Answer:extrinsic rewards can undermine intrinsic motivation.
Explanation: In today's world we have been exposed to doing something because you will get something in return and this kills that personal and internal motivation in which one does something only because they love doing it and jt makes them happy.
The children were first motivated by the reward that they got and that stayed in their mind ,now it is hard for them to change their mind to being motivated only by the love of drawing.