http://www.hpl.hp.com/research/scl/papers/feedbacks/feedbacks.pdf Why does the distribution of user contributions obey a power law? A significant percentage of online content is now published and consumed via the mechanism of crowdsourcing. While any user can contribute to these forums, a disproportionately large percentage of the content is submitted by very active and devoted users, whose continuing participation is key to the sites’ success. As we show, people’s propensity to keep participating increases the more they contribute, suggesting motivating factors which increase over time. This paper demonstrates that submitters who stop receiving attention tend to stop contributing, while prolific contributors attract an ever increasing number of followers and their attention in a feedback loop. We demonstrate that this mechanism leads to the observed power law in the number of contributions per user and support our assertions by an analysis of hundreds of millions of contributions to top content sharing websites Digg.com and Youtube.com. Fang Wu, Dennis M. Wilkinson and Bernardo Huberman 2009-05-04 23:13:00 attention social media crowdsourcing http://www.hpl.hp.com/research/scl/papers/crowd/crowd.pdf How to solve the digital commons dilemma. attention social networks reputation crowdsourcing The tragedy of the digital commons does not seem to prevent the copious voluntary production of content that one witnesses in the web. We show through an analysis of a massive data set from Youtube that the productivity exhibited in crowdsourcing exhibits a strong positive dependence on attention, measured by the number of downloads. Conversely, a lack of attention leads to a decrease in the number of videos uploaded and the consequent drop in productivity, which in many cases asymptotes to no uploads whatsoever. Moreover, we observed that uploaders compare themselves to others when having low productivity and to themselves when exceeding a personal threshold. Bernardo A. Huberman, Daniel M. Romero and Fang Wu 2008-09-11 12:00:00 http://www.hpl.hp.com/research/scl/papers/howopinions/wine.pdf How web discourse evolves. To appear in the Proceedings of the Workshop on Internet and Network Economics-2008 opinion formation social networks polarization crowdsourcing WINE No aspect of the massive participation in content creation that the web enables is more evident than in the countless number of opinions, news and product reviews that are constantly posted on the Internet. Given their importance we have analyzed their temporal evo- lution in a number of scenarios. We have found that while ignorance of previous views leads to a uniform sampling of the range of opinions among a community, exposure of previous opinions to potential review- ers induces a trend following process which leads to the expression of increasingly extreme views. Moreover, when the expression of an opinion is costly and previous views are known, a selection bias softens the ex- treme views, as people exhibit a tendency to speak out differently from previous opinions. These findings are not only robust but also suggest simple procedures to extract given types of opinions from the population at large. Fang Wu and Bernardo A. Huberman 2008-09-11 12:00:00