ABSTRACT
Meanwhile, mobile social networks (MSNs) and online social networks (OSNs) are increasingly centered on contributions by their users. User-generated content (UGC) such as Amazon and Yelp reviews, Wikipedia articles, blogs, or YouTube videos now constitute a large fraction of the relevant, easily accessible content that makes MSNs/OSNs extremely useful; crowdsourcing tasks to the online public is increasingly common-ranging from systems based on unpaid contributions such as games with a purpose or online question and answer (Q&A) forums (Y! Answers, Quora, and Stack Overflow to name a few) to platforms for paid crowdsourcing such as Amazon’s Mechanical Turk and TopCoder. But although some Web sites consistently attract high-quality contributions, other seemingly similar sites are overwhelmed by junk, and still others fail due to too little participation. ere is a growing body of work in the social psychology literature on what factors motivate,
or constitute rewards for, participants in these social computing systems, and on user experience and interface design to exploit these factors.
