Garth Sundem

Brain Trust

Here's How Rewarding Good Behavior Leads to Bad Behavior

Study: Positive reinforcement can undercut a child's intrinsic motivation

Posted Apr 26, 2016

Pixabay public domain
Source: Pixabay public domain

As every parent knows, positive reinforcement creates more good behavior. A dollar for cleaning your room, a milkshake for getting good grades, extra screen time for being nice to a sibling—these rewards are a way to shape how your kids act and even feel.

Unfortunately, a study in the journal Child Development also shows that our intuition about positive reinforcement can be exactly wrong. In this study, rewarding a child's sharing resulted in the child choosing to share less.

The test was done with 48 3-year-olds, who chose how many marbles to share with a puppet. During a game, it seemed as if a child happened to get three marbles while the puppet got only one. Offering hope for humanity, half of the children noticed the disparity and gave the puppet a marble without further prompting. If not, the puppet said, "I only got one marble" and then "I want to have as many marbles as you" and then, if needed, "Will you give me one?"

Now is when the experiment gets interesting. When a child did finally cough up a marble, some simply moved on without result, some were praised ("Oh thank you for sharing a marble with me! That was really nice"). And some were rewarded with a balloon, bracelet or animal eraser.

Time passed. And then the kids were tested again—over three related but different games. Can you guess which kids chose to share? Here's what happened: "Children continued to equalize an unfair outcome after having experienced praise or a neutral response from the favored play partner but shared less often after they had received material rewards," the paper writes.

They did it again, replacing the sympathetic puppet with an impartial experimenter. Even without the empathy created by collaborating with a cute little monster puppet, kids who had been rewarded for their sharing went on to share less. In fact, they went on to share less even than kids who had received no praise. It wasn't that praise was great and an extrinsic reward was a little less good - it was that rewarding a child's sharing actually did harm, leading to less sharing than if the researchers offered nothing at all.

There are a couple takeaways. First, as any parent knows but to the researchers' apparent surprise, the study provides more evidence that the idea of fairness exists even in very young children (and other experiments show that it's only later that we learn to temper this instinct to share at our own expense...). Second, and probably more controversially, they say that the work, "provides strong evidence for a common underlying intrinsic motivation of fairness."

In this study, the fairness of a child that learned to expect a reward was always tied to the expectation of the reward. When the reward was absent, so was fairness. Even more, it went beyond kids coming to expect a kind of pay-for-play in this marble game. "Receiving a reward initially in the collaborative sharing context diminished children's motivation to share in new situations in which they had never been reinforced before," the paper writes.

In other words, rewarding fairness made kids overall less fair on future tests. Want to know what to do about it? The researchers are pretty clear: "Parents and educators should be encouraged to rely on intrinsic motivation and reinforce feelings of autonomy and competence as much as possible rather than to provide superfluous material incentives, which can even have detrimental effects."

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