In a New York Times op-ed, Sendhil Mullainathan (professor of economics at Harvard) laments that it is difficult to get people to try new things or experiment. He gives himself as an example, saying that it is difficult for him to try generic soda, even though the cost to him is low, and he drinks 2 liters of Diet Coke daily. However, his article has a relative lack of references to literature on past efforts to get people to try new things.
What methods have been studied to get people to try new things/experiment (without forcing them)? What has worked, and what has been less successful?