Local competition increases people's willingness to harm others

Abstract

Why should organisms incur a cost in order to inflict a (usually greater) cost on others? Such costly harming behavior may be favored when competition for resources occurs locally, because it increases individuals' fitness relative to close competitors. However, there is no explicit experimental evidence supporting the prediction that people are more willing to harm others under local versus global competition. We illustrate this prediction with a game theoretic model, and then test it in a series of economic games. In these experiments, players could spend money to make others lose more. We manipulated the scale of competition by awarding cash prizes to the players with the highest payoffs per set of social partners (local competition) or in all the participants in a session (global competition). We found that, as predicted, people were more harmful to others when competition was local (Study 1). This result still held when people "earned" (rather than were simply given) their money (Study 2). In addition, when competition was local, people were more willing to harm ingroup members than outgroup members (Study 3), because ingroup members were the relevant competitive targets. Together, our results suggest that local competition in human groups not only promotes willingness to harm others in general, but also causes ingroup hostility.

Keywords: Scale of competition; conflict; contests; harming; hostility; spite.

Figure 1

The mean amount spent on burning each partner's money was significantly higher when competition was local compared to global, regardless of whether the money was simply given to participants (Study 1) or “earned” by doing a short task (Study 2). Under global competition, people spent less on burning when money was earned than when money was unearned, but this was not the case under local competition. Because these are the amounts spent burning each other person, the 4:1 burning ratio in the experiment means that participants in local competition usually had no money left in their endowments. Boxes show the interquartile range, and lines show 1.5 times the range. Letters denote significant differences.

Figure 2

In Study 3, people spent more on burning each ingroup member's money under local competition compared to global, but the scale of competition had no effect on the amount spent burning each outgroup member's money. When competition was local, people spent more on burning each ingroup member than each outgroup member, but there was no such difference when competition was global. (Note that if total amounts spent, rather than amounts spent per person, are considered, participants spent more on burning outgroup members than ingroup members when competition was global.) Boxes show the interquartile range, and lines show 1.5 times the range. Letters denote significant differences.