Using dozens of bot accounts, The Wall Street Journal did an investigation and determined that TikTok’s algorithm needs only one piece of information to determine what you want to watch: the amount of time you spend watching individual videos. Observing your watch time and rewatching is enough for them to fill your “For You” page with recommended videos that are right in your wheelhouse after just an hour or two. That this happens so quickly and completely — 90-95% of what users see on TikTok is algorithmically determined — leads to users going down narrow-interest rabbit holes that can be dangerous, […]

Read more: How TikTok’s Algorithm Figures You Out