Mass psychogenic illness, also known as mass hysteria, is when a group of people manifest physical symptoms from imagined threats. History is littered with outbreaks of mass hysteria. Recently, alleged cases of Tourette's syndrome appeared all over the world. Was it real or mass psychogenic illness? While the term is often avoided for fear of ridiculing something more serious, mass psychogenic illness (MPI) — also known as mass sociogenic illness (MSI) or mass hysteria — is a real occurrence that can cause a variety of physical symptoms to manifest in groups of people despite the lack of any physical cause. Often compared to conversion disorder , in which emotional issues are "converted" into physical problems, MPI tends to occur among people who share anxieties, fears, and a sense of comm
