Meg decides to teach her dog, Bo, to roll over. She rewards…

Meg decides to teach her dog, Bo, to roll over. She rewards him for successive approximations of the rolling behavior. Then, when he masters the trick, Meg rewards him each time he performs the behavior with a food treat. After a day of rewarding him each time, Meg begins to reward Bo after each tenth time he performs the trick. This is an example of what reinforcement schedule?