Facebook researchers intentionally modulated the news feeds of almost 700,000 users for a week in January 2012. Some saw content that had mostly happy, positive words; some were served content that analysis showed was sadder than average. The researchers found that at the end of the week, the manipulated Facebook users or, as the New York Times has dubbed them, the lab rats were themselves more likely to post using correspondingly extra-positive or extra-negative words. Facebook’s data use policy states that users information will be used for internal operations meaning that any user can become a lab rat.”]