Time and again, researchers have discovered that when videos with political or ideological content are uploaded to the platform, YouTube’s “recommender” algorithm will direct viewers to more extremist content after they have watched the first one. Given that most people probably have the autoplay feature left on by default, that means that watching YouTube videos often leads people to extremist sites.

Strangely, this doesn’t just hold for political or other types of controversial content. Zeynep Tufekci, a well-known technology commentator, found that videos about vegetarianism led to videos about veganism, videos about jogging led to videos about running ultramarathons, and so on. “It seems,” she wrote, “as if you are never ‘hardcore’ enough for YouTube’s recommendation algorithm. It promotes, recommends and disseminates videos in a manner that appears to constantly up the stakes.”