E. computer proficiency. sequential prisoner??s dilemma games. Experiencing impartiality to invoke fairness in the n-pd: Some experimental results. Sharpe. Jeppensen and Frederiksen 2006 . 2004 . and M. contributions to online soci al networks benefit others in the networks except for the contributor. Studies show that one determining factor for indirect reciprocity is the availability of information about cooperation level of other participants in the group Brandt and Sigmund 2005. she stays in the network longer and is more likely to re alize that the value of file sharing from others and behave reciprocally. The incentive could be reputational. starting an avalanche across the network. and pure altruism wher e an individual contributes Louis vuitton of the concerns of others?? welfare.L. Preferential attach ment and mutuality in electronic knowledge networks. It is what one does: why people pa rticipate and help others in electronic communities of practice. Intrinsic factors refer Louis Vuitton UK the satisfaction obtained from the action of creating contents and contributing to social networks such as fun and joy in solving challenges Shah 2006. and Rao H. and S. Faraj. Oosterbeek. G. Harvard University Press. Many social factors exhibit positive feedback and. R. M. By studying how individuals change server settings with the social environment. Ang. 2004 . The resu lts indicate that indire ct reciprocity is a dynamic social force as individual behaviors are significantly influen ced by others?? behavior in a social network. K. Our analysis indicates that a network user significan tly increases her propensity to contribute after gaining special titles from the network. We discuss the theo retical foundation of private contribution to public goods in the next section. Recent social network studies Faraj and Johnson 2005. overlooks the social nature of peer-to-peer networks where individual behavior is both influenced by social environment as well as a part of the social environment that affects others. Y. In the context of a music sharing network. 2003. some contributors are undercover employees of viral ma rketing firms that intend to Louis Vuitton Outlet certain music groups or artists instead of benefiting the community. where contributions and benefits are pooled and shared. D. religion belief. however. e. Free-ri ding has also been reported as a concern in studies on virtual professional networks. 2003. Greiner and Levati 2005. due to data limitations. give access to other contributors only. S econd. Indirect reciprocity can stabilize cooperation without the second-order free rider problem. For example. However. First. Mike Smith and seminar participants at the University of Texas at Austin. A. In either case. individuals may not have repeated interactions and cannot directly reciprocate to each other. Xia et al. E. The result is consistent with the approach taken in prior experimental studies but contradictory to Kandori 1992 ??s suggestion that enforcement of social norm is itself a public good. Gachter. Indirect re ciprocity. identity verification. Slaughter. indicating that the multicollinearity problem is not severe e nough to affect the regression results. Management Science 47 9 1203-1219. L. B. Such punishment mechanisms serve as a st rong deterrence to anti-soc ial behaviors. et c. Winter-ebmer. A foundation for the study of group decision support systems. This social enforcement mechanism provides an Louis vuitton uk tool to punish free riders and reward contributors. Asvanund. Wasko. For example. We discuss the theo retical foundation of private contribution to public goods in the next section. Reci procity or generalized exchange? Structuring of electronic knowledge networks. W. However. We also find that individuals with high download needs tend to increase their contribution probability when they face more network congestion.g. 2004. Spain. 2000a. and sustainabili ty: A resource-based model of online social structures. Reci procity or generalized exchange? Structuring of electronic knowledge networks. We conduct the analysis using a panel data by observing 103. 2005 . D. To address the concern. The combination of low benefits and high costs indi cates that economically ra tional individuals will provide little contribution to online social networks. In the context of a Louis Vuitton sharing network. could be a double-edged sword. E.A. extrinsic. individual interactions in peer-to-peer networks resemble one-shot games where Prisoner??s dilemma is prevalent. K. Virtual commons: why free-riding can be tolerated in file sharing networks? Proceedings of International Conference on Information Systems. Foundations of human sociality: Economic experiments and et hnographic evidence from fifteen small-scale societies . Frohlich. Telang. but also when she observes an increase in wait time. 2006. Ledyard. About 17% of all network users receive the title of Value User . Ostrom. Table 4 reports individual co ntributors?? enforcement of social norms to encourage indirect reciprocity in the peer-to-peer network. otivation factors actually influe nce individual behavior in social networks. Proceedings of National Louis Vuitton Outlet of Science 102 7 2666-2670. 2005. Once a contributor makes the contribution decision. Relative Performance of Incentive Mechanisms: Computational Modeling and Simulation of Delegated Investment Decisions. Hughes. R. Ba. Parameswaran et al. we do not know the process through which social environment influences individuals. In the peer-to-peer network studied in this paper. E. and moral hazard.. Testing theories of fairne ss ?C Intentions matter. little is known about how the social norms are formed and enforced in online social networks. Gummadi. R. Greiner and Levati 2005. Y. 2000b . Review of Economic Studies. Fehr. A. Table 2 shows the correlation matrix for the key variables.