Everyday experience shows that humans are often altruistic towards unrelated individuals, even strangers in need in the absence of return. Evolutionary psychology has been coping with the problem of how indiscriminative altruism could have been selected for, that are obviously harmful to individual's survival and reproduction. Costly signal theory states that individuals who engage in altruistic acts serve their own interest by reliably demonstrating their qualities underlying the altruistic act that may be useful for the group mates in future social interactions, such as forming friendships, alliance, getting mates. Whereas this explanatory model has been supported by studies in hunter-gatherer communities, very few well-controlled empirical studies have been made in industrial societies. In the present study on behalf of a charity organization 186 students of 12 different seminary groups were asked to offer support to unfamiliar persons in need. In accordance with our predictions, the results show that significantly more subjects are willing to give assistance if they can make their charity offers in the presence of their group mates than in a situation when the offers are kept in secret. The likelihood of charity service was strongly influenced by the expected cost of altruistic behavior: more subjects offered costly assistance in groups in which they could make their offers in public than in the ones where they did not have a chance to do it publicly. Publicly demonstrated altruistic offer yields a long-term benefit: subjects who were willing to participate in a particular charity activity gained significantly higher reputation scores than the others. Costly acts of generosity signaled the altruist's trustworthiness, but did not signal another presumed personality trait of altruists: ability to organize. Contrary to one of our predictions, no difference between sexes was found in reputation-gaining strategy, which needs an explanation.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.