Our Aversion to A/B Testing on Humans Is Dangerous - Facts So Romantic

Nautilus 

Facebook once teamed up with scientists at Cornell to conduct a now-infamous experiment on emotional contagion. Researchers randomly assigned 700,000 users to see on their News Feeds, for one week, a slight uptick in either positive or negative language or no change at all, to determine whether exposure to certain emotions could, in turn, cause a user to express certain emotions. The answer, as revealed in a 2014 paper, was yes: The emotions we see expressed online can change the emotions that we express, albeit slightly. Conversations about emotional contagion were quickly shelved, however, as the public disclosure of the study sparked an intense backlash against what many perceived to be an unjust and underhanded manipulation of people's feelings. Facebook would later apologize for fiddling with users' emotions and pledge to revise its internal review practices.