Why Violence Spreads: The Contagion of International Terrorism

Abstract

This study examines the spread of international terrorism from 1968 to 1974. Using Poisson and negative binomial probability models, a diffusion of international terrorism was found in the first segment of the time period (1968–1971) and contagion as a direct modeling process in the second (1973–1974). Accordingly, the theory of hierarchies in which the diplomatic status of a country predicts its degree of imitability was found to operate among Latin American countries during the second portion of the overall period, but not during the first. An inverse hierarchy is suggested as an explanation for the contagion of violence from Latin America and other third world countries to Western Europe. Autocorrelation functions were used to assess which forms of terrorism were most contagious in which regions.