The overjustification effect is a phenomenon where the presence of an extrinsic reward can decrease internal motivation to perform a task. Much of the groundbreaking work in this area was done by Richard Nisbett and Mark Lepper, two social psychologists with an interest in how cognition impacts human behavior. A number of studies have confirmed their findings, although the concept has some critics.
The original research to explore the overjustification effect involved a group of preschoolers who were given markers and asked to draw. All of them enjoyed drawing prior to the experiment and experienced internal motivation in the form of pleasure and satisfaction from completing drawing projects. Some children were promised a reward for drawing, while others were given a surprise reward, and a third group received nothing at all. The researchers waited to take up the second part of the experiment, an observation session to determine how the rewards or lack thereof influenced behavior.
When the researchers returned to observe the children at play, they noted that the children who received a promised reward during the experiment were the least likely to draw. These children had come to associate their drawing with the external motivation, the reward for doing the work, rather than the internal motivators that drove them to start drawing in the first place. Other studies on the overjustification effect have looked at different populations to see if the effect is consistent through different age groups, activities, and types of rewards. As a general rule, it is; those who receive promised rewards for activities will stop engaging in them for their own sake.
This research is part of a larger field of study on self-perception. Under the overjustification effect, people begin to associate a task with the external motivation and believe that is why they do it, discarding internal rewards. A pleasurable activity can turn onerous when a transactional reward enters the scenario. A painter, for example, may not paint for pleasure when she is accustomed to being paid for her work.
Some critics of the overjustification effect believe that the reward acts as a reinforcement to encourage repetition of the behavior, rather than extinguishing it. The belief that rewards reinforce behavior can be widely seen in the form of incentives offered in a variety of settings, from the workplace to the classroom. Many behavior modification programs designed to encourage positive behaviors while discouraging others use rewards for their participants to cultivate a desired behavior.