Centrality and power revisited: actor success in group decision making

For many years, network analysts viewed positional centrality as a source o f social power. More recently, laboratory studies of exchange networks have called the centrality-power link into question: under zero-sum exchange co nditions, the ability of certain actors to directly exploit others has been found to account for power independent of actors' centrality. But most obs ervers believe that in non-zero-sum communication networks, centrality shou ld positively affect power. In this study we examine the effect of centrali ty on power in a communication network involving group voting on political issues. Using a model in which actors' votes are determined by the strength of their initial positions and the social;pressures to which they are subj ected, we conduct computer simulations to examine the extent to which actor s in various network positions achieve favorable political outcomes. Our fi ndings indicate that the link between centrality and power is highly contin gent on the structure of the network. In networks with a central actor and an odd number of subgroups, central actors fail to dominate. In fact, in th ese networks, when peripheral actors are able to directly influence one ano ther, the central actor becomes the least powerful in the network. In netwo rks with a central actor and an even number of subgroups, however, the cent ral actor dominates even in situations with connected peripherals. The high ly contingent effect of centrality on power accords with the findings of ex change theorists who have studied power under zero-sum conditions. This rai ses questions about the nature of the distinction between communication and exchange networks. (C) 1998 Elsevier Science B.V. All rights reserved.