The Web 2.0 movement has brought a new generation of usability and socio-technical change to the Web. At the same time, several so-called Web 2.0 applications had enormous success: Wikipedia,, Flickr, YouTube, Facebook, Twitter, Geni – to name just a few. Having differing objectives, they all have something in common: huge amounts of enthusiastic users contributing and creating a plethora of content. The high acceptance of these applications with Web users from all over the world prove that they are usable and – more importantly – provide some kind of benefit. Each of the applications has incentive structure well in place, triggering user interest and involvement.
The aim of the workshop is to address the following questions around incentives and motivation of Web applications: what is the motivation for a user to (install and) use a tool? Which incentive structures can be applied to the Web, which cannot? Moreover, incentives are a crucial topic for future Web generations: Web paradigms, like the Semantic Web or the 3D Web, that are novel and unfamiliar to end users, aim to involve wide user bases. WEBCENTIVES will attract contributions analyzing, applying, and designing incentive structures for Web applications. We want to emphasize that the workshop also aims at failures, i.e. cases where incentives failed, in order to understand why they failed and to disseminate the lessons learned.


WEBCENTIVES will provide a mix of invited talks, paper presentations selected from submitted papers by a programme committee, demo sessions, and enough time for discussions.
The workshop will be open to all interested parties and aims at bringing together

The eventual schedule will be fixed after the selection of the papers and demos.


The objective of WEBCENTIVES is to foster the thinking process around incentives, motivations, and benefits of Web applications. We aim at submissions that

Topics include, but are not limited to:

Review process and submission

We aim at three different kinds of submission: (1) research papers of the length of no more than 8 pages (ACM style) presenting mature work, early prototypes and methodologies, (2) position papers of the length of 4 pages presenting early work and elaborated ideas, and (3) demo outlines of the length of 2 pages.
The submitted papers will be reviewed by 3 reviewers each in a semi-blind review process. We will use the Easychair submission system for that purpose.

Please submit your papers here:

Incentives for attending and submitting to the workshop

All accepted papers will published with the conference. We will also invite a selection of the accepted papers to be published at a special issue of the International Journal of Knowledge Engineering and Data Mining (IJKEDM).

Furthermore we plan to invite a proliferate speaker to present as an invited speaker to the workshop to provide an excellent forum for the discussion of this important topic.

It has also to be noted that the workshop's location is Madrid, which is famous for its beautiful parks and museums. April is a wonderful time to enjoy Spain.

Invited Talk: Arpita Ghosh

Arpita Ghosh received her B.Tech from IIT Bombay in 2001, and her PhD from Stanford University in 2006. She is currently a research scientist in the microeconomics group at Yahoo! Research. Her research focuses on algorithms and mechanism design in the context of the Web, particularly online advertising, social networks, social lending and privacy preserving mechanisms.

Talk: Charity Auctions on Social Networks

Slides (.pdf)

Charitable giving is similar to content creation on the Web: both result in public goods, which can be enjoyed not just by the donor (or creator), but by everyone else as well. In both cases, however, the observed level of contributions exceeds that predicted by classical models of public goods. The question of why people give has been the subject of extensive research in the economics literature, both with a view to developing models that best predict observed contributions, as well as to design fundraising mechanisms to maximize giving.

In this talk, I will begin with a brief overview of research on charitable giving. Classical models have tried to explain observed contributions in terms of public and private benefit alone. However, accounting for social effects and the effect of donations on future contributions (such as with gift matching) leads to models whose predictions more closely match reality. Experimental evidence also shows that matching contributions, as well as social factors can increase contributions to charity. Motivated by this, we explore the idea of matching contributions in a social network setting, where an individual in a social network can bid to match her friends' contributions through a charity auction. Individuals care about the contribution of their neighbors, and are allowed to specify contributions that are conditional on the those of their neighbors. We give a mechanism for this setting that raises the largest individually rational contributions given the conditional bids, and analyze the equilibria of this mechanism in the case of linear utilities. We show that if the social network is strongly connected, the mechanism always has an equilibrium that raises the maximum possible total contribution, and characterize social networks for which a non-zero equilibrium exists.


Mixing Financial, Social and Fun Incentives for Social Voting - Frank Smadja

Slides (on

YouTube’s Collaborative Annotations - Michael Fink, Sigalit Bar, Aviad Barzilai, Isaac Elias, Julian Frumar, Herb Ho, Ryan Junee, Nir Kerem, Simon Ratner, Jasson Schrock and Ran Tavory

Slides (.pdf)

MultiRank: Reputation Ranking for Generic Semantic Social Networks - Xixi Luo and Joshua Shinaver

Slides (.pdf)

A new life for a dead parrot: Incentive structures in the Phrase Detectives game - Jon Chamberlain, Massimo Poesio and Udo Kruschwitz

Slides (.pdf)


Monday, April 20, 2009
Proceedings (.pdf)

Program Committee


Target audience

The workshop will be open to all interested parties and aims at bringing together

Important Dates


Katharina Siorpaes
STI Innsbruck, Austria
Email: katharina (dot) siorpaes (at) sti2 (dot) at