Acknowledgements: We thank John McMillan, David Laibson, Colin Camerer, and three anonymous referees for useful comments. We thank Mandar Oak and Rosa Stipanovic for research assistance. For financial support, Frederick and Loewenstein thank the Integrated Study of the Human Dimensions of Global Change at Carnegie Mellon University (NSF Grant SBR-9521914), and O’Donoghue thanks the National Sci...