Final answer:
Sammy's decline in performance after being paid for good grades is an illustration of the overjustification effect, where external rewards can decrease intrinsic motivation for a task.
Step-by-step explanation:
The scenario described with Sammy's grades dropping after being paid for good performance is an example of the overjustification effect. This psychological phenomenon occurs when an external incentive like money decreases a person's intrinsic motivation to perform a task because the task is now associated with the external reward, rather than the personal satisfaction or interest that initially drove the behavior. Essentially, when Sammy began receiving money for his grades, his internal drive to achieve good grades for personal satisfaction may have diminished because his focus shifted to the external reward of money, which overjustified the task of studying and may have reduced the personal value he placed on education.
It's also important to note that while tangible rewards like money can sometimes negatively impact intrinsic motivation, intangible rewards like praise might actually foster it. However, in Sammy's case, receiving money for grades likely prompted him to see studying and getting good grades as a 'job' rather than an intrinsically rewarding activity, leading to a drop in his performance when those intrinsic motivations were overshadowed by extrinsic rewards.