Regulators in the UK are investigating a controversial experiment Facebook conducted with users' news feeds.
The social network has come under criticism in recent days after it was revealed last week that it had manipulated the news feeds of 689,003 users to determine if happiness or negativity could be contagious on the social network. The users were unaware, however, that Facebook was toying with their feeds and possibly altering their emotions.
Critics say the social network lacks transparency and it was unethical to fiddle with user data without alerting people first. The uproar has led the UK's Information Commissioner's Office, which is responsible for enforcing the country's Data Protection Act, to investigate whether any data-protection laws were violated by the study.
"We're aware of this issue, and will be speaking to Facebook, as well as liaising with the Irish data protection authority, to learn more about the circumstances," a spokesman for the office told The Register, which first reported the investigation.
Facebook's study, called "Experimental evidence of massive-scale emotional contagion through social networks," was conducted in January 2012 with researchers from Cornell and UC San Francisco.
While carrying out the study, Facebook altered users' news feeds to show either more positive or more negative posts and observed whether users' subsequent posts reflected this altered mood.
Noting that people are upset by the study, Facebook said it was taking steps to improve the process.
"The study was done with appropriate protections for people's information and we are happy to answer any questions regulators may have," a Facebook representative said in a statement.
It's unclear how this will play out or if any US government agencies like the Federal Trade Commission will weigh in on the matter -- as it did over Facebook's privacy practices in 2011. CNET has contacted the FTC for comment and will update this report when we learn more.