  The dynamical origin of opinion polarization in the real world is an
interesting topic physical scientists may help to understand. To properly model
the dynamics, the theory must be fully compatible with findings by social
psychologists on microscopic opinion change. Here we introduce a generic model
of opinion formation with homogeneous agents based on the well-known social
judgment theory in social psychology by extending a similar model proposed by
Jager and Amblard. The agents' opinions will eventually cluster around extreme
and/or moderate opinions forming three phases in a two-dimensional parameter
space that describes the microscopic opinion response of the agents. The
dynamics of this model can be qualitatively understood by mean-field analysis.
More importantly, first-order phase transition in opinion distribution is
observed by evolving the system under a slow change in the system parameters,
showing that punctuated equilibria in public opinion can occur even in a fully
connected social network.
