Premack Principle

What is the Premack principle?

The Premack principle, often nicknamed “Grandma’s Law,” proposes that access to an activity with a higher baseline probability can reinforce an activity with a lower baseline probability when access is made contingent on performing the latter. Premack’s 1959 paper states the idea in terms of independently measured response rates.

Premack principle example

If someone spends more free-choice time playing a game than practicing vocabulary, making game access depend on vocabulary practice illustrates the proposed contingency.

Evidence and limits

The original paper presents an early generalization and experimental methods, including a monkey’s responses to different devices it could operate. Premack explicitly described the evidence as insufficient to prove the full claim.

Using the principle

In education, parenting, workplace design, or personal routines, the familiar idea is “first this, then that.” But the order alone does not show that reinforcement occurred.

An application needs information about the person’s actual activity pattern and what happens under the contingency. Merely pairing two activities, or assuming one is preferred, is not enough.