When you creep on others on Facebook, Facebook creeps on you. Not only does it know where you live and what your favorite movie is, but it watches and records your every move — including every time you obsessively stalk your ex. And it makes sure to show this person to you everywhere, from your search results to your News Feed.
Facebook knows whose profiles you visit frequently, and since September 2012, it has recorded your entire Facebook search history. That’s right. It has documented every search you ever conducted through the site, along with the date and time. It may be reasonable for Facebook to have some idea of whom you search for, but it is incredibly creepy to see evidence of their data collection. Every time you searched for your middle school bully, your high school crush, or your attractive coworker is on file. And yes, this includes every obsessive search you conducted of your ex, including his ex, his current flame, his mom, your mutual friends, and so on. Want proof? Go to your Facebook profile, click "Activity Log," check “Include,” and voilà! Observe your entire Facebook history. Graph search has only made this worse, as now Facebook has a record of your searches for things like, “pictures of me and [name].”
Not only does Facebook know and record whom you stalk, it also promotes those people in your search results. Let’s say you periodically search for your friend (or ex), Damien. The next time you type “Da-,” Facebook will automatically assume you are searching for Damien, and not, say, as David, Dalia, or Daniel.
The final proof that Facebook knows too much about you comes from one of the precious and complicated algorithms about which it is most secretive: EdgeRank, which selects what goes into your News Feed. While we do not know exactly how Facebook determines what shows up in your feed, we know that it serves up content based on whom you interact with often, and whom you've been engaging with recently. According to Lars Backstrom, Facebook's engineering manager for News Feed ranking,"For each user, we try to come up with a final score to determine how relevant that particular story is to that particular user .... In the end, those scores build your personalized News Feed.” Facebook tries to balance what seems important to other people (i.e., items that are being shared, and have a number of comments and likes), and what it believes is important to you (i.e., friends with whom you interact, and the people you stalk the most). Because Facebook knows how many times you went through your ex’s profile, it serves his or her pictures up in your News Feed.
Facebook also recently announced some new features that will potentially increase how often your News Feed shows the people you stalk. The Story Bump feature will promote older content that you haven't seen, but which seems relevant to your interests, and the Last Actor feature will fill your News Feed with stories about the people you interacted with that day.
Facebook learns about you over time, from who you want to see more of, to what stories you might find interesting. While it seems creepy that Facebook knows and records so much about you, it is only using the information you provided to it. This is not to say that you should be completely paranoid about your wildest secrets being revealed. Your data is still private, and you can always change your user settings, delete your history, and so on. However, the next time you stalk your ex, be aware that Facebook is maintaining a record of your activity, and that the more you look for certain people, the more Facebook will try to deliver them to you.