Berlin 2012 – scientific programme

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SOE: Fachverband Physik sozio-ökonomischer Systeme

SOE 19: Social Systems, Opinion and Group Dynamics II

SOE 19.2: Talk

Thursday, March 29, 2012, 11:45–12:00, H 0110

Reconciling long-term cultural diversity and short-term collective social behavior — •Diego Garlaschelli — Lorentz Institute for Theoretical Physics, University of Leiden, Niels Bohrweg 2, NL-2333 CA Leiden, The Netherlands

An outstanding open problem is whether collective social phenomena occurring over short timescales can systematically reduce cultural heterogeneity in the long run. Theoretical models suggest that short-term collective behavior and long-term cultural diversity are mutually excluding, since they require very different levels of social influence. The latter jointly depends on two factors: the topology of the underlying social network and the overlap between individuals in multidimensional cultural space. However, while the empirical properties of social networks are intensively studied, little is known about the large-scale organization of real societies in cultural space, so that random input specifications are necessarily used in models. Here we use a large dataset to perform a high-dimensional analysis of the scientific beliefs of thousands of Europeans. We find that inter-opinion correlations determine a nontrivial ultrametric hierarchy of individuals in cultural space. When empirical data are used as inputs in models, ultrametricity has strong and counterintuitive effects. On short time-scales, it facilitates a symmetry-breaking phase transition triggering coordinated social behavior. On long time-scales, it suppresses cultural convergence by restricting it within disjoint groups. Thus the distribution of individuals in cultural space appears to optimize the coexistence of short-term collective behavior and long-term cultural diversity.