In open environments there is no central control over agent behaviors On the con trary agents in such systems can be assumed to be primarily driven by self interests Under the assumption that agents remain in the system for signi cant time periods or that the agent composition changes only slowly we have previously presented a pre scriptive strategy for promoting and sustaining cooperation in t...

Disengagement from radical social groups is a complex process initiated by the experience of a crisis, or disillusionment causing a re-evaluation of involvement. This paper provides a review of the experiences that hinder group involvement and increases the likelihood of disengagement. Utilising the categorisation by Klandersman (2005) and Demant et al. (2008a), the factors are discussed under ...

We study here Flickr groups in order to see whether they are actual communities or rather essentially thematic clusters. We describe a methodological framework for the analysis of networks of group members, measuring social density and tag dispersion among groups and give some results on a sample of 450 groups having around 500 members each.

We demonstrate that correlated equilibrium can express conformity to norms and the coordination of behavior within social groups. Given a social group structure (a partition of players into social groups), we propose three properties that one may expect of a correlated equilibrium consistent with social group structures satisfying behavioral conformity. These are: (a) within-group anonymity (co...

A computational model based on concept polarity is proposed to investigate the influence of communications across ‘diacultural groups’. The hypothesis is that there are communities which can be characterized by a network of concepts and the corresponding valuations of those concepts that are agreed upon by the members of the community. We apply an existing research tool, ECO, to generate commun...

We consider a situation in which individuals search for accurate decisions without direct feedback on their accuracy, but with information about the decisions made by peers in their group. The "wisdom of crowds" hypothesis states that the average judgment of many individuals can give a good estimate of, for example, the outcomes of sporting events and the answers to trivia questions. Two condit...

Social outliers draw a lot of attention from those inside and outside their group and yet little is known about their impact on perceptions of their group as a whole. The present studies examine how outliers influence observers' summary perceptions of a group's behavior and inferences about the group's descriptive and prescriptive norms. Across 4 studies (N = 1,718) we examine how observers per...

In recent years, social synchrony has attracted much attention from different research areas including biology, physics, psychology, and engineering. It is widely believed that synchrony, as an outcome of evolutionary selection, can increase the cohesion of social groups and thus lead them to perform better when dealing with complex tasks. This chapter briefly reviews several quantitative aspec...