Diffusion and Emergence in Social Networks

www.nda.ac.jp/~nama Diffusion is the process by which new products and practices are invented and successfully introduced into society. Numerous studies on the diffusion of individual innovations have been conducted, many exhibiting common features such as the famous S-shaped diffusion curve. One basic question posed by innovation diffusion is why there is often a long lag time between an innovation’s first appearance and the time when a substantial number of people have adopted it. An extensive amount of theoretical and empirical literature has been devoted to this phenomenon and the mechanisms behind it. New ideas, products, and innovations often take time to diffuse, a fact that is often attributed to the heterogeneity of human populations. In this chapter, we provide an overview of research examining how the structure of social networks impacts diffusion process. The diffusion process enhances innovations via feedback of information about the innovation’s utility—which can be used to make future improvements—to many different users. This aspect of the diffusion process is similar to the micro-macro loop, which is an essential part of emergence. The aim of this research is to understand how the structure of social networks determines the dynamics of various types of emergent properties occurring within those networks. For emergence at the social level, patterns of social interactions are critical