The scientific journal that published a controversial Facebook experiment on mood manipulation says it's concerned that the company didn't follow scientific ethics and principles of informed consent.
While it stopped short of retracting the study, the Proceedings of the National Academy of Sciences said it typically publishes experiments that have allowed subjects to opt out of research.
Facebook appeared to have been exempt from this rule because all users agree to a policy on data use when they open an account, constituting informed consent for research, according to PNAS.
"Based on the information provided by the authors, PNAS editors deemed it appropriate to publish the paper," said a statement by editor-in-chief Inder Verma.
"It is nevertheless a matter of concern that the collection of the data by Facebook may have involved practices that were not fully consistent with the principles of obtaining informed consent and allowing participants to opt out."
The journal explained that the US government protects those who participate in research by establishing best practices that scientists obtain informed consent and allowing subjects to opt out, a policy known as the Common Rule.
It said that Cornell University reviewers determined ahead of publication that Facebook's experiment did not fall under the government's human research protection program because it was conducted for internal purposes.
PNAS's statement followed a formal complaint filed by privacy activists to US regulators seeking an urgent investigation.