Facebook is no stranger to controversies over privacy concerns. That's why it is so important to regularly double-check your Facebook privacy settings.
But, it looks like that might not always be enough. Facebook apparently conducted a psychological study on nearly 700,000 users without their knowledge. That has led research professionals to speak out against the social media site for its unethical behavior.
The experiment hid certain elements from 689,003 peoples' news feed – about 0.04% of users, or 1 in 2,500 – over the course of one week in 2012. The experiment hid "a small percentage" of emotional words from peoples' news feeds, without their knowledge, to test what effect that had on the statuses or "Likes" that they then posted or reacted to.
The research found that Facebook users' emotions were reinforced by the posts they saw. The researchers called this "emotional contagion."