When we think of our social networks these days, we usually don't include that girl with the pink mat in yoga class or the man with the blue backpack you see on your morning commute. But according to new research, you and so-called "familiar strangers"—that is, people you see all the time but never talk to—are all part of a real-life hidden social network that could be beneficial to all parties and could also help epidemiologists understand how disease spreads.
The concept of a "familiar stranger" isn't new. The term was first coined in the 1970s to describe people whom you see on a regular basis but never talk to or know anything about. Chances are that if you go to work at the same time every day and ride the same bus every day, you'll begin to notice that people will look similar. The same logic applies to people who, like yourself, hit the gym in the evening, people who shop at the same grocery store and whom you always see in the frozen aisle. You know each other — even if you don't really know each other.
But as Scientific American's Sarah Fecht notes, these informal networks have never really been studied despite scientists' belief that they are important to the way contemporary society works. Enter Lijun Sun and the team at the Future Cities Laboratory in Singapore, with the first study to map out these "familiar strangers" in a metropolitan area. The study looked at 30 million bus trips taken by 2.9 million people. Thanks to smart-card technology, the researchers were able to pinpoint who is riding where, when, and with whom.