Charla Invitada: Group decision making: opinion consensus vs polarization

FEDERICO VAZQUEZ

Villa Carlos Paz, Cordoba.

Workshop; XIII LATIN AMERICAN WORKSHOP ON NONLINEAR PHENOMENA (LAWNP 2013); 2013

Universidad Nacional de Cordoba

Homophily (love of the same) and persuasive arguments are two social mechanisms that promote opinion polarization in human groups. We explore the dynamics of these mechanisms within two simple agent-based models for opinion formation. In the rst model, each individual can take one of two opinions, for instance to decide whether a person suspected of a crime is guilty or not guilty. In a single step, an individual can either adopt the opinion of one of its interacting neighbors (imitation), or drop a connection with an opposite-opinion neighbor and form a new connection with another same-opinion person. In this way, homophily is implemented by promoting interactions between like-minded individuals that tend to group together. Depending on the relative rates associated to the imitation and reconnection processes, the group can either reach global consensus or split in two subgroups formed by people that share the same opinion. In the second model, we introduce an integer number k (M  k  M) that measures the degree of extremism of an individual about its opinion, so that k = M (M) represent individuals who are totally convinced that the suspected person is guilty (not guilty). In a single step, a pair of individuals with convictions k and k´ are chosen at random. If they have the same opinion [sign(k) = sign(k´)], then they increase their convictions in one unit after they talk, by persuading each other using dierent arguments. If they have opposite opinions [sign(k) not equal sign(k´)], then with the same probability 1/2 one individual becomes less convinced while the other becomes more convinced. The evolution of the system is characterized by two time scales, an initial transient polarized state where the opinion distribution is peaked at the two extreme values k = M and k = -M, followed by a relaxation to the consensus in one of these two extreme opinions.