Vibha's homework used to be very untidy and that too if she would submit it at all. Her teacher told her, "If you submit neat work on time, I will give you a star sticker in you copy. After you have collected 5 stars, I will give you a Chocolate Bar".
Name the technique used by the teacher :

Token Economy

Persons with behavioural problems can be given a token as a reward every time a wanted behaviour occurs. The tokens are collected and exchanged for a reward such as an outing for the patient or a treat for the child. This is known as token economy.