Interesting article in The Post today:
Deci's research into the counterproductive effects of threats and rewards has been replicated among high school students learning verbal skills, preschoolers trying to draw, and adults targeted by weight-loss, anti-smoking and traffic safety programs. In each case, external threats and rewards made it less likely that people would feel internally fired up about the goal.
So why are rewards and punishments employed so liberally?
"People like it because it is easy," Deci said. "It is easy to offer a reward, but it is not easy to help people find their own motivation."