People who grow up outside of cities are better at finding their way around than urbanites, a large study on navigation suggests. The results, described online on March 30 in Nature, hint that learning to handle environmental complexity as a child strengthens mental muscles for spatial skills. 

Nearly 400,000 people from 38 countries around the world played a video game called Sea Hero Quest, designed by scientists and game developers as a fun way to collect data about people's brains. Players piloted a boat in search of various targets.

On average, people who said they had grown up outside of cities, where they would have probably encountered lots of complicated paths, were better at finding the targets than people who were raised in cities.

What's more, the difference between city residents and outsiders was most obvious in countries where cities tend to have simple layouts (布局), such as Chicago with its streets laid out at 90-degree angles. The simpler the cities, the bigger the advantage for people from more rural areas, cognitive scientist Antoine Coutrot of CNRS and his colleagues report.

Still, from these video game data, scientists can't definitively say that the childhood environment is behind the differences in navigation. But it's possible. "As a kid, if you are exposed to a complex environment, you learn to find your way, and you develop the right cognitive processes to do so," Coutrot says.

Other factors have been linked to navigational performance, including age, gender, education and even a superior sense of smell. Figuring out these details will give doctors a more precise baseline (基准) of a person's navigational abilities. That, in turn, might help reveal when these skills weaken, as they do in early Alzheimer's disease, for instance.