Felix Salmon, writing about the “Viral Math” which supports sites like Upworthy:
To put it another way: at the moment, Facebook assumes that people click on exactly the material that they want to click on, and that if it serves up a lot of clickbaity curiosity-gap headlines, then it’s giving its users what they want. Whereas in reality, those headlines are annoying. Curiosity-gap headlines are a bit like German sentences: you don’t know what they mean until you get to the end, which means that the only way to find out what your friend is saying is to click on the headline and serve up another pageview to Upworthy. (Or ViralNova, or Distractify, or whomever.) It’s basically a way of hacking real-world friendships for profit, and there’s no way Facebook is going to allow it to continue indefinitely.
I think Felix is underestimating Facebook here. Facebook doesn’t just know what you click on on-site: it’s also tracking what you do once you leave, and storing this data for further use. It’s entirely possible it knows how long you spend on content which you click on; it definitely knows if you quickly bounce back to Facebook. Given this, it’s hard to imagine it won’t factor this into what content it serves up to you, if not now, then in the future.