The opportunity cost of social relations: on the effectiveness of small worlds

The aim of this paper is to extend the theoretical literature on knowledge and network structure by studying the use of social networks as a learning mechanism. The novelty of this approach is suggested by the empirical evidence on informal trading of know-how. In the model, we consider a set of actors who create and diffuse knowledge with the aim of increasing their own personal knowledge. They are located on a lattice (identifying the social space) and are directly connected to a small number of other individuals. We assume that individuals can learn individually or socially, and that individuals choose how to learn on the basis of a cost-benefit comparison. Within this framework, we compare network structures in terms of efficiency and equity. We find that the opportunity cost of using the network affects its optimal structure in terms of aggregate performance and that the small world does not emerge unambiguously as being the most efficient.