Public charity offer as a proximate factor of evolved reputation-building strategy: an experimental analysis of a real-life situation Tamas Bereczkei ⁎ , Bela Birkas, Zsuzsanna Kerekes University of Pécs, Pécs, Hungary Initial receipt 2 October 2006; final revision received 6 April 2007 Abstract Although theoretical considerations suggest that a considerable portion of human altruism is driven by concerns about reputation, few experimental studies have examined the psychological correlates of individual decisions in real-life situations. Here we demonstrate that more subjects were willing to give assistance to unfamiliar people in need if they could make their charity offers in the presence of their group mates than in a situation where the offers remained concealed from others. In return, those who were willing to participate in a particular charitable activity received significantly higher scores than others on scales measuring sympathy and trustworthiness. Finally, a multiple regression analysis revealed that while several personality and behavior traits (cooperative ability, Machiavellianism, sensitivity to norms, and sex) play a role in the development of prosocial behavior, the possibility of gaining reputation within the group remains a measurable determinant of charitable behavior. © 2007 Elsevier Inc. All rights reserved. Keywords: Altruism; Charity; Reputation; Generosity 1. Introduction One of the key questions in evolutionary biology and psychology is why individuals help strangers without the possibility of return (Batson, van Lange, Ahmad, & Lishner, 2003; Bowles & Gintis, 2004; Fehr & Rockenbach, 2004; Gintis, Bowles, Boyd, & Fehr, 2003). Several scholars have proposed that humans evolved in small groups with frequently repeated interactions and reputation-building mechanisms (cf., Fehr & Rockenbach, 2004; Johnson, Stopka, & Knights, 2003). Individual selection can favor cooperative strategies directed towards recipients who have helped others in the past. Nowak and Sigmund (1998) state that cooperation pays because it presents the cooperating individual as a valuable community member. Subsequent repayment is channeled towards these members of the group in various ways, but, ultimately, it frequently involves individuals' privileges or their access to resources (Alexander, 1987). This means that altruistic acts may enhance the altruist's status and reputation in his/her social group and yield a long-term benefit, in spite of the obvious short-term cost (Wedekind & Braithwaite, 2002). The effect of reputation building on cooperation with group members has recently been explored using computer simulations and experimental games (Barclay, 2004; Fehr & Fischbacher, 2003; Milinski, Semmann, & Krambeck, 2002a; Wedekind & Milinski, 2000). In reciprocity, trust, and public goods games, players showed a strong preference to give to those who had proven to be generous in previous transactions. It is also well documented that humans are often altruistic to nonreciprocators, even to strangers (e.g., they donate to charities) (Milinski, Semmann, & Krambeck, 2002b; Roberts, 1998; Semmann, Krambeck, & Milinski, 2005). Donations may be given to people outside the social group, but they deeply influence the social attitude of in- group members towards the altruist. For example, a donation to charity organizations that is made in public may function as a conspicuous signal of an individual's propensity to cooperate with group mates (Milinski et al., 2002a). Experimental games can provide “naturalistic” conditions for examining the impact of the costs and benefits of an altruistic act on decision making, including opportunities for Evolution and Human Behavior 28 (2007) 277 – 284 ⁎ Corresponding author. Institute of Psychology, University of Pécs, Ifjúság u. 6, H-7624 Pécs, Hungary. E-mail address: btamas@btk.pte.hu (T. Bereczkei). 1090-5138/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.evolhumbehav.2007.04.002