The dynamics of opinion expression
Felix Gaisbauer, Eckehard Olbrich, and Sven Banisch
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Submission date: 05. Feb. 2020
paper prepared for: Physical Review E
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Modelling eﬀorts in opinion dynamics have to a large extent ignored that opinion exchange between individuals can also have an eﬀect on how willing they are to express their opinion publicly. Here, we introduce a model of public opinion expression. Two groups of agents with diﬀerent opinion on an issue interact with each other, changing the willingness to express their opinion according to whether they perceive themselves as part of the majority or minority opinion. We formulate the model as a multi-group majority game and investigate the Nash equilibria. We also provide a dynamical systems perspective: Using the reinforcement learning algorithm of Q-learning, we reduce the N-agent system in a mean-ﬁeld approach to two dimensions which represent the two opinion groups. This two-dimensional system is analyzed in a comprehensive bifurcation analysis of its parameters. The model identiﬁes social-structural conditions for public opinion predominance of diﬀerent groups. Among other ﬁndings, we show under which circumstances a minority can dominate public discourse.