In 2006 the Stanford researchers Sanford DeVoe and Jeffrey Pfeffer reported that people who are paid by the hour think about their time in terms of money. Using U.S. Census survey data, they found that people paid hourly spend about 36 percent less time volunteering than salaried people.
In a further study, salaried people who calculated their hourly pay changed too. “Once the value of their hour was made plain to them, they began to think more like hourly employees.”