A former Facebook Inc employee revealed herself on Sunday as the whistleblower who leaked a trove of internal company research that served as the basis of a Wall Street Journal investigative series.

       The leak led to a Senate hearing and a new wave of criticism over the negative impact of the social media giant's apps.

       Frances Haugen appeared on Sunday on the television program "60 Minutes." She will testify before a Senate subcommittee on Tuesday in a hearing titled "Protecting Kids Online," about the company's research into Instagram's effect on the mental health of young users.

       Last week, a Facebook executive testified to U.S. senators and disputed the Journal's characterization of the research, pointing out other findings that she said showed the app's positive impact on teens.

       Haugen was a product manager at Facebook for more than two years, according to her LinkedIn profile. She also worked as a product manager at Google, Pinterest and Yelp.

       Haugen said she'd seen problems at other social media companies, but "it was substantially worse at Facebook than anything I'd seen before."- Reuters