德西效应
是指在某些情况下，当外加报酬和内感报酬兼得的时候，不但不会使工作的动机力量培增，积极性更高，反而其效果降低，变成是二者之差，外加报酬（主要是奖励）反而会抵消内感报酬的作用。
【实验】德西在1971年作了专门的实验。他让大学生做被试，在实验室里解有趣的智力难题。实验分三个阶段，第一阶段，所有的被试都无奖励；第二阶段，将被试分为两组，实验组的被试第完成一个难题可得到1美元的报酬，而控制组的被试跟第一阶段相同，无报酬；第三阶段，为休息时间，被试可以在原地自由活动，并把他们是否继续去解题作为喜爱这项活动的程度指标。
【结果】实验组（奖励组）被试在第二阶段确实十分努力，而在第三阶段继续解题的人数很少，表明兴趣与努力的程度在减弱，而控制组（无奖励组）被试有更多人花更多的休息时间在继续解题，表明兴趣与努力的程度在增强。
【分析】这个结果表明，进行一项愉快的活动（即内感报酬），如果提供外部的物质奖励（外加报酬），反而会减少这项活动对参与者的吸引力。
关于德西效应的可能解释：
1、原有的外加报酬距有关需要满足的水平太远，对外加报酬的要求太强烈；
2、直接激励的原有强度不足；
3、价值观（思想信念）的某种偏差，未能将需要层给结构调整得合乎工作要求。
【应用】处理好这几个因素，一般会降低外加报酬对内感报酬的消极影响，外加报酬会在不影响内感报酬的情况下发挥自身的作用。
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美国心理学家德西在1971年做了一个专门的实验。他让大学生做被试者，在实验室里解有趣的智力难题。实验分三个阶段，第一阶段，所有的被试者都无奖励；第二阶段，将被试者分为两组，实验组的被试者完成一个难题可得到1美元的报酬，而控制组的被试者跟第一阶段相同，无报酬；第三阶段，为休息时间，被试者可以在原地自由活动，并把他们是否继续去解题作为喜爱这项活动的程度指标。
结果，实验组(奖励组)被试者在第二阶段确实十分努力，而在第三阶段继续解题的人数很少，表明兴趣与努力的程度在减弱，而控制组(无奖励组)被试者有更多人花更多的休息时间在继续解题，表明兴趣与努力的程度在增强。
德西在实验中发现：在某些情况下，人们在外在报酬和内在报酬兼得的时候，不但不会增强工作动机，反而会减低工作动机。此时，动机强度会变成两者之差。人们把这种规律称为德西效应。这个结果表明，进行一项愉快的活动(即内感报酬)，如果提供外部的物质奖励(外加报酬)，反而会减少这项活动对参与者的吸引力。
所以，对于学生感兴趣的事情，过分的奖励反而会降低其动机。有一群孩子在一位老人家门前嬉闹，叫声连天。几天过去，老人难以忍受。于是，他出来给了每个孩子10美分，对他们说：“你们让这儿变得很热闹，我觉得自己年轻了不少，这点钱表示谢意。”孩子们很高兴，第二天仍然来了，一如既往地嬉闹。老人再出来，给了每个孩子5美分。尽管有些不高兴，走了不少孩子，但是仍然还有一部分孩子无精打采的徘徊。第三天，老人只给了每个孩子2美分，孩子们勃然大怒，“一天才2美分，知不知道我们多辛苦！”他们向老人发誓，再也不会为他玩了！接着一哄而散，再也没有来。
这个原理是，把孩子们的内在动机——玩的兴趣，转化为外在动机——为了报酬。而外在动机是可以控制的，当刺激物逐渐减少的时候，诱因和驱力也在降低，于是动机在丧失，孩子们的行为产生了“消退”。
反之，在学习上，单纯的赏识教育不会使学生产生强烈而持久的学习动机；而只有使外在动机逐渐过渡到内在动机，学生对学科学习产生了浓厚的兴趣，才会产生理想的学习状态。
这个过渡是不断地刺激大脑中的快感中枢，实验表明，当科学家刺激小白鼠的快感中枢时，它会废寝忘食的压杆，以获得快感的刺激。这和学生在网吧忘记一切的打网游，是异曲同工的。但是在学习上，如何获得这种刺激呢？一般有四个方面：1、发现的学习；2、克服困难的学习；3、取得成就的学习；4、为自己信念的学习。学习的愿望是人类与生俱来的，学习是艰苦的，但是其本质仍然是快乐的，是体验的快乐、过程的快乐、紧张思考后放松的快乐和豁然开朗愉悦的快乐。
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Effects of externally mediated rewards on intrinsic motivation
CONTRIBUTORS:
Author: Deci, E. L. (University of Rochester)
JOURNAL: Journal of personality and social psychology, 18(??), 105 - 115. YEAR:1971
PUB TYPE:Journal Article
SUBJECT(S):None
DISCIPLINE:Psychology
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The Overjustification Effect
The Overjustification Effect
Following on the heels of Daryl Bem’s 1965 theory of self-perception, the overjustification effect states that how individuals will feel toward performing certain tasks is determined by whether they are intrinsically or extrinsically motivated to perform the task (Deci, 1971). Using the self-perception theory’s prediction that when extrinsic motivations are present they will take precedent over intrinsic motivations, the overjustification effect reveals the importance of motivation on performance (Lepper, Greene, & Nisbett).
Understanding Motivation
In understanding the overjustification effect, it is important to distinguish between the two types of motivation present: intrinsic and extrinsic.
