Briefly defined, the Premack Principle is the concept that a behavior of high probability can be used to reinforce a behavior of lower probability. For instance, in the example referenced above, there is a higher probability that a child will eat her spinach although she doesn’t enjoy it if she is allowed a food she wants, such as ice cream, after she has finished the less desirable food. The reward of eating ice cream becomes a more potent motivator to eat her spinach first. The reinforcement is positive for the child and always is given immediately after the target behavior has been achieved.
To illustrate a classic use of Grandma’s Rule, the author considers the use of the Premack Principle in lengthening the time young students are able to stay in their seats. As it is often difficult for children new to elementary school to sit for extended periods of time
(Cipani, 2008), it is unreasonable for teachers to set the initial in-seat standard for too long. In many cases, younger elementary children just need to be allowed to develop the skill of staying seated for periods of time for up to 30 minutes (Cipani, 2008).