title: Human cooperation in groups: variation begets variation.
abstract: Many experiments on human cooperation have revealed that individuals differ systematically in their tendency to cooperate with others. It has also been shown that individuals condition their behaviour on the overall cooperation level of their peers. Yet, little is known about how individuals respond to heterogeneity in cooperativeness in their neighbourhood. Here, we present an experimental study investigating whether and how people respond to heterogeneous behaviour in a public goods game. We find that a large majority of subjects does respond to heterogeneity in their group, but they respond in quite different ways. Most subjects contribute less to the public good when the contributions of their peers are more heterogeneous, but a substantial fraction of individuals consistently contributes more in this case. In addition, we find that individuals that respond positively to heterogeneity have a higher general cooperation tendency. The finding that social responsiveness occurs in different forms and is correlated with cooperativeness may have important implications for the outcome of cooperative interactions.
authors.affiliation: Theoretical Research in Evolutionary Life Sciences (TRÊS), University of Groningen, 9747 AG Groningen, Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: van den Berg
authors.affiliation: Theoretical Research in Evolutionary Life Sciences (TRÊS), University of Groningen, 9747 AG Groningen, Netherlands.|The Centre for Decision Research and Experimental Economics (CeDEx), University of Nottingham, Sir Clive Granger Building, University Park, Nottingham NG7 2RD, UK.
authors.forename: Lucas
authors.initials: L
authors.lastname: Molleman
authors.affiliation: University of Jyvaskyla, Department of Biological and Environmental Science, P.O.Box 35, FI-40014 University of Jyvaskyla, Finland.|University of Jyvaskyla, Centre of Excellence in Biological Interactions, P.O.Box 35, FI-40014 University of Jyvaskyla, Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Junikka
authors.affiliation: University of Jyvaskyla, Department of Biological and Environmental Science, P.O.Box 35, FI-40014 University of Jyvaskyla, Finland.|University of Jyvaskyla, Centre of Excellence in Biological Interactions, P.O.Box 35, FI-40014 University of Jyvaskyla, Finland.
authors.forename: Mikael
authors.initials: M
authors.lastname: Puurtinen
authors.affiliation: Theoretical Research in Evolutionary Life Sciences (TRÊS), University of Groningen, 9747 AG Groningen, Netherlands.
authors.forename: Franz J
authors.initials: FJ
authors.lastname: Weissing
mesh_terms: D000328:Adult; D003299:Cooperative Behavior; D005260:Female; D005716:Game Theory; D006801:Humans; D008297:Male; D055815:Young Adult