Intrinsic motivation is the desire to perform an activity out of the enjoyment derived from the activity itself. In performing an intrinsically motivated activity, an individual expects no external reward; the activity is a reward in itself. An example of an intrinsically motivated activity would be one that a person does as a hobby or in his or her free time.
Extrinsic motivation is the motivation to perform an activity because the activity leads to something else. The desire to perform an extrinsically motivated activity comes not from the activity itself, but from rewards or benefits associated with the activity. An example of an extrinsically motivated activity would be chores that are preformed for an allowance. The chores themselves are not pleasurable, but the cash that result from completing them is.
Both intrinsic and extrinsic motives can be present in an activity. In such a case, the salience of extrinsic motivation over intrinsic motivation is the basis for the overjustification effect.
Origins of the Overjustification Effect
In 1971, Deci suggested that in a situation where an individual was to receive a reward for an activity, and knew about the reward prior to participating in said activity, then the individual would attribute his or her behavior to the reward instead of the activity itself. Deci’s theory led to the hypothesis that once an activity is associated with the external reward, a person will be less inclined to participate in the activity in the future without a reward present.
Deci (1971) conducted a study in which students were either asked to solve puzzles for money or no money. After the payment stopped, the researchers noted if the students continued to work on the puzzles. Those that had received money (an extrinsic motivation for solving the puzzles) did in fact become less inclined to work on the puzzles once they were no longer paid to do so. The students who had not been paid (they only had intrinsic motivation) continued to show an interest in the puzzles.
Confirming the Overjustification Hypothesis
Two years after Deci’s study, a group of researchers tested the overjustification hypothesis in a field experiment. Lepper, Greene, and Nisbett (1973) went to a nursery school and observed children’s intrinsic interest in various activities. The children were then put into one of three conditions for the experiment.
• In the first condition, known as the “expected-award condition,” children were told they would receive a reward (a certificate with a seal and a ribbon) for partaking in the activity that they were previously doing out of pure intrinsic interest.
• In the second condition, the “unexpected-award condition,” the children were not told of the reward until after they finished the activity.
• In the third condition, also called the “no-reward condition,” the researchers did not tell or give the children any reward. This group thus served as the control group, since extrinsic rewards were not involved either before or after performance.
The extrinsic reward phase ended with the researchers giving the children the certificates based on their condition group. In the following phase, the researchers let the children go about their activities, but this time without offering or giving any rewards. In accordance with the overjustification hypothesis, the children in the “expected-reward condition” had become less interested in their activities since the introduction of the extrinsic motivation. However, there was no change in the interest of the group who received the reward unexpectedly. This is because the children in this condition did not know about the reward until after the activity, and therefore attributed their behavior to an enjoyment of the activity. Similarly, those who did not expect or receive a reward had no extrinsic motivation, and showed no decline in interest as a result.
Controversies over the Overjustification Effect
The overjustification effect is wholly disquieting to behavioral psychologists, whose theories conflict with overjustification. These so-called behaviorists began doing their own studies to disprove the overjustification effect.
A reply to this critique was fast in coming by motivationalists (those who support self-perception and overjustification). Deci, along with Cascio and Krusell (1975), acknowledged Calder and Staw’s doubts as to whether non-contingent monetary rewards would result in the overjustification effect. However, they did not say the overjustification effect was incorrect in this area; merely that other studies needed to be done.
In 1983, R. M. Ryan, V. Mims, and Koestner placed their support behind the overjustification effect. They addressed Calder and Staw’s argument that non-contingent rewards discredit the overjustification effect by countering that non-contingent rewards are not tied to the activity in question. Thus, they run little risk of undermining intrinsic motivation.
Meta-analyses and the Conclusion to the Controversies
With so many studies into the overjustification effect, meta-analyses of these studies were eventually done. In one significant meta-analysis in 1995, psychologists Tang and Hall sufficiently concluded that physical rewards which were made contingent upon completing an activity, did in fact undermine intrinsic interest in the activity.
Twenty-five years after Calder and Staw (1974) published their firsts doubts, another meta-analysis was performed in 1999 that confirmed that extrinsic motivation has a negative impact on intrinsic motivation. This meta-analysis is the work of Deci, Koestner, and Ryan (1999). It examined 128 carefully conducted experiments and found that tangible rewards do, indeed, greatly weaken intrinsic motivation.
Relevance for Everyday Life
The overjustification effect, as stated in Deci, Koestner, and Ryan’s meta-analysis, has significant consequences for many people. When control is placed on individuals by offering them incentives, the long term effect will be a loss in intrinsic motivation, accompanied by negative performance. This applies to classrooms, sports teams, as well as other environments. Should a reward be present, there is a risk of losing the enjoyment of the activity for itself.
Works Cited
Bem, D. J. (1967). Self-perception: An alternative interpretation of cognitive dissonance phenomena. Psychological Review, 74, 183–200.
Deci, E. L. (1971). Effects of externally mediated rewards on intrinsic motivation. Journal of Personality and Social Psychology, 18, 105-115.
Lepper, M. R., Greene, D., & Nisbett, R. E. (1973). Undermining children's intrinsic interest with extrinsic rewards: A test of the “overjustification” hypothesis. Journal of Personality and Social Psychology, 28, 129–137.
Lepper, M. R. & Greene, D. (1974). Effects of Extrinsic Rewards on Children's Subsequent Intrinsic Interest. Child Development, 45, 1141-1145
Deci, E. L., Cascio, W. F., & Krusell, J. (1975). Cognitive evaluation theory and some comments on the Calder and Staw critique. Journal of Personality and Social Psychology, 31, 81-85.
Ryan, R. M., Mims, V., & Koestner, R. (1983). Relation of reward contingency and interpersonal context to intrinsic motivation: A review and test using cognitive evaluation theory. Journal of Personality and Social Psychology, 45, 736-750.
Tang, S-H., & Hall, V. C. (1995). The overjustification effect: A meta-analysis. Applied Cognitive Psychology, 9, 365-404.
Deci, E. L., Koestner, R., & Ryan, R. M. (1999). A meta-analytic review of experiments examining the effects of extrinsic rewards on intrinsic motivation. Psychological Bulletin, 125, 627-668.
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