Our home is on fire, but that's OK, apparently

The full scope of the experiment only became public two years later, when researchers finally admitted what they had done. Facebook’s data scientists had manipulated the feeds of 689,003 people—removing either all the positive posts or all the negative ones to measure the emotional fallout. If your feed in January 2012 felt unusually bleak or suspiciously upbeat, you may have unknowingly been part of the study. The team behind it, led by data scientist Adam Kramer, published their findings in a scientific journal and laid out the results in cold detail: “When positive expressions were reduced, people produced fewer positive posts and more negative posts; when negative expressions were reduced, the opposite pattern occurred,” the paper said. It was hard proof that emotions are contagious—and social media could be weaponized to control mood at scale. The study ran for just one week, but for those caught in the algorithmic crossfire, the emotional effects may have lasted much longer.