The only thing you can be sure of with Facebook is that just when you've become used to the latest rules that apply to what you see in your news feed, it decides to change the approach. The latest news feed switch will see more prominence given to "quality" news articles — and less to single-image memes. Bad luck, kittens.
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Facebook explains the changes in an announcement post:
We've noticed that people enjoy seeing articles on Facebook, and so we're now paying closer attention to what makes for high quality content, and how often articles are clicked on from News Feed on mobile. What this means is that you may start to notice links to articles a little more often (particularly on mobile . . . This means that high quality articles you or others read may show up a bit more prominently in your News Feed, and meme photos may show up a bit less prominently.
Facebook will also begin including related articles under some news posts, and reposting some news stories if they have attracted comments from your friends. As ever, while you don't have ultimate control over what Facebook shows you, you can improve its usefulness by decluttering your news feed.
News Feed FYI: Helping You Find More News to Talk About [Facebook Newsroom]