Remember opting in to that psychology experiment Facebook performed in early 2012? Well you did, according to their terms of service.
In January 2012, Facebook manipulated the news feed posts of approximately 700,000 users to highlight either negative or positive emotions, to see if this would influence those users’ moods and status updates. After publishing the results last week, Facebook claimed that their terms of service (which all Facebook users must agree to) include the right to use any data they collect for research.