If you have a Facebook account, you could have been part of a massive psychological experiment conducted by the social media site.
Facebook says it manipulated the news feeds among nearly 700,000 users, according to Daily Mail, as part of a new study. The goal was to determine how the posts that users see affect their moods and their own posts.
A study by the PNAS Journal says seeing more negative posts caused positive responses, but also caused more negative posts by the users.
According to the study, "These results indicate that emotions expressed by others on Facebook influence our own emotions, constituting experimental evidence for massive-scale contagion via social networks."
Many are outraged by the invasion of privacy, and some argue that they should have been informed that they were part of an experiment. Adam Kramer, one of the data scientists on the study posted an apology on his Facebook saying his team was "very sorry for the way the paper described the research and any anxiety it caused." Facebook maintains that none of the data was affiliated with a specific account, but many users still feel violated by the study.
Here's how some are reacting on Twitter: