I can’t wait to see how this one plays out: At Panera’s new nonprofit restaurant in St. Louis, they’re asking customers to pay what they can afford: “Take what you need, leave your fair share.” According to the Damn, I Wish I’d Thought of That blog:Their cashiers provide receipts that include suggested donations based on what customers have ordered and then direct them to donation boxes throughout the restaurant. And for those who can’t pay, they’re invited to volunteer their time. While still early in the experiment, the location’s revenues were up 20 percent on opening day. The lesson: If you give your customers the chance to show their altruistic side, they’re likely to thank you with surprising generosity.I think this is fascinating – implementing social norms in a market norms setting.Here’s why I think people will pay:Social norms — values of sharing, community and altruism — are enormously powerful motivators. Market norms — emphasizing calculated self-interest, individualism and equal exchange — have a place when you’re selling sandwiches. But social norms work best to inspire generosity. And that’s what Panera is seeking to put into play. They apparently have plans to open a couple more as well. Good for them.