Facebook faced a wide range of criticisms after emerging it had conducted a psychology experiment on nearly 700,000 users without their knowledge.
"The test saw Facebook manipulate news feeds to control which emotional expressions the users were exposed to," BBC reported.
The research was done in collaboration with two US universities to gauge if "exposure to emotions led people to change their own posting behaviours", the report said.
Facebook claimed there was "no unnecessary collection of people's data", according to the report.
"None of the data used was associated with a specific person's Facebook account," Facebook said.
BBC said Cornell University and the University of California at San Francisco were involved in the study.