Which phenomenon describes a decrease in motivation due to external rewards for a previously enjoyable task?

The phenomenon that describes a decrease in motivation due to external rewards for a previously enjoyable task is Cognitive Evaluation Theory. This theory, developed by Edward Deci and Richard Ryan, focuses on how external factors, such as rewards or incentives, can impact intrinsic motivation. When individuals are motivated by intrinsic enjoyment and then introduced to external rewards, it can undermine their original intrinsic interest in the activity. This is because individuals may begin to perceive the task as a means to an end—specifically, to receive the reward—rather than an enjoyable activity in its own right.

In essence, when a task that was once pursued for its inherent enjoyment becomes associated with extrinsic rewards, the person may start to experience a decline in motivation as the joy of the activity is overshadowed by the expectation of external compensation. Recognizing this idea is crucial for understanding how motivation works in organizational settings and how leaders can structure rewards to foster rather than diminish intrinsic motivation.

Other options may touch on motivation but do not specifically refer to the effect of external rewards diminishing intrinsic enjoyment. Therefore, Cognitive Evaluation Theory aptly captures the essence of this phenomenon.