Facebook apologizes for 'secret' research

Facebook communicated "terribly" about a controversial study in which it secretly manipulated users' feelings, the social network's Chief Operating Officer Sheryl Sandberg admitted Wednesday.

Her comments came as British authorities said they will question Facebook over the experiment to see whether it broke privacy laws.

The research was an experiment as part of product testing, Sandberg told a women's business seminar in New Delhi when asked whether the study was ethical.

"This was communicated terribly and for that communication we have apologized," she said, before adding: "We take privacy at Facebook really seriously."

Facebook clandestinely altered the emotional content of feeds of nearly 700,000 users, giving some sadder news and others happier news in the 2012 study aimed at better understanding "emotional contagion."

The study, published in June, prompted online anger and put the world's most popular networking site on the defensive.

Britain's independent data watchdog, the Information Commissioner's Office, is liaising with the Irish data protection authority "to learn more about the circumstances" of the study, a spokesman said.

Facebook's European headquarters are based in the Irish capital Dublin, meaning EU laws apply to its operations there.

"We work closely with regulators all over the world," Sandberg said.

In the study, Facebook placed positive or negative posts in users' feeds to gauge how this affected their mood — without their consent or knowledge.

The results indicate "emotions expressed by others on Facebook influence our own emotions, constituting experimental evidence for massive-scale contagion via social networks," researchers said.