CentralNotice From Wikipedia, the free encyclopedia Jump to navigation Jump to search Main article: Mass psychogenic illness In sociology and psychology, mass hysteria (also known as mass psychogenic illness , collective hysteria , group hysteria , or collective obsessional behavior ) is a phenomenon that transmits collective illusions of threats, whether real or imaginary, through a population and society as a result of rumors and fear. [1] [2] In medicine, the term is used to describe the spontaneous manifestation—or production of chemicals in the body—of the same or similar hysterical physical symptoms by more than one person. [3] [4] A common type of mass hysteria occurs when a group of people believes that it is suffering from a similar disease or ailment, [5] sometimes referred to as mass psychogenic illness or epidemic hysteria . [6] 1 Middle Ages 2 15...