Outbreaks of mass hysteria are not uncommon in primitive and modern cultures alike. A group of
people will exhibit bizarre behavior, including seizures, tremors, running amok, comatose-like trance or
possession states, or other sudden hysterical symptoms with no identifiable medical cause. Western psychiatrists
call this Mass Psychogenic Illness. Mass hysteria usually starts with a single individual, and this quickly spreads
to others, particularly in close settings such as schools, nunneries, or factories, particularly if individuals are
subject to intense anxiety of stress. Sometimes these states are voluntarily elicited in religious or healing
ceremonies, with incessant drumming, excitement and suggestibility as one person after another falls into a trance
or possession state. Sometimes the outbreak will pertain to a collective fear that is entirely false, for example a
collective delusion that there is a poisonous gas in the air-and many people will fall victim to symptoms of toxic
poisoning despite the fact that there is nothing in the air. A mass dancing mania emerged following the Black
Plague epidemic of the 14th century. People would hop, dance, clap hands and jump about in a frenzy, often
naked. How hysteria spreads from the initial case to a group is deeply mysterious. Perhaps hysteria can be
contagious much in the same way as a violent mood can spread in a mob and lead to a riot, or there is some sort
of decoupling of an individual’s personality in the context of group dynamics.