At the rush hour crosswalk, you make your way through the oncoming crowd, your eyes darting over the faces in front of you. This location may seem like something you are doing on your own. But scientists studying crowd movements have found that a simple journey through a crowd is much more like a dance that we perform with the people around us.
And therefore, it may not be a big surprise to learn that a person looking at a phone, lost in a private world while walking, really messes with vibration, according to a study published on Wednesday in the journal Science Advances.
Humans use a variety of visual cues to predict where other members of the crowd will go next, said Hisashi Murakami, a professor at the Kyoto Institute of Technology and author of the new article. He was curious as to what would happen if attention to these details was interrupted, so in a series of outdoor experiments on the Tokyo University campus, he and his colleagues filmed two groups of students on a catwalk of about 30 meters long.
The groups walked towards each other at a normal pace. When the groups got together, the students intuitively performed a familiar maneuver to those who study crowds: they formed clues. When a person in front of a group found a way through the approaching group, other people stood behind that person, creating several tracks of walkers passing each other. This was easy and almost instantaneous.
The researchers then asked three of the students to perform a task on their phones while walking – simple one-digit addition, not too tiring, but enough to keep their gaze directed downward instead of forward.
When these students were placed at the back of their group, the distraction did not affect the way the groups passed each other. But when distracted hikers were in front of the group, there was a dramatic slowdown in the walking pace of the entire group. It also took longer for free bands to form.
Distracted people also did not move smoothly. They took long strides to the side or dodged the others in a way that researchers rarely saw when there were no distractions. Inattentive pedestrians in the experiment induced this behavior in others as well; people who were not looking at their phones moved more restlessly than when there was no one looking at the phone. It seemed that some people who did not pay full attention to navigation could change the behavior of the entire crowd of more than 50 people.
Looking at someone’s phone can have this effect because it deprives other people of the information contained in our eyes, the researchers suggest. Where we look as we move, it conveys details of where we intend to go next. Without it, it is more difficult for passers-by to avoid us elegantly. And simply dodging other people as we go, looking away, instead of moving purposefully, makes us even more unpredictable.
As more and more people use smartphones and other devices that contribute to distracted walking, it may be necessary for architects and urban planners concerned with the movement of the crowds to take into account this altered behavior, the researchers say.
Dr. Murakami then plans to track people’s eye movements as they pass others. He hopes that these studies will reveal how our eyes help us navigate the crowds – what messages we convey about our next steps as we perform this daily ritual, all without knowing it.