At the heart of economic theory is homo economicus, the economist’s model of human behavior. In traditional classical economics and in Neo-classical economics it was assumed that people acted in their own self-interest. Adam Smith argued that society was made better off by everybody pursuing their selfish interests through the workings of the invisible hand. However, in recent years, mainstream economists have tried to include a broader range of human motivations in their models. There have been attempts to model altruism and charity. Behavioral economics has drawn on psychological insights into human behavior to explain economic phenomena.