"And for that communication we apologize," said Sandberg, according to the Wall Street Journal. "We never meant to upset you."
In an interview with India's NDTV, Sandberg added that "Facebook cannot control emotions of users. Facebook will not control emotions of users."
Sandberg's comments came a day after British regulators said they were looking into the Facebook newsfeed study, which randomly but selectively tweaked some newsfeeds to be more positive or more negative to see whether those emotional tones would change Facebook users' behavior. The study, which was published in the Proceedings of the National Academy of Sciences, affected nearly 700,000 English-speaking accounts without the knowledge of their owners, raising questions about the methodology and ethics of Facebook's research.
Some have taken the opportunity to argue that a culture of "free" has largely misled Internet users into giving up their personal data without a full appreciation of how it might be used — a poor tradeoff we haven't even realized we've made, according to Arizona State University media scholar Dan Gillmor.
"What's lacking in a world of monopoly and oligopoly communications is accountability," Gillmor wrote in a blog post Tuesday. "There's almost none today, and the risks are growing."