Two more links about the facebook study
From Wired,Everything You Need to Know About Facebook’s Controversial Emotion Experiment, making the argument that an IRB reviewing the study would likely have approved it:
The [hypothetical] IRB might plausibly have decided that since the subjects’ environments, like those of all Facebook users, are constantly being manipulated by Facebook, the study’s risks were no greater than what the subjects experience in daily life as regular Facebook users, and so the study posed no more than “minimal risk” to them.
Also, see here:
[C]ritics of the Facebook experiment should at least be aware that we are talking about a mode of research that existed long before Facebook, and that federal ethics advisors and regulators specifically decided that it should proceed.