Premack's principle

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Premack's principle, or the relativity theory of reinforcement, states that more probable behaviors will reinforce less probable behaviors.[1][2]


The principle was derived from a study of Cebus monkeys by Professor David Premack, but has explanatory and predictive power when applied to humans. This is evidenced by the fact that therapists use the principle in applied behavior analysis. Premack's Principle suggests that if a person wants to perform a given activity, the person will perform a less desirable activity to get at the more desirable activity. In behaviorist terms, activities become reinforcers. An individual will be more motivated to perform a particular activity if they know that they will be able to partake of a more desirable activity as a consequence. If high-probability behaviors (more desirable behaviors) are made contingent upon lower-probability behaviors (less desirable behaviors), then the lower-probability behaviors are more likely to occur. More desirable behaviors are those that individuals spend more time doing if permitted; less desirable behaviors are those that individuals spend less time doing when free to act.

Although high-probability behaviors are made contingent upon lower-probability behaviors, if a schedule requires much more of the high-probability behavior than the low-probability behavior then Premack's principle may be violated. In a study done by Mazur in 1975, he showed that a low-probability behavior can actually reinforce a high-probability behavior.


David Premack and his colleagues conducted many experiments to test the theory of the Premack principle, specifically its effectiveness on humans. One of the earliest studies was conducted with young children. Premack gave the children two response alternatives, which were either eating candy or playing a pinball machine. These responses were