Does giving children rewards, such as toys, candy, or money, undermine their interest in

Does giving children rewards, such as toys, candy, or money, undermine their interest in learning?  Long ago E.L. Thorndike concluded that learning is controlled by its consequences.  If a behavior is reinforced, it is more likely to be repeated.  Ever since then, generations of educators and parents have been rewarding children hoping to reinforce their motivation to learn.  Unfortunately, many studies have shown that when children are given rewards for their behavior, they often lose interest in that behavior compared to students who are not given rewards.
Should we abolish grades, incentives, and even praise?  First, it is important to make a distinction among various types of rewards.  Intrinsic rewards are ones that naturally follow from performing a behavior well, such as seeing a tennis ball go over the net when it is hit well.  Extrinsic rewards come from an outside source, such as praise from a teacher, or candy for reading a certain number of books.  Extrinsic rewards have been shown to negatively affect motivation—but only under certain conditions.
Rewards can be categorized into three types of contingencies (what the reward is predicated on). 
Task-contingent rewards:  Children are rewarded merely for participating in an activity without regard to any standard of performance.  Most studies find that motivation and interest decline in task-contingent situations.
Performance-contingent rewards:  Children are rewarded when they meet certain performance criteria.  Research is mixed here; sometimes these rewards reduce interest in an activity, and sometimes they don’t.
Success-contingent rewards: Children are given rewards for a good performance that is linked to the achievement of a goal.  These types of rewards have been shown to increase interest and motivation.
Alfie Kohn believes that a system of rewards (regardless of whether they are task, performance, or success contingent) are inherently limiting because they serve only to manipulate people’s behavior.  Once the rewards stop, argues Kohn, children’s attitudes toward the learning or their commitment to learning may not change.  Therefore, for learning to be rewarding in and of itself, it must be made meaningful—something children want to do because it helps them make sense of their world.  Kohn suggests the following ways to tap children’s motivation and sense of discovery.
Allow for active learning.
Give reasons for assignments.
Elicit their curiosity.
Set an example.
Welcome mistakes.
Sources: 
Chance, P. (November, 1992).  The rewards of learning.  Phi Delta Kappan, 200–207.
Kohn, A. (1993).  Punished by rewards: The trouble with gold stars, incentive plans, A’s, praise, and other bribes.  New York: Houghton Mifflin.
Murray, B. (June, 1997).  Rewards should be given when defined goals are met.  APA Monitor, 26.

Respond to the forum by answering the following questions: Should adolescents receive money for grades? How much is reasonable, and would it be motivating? On the other hand, is buying a computer for straight A’s unreasonable? How would you handle this as a parent? What about sports, should everyone who tries out make the team? Explain your answer