The overjustification effect occurs when you add a reward to a previously-unrewarded activity. That shifts motivation from inner motivation to outer motivation, which then undermines the inner motivation.

Mattias Johanssen, in a fantastic video about programmers losing motivation, describes a scenario in which you go over to dinner at a friend’s house and have a wonderful dinner. At the end of the dinner, you say, “Thank you for such a wonderful dinner! To show my appreciation, I would like to give you $100.”

Of course, this immediately makes you a weird person, and even though you are offering more than your previous thanks, it somehow cheapens the dinner.

Something similar happens in the overjustification effect. When money (or another external motivator) enters the picture, the internal motivation that compelled you to make the dinner or write the song in the first place gets undermined.

But that’s not the worst part of the overjustification effect. When your motivation shifts from intrinsic to extrinsic, motivated by external rewards, quite often your intrinsic motivation can be permanently lost. It doesn’t come back even when the external motivation is removed. This gives external motivators the possibility for violent and extraordinary effects on your ability to create. Sometimes, you don’t recover.

Of course, theories and experiments are limited in psychology because you can only test things in the most restrictive of circumstances. But there is one experiment that vividly illustrates the over-justification effect, and the results are a bit disturbing.

In 1973, Mark Lepper, Daniel Greene and Richard Nisbett performed an experiment with a group of schoolchildren that demonstrated how easily intrinsic motivation can be lost. They took a group of children and allowed them to play with a variety of toys, including drawing with crayons.

When kids did elect to draw, simply because they were interested in doing so, the researchers selected them and divided them into three groups. The first group told they’d be awarded with glittery, colorful awards if they drew in the next playtime. The second group was spontaneously given the award after freely choosing to draw. And the third group was not told of or given an award at all. Over a period of a few days, this process repeated, and then the scientists disappeared for two weeks.

Humans have an intense repulsion to being controlled or pressured; when we sense our autonomy has been lost, we immediately lose our motivation.

When they came back, the first group of kids had entirely lost their desire to draw. They spent significantly less time drawing vs. the other kids, and they showed a lot less interest in the activity when prompted. They just didn’t care anymore. The activity had been perverted by the reward.

The overjustification effect is powerful, but it cannot be the whole story because it’s not always true. There are times when you write music that you love, and you’re paid well to do it, and being paid for that music doesn’t affect your motivation at all. And it’s not like the kids in group B, who were spontaneously awarded — you may know well in advance that you are going to be paid for the work, or you might already have been paid.

Why does this happen? When does external motivation kill your desire, and when does it not? How can we get external rewards and still desire to create?

The answer is described by a second theory: cognitive evaluation theory.