1. 收斂理論---Convergence theory
　　Convergence theory holds that crowd behavior is not a product of the crowd itself, but is carried into the crowd by particular individuals. Thus, crowds amount to a convergence of like-minded individuals. In other words, while contagion theory states that crowds cause people to act in a certain way, convergence theory says the opposite: that people who wish to act in a certain way come together to form crowds. An example of convergence theory states that there is no homogeneous activity within a repetitive practice, sometimes observed when an immigrant population becomes common in a previously homogeneous area, and members of the existing community (apparently spontaneously) band together to threaten those trying to move into their neighborhoods. In such cases, convergence theorists contend, the crowd itself does not generate racial hatred or violence; rather, the hostility has been simmering for some time among many local people. A crowd then arises from convergence of people who oppose the presence of these neighbors. Convergence theory claims that crowd behavior as such is not irrational; rather, people in crowds express existing beliefs and values so that the mob reaction is the rational product of widespread popular feeling.
　　2. 群體心理學的概念
　　Crowd psychology is a branch of social psychology. Ordinary people can typically gain direct power by acting collectively. Historically, because large groups of people have been able to affect dramatic and sudden social change in a manner that bypasses established due process, they have also provoked controversy. Social scientists have developed several different theories for explaining crowd psychology, and the ways in which the psychology of the crowd differs significantly from the psychology of those individuals within it. Carl Jung coined the notion of the Collective unconscious.