1. Rewards punish. Both because they are controlling and also because some people do not get the rewards they want and work for - which essentially makes them indistinguishable from punishment. Rewards and punishments are fundamentally similar in that both are used to elicit a "type of behavior that the natural field forces of the moment will not produce." The experience of feeling controlled and punished is an impediment to working or learning effectively. And their long-term use requires offering more and more treats or sanctions to get people to continue acting the way we want them to.
2. Rewards (and punishments) create or exacerbate imbalances of power, and disrupt relationships in ways that are linked to learning, productivity, and the development of responsibility. Knowing that someone is sitting in judgment of what you do contributes to a level of anxiety that interferes with performance, and a feeling of being evaluated rather than supported.
3. Rewards do not attend to the reasons that the trouble developed in the first place - why the child is screaming or student is ignoring homework.
4. Rewards discourage risk-taking. While evidence indicates that the human tendency is towards optimal challenge, making sense of the world, and fooling around with unfamiliar ideas, when working for a reward, we do what is necessary and no more.
5. Rewards smother people�s enthusiasm for activities they may otherwise enjoy, and undermine the intrinsic motivation that promotes optimal performance.

Alternatives to Rewards

When needing to accomplish a particularly uninteresting task that we can't find any interesting way of doing, we can use alternatives to artificial enticements. We can, for example: 1) imagine the way things look to the person doing the work and acknowledge candidly it may not seem particularly interesting; 2) offer a meaningful rationale for doing it anyway, pointing perhaps to the long-term benefits or the way it contributes to some larger goal; 3) give the individual as much control as possible over how the job gets done.

Source

Alfie Kohn, Punished By Rewards

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