Dan Ariely is a psychologist and author. His first book, Predictably Irrational, described real-life examples of how people make economic decisions. Instead of using mathematical models, he set up experiments (many with MIT students) to show that people often act in irrational ways.
He spoke on NPR recently about his new book, The Upside of Irrationality. One of the axioms he tested was whether receiving more money stimulates people to work more effectively. He found, counterintuitively, that when offered big bonuses to do small tasks, people flubbed more often than when offered small bonuses.
Another experiment showed that even when people were paid for a task like building structures from Lego, they lost motivation if they saw the work undone. His findings do not argue for eliminating paychecks, but rather encourage us to treat the relationship between salary and performance as indirect. Satisfaction at work comes from more than just money.