Rom the grand mean (44.35 of 100 US cents). The y axis depicts the sender country, whereas the bar colors and labels represent receiver nationality. The numbers in parentheses indicate the mean contribution for each sender nation.10840 | www.pnas.org/cgi/doi/10.1073/pnas.Dorrough and Gl knerattributes (i.e., trustworthy, friendly, generous, and likeable) and nonrelated filler attributes (i.e., attractive, spirited, extraverted, and athletic) as well as on the dimension wealthy vs. not wealthy. Instructions were provided in the respective national languages to avoid foreign language effect on choice behavior (47). It was common knowledge that one of the interactions was randomly selected and incentivized after study completion. Participants received payments between US 2.00 and US 5.00, consisting of a US 2.00 base XAV-939MedChemExpress XAV-939 payment plus a US 0?.00 bonus payment, depending on their decisions during the study. Study 2 (n = 485) aimed to replicate and extend results from study 1 with an expanded set of 10 different nations but with smaller subsamples that were not representative of the respective GW0742MedChemExpress GW0742 nation’s populations. Therefore, in addition to the nations used in study 1, study 2 included individuals from Afghanistan, Bangladesh, France, and Spain. These additional nations were associated with the largest possible participant pools on AmazonMechanical Turk, which was the recruitment platform used in study 2. The materials and procedure were essentially the same as in study 1 except for the fact that the payment (of the same magnitude) was realized with an Amazon voucher. All studies were approved by the ethics committee of the University of Goettingen and were conducted in accordance with the approved guidelines. Informed consent was obtained by the online survey platforms (for further information, see SI Appendix). The data of all three studies can be found at https://osf.io/phgbs. ACKNOWLEDGMENTS. We are indebted to Christoph Engel and two anonymous reviewers for helpful comments on an earlier version of this article. Furthermore, we thank Neele Carqueville for administrative support in preparing the studies and Heather Fiala for proofreading. We thank the University of Hagen for covering open-access publication fees.1. Hardin G (1968) The tragedy of the commons. Science 162(3859):1243?248. 2. Sally D (1995) Conversation and cooperation in social dilemmas: A meta-analysis of experiments from 1958 to 1992. Ration Soc 7(1):58?2. 3. Kreps DM, Milgrom PR, Roberts J, Wilson RB (1982) Rational cooperation in the finitely repeated prisoners’ dilemma. J Econ Theory 27(2):245?52. 4. Fehr E, Schmidt KM (1999) A theory of fairness, competition, and cooperation. Q J Econ 114(3):817?68. 5. Dawes CT, Fowler JH, Johnson T, McElreath R, Smirnov O (2007) Egalitarian motives in humans. Nature 446(7137):794?96. 6. Van Lange PAM (1999) The pursuit of joint outcomes and equality in outcomes: An integrative model of social value orientation. J Pers Soc Psychol 77(2):337?49. 7. Pruitt DG, Kimmel MJ (1977) Twenty years of experimental gaming: Critique, synthesis, and suggestions for the future. Annu Rev Psychol 28:363?92. 8. Bogaert S, Boone C, Declerck C (2008) Social value orientation and cooperation in social dilemmas: A review and conceptual model. Br J Soc Psychol 47(3):453?80. 9. Alexander RD (1974) The evolution of social behavior. Annu Rev Ecol Syst 5:325?83. 10. Fischer I, et al. (2013) Fusing enacted and expected mimicry generates a winning strategy that pr.Rom the grand mean (44.35 of 100 US cents). The y axis depicts the sender country, whereas the bar colors and labels represent receiver nationality. The numbers in parentheses indicate the mean contribution for each sender nation.10840 | www.pnas.org/cgi/doi/10.1073/pnas.Dorrough and Gl knerattributes (i.e., trustworthy, friendly, generous, and likeable) and nonrelated filler attributes (i.e., attractive, spirited, extraverted, and athletic) as well as on the dimension wealthy vs. not wealthy. Instructions were provided in the respective national languages to avoid foreign language effect on choice behavior (47). It was common knowledge that one of the interactions was randomly selected and incentivized after study completion. Participants received payments between US 2.00 and US 5.00, consisting of a US 2.00 base payment plus a US 0?.00 bonus payment, depending on their decisions during the study. Study 2 (n = 485) aimed to replicate and extend results from study 1 with an expanded set of 10 different nations but with smaller subsamples that were not representative of the respective nation’s populations. Therefore, in addition to the nations used in study 1, study 2 included individuals from Afghanistan, Bangladesh, France, and Spain. These additional nations were associated with the largest possible participant pools on AmazonMechanical Turk, which was the recruitment platform used in study 2. The materials and procedure were essentially the same as in study 1 except for the fact that the payment (of the same magnitude) was realized with an Amazon voucher. All studies were approved by the ethics committee of the University of Goettingen and were conducted in accordance with the approved guidelines. Informed consent was obtained by the online survey platforms (for further information, see SI Appendix). The data of all three studies can be found at https://osf.io/phgbs. ACKNOWLEDGMENTS. We are indebted to Christoph Engel and two anonymous reviewers for helpful comments on an earlier version of this article. Furthermore, we thank Neele Carqueville for administrative support in preparing the studies and Heather Fiala for proofreading. We thank the University of Hagen for covering open-access publication fees.1. Hardin G (1968) The tragedy of the commons. Science 162(3859):1243?248. 2. Sally D (1995) Conversation and cooperation in social dilemmas: A meta-analysis of experiments from 1958 to 1992. Ration Soc 7(1):58?2. 3. Kreps DM, Milgrom PR, Roberts J, Wilson RB (1982) Rational cooperation in the finitely repeated prisoners’ dilemma. J Econ Theory 27(2):245?52. 4. Fehr E, Schmidt KM (1999) A theory of fairness, competition, and cooperation. Q J Econ 114(3):817?68. 5. Dawes CT, Fowler JH, Johnson T, McElreath R, Smirnov O (2007) Egalitarian motives in humans. Nature 446(7137):794?96. 6. Van Lange PAM (1999) The pursuit of joint outcomes and equality in outcomes: An integrative model of social value orientation. J Pers Soc Psychol 77(2):337?49. 7. Pruitt DG, Kimmel MJ (1977) Twenty years of experimental gaming: Critique, synthesis, and suggestions for the future. Annu Rev Psychol 28:363?92. 8. Bogaert S, Boone C, Declerck C (2008) Social value orientation and cooperation in social dilemmas: A review and conceptual model. Br J Soc Psychol 47(3):453?80. 9. Alexander RD (1974) The evolution of social behavior. Annu Rev Ecol Syst 5:325?83. 10. Fischer I, et al. (2013) Fusing enacted and expected mimicry generates a winning strategy that pr.
