The Lepper, Greene And Nisbett Experiment And Overjustification

Lepper, Greene, and Nisbett’s experiment in overjustification became a classic in psychology. It represents an important nuance in the theory of operant conditioning, as it is based on the typical reward and punishment scheme. Specifically, it breaks with the idea that a reward reinforces behavior.

The researchers, who were professors at Stanford University, showed that under certain specific conditions, an award  can discourage a person. Overjustification refers precisely to that reality: do not reward what does not require a reward. There is no need to create additional incentives when what needs to be done does not involve overexertion or there is already an intrinsic motivation.

The overjustification experiment starts from two concepts: intrinsic motivation and extrinsic motivation.

• The first is the one that has its origin in the subject himself. For example, that spontaneous desire to eat ice cream in hot weather.
• Extrinsic motivation is the one that comes from the environment. For example, when someone offers a reward for a lost item.

The overjustification experiment

The experiment of overjustification was carried out in a kindergarten, with children between 3 and 5 years old. The researchers visited the place and noticed that the children showed great interest in drawing with some paintings that the teacher had taken a few days ago. In other words, the children had an intrinsic motivation to use these elements.

Based on this fact, Lepper, Greene, and Nisbett divided the children into three subgroups. They would all carry out the same activity: drawing with such attractive paints. However, in each group some variation was introduced, as follows:

• Group 1. This group of children were told that if they participated in a drawing activity, with the famous paintings, in the end they would be given a reward. This consisted of a “good player” diploma. It was the “expected reward” group.
• Group 2. This group was not told anything initially. However, at the end of the activity they were surprised by  giving them their “good player” diploma. It was the “unexpected reward” group.
• Group 3. This group was neither promised a reward, nor was it unexpectedly awarded. It was the “control group.”

The development of the experiment

Once the groups were defined, one of the researchers showed up the next day in kindergarten. He told the whole group that a man who wanted to see what they were capable of doing with “magic paintings” was going to go. Then, he spoke to the children in the three groups, separately.

To the first group, he said that “the gentleman” had brought a lot of prizes to distribute among them  if they agreed to participate in the activity. He showed them the good player’s diploma and said “ Would you like to win one? ”The children obviously agreed to participate.

Groups 2 and 3 were simply asked to draw pictures with the magic paintings to show them “to the Lord”. They all accepted as well. Later, each of the children, separately, entered a room called a “magic classroom.” There, “the lord” was waiting for them, reaffirming the messages that had already been given to them before.

The interesting results

A week later, the investigators returned to the scene. They wanted to see if the experiment had in any way affected the children’s intrinsic motivation, that is, their taste for paintings and their desire to use them. As expected, the children who had received the diploma of good player, now showed less interest in the paintings.

What Lepper, Greene, and Nisbett wanted to prove was that offering extrinsic motivation lowers intrinsic motivation. In theory, the opposite should happen: having been rewarded for using the paintings, they would have more interest in them than that of the children who had not been rewarded. But the opposite was true.

The children who had not been rewarded showed a similar interest in using the paints as before. This proved that introducing a reward, when it is not necessary, has a negative effect in terms of motivation. This is precisely overjustification. The researchers concluded that extrinsic motivation is only effective when intrinsic motivation is very low.