From 2010 to 2011, I worked on YouTube’s artificial intelligence recommendation engine—the algorithm that directs what you see next based on your previous viewing habits and searches. One of my main tasks was to increase the amount of time people spent on YouTube. At the time, this pursuit seemed harmless. But nearly a decade later, I can see that our work had unintended—but not unpredictable—consequences. In some cases, the AI went terribly wrong.