When irrational, or wild and uncontrollable behavior spreads rapidly through a crowd, or through a section of society. The notorious Salem witch trials in seventeenth-century Massachusetts, in which innocent people were put to death, was an example. So was the mass panic that spread in a number of American cities in 1938, when a radio broadcast of Orson Welles' adaption of H. G. Wells' novel The War of the Worlds - about the invasion of earth by Martians - was misinterpreted as a genuine news report of a real event.