Opinion Dynamics On Network With Dual-Communities

Along with the advancement of socialization and informatization, the Internet has gradually become a new medium of opinion spreading. Especially, there are drastic discussions and arguments of controversial topics related to people’s social lives in today’s fast-growing online opinion communities and this phenomenon has furthermore indicated the important role the online communities play in the spreading of public opinions. In addition, social media have recently become to diversify in this kind of network, and have had a prominent effect on the dynamics of public opinions. Therefore, through the research on the interior regular pattern and its influence factors, we may deeply understand the people’s interactive action, and thus, have practical values for the governments and the community managers in guiding public opinions.Essentially, opinion spreading is one kind of group behavior where the actors carry on the opinion interaction. It can be influenced by the community where the actor belongs to. Therefore, based on the analysis of opinions, opinion actors, opinion spreading processes and the opinion spreading environment, this thesis aims to study the opinion dynamics under two different levels which are the characteristic of the community and the public information of the community.This thesis uses the agent-based modeling approach to study the opinion dynamics on a social network with dual-communities. Firstly we focus on the characteristics of the community, including the inter-connection of the communities, the communities’tolerance and the cohesion of the communities, and considers the initial opinion distribution state of the communities at the same time. A network model for opinion evolution under the mechanism of the tolerance of the communities is proposed. The simulation result indicates that the tolerance of the two communities has a great effect on the final opinion distribution states and the sizes of the two communities. We can furthermore observe the continuous phase change process from the consensus to polarization and to fragmentation. Simultaneously, the community size grows with the increase of the tolerance of the community. Besides, the inter-connection of the communities, the cohesion of the communities, and the initial opinion distribution state of the communities also influence the spreading of opinions.The second main contribution of this thesis is to study the effect of mass media by adding an agent that represents the mass media into one of the communities in the proposed agent-based model, considering whether the mass media influence the opinion of the current community at the same time can affect the opinion of the other community. In computer simulations, we observe how the contact probability and the opinion of the mass media influence the opinion evolution. The result shows that, when there is a mass-media agent in community A, which opinion is equal with the average opinion of community A, and simultaneously when the tolerance of the two communities is large and the connection of the two communities is close, the mass media can affect the opinion of the members in community B. On the contrarily, when the opinion of the mass media is different from the average opinion of community A, the mass media can just effect the opinion in community A and have no effect on the opinion in community B. Besides, when the contact probability of the mass media with the members in community A is getting larger, the opinions of more members of community A are to be assimilated to the opinion of the mass media.