Humans prefer to walk ‘as the crow flies’, even if it takes more time

HUMANS still want to travel as the crow flies when walking even if it takes them longer, a study suggests.

Researchers from Massachusetts Institute of Technology (MIT) have discovered that the human brain is not good at sticking to the shortest path if it appears to deviate from the destination.

Instead, humans choose paths that point most directly toward their destination, even if they end up being longer – referred to as the “pointiest path”. It may explain why attempting to follow GPS instructions, which take the shortest route, can often be confusing.

The discovery was made by tracking the movements of 14,000 Americans as they travelled in Boston and Cambridge, Massachusetts.

The strategy – known as vector-based navigation – is also used by insects and primates, and scientists believe it may have evolved to let the brain devote more power to other, potentially lifesaving, tasks.

“There appears to be a trade-off that allows computational power in our brain to be used for other things – 30,000 years ago, to avoid a lion, or now, to avoid a perilous SUV,” said Carlo Ratti, professor of urban technologies in MIT’S Department of Urban Studies and Planning.

“Vector-based navigation does not produce the shortest path, but it’s close enough to the shortest path, and it’s very simple to compute it.”

Prof Ratti first became interesting in the phenomenon while walking the route between his home and office 20 years ago, when he noticed that he was inadvertently taking different routes.

“Surely one route was more efficient than the other, but I had drifted into adapting two, one for each direction,” added Prof Ratti.

“I was consistently inconsistent, a small but frustrating realisation for a student devoting his life to rational thinking.”

Prof Ratti added. “Based on thousands of walkers, it is very clear that I am not the only one: human beings are not optimal navigators.”

When his lab acquired a data set of anonymised GPS signals from the cell phones of pedestrians he realised that others were also choosing odd routes.

“Instead of calculating minimal distances, we found that the most predictive model was not one that found the shortest path, but instead one that tried to minimise angular displacement – pointing directly toward the destination as much as possible, even if travelling at larger angles would actually be more efficient,” added Paolo Santi, a principal research scientist at MIT.

“We have proposed to call this the pointiest path.”

The research was published in the journal Nature Computational Science.