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ABA Concepts

The Premack Principle in Applied Behavior Analysis

The Premack principle states that access to a higher-probability behavior can serve as reinforcement for a lower-probability behavior. Often explained to parents as grandma's rule (first eat your vegetables, then you can have dessert), it is one of the most practical tools in applied behavior analysis for increasing low-rate behaviors. This article explains the original research by David Premack, how to identify high-probability and low-probability behaviors through observation and preference assessment, and how the principle connects to the response deprivation hypothesis. You will find clinical examples for classroom routines, homework, self-care, and transitions, along with step-by-step guidance for implementing Premack-style contingencies, writing contracts, and avoiding common mistakes. We also cover how the Premack principle appears on the BCBA exam and how it differs from the high-probability request sequence. Use this guide to apply the principle ethically and effectively and to answer related exam questions with confidence.

April 1, 2024

What Is the Premack Principle?

The Premack principle, named for psychologist David Premack, states that making the opportunity to engage in a high-probability behavior contingent on the occurrence of a low-probability behavior will function as reinforcement for the low-probability behavior. In everyday terms, "first work, then play." It is also called grandma's rule.

The key insight is that reinforcers can be behaviors, not only objects. Instead of asking what stimulus a child likes, we ask what the child does often when given free access. Those high-rate behaviors become reinforcement for behaviors the child does less often.

How the Principle Works

Identifying high-probability and low-probability behaviors

Behavior probability is determined by observing what a person chooses to do during free access. If, in an unstructured period, a student spends 15 minutes drawing and 1 minute reading, drawing is the high-probability behavior and reading is the low-probability behavior. A contingency that requires reading before drawing may increase reading.

  • Free-operant observation: Record how much time the learner spends in each activity when nothing is required.
  • Preference assessments: Multiple stimulus and paired stimulus assessments can identify high-preference activities.
  • Caregiver interviews: Useful for generating candidates but need verification through observation.

Structuring the contingency

The statement should be explicit and the requirement clear: "When you finish five math problems, you may have five minutes of video games." Access is available only after the low-probability behavior is complete.

The Response Deprivation Hypothesis

Later research by Timberlake and Allison suggested that the Premack effect may occur because the contingency restricts access to the preferred behavior below its baseline level. The response deprivation hypothesis says that a contingent behavior will be reinforcing if the contingency makes access to it fall below baseline. This explains why sometimes a lower-probability behavior can serve as a reinforcer: if the child engages in a certain behavior very little, but restricting it below that level makes it valuable, it may still work. For the exam, know that response deprivation is an extension that emphasizes restricted access and that it ties back to motivating operations.

Clinical and Educational Examples

  • Homework: A teenager who spends hours on a gaming console but avoids homework earns 30 minutes of gaming after completing 30 minutes of homework.
  • Self-care: A child gets to watch a favorite show after brushing teeth and putting on pajamas.
  • Classroom transitions: A student who struggles to leave recess may be allowed a minute with a preferred toy after lining up.
  • Adult behavior: An adult uses a favorite podcast only while exercising, which makes exercising more likely.
  • Therapy sessions: After three correct responses on a demanding discrete trial program, the learner earns a short break with a favorite activity.

Implementation Steps

  1. Observe the learner and identify at least two activities with a high probability and the target behavior with a low probability.
  2. Define the target behavior precisely, including the amount or duration required.
  3. Set the requirement at a level the learner can reach. Begin low and increase gradually.
  4. State the rule clearly, using a visual if needed: first, then.
  5. Deliver access immediately after the requirement is met, and withhold access if it is not.
  6. Collect data on the target behavior and review whether it increases.
  7. Fade the contingency or shift to natural reinforcers over time.

Common Mistakes

  • Reversing the order: Letting the learner play first and then asking for the task usually fails because the reinforcer is already consumed.
  • Making access freely available elsewhere: If the preferred activity is available at other times without a requirement, the contingency loses value.
  • Requirements that are too large: This produces ratio strain. Start with achievable steps.
  • Not checking preference: Preferences shift. A high-probability behavior last month may not be today.
  • Using it as a threat: The statement should be framed as a positive contingency, not a punishment.

Premack vs High-Probability Request Sequence

These are often confused. The Premack principle uses a preferred behavior as a consequence for a low-probability behavior. The high-probability request sequence (high-p), related to behavioral momentum, presents several easy requests the learner is likely to follow, in rapid succession, before a difficult request in order to increase compliance. One is a consequence strategy; the other is an antecedent strategy.

Using Contracts and Token Systems

Premack contingencies can be incorporated into contingency contracts and token economies. A student might earn tokens for completing tasks and then trade them for time with a preferred activity. This combines the Premack principle with conditioned reinforcement and allows reinforcement to be delivered more flexibly.

Ethical Considerations

Ensure the learner has access to basic needs and rights independent of contingencies. Preferred activities that are contingent should not include essential items such as meals, comfort items needed for regulation, or communication devices. Behavior analysts must also think about social validity: caregivers and clients should find the plan acceptable and doable.

How It Appears on the Exam

You may see a scenario describing a client who rarely does a task and often does another activity, and be asked what procedure will increase the task. The correct answer is a contingency making the high-probability activity available after the low-probability task. Other items ask you to distinguish Premack from high-p sequences, or ask what happens if you reverse the order. Remember that the principle is about relative probability and that reinforcers may be behaviors.

Key Takeaways

The Premack principle uses a high-probability behavior as reinforcement for a low-probability behavior. Identify behavior probability through observation, state the contingency clearly, start with achievable requirements, and monitor effects with data. Distinguish it from the high-p request sequence and recognize the role of response deprivation.

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