Psychologically, there is a big, big difference between offering cash and offering almost anything else. In "Predictably Irrational", Dan Ariely ran an experim

Psychologically, there is a big, big difference between offering cash and offering almost anything else. In "Predictably Irrational", Dan Ariely ran an experiment where people were asked to perform a certain task, where each person was offered one of three payments for the task: $5, $0.50, or nothing. The people who were offered more money worked harder at the task... But the people who were asked to work for free worked harder than either of the groups that were offered cash. Then he performed a similar experiment, except he offered candy equivalents: cheap candy, expensive candy, or nothing. All three groups worked with approximately the same amount of effort. Then he performed the same experiment -- offering candy -- except that he told each participant how much the candy was worth. People worked as hard as if they had been offered the candy's equivalent in cash. http://bookoutlines.pbworks.com/Predictably-Irrational http://bookoutlines.pbworks.com/Predictably-Irrational