Observational vs. Interactive Learning in Locational Choice: Evidences on ICT Clusters Formation and Stability

The paper provides new insights into the mechanisms of “ICT clusters” formation. The basic assumption is that clusters can be explained as the result of a locational norm, i.e. as an alignment of locational choices proceeding from both mimetic behaviours and sequential and cumulative interactions. We distinguish informational externalities (and observational learning) from network externalities (and interactive learning) in location processes, in order to compare the respective economic properties of stability of locational cascades and locational clusters. We show as a result that informational effects play a major role in the formation of ICT clusters, whereas network effects are the significant condition of their stability. Silicon Valley and Silicon Sentier (Paris) are briefly studied and compared in order to illustrate our theoretical purpose.