An economist‘s solution to the question—how can performance of employees be improved?—is to use monetary sticks and carrots, e.g., piece-rates, bonuses, and other pay for performance schemes that increase workers‘ productivity. Until recently, most economic research assumed that people are economically rational, i.e., primarily motivated by material gains. However, an expanding research, inspired by psychological phenomena and aided by experimental evidence, has revised these assumptions. Although money is still widely regarded as a basic motive for increasing effort, a growing body of literature incorporates more complex human behavior (such as reciprocity, gratitude, comparative wages, social infrastructure, and fairness) that suggest non-monetary factors matter equally, if not more,