New Delhi, July 3 (ANI): Facebook's Chief Operating Officer, Sheryl Sandberg, apologised for psychological experiment and said it was terribly communicated. Addressing a conference of Federation of Indian Chambers of Commerce and Industry (FICCI) Ladies Organisation in New Delhi, Sandberg stressed that Facebook takes privacy and security issues seriously as people share on the social networking site. In 2012, Facebook manipulated the timeline of over six lakh users for nearly a week, showing only positive status for one set of users while showing negative updates for the other set. The experiment was conducted without bringing to knowledge of the users, whose timelines were manipulated, thereby raising privacy concerns.