Facebook’s ability to discern with creepy accuracy the “people we may know” has surprised, delighted, and horrified its users for years. While the magic sauce behind friend suggestions has always been a bit mysterious, it now includes some potentially unsettling information. Thanks to tracking the location of users’ smartphones, the social network may suggest you friend people you’ve shared a GPS data point with, meaning your friend suggestions could include someone whose face you know, but whose name you didn’t until Facebook offered it up to you.
Last week, I met a man who suspected Facebook had tracked his location to figure out who he was meeting with. He was a dad who had recently attended a gathering for suicidal teens. The next morning, he told me, he opened Facebook to find that one of the anonymous parents at the gathering popped up as a “person you may know.”
The two parents hadn’t exchanged contact information (one way Facebook suggests friends is to look at your phone contacts). The only connection the two appeared to have was being in the same place at the same time, and thus their smartphones being in the same room. The man immediately checked the privacy settings on his phone and saw that Facebook “always” had access to his location. He immediately changed it to “never.” (He also did not want to reveal his identity for this story.)
It turns out his suspicions were correct.
“People You May Know are people on Facebook that you might know,” a Facebook spokesperson said. “We show you people based on mutual friends, work and education information, networks you’re part of, contacts you’ve imported and many other factors.”
One of those factors is smartphone location. A Facebook spokesperson said though that shared location alone would not result in a friend suggestion, saying that the two parents must have had something else in common, such as overlapping networks.
Facebook has gotten more aggressive in its use of smartphone location data in the last year, tracking which stores you go to in order to tell advertisers if their online ads worked and letting advertisers use your phone’s location to geotarget you with ads. But until now, most people didn’t realize that Facebook was also tracking their phone’s location to suggest friends to them.
The implications of this are far-reaching. There are situations in which this could be incredibly useful.