description of the noise effects. The results show that social influence makes the system dynamics more stable against the presence of noise and that the latter only has a marginal influence on the general qualitative picture obtained without any errors. It is however worth stressing that noise has in general a positive effect in the formation of monocultural final states, giving rise to polarized societies for large enough values of it, independently of the other parameters ruling the size of the social influence and the strength of the mass media effect. Nevertheless, the fact that we have not distinguished between the two error mechanisms in this study does not allow to better understand the specific role each one plays on the dynamics of the system and further studies are needed where these two types of errors were considered as independents. We also think about the need to conduct more detailed studies exploring the implications of the social influence with respect to the dyadic one. The introduction of different models which better study the inter-relations between the dyadic interaction and social influence on a social system could be of importance to further elucidate the robustness of the results found here. This work is currently in progress. A. H. R. thanks to the International Center for Theoretical Physics (ICTP), were the major part of this work was carried out. Y. M. is supported by Spanish MICINN through projects FIS2008-01240 and FIS2009-13364-C02-01. Acknowledgements [1] N. Gilbert and K. G. Troitzsch, Simulation for the social scientist (Open University Press, England, 2005). [2] Artificial Societies , edited by N. Gilbert and R. Conte (Routledge, London, 1995). [3] J. M. Epstein and R. L. Axtell, Growing Artificial Societies (The MIT Press, Washington, D.C., 1996). [4] V. Grimm and S. F. Railsback, Individual-based Modeling and Ecology (Princeton, NJ: Uni- versity Press, 2005). [5] R. L. Goldstone and M. A. Janssen, TRENDS in Cognitive Sciences 9 , 424 (2005). [6] E. Bonabeau, PNAS 99 , 7280 (2002). 20