Facebook apparently wants to control your mood. Along with researchers from Cornell University and the University of California San Francisco, the world's largest online social networking site tweaked users' news feeds to find out how they felt about it, and what they would write in response.
Revelations of this secretive experiment on hundreds of thousands of users shows the increasing power of such sites, and of such large companies, to manipulate people in sophisticated ways.
For the experiment, Facebook changed the news feeds for nearly 700,000 people for one week in 2012 to see how much discomfort might result. They conducted the psychological experiment by changing the content of the news feeds to include a large number of happy and positive words, or, for contrast, sadder than usual language. They then studied what users posted to see how contagious emotions are between people who never meet in person, but only write online.