Premack Principle

The Premack Principle (often referred to colloquially as 'Grandma's Rule') states that a learner will complete a non-preferred, low-probability task if it is immediately followed by the opportunity to engage in a highly preferred, high-probability activity. For example: 'Eat your vegetables (low-probability), then you can play outside (high-probability)'.

This principle provides the scientific foundation for First-Then boards and visual schedules. It is a highly effective way to structure demands in a way that uses natural, motivation-based reinforcement contingencies without resorting to arbitrary rewards.