"What beautiful music!" I shout loudly as my 9-year-old son practices playing the violin. He's used to this praise; I give rewards like that most days. But every once in a while, I skip it, and when I do, I can see the disappointment on his face when he's finished.
Am I a bad mom? Conventional wisdom says that consistency is key to parenting since it enables your child to predict how you'll react, leading to good behavior. And it's true that children need some level of predictability in their lives, particularly when it comes to discipline.
But research suggests that inconsistent gifts and praise can have a greater effect on motivation. While we all like to live in a predictable world, we often respond more strongly to unpredictable rewards.
In one experiment, my colleagues and I told participants they'd be paid if they could drink about one-and-a-half quarts of water in two minutes or less. In one condition, we offered people a $2 fixed reward. In another, there was an uncertain reward of either $2 or $1. The certain reward was a better deal, yet many more people successfully met the challenge when assigned an uncertain reward. Resolving the uncertainty—whether they would win $1 or $2—was significantly more motivating than winning $2 for sure.
Here is one of the reasons why uncertainty is motivating. What scientists call "intermittent (间歇性) reinforcement" —rewarding behavior on some but not all occasions—makes it morearduous to know when rewards will show up. If you very often, but don't always, praise your child for completing their chores, they'll keep up the good behavior in the hope of receiving praise the next time.
So don't assume that if kids are always praised for finishing their homework, they'll be more likely to do it. Do praise young people for a job well done, just not every time. And pick rewards out of a hat when they complete chores—the surprise prize might keep everyone motivated to get things done.