Has Facebook ever made you feel miserable? It may have been by design. Details have emerged about a piece of research carried out by the social network into “emotional contagion” – whether lots more negative or positive posts appearing in their news feeds could affect the negativity and positivity of their own status updates on Facebook. The study was based on tweaking the feeds of nearly 700,000 Facebook users, but its revelation has caused a storm of comment and protest over the weekend. There are essentially two camps of opinion: one says that this is outrageous manipulation without informed consent from those users, and the other more relaxed view says that of course Facebook and companies like it will be running this kind of research to understand more about the way we use them. “The reason we did this research is because we care about the emotional impact of Facebook and the people that use our product,” wrote Adam Kramer, one of the researchers. But controversy around the project will rumble for a day or two yet.