Where does it say they provide the raw feed? Everywhere I look in the Facebook help, terms and privacy policy it mentions how they use algorithms to determine what stories appear, and how they use information provided by users to pick stories. They also mention using user information for internal testing and analysis.

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.'