They seem to be following those terms, they were choosing positive and negative stories for feeds, and then analyzing the data to see if users then posted more positive or negative posts in return.
1. '...we may make friend suggestions, pick stories for your News Feed, or suggest people to tag in photos...'
2. 'The News Feed algorithm uses several factors to determine top stories...'
3. 'How we use the information we receive... for internal operations, including troubleshooting, data analysis, testing, research and service improvement.'
You did not answer my other question. Here is a more direct question.
Should Facebook be exempt from laws on human experimentation?
Facebook should obviously be bound to the same laws as everyone else. Which human experimentation laws did they break? Users registered on Facebook and agreed to the terms of service, and how Facebook will choose which stories they view, and analyze their response.
This is no different than a television series like I mentioned earlier. You can argue you want the raw footage from a reality television show, and not the heavily edited version designed to manipulate your emotions, but that's not your choice.