, also called collective hysteria
, mass psychogenic illness
, or collective obsessional behavior
, is the sociopsychological phenomenon
of the manifestation of the same or similar hysterical symptoms
by more than one person. A common manifestation of mass hysteria occurs when a group of people believe they are suffering from a similar disease
Mass hysteria typically begins when an individual becomes ill or hysterical during a period of stress. After this initial individual shows symptoms, others begin to manifest similar symptoms, typically nausea, muscle weakness, fits or headache.
Sightings of religious miracles are often attributed to mass hysteria.
Cases of moral panic often have symptoms that overlap with mass hysteria.
American paranormal and UFO researcher Jerome Clark
argues that mass hysteria is often a flimsy post hoc
explanation and "a classic blame-the-victim strategy
" in cases where authorities or experts can find no explanation for puzzling or frightening events.
Two notable cases where mass hysteria was controversially claimed as the cause of an incident are the toxic lady event and the 2007 Peruvian meteorite event.