Photo: Colourbox

People constantly return to 25 places throughout their life

Friday 22 Jun 18

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Sune Lehmann Jørgensen
Associate professor
DTU Compute
+45 45 25 39 04

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Laura Alessandretti
Postdoc
DTU Compute
+45 45 25 30 40
New scientific study shows that people constantly return to 25 places. The result will help researchers to understand human mobility.

At any given time, people will only regularly return to a maximum of 25 places. That is all our brain can grasp. This is the finding of a scientific study that reveals entirely new sides of who we are as humans and how we function.

The study has just been published in Nature Human Behaviour and is based on analyses of 40,000 people’s mobile data and four sets of data—including data from the SensibleDTU data collection project, where DTU students in 2015 were issued with a smartphone to reveal their habits.

The study is the first of its kind to investigate people’s mobility over time and study how the behaviour changes. Behind the project are DTU; City, University of London; and Sony Mobile Communications.

“I expected to see a difference in the behaviour of DTU students and a wide section of the population. But that was not the case. SensibleDTU showed that the students returned to a limited number of places, even though the places changed over time. The result was the same when we scaled up the project to 40,000 people of different habits and gender from all over the world. It was not expected in advance. It came as a surprise,” says Laura Alessandretti, Postdoc at DTU Compute.

Old places disappear
An important partial result of the study is that people are constantly in motion and continue to find new places. They move to a new home, find a new favourite restaurant, find a new bar, or start going to another gym, etc.

But the number of places is constantly at 25 in a given period. If a new place is added to the list, one of the places disappears. The pattern is the same when the researchers divide the locations into categories based on how often and how long time they spend at the location.

“People are not static. We typically have our favourite summer, winter, spring, and autumn places. But they change in an interesting way. We visit a constant, fixed number of places—and it’s not due to lack of time. There are many indications that it’s our brain that makes this decision. We don’t know the mechanism behind. But it tells us that all people have a limit, which we aren’t aware of,” says Sune Lehmann, Associate Professor at DTU Compute.

Many friends and locations
He notes that the study has similarities with the studies conducted by the English anthropologist Robin Dunbar, who showed that there is a limit to how many friends we have. The studies from SensibleDTU show that if you have a tendency to visit many places, you also tend to have many friends. The correlation between the social aspect and the number of locations has not been demonstrated before.

“We can use the study to become better at understanding people’s mobility and behaviour. We are now billions of people on the planet, and we are constantly moving between many places when going work, shopping, etc. This creates both pollution and chaos. The better we understand human movements, the better we can design systems to move around in the public space,” says Sune Lehmann.

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