The Premack Principle: Definition and Examples

Everyone already knows this one by its folk name: "grandma's rule." Eat your vegetables and then you get dessert. David Premack's contribution was showing it holds generally, and that it works because of the relative probability of the two behaviors rather than anything about food or treats.

What Premack actually showed

Premack published the finding in Psychological Review in 1959. The insight that made it useful was a reframing: a reinforcer does not have to be a thing. It can be an activity. And which activities reinforce which is not fixed, it depends on what the individual is currently more likely to do.

That last part is the piece most summaries drop, and it is the part that matters clinically. The relationship is relative and it reverses. If a child would rather draw than read, drawing reinforces reading. For a child who would rather read, the arrangement runs the other way. There is no universal list of reinforcing activities, only an ordering that belongs to one person at one time.

How the Premack principle is arranged

Three steps, and the order is the whole procedure.

1. Find out what is high-probability. Observe what the person does when given free choice, or run a preference assessment. Guessing is where this usually fails.
2. Identify the low-probability behavior you want more of.
3. Make access contingent. The preferred activity becomes available only after the non-preferred one, and reliably so.

Worked examples

Classroom. A student rushes through worksheets to get to the classroom tablet. Arranging ten minutes of tablet time after a completed worksheet uses the tablet as the reinforcer. No tokens, no stickers, nothing to fade later.

ABA session. A learner will happily jump on a trampoline for twenty minutes and will tolerate about four minutes of table work. Two minutes of trampoline after each short work block turns the preferred activity into the payoff, and the work block gradually lengthens.

Adult, no clinician involved. You would rather scroll your phone than answer email. Answering five emails before you scroll uses the same contingency on yourself. It works for the same reason and fails for the same reason: only if you actually hold the line.

Where the Premack principle goes wrong

Access without the contingency. If the trampoline is available regardless, it reinforces nothing. The single most common failure is letting the preferred activity happen anyway when the learner protests.

Getting the probabilities backwards. Adults routinely assume they know what a learner prefers and are wrong. If the "reinforcer" is not actually higher-probability, the arrangement is just an extra demand, and it will look like the procedure failed when the assessment failed.

The ratio being too big. Thirty minutes of work for two minutes of trampoline is not a reinforcement arrangement, it is a reason to escape. Start with a requirement the learner will actually meet and increase it slowly.

Satiation. A high-probability behavior stops being high-probability once the person has had enough of it. The ordering that held at nine in the morning may not hold by lunchtime, which is why preference is checked repeatedly rather than once.

Its place in current practice

The Premack principle is not a separate intervention so much as a way of finding reinforcers when tangible ones are unavailable, unhealthy, or ineffective. Being able to run reinforcement off activities the learner already chooses is genuinely useful in schools, where snacks and toys are often impractical.

It sits inside the broader reinforcement task in the BCBA Test Content Outline, and it connects directly to preference assessment, which is its own task (F.4) precisely because knowing the ordering is the hard part.