“…The sudden spread of intense delusion-like ideas through the population are well-documented and frequently occur over time and across cultures and have variously been called 'mass delusion', 'social delusion' and have been studied alongside 'mass hysteria' (Bartholomew, 2001). Episodes of socially-transmitted delusion-like belief outbreaks have included beliefs in a 'phantom anaesthetist' who was believed to be prowling the community and 'gassing' members of the public (Bartholomew & Victor, 2004), a 'windshield pitting epidemic' attributed to non-existent 'H-bomb tests' (Medalia & Larsen, 1958), frequent waves of beliefs about malicious penis stealing episodes (Dan, Mondal, Chakraborty, Chaudhuri, & Biswas, 2017), the kidnapping of children to use their decapitated heads in the foundations of new buildings (Barnes, 1993), and an invasion of foreign airships, before capable technology was available (Holman, 2016) to name but a few. Notably, these are distinct from conspiracy theories in that rather than being "explanations for important events that involve secret plots by powerful and malevolent groups" (Douglas, Sutton, & Cichocka, 2017) they typically involve new and idiosyncratic phenomena that reflect a direct and personal risk to the individual believer.…”