Abstract: Calls for censorship have been made in response to the proliferation of flat Earth videos on YouTube, but these videos are likely convincing to very few. Instead, people may worry these videos are brainwashing others. That individuals believe other people will be more influenced by media messages than themselves is called third-person perception (TPP), and the consequences from those perceptions, such as calls for censorship, are called third-person effects (TPE). Here, we conduct three studies that examine the flat Earth phenomenon using TPP and TPE as a theoretical framework. We first measured participants’ own perceptions of the convincingness of flat Earth arguments presented in YouTube videos and compared these to participants’ perceptions of how convincing others might find the arguments. Instead of merely looking at ratings of one’s self vs. a general ‘other,’ however, we asked people to consider a variety of identity groups who differ based on political party, religiosity, educational attainment, and area of residence (e.g., rural, urban). We found that participants’ religiosity and political party were the strongest predictors of TPP across the different identity groups. In our second and third pre-registered studies, we found support for our first study’s conclusions, and we found mixed evidence for whether TPP predict support for censoring YouTube among the public.