The funny thing is that this would be very easy for Facebook to fix - just a line of text under each friend request explaining the suggestion:
* "You're both friends of Duffman McPartyDude"
* "We found Psycho Ex Boss's phone number in your contacts"
* "Location Services confirms you were both frequenting a dubious drinking establishment at 4am three Saturdays ago"
Would they do it though? Of course not. It would scare the hell out of their users if they knew how this algo actually worked.
Or, if one or both parties were running the Facebook app with location services enabled, it could also have been GPS too.
I wrote about this a few days ago.[0] Basically, new Facebook accounts that you run on the app with location services enabled will provide creepy location-based friend suggestions by default.
it could also use 'same ip' data, apparently, so if they were using the bar wifi you'd get a friend suggestion, even if you never gave location access to facebook.
The article has lots of words and stupid pictures so here is a summary: if you give someone your number (via any app or medium) and they have the FB app installed, it will recognize it as the number of a user and trigger the friend suggestion.
The best way to handle the advent of this information is to treat your public facebook profile as public information and assume even the creepiest stalkeriest guy on the internet has access to it. Cause they do.
>The other person may have searched for her on Facebook, causing her to be listed as a possible friend. Or perhaps Facebook uses location data to group people that are in the same location for an extended period of time.
Probably the first -- since I, and millions of people, stay with hundreds of people we don't know for the same period of time and more (in bars, airports, workplaces, queues, concerts, shops, etc), and they still are not suggested to us.
Ah, the wonderful feature the spies on my location to suggest me friends that are in my phone book, but aren't connected on Facebook in any way whenever I get to actually hang out with them.
> There is probably an explanation for this that doesn't boil down to "FB watched our GPS and noticed our phones sat next to each other at the same location for several hours," but it still felt sufficiently creepy to make me uninterested in sticking around to figure it out.
That's exactly what happened[1].
> "Location information by itself doesn’t indicate that two people might be friends," said the Facebook spokesperson. "That’s why location is only one of the factors we use to suggest people you may know.”
I remember a post on here last year about Facebook suggesting patients of a psychologist as friends. It did this by location. Perhaps you or one of your friends had a facebook app on their phone with the location information turned on?
I don’t see this working. Too many people on Facebook accept friend requests from unknown people already for it to work. I guess you could have some kind of “have you actually met this person in real life” test, but that’s an annoying friction, and people seem to enjoy inflating “friends” regardless.
I am pretty sure Facebook also makes a friend suggestion to you when the other person searched for your name or looked at your profile at any time in the past. Maybe your neighbor searched for your name after you gave your phone number to them.
The data isn’t public. It’s based on the friend finding feature. If you fill a contact list with phone numbers Facebook will automatically suggest the person with that number as your friend. So if you make a contact list with all possible phone numbers, you can know who they belong to.
Their "Suggest a Friend" algorithm uses lots of factors, including IP address history.
This is also probably why this is a "wontfix" issue for Facebook, since the "creepiness" of friend suggestion accuracy is considered critical to their business success, going by how much effort they put into it.
Coincidentally (or not), Facebook presented this as an upcoming Messenger feature today [1]
> If you can't find a friend and become worried about their safety, Messenger could one day let you send a request to see their location. A timer would begin on the friend's phone that gives them a chance to approve or deny the request. If the timer expires on its own, their location would be sent to you automatically.
Just yesterday somebody warned that Facebook does location-based friends suggestion (was suggested to friend a taxi driver) and promptly accused to be tin foil hatter.
This happened multiple times to me in the past as well. Most likely the other person searched for my name on FB causing FB to recommend the searcher as friend to me (LinkedIn uses the same technique). Location data sounds strange, that'd mean FB would constantly recommend other people sitting in the same restaurant etc.
And if a friend had put your name and phone number in their phone, and they synced their contact list with FB and merged the contacts, welcome to the system (at least Android has this function, it can have contacts from many sources like Skype, FB, WhatsApp, GMail, and can put all of them under 1 person in the Contacts app).
I wonder if the linking is even necessary, if FBs dark pattern made your friends upload their contact list, they could just infer that since Alice and Bob are your FB friends and they both have your name and number on their uploaded contacts, they can probably associate that number with your FB profile with x% certainty (a higher percentage if your FB friends Cedric, Dave, Emily and Fritz also have the same name and number...).
Fun stuff huh? /s Someone should associate that Patrick Stewart "Extras" line "But it's too late, I've seen everything." with Mr. Zuckhole.
Not to detract from your main point, which is very sound, but on this:
> whereas that walk out by the lake with Sarah
If you both have the Facebook app with location tracking on, Facebook does know about this, which is why you sometimes get friend suggestions for people after you spent time near them (eg you were at the same party or they visited your house to do cleaning or plumbing), even if you have no mutual friends.
Strange coincidence! A friend on fb posted a message tonight along the lines of "going to a new friend's house, if I don't check in by midnight, call the police". I've definitely let a friend know when making a craigslist or airbnb transaction. I probably would rather just let a friend know where I was going but it's nice there's an alternative and I'm sure this service can be run rather cheaply.
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