We all know that Facebook manipulates what pops up in your news feed, from baby photos to party pictures, but it turns out that the company was also using your news feeds to perform a mass science experiment. In January 2012, Facebook changed the number of positive and negative posts in the feeds of almost 700 thousand users to see if it would influence users emotional moods and status updates. Facebook was trying, it turns out, to make you sad. Michelle Meyer is Assistant Professor of bioethics at Union Graduate College and Mt. Sinai Medical School.