The overjustification effect is a phenomenon of the psychology of motivation , studied and introduced by the researchers Lepper, Greene and Nisbett. According to this phenomenon, our intrinsic motivation to do a certain activity decreases when we are offered a reward for it.

In this article we take a look at human motivation and explain what this effect consists of. In addition, we will see in detail how the experiment that made it known developed and the results that emerged and that demonstrated such an effect.

What is human motivation?

Before explaining what the effect of over-justification is, let’s address the concept of motivation, and explain its two major subtypes: intrinsic and extrinsic motivation . All this, because they are concepts inherent to this phenomenon we are going to talk about.

What is motivation? Some authors define it as “the dynamic root of behaviour”. But… what exactly does it mean?

Etymologically, the term “motivation” derives from the Latin “motivus” or “motus”, which means “cause of movement” . Thus, motivation underlies all kinds of behaviour that we manifest, we could say that it is its “cause” or engine, and it has to do with the desire we have to do a certain action or task, in order to satisfy a need, or to get something we want.

Broadly speaking, there are two types of human motivation: intrinsic motivation and extrinsic motivation. Let’s see, in a summarized way, what each one of them consists of:

1. Intrinsic motivation

Intrinsic motivation is that motivation that is given inherently to the task , that is, the task itself motivates us, we like it, and such motivation has nothing to do with external reinforcers or rewards.

We simply enjoy doing a certain action (e.g. homework). This is the intrinsic motivation, a very important motivation especially in the educational field, where the ideal is that the child learns for the mere pleasure of learning.

2. Extrinsic motivation

Extrinsic motivation, on the other hand, is “outside” the task ; it is the motivation towards the prize or reward that we get by completing a certain task. That is, we perform certain actions to get something from the outside, such as a compliment, money, a prize…

Over-justification effect: what is it?

The effect of over-justification is a phenomenon within psychology (more specifically, basic psychology, which encompasses the psychology of motivation), which occurs when an external stimulus (for example a reward, a prize … that makes up extrinsic motivation) reduces the intrinsic motivation that someone has to perform a certain task .

To quickly illustrate the effect of over-justification, let’s take an example: a child loves to read (i.e., has a strong intrinsic motivation for reading), and he reads for the pleasure of reading.

Suddenly, his father tells him that every time he finishes a book, he’ll give him 5 euros as a prize, to be spent on whatever he wants. This can cause the child’s intrinsic motivation for reading to decrease, because the motivation he has for reading is influenced by the motivation for getting the £5 (external reward).

In other words, he will no longer read just for the pleasure of reading, but also to get his reward. This is the effect of over-justification, which can occur in both children and adults.

The experiment

Who discovered (and how) the effect of overjustification? The researchers Lepper, Greene and Nisbett, through a field experiment developed with children , in a kindergarten.

The investigation of the effect of over-justification is based on the following hypothesis: “when we associate a certain activity with an external reward (extrinsic motivation), we will be less interested in carrying out that activity (intrinsic motivation) if in the future, there is no such reward”.

1. Methodology: first phase of the experiment

Lepper, Greene and Nisbett’s experiment was conducted in a kindergarten. There they observed that the children had a certain interest in carrying out different educational activities .

In their experiment of the over-justification effect, the researchers placed the children (who were 3 to 5 years old) to draw and play with markers. Specifically, they placed them in three different experimental conditions, which were

1.1. Condition 1 (expected reward)

The first condition was “expected reward”. It consisted in promising the children that they would receive a “good player” ribbon, just for participating in the activity of drawing with markers.

It is important to note at this point that the children, prior to the experiment, already performed this activity, spontaneously, simply because they enjoyed doing it (intrinsic motivation).

1.2. Condition 2 (unexpected reward)

The second condition in the experiment was “unexpected reward”. Here, the children were not initially told that they would receive a reward for doing the activity (they were told nothing). Later, at the end of the activity, they were given the prize .

1.3. Condition 3 (no reward)

In the third and last condition, called “no reward”, the children were simply not told about prizes and rewards at any time . That is, in this condition no prizes were given to the children for finishing the drawing activity; it was the control group.

2. Methodology: second phase of the experiment

After the application of these conditions, and at the end of the first phase of the experiment, the researchers observed the children in a free environment, where they could play whatever they wanted without premises or restrictions .

The aim of this second phase of the experiment on the over-justification effect was to determine whether or not there were more children playing drawing, this time without the promise of a final reward for it.

3. Results

What results did the Lepper, Greene and Nisbett experiment provide on the over-justification effect? We will know each of them, according to the experimental condition applied and in relation to the overjustification effect.

3.1. Expected reward condition

First of all, it was observed that the children subjected to the first experimental condition (expected reward), played much less drawing with the markers in the second phase of the experiment (free play).

If we apply the theory of the over-justification effect to this result, we can think that the children had diminished or even lost their original intrinsic motivation for the activity by having a reward (extrinsic motivation) for doing it (in the previous phase of the experiment).

We must bear in mind that they had never had this reward before, and that suddenly someone was “rewarding them for playing”.

3.2. Unexpected reward condition

Another result of the experiment showed how the children of the second experimental condition (unexpected reward), had not changed their interest in drawing, and drew the same in the phase of free play .

Thus, it was attributed that the children enjoyed drawing prior to the experiment, just as they also enjoyed the activity in the experimental condition (since they did not know they would be rewarded), and just as they played in the second phase of the experiment (free play).

3.3. Unrewarded condition

Finally, the children in the third experimental condition (without reward), also showed no change in their drawing behaviors or in their interest in the activity. That is, they drew the same way in the free play stage.

Following the effect of overjustification, as they had never been rewarded for doing so (in the first phase of the experiment), their intrinsic motivation had remained “intact” .

Bibliographic references:

  • Grzib, G. (2002). Cognitive and behavioural bases of motivation and emotion. Ramon Areces Centre of Studies. Madrid.
  • Pintrich & Shunck (2006). Motivation in educational contexts. Theory, research and applications.
  • Reeve, J. (2010). Motivation and emotion. 5th Edition. McGraw- Hill/Interamericana. Mexico.
  • Ryan, R. M.; Deci, E. L. (2000). “Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being”. American psychologist 55 (1): 68-78.