theodp writes: Slate reports that buying local vegetables and organic products may turn you into a heartless jerk. University of Toronto researchers found that virtuous shopping can actually lead to immoral behavior. In their study, subjects who made simulated eco-friendly purchases ended up less likely to exhibit altruism in a laboratory game and more likely to cheat and steal. The findings add to a growing body of research into a phenomenon known among social psychologists as "moral credentials" or "moral licensing." When people have the chance to demonstrate their goodness, even in the most token of ways, they then feel free to relax their ethical standards in other areas. For example, researchers at Northwestern reported that subjects who wrote self-flattering stories later pledged to give less money to charity than others. And in another recent study, participants who recalled their own righteous deeds were less inclined to donate blood, volunteer, or engage in other "prosocial" acts. They were also more likely to cheat on a math assignment. Elsewhere on Slate, Al Gore rebuffed criticism of his green technology investments as he discussed how he hopes his new book will help people find solutions to the problem of global warming (sorry, couldn't resist!).