 In Applied Behavior Analysis, the Premack principle is sometimes known as "grandma's rule," which states that making the opportunity to engage in high-frequency behavior contingent upon the occurrence of low-frequency behavior will function as a reinforcer for the low-frequency behavior .In other words, an individual must "first" engage in the desired target behavior, "then" they get to engage something reinforcing in return.For example, to encourage a child who prefers chocolate candy to eat vegetables (low-frequency behavior), the behaviorist would want to make access to eating chocolate candy (high-frequency behavior) contingent upon consuming the vegetables (low-frequency behavior).