Facebook tightens research guidelines

Facebook has tightened its research guidelines following uproar over its disclosure this summer that it allowed researchers to manipulate users' feeds to see if they could change their mood.

At issue was study in which Facebook allowed researchers to manipulate the content that appeared in the main section, or "news feed," of small fraction of the social network's users. During the weeklong study in January 2012, data-scientists were trying to collect evidence to prove their thesis that people's moods could spread like an "emotional contagion" depending on what they were reading.

Facebook said Thursday that in the past three months it has given researchers clearer guidelines on research procedures and has created an internal panel that will review projects. But there will not be an external review process.