That is what Dan Ariely's research suggests:
We've recently gathered evidence suggesting that dangling exorbitant sums of money in front of workers doesn't improve performance. If anything, it negatively affects it. It could be true that the spectre of windfalls will increase activity. If I offered you a £1 million bonus for exceptional performance, you might work more hours and check Facebook less. But would your input be more thoughtful? More creative? Would you be more likely to tap your full-brain potential? Doing more doesn't equal doing better.