In one study, girls in the fifth and sixth grades tutored younger children much less effectively if they were promised free movie tickets for teaching well. The study, by James Gabarino, now president of Chicago's Erikson Institute for Advanced Studies in Child Development, showed that tutors working for the reward took longer to communicate ideas, got frustrated more easily, and did a poorer job in the end than those who were not rewarded. Such findings call into question the widespread belief that money is an effective and even necessary way to motivate people. They also challenge the behaviorist assumption that any activity is more likely to occur if it is rewarded. But Kenneth McGraw, associate professor of psychology at the University of Mississippi, cautions that this does not mean behaviorism itself has been invalidated.
Researchers offer several explanations for their surprising findings about rewards and performance.
First, rewards encourage people to focus narrowly on a task, to do it as quickly as possible and to take few risks. Second, people come to see themselves as being controlled by the reward. Finally, extrinsic rewards can erode intrinsic interest. People who see themselves as working for money, approval or competitive success find their tasks less pleasurable, and therefore do not do them as well. The last explanation reflects 15 years of work by Ryan's mentor at the University of Rochester, Edward Deci.