Answer:
Overjustification effect
Step-by-step explanation:
The overjustification effect happens when an external motivator, e.g. reading rug time, decreases someone's personal motivation to do something. I.e. Students that used to line up properly will only do it if they are rewarded with reading rug time, even if they did it before just because they felt it was correct. The external motivator actually diminished some students' motivation to act correctly.