Companies have been purposely making people feel bad about themselves for a very long time. Ads intentionally make people feel ugly, lazy, stupid, fat, dirty, smelly, dandruffy, lonely and ashamed so they'll buy whatever product is on offer. Commerce is all about manipulating people for profit. I'm not a Facebook fan, but tell me how this is worse than standard operating procedure with every other consumer product?
Because those aren't psychological experiments. Nobody's claiming it's ethical for an ad company to make you feel bad about yourself, but that's not really the point here. The point is that there are strict ethics rules for running experiments, and one of those rules is, except for a limited exception (that does not apply), the subjects need to be knowingly taking part in the experiment.
Companies rigorously test and refine ads to manipulate emotions and behavior on a scale two or three orders of magnitude greater than Facebook's experiment.
Is Facebook's experiment different because they published the results in an academic journal?