In "Lack of autonomy and self-control: Performance contingent rewards lead to greater depletion" by Mark Muraven, Heather Rosman, and Marylene Gagne, they explore how self-control comes into play in the workplace. People who have ever been addicted to cigarettes know that it takes a lot of self-control when trying to stop. This depletes their energy and will-power over other things. Same thing with dieting. People exert self-control by not eating any sweets and forcing themselves to go to them gym. This wears them out and, oftentimes, there is a breaking point and they just can't do it anymore and eat a huge piece of cake and give-up. That is why I believe dieting doesn't work. It's tons more effective to just limit your intake of sweets than to completely shun them and hit the gym in moderation. The study I found says the same thing applies in business. People who are given rewards to complete projects have to exert self-control over their time, forcing themselves to complete as many projects as possible in the least amount of time. The study found that "self-control that feels more externally determined is more depleting than self-control that feels more personally chosen" (Muraven 8). This makes the quality of their later assignments in, say 2 months time, of worser quality than projects completed towards the beginning of that time because projects are no longer something that employees are personally motivated about, but rather feel pressured to complete for money.
In my opinion, the same goes for school. Students that understand the importance of what they are learning and enjoy the subject are more likely to take more time on assignments because they are personally motivated to spend their time on them and not try to just get the assignment done soon and not focus on the quality or content of the assignment. They do it just to keep their grade up (which is similar to the incentives in the workplace that don't work).
Muraven, Mark, Heather Rosman, and Marylene Gagne. "Lack of autonomy and self-control: Performance contingent rewards lead to greater depletion.." Academic Source Complete. Dec 2007. Web. 20 Feb 2010.