elf-control resolves conflict between altruistic and selfish impulses. Self-control requires energy, and in work environments controlling one’s short-run desires can have a detrimental impact on subsequent productivity. Further, controlling selfish impulses is more difficult when costs of altruistic effort for others are monetized. Brain imaging data suggest altruism is mediated by social reward systems. These systems may be difficult to activate (that is, self-control more difficult) in the presence of pecuniary costs, as money is perceived as an individual resource.