Hits and flops dynamics

We discuss the influence of various mechanisms of information contagion on the dynamics of choices in social networks of decision makers. We show that both polling and contagion processes often end up in herding behaviour, wi th most agents taking uniformly either one view or another, even in disorde red systems. In the parameter transition regime, the outcome of the dynamic al process depends on the precise instanciation of disorder. For instance, when agents face a ternary choice between similar products A and B with the possibility of laking none, the initial distribution of early buyers drast ically influences the outcome of the selection process. (C) 2000 Elsevier S cience B.V. All rights reserved.