An online privacy organization filed a complaint against Facebook with U.S. regulators Thursday, saying the company "purposefully messed with people's minds" in conducting a controversial 2012 experiment.
Facebook has come under fire after details of the study were released recently. The social network slightly altered which posts some users saw on their feeds, with some seeing happier updates and others seeing more negative ones.
The goal was to see whether the emotional content of posts was contagious.
The study has already drawn scrutiny from United Kingdom regulators, and the Electronic Privacy Information Center is hoping the Federal Trade Commission will also look into it.
EPIC says the study was deceptive to users, and has accused the social networking site of not getting permission from users to conduct the study.
Facebook officials have acknowledged that the study was mishandled.
"It's clear that people were upset by this study and we take responsibility for it. We want to do better in the future and are improving our process based on this feedback," the company has said in a release. "The study was done with appropriate protections for people's information and we are happy to answer any questions regulators may have."
One of the Facebook employees behind the study said in a post that "my coauthors and I are very sorry for the way the paper described the research and any anxiety it caused."
During the study, which lasted just one week, researchers found that the emotional bent of posts did appear to be contagious. Users who saw happier posts were more likely to post positive updates, and users exposed to sadder content were more negative in their posts. The hundreds of thousands of users affected were not notified that they were part of the project.
If the FTC does act against the company, it wouldn't be the first time.
After Facebook was accused of telling its users they could keep their information private on its social network, the company repeatedly allowed that information to be shared and made public. Facebook and the FTC came to an agreement in 2012 that the company would improve how it notified users about privacy changes. Facebook also agreed to gain users' consent before sharing their information.
The FTC has not commented on whether it will look into the recent dust-up.