title: Costs for switching partners reduce network dynamics but not cooperative behaviour.
abstract: Social networks represent the structuring of interactions between group members. Above all, many interactions are profoundly cooperative in humans and other animals. In accordance with this natural observation, theoretical work demonstrates that certain network structures favour the evolution of cooperation. Yet, recent experimental evidence suggests that static networks do not enhance cooperative behaviour in humans. By contrast, dynamic networks do foster cooperation. However, costs associated with dynamism such as time or resource investments in finding and establishing new partnerships have been neglected so far. Here, we show that human participants are much less likely to break links when costs arise for building new links. Especially, when costs were high, the network was nearly static. Surprisingly, cooperation levels in Prisoner's Dilemma games were not affected by reduced dynamism in social networks. We conclude that the mere potential to quit collaborations is sufficient in humans to reach high levels of cooperative behaviour. Effects of self-structuring processes or assortment on the network played a minor role: participants simply adjusted their cooperative behaviour in response to the threats of losing a partner or of being expelled.
authors.affiliation: Research Group Evolution of Cooperation and Prosocial Behaviour, Courant Research Centre Evolution of Social Behaviour, University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany peter.bednarik@bio.uni-goettingen.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Bednarik
authors.affiliation: Research Group Evolution of Cooperation and Prosocial Behaviour, Courant Research Centre Evolution of Social Behaviour, University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Fehl
authors.affiliation: Research Group Evolution of Cooperation and Prosocial Behaviour, Courant Research Centre Evolution of Social Behaviour, University of Göttingen, Kellnerweg 6, 37077 Göttingen, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Semmann
mesh_terms: D003299:Cooperative Behavior; D005260:Female; D005716:Game Theory; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D060756:Social Networking; D055815:Young Adult
keywords: Prisoner's Dilemma; cooperation; dynamic network; evolutionary game theory; partner switching