I.

Introduction

Hysteria, type of mental illness, in which emotionally laden mental conflicts appear as physical symptoms, called conversion reactions, or as severe mental dissociation. In modern psychological classification, hysteria is known as somatization disorder or conversion disorder, depending on the specific symptoms displayed. Psychiatric diagnosis of hysteria depends on recognition of a mental conflict and of the unconscious connections between conflict and symptoms. The term mass hysteria is applied to situations in which a large group of people exhibit the same kinds of physical symptoms with no organic cause. For example, one incident of mass hysteria reported in 1977 involved 57 members of a high school marching band who experienced headache, nausea, dizziness, and fainting after a football game. After a fruitless search for organic causes, researchers concluded that a heat reaction among a few band members had spread by emotional suggestion to other members of the band. The term collective stress reaction is now preferred for these situations.