In this TED Videocast, Dan Pink talks about how extrinsic motivators reduce performance. Hard to swallow for business people, but well known in the scientific community.
If you are interested in looking closer at the scientific evidence, I recommend:
No amount of scientific evidence will convince people who have a reward system. Rewards are addictive. Facing up to facts requires breaking the addiction. On the other hand, if you consider starting a company, I suggest you look at the evidence before charging ahead and implement the same kind of extrinsic reward systems that are holding your competitors back.
The research showing the problems with extrinsic rewards goes back at least 50 years. Business people are ridiculously behind. So much so that management consulting giant McKinsey is speaking up about the problem. McKinsey must of course careful not to offend their clients, so they are softening the blow a bit in their article. I think it is great that they speak up, despite the risks inherent in going against prevalent management superstitions.