We design cities. They are our home. They are our work, and they make us happy. We are terrible at getting around them.
Mobile phone data from more than 14,000 people shows that humans have a hard time calculating the fastest route through cities. The reason is simple: Our brains want to direct our attention in the direction we're going, even if it's not the best way to get there.
This is the 'pointiest way' according to MIT researchers. They believe that our brains prioritise other tasks at the expense of navigational efficiency.
"There seems to be a tradeoff that allows computational power from our brain to be used to do other things 30,000 centuries ago, to avoid a lion or now to avoid a perilous SUV," Carlo Ratti, an engineer at MIT's Senseable City Laboratory, says.
"Vector-based navigation doesn't produce the shortest route, but it is close enough to it, and it is very easy to compute."
Ratti, a University of Cambridge student in the UK, planted the seeds of this study two decades ago. Ratti noticed that he took one route to reach his department building, but a different route back to his bedroom. The pattern of behavior was consistent, despite the fact that one route is longer than the other.
Technology has advanced and we now have the ability to collect huge amounts of data about our activities. Many people in cities have a powerful computer that tracks their movements. This is a great resource for scientists who want to understand why we choose certain paths.
Researchers were able to access this data anonymously from more than 14,000 pedestrians. Their GPS coordinates were recorded during their movements around San Francisco, California and Boston, Massachusetts over the course of one year. These data included more than 550,000 paths, enough data to identify patterns.
A fascinating pattern emerged, it was evident. The majority of pedestrians chose the route that would allow them to face their destination more directly, rather than taking the shortest path.
Researchers then created a model that could predict the irrational path patterns in the data. This proved that people prefer to face their destination.
"Instead of calculating minimum distances, we found out that the best predictive model did not find the shortest path. Instead, it tried to minimize angular displacement pointing straight toward the destination as much possible. Even though traveling at greater angles would be more efficient," Paolo Santi, MIT computer scientist, and the Italian National Research Council in Italy.
"We propose to call this the most direct path."
People also tend to take different routes when going round the world, as Ratti discovered at Cambridge.
It's not just humans who have seen the most direct path. It has also been observed in animals as vector-based navigation. These studies show that the brain calculates vectors in order to navigate. Since most people don't have top down maps to guide them, vector-based navigation seems like the best option.
This is because evolution does not seek optimization but rather "sure, okay, that works, it's not dead", a term that has been called "survival to the adequate".
These findings could be used to design better cities but also highlight the importance of understanding how brains and machines interact.
Computers are perfectly rational. They do what code tells them. Brains, however, are able to achieve a 'bounded logic' of 'good enoughs and necessary compromises. These two entities are becoming increasingly intertwined and collide on Google Maps or Facebook. It's important to keep in mind how they differ," Ratti wrote for The Conversation.
"The more technology is embraced by people, the more it is important to create technologies that can accommodate human idiosyncrasies and irrationalities."
Nature Computational Science published the research.
