Facebook has a ready-made excuse for people who are upset that it conducted a massive psychological experiment on some 600,000 users — they all consented to it as part of Facebook’s user agreement, which says that the company may use their data for unspecified “research.” However, Forbes did a little digging and found that Facebook didn’t add “research” as an acceptable use for user data until months after it conducted its infamous experiment. “In January 2012, the policy did not say anything about users potentially being guinea pigs made to have a crappy day for science, nor that ‘research’ is something that might happen on the platform,” Forbes reports. “Four months after this study happened, in May 2012, Facebook made changes to its