Redefining epidemic hysteria: an example from Sweden.

François Sirois' influential paradigm for diagnosing episodes of epidemic hysteria is discussed. The part of his schema addressing the large diffuse outbreak should be eliminated as it does not possess characteristic features of mass hysteria and overlooks the potential social, cultural, political, ritualistic and institutional patterning of collective behavior. A case study involving the collective delusion of phantom rockets over Sweden during 1946 illustrates the complexities of such episodes.