better sense of direction than I do.
And Baxter is no exception. If one day, on one of our walks, he spots a cat sitting on the front porch of a house, he will remember that house forever. Months can go by, but the next time we pass that house Baxter will start pulling for the porch, even if there are no felines to be found. So, when I struggle with Baxter to remember some task he had mastered the day before (such as bringing me my slippers) only to be met with a completely blank stare, I am not tempted to think he has a bad memory. Perhaps it's situational. Perhaps it's a matter of choice (it is a rather subservient task). Or perhaps it has more to do with the type of memory being called upon. Perhaps dogs just have some sort of built-in GPS that marks all the great spots along the trail.
Intrigued by this possibility, I looked into it a bit more. Of course, my favorite dog book The Truth About Dogs by Stephen Budiansky has an answer. As it turns out, scientists have discovered that dogs actually DO have some sort of geographic mapping capability hardwired into their brains. When they see or smell something particularly interesting (a dead squirrel, for example), their brains map that location like a geographical coordinate in space. A sort of doggy longitude and lattitude. Budiansky cites research done by psychologist Nicole Chapuis that shows dogs can form "mental maps of their environment, and through a combination of recognizing familiar landmarks and dead reckoning determine their location and the relative orientation of sites of interest, even along unfamiliar routes." It's particularly interesting to me that dogs don't necessarily find their way back to places by retracing a previous route (which is how I usually have to do it). They take short cuts, because, rather like a GPS, they've mapped the spot in their minds, not just the route.
Alas, after seven years of daily walks, Baxter must have mapped the location of every cat he's spotted in two home cities and dozens of vacation destinations. No wonder he doesn't have room to remember my slippers!