Pay and motivation once more

From Intrinsic Motivation at Work:

"[E]xtrinsic incentives can have a greater influence on behaviour when intrinsic motivation is moderate to low. But if intrinsic motivation is already high... monetary incentives provide little or no additional force. Past some point, it simply becomes impossible to be "more motivated" in any sustainable way. So if you are successful in building high intrinsic motivation, don't expect your pay system to have a major positive effect on performance."

Once again, you'd think on this basis that performance-related pay would be better employed for crappy, boring jobs, rather than at the top where you would hope people are already fairly well-motivated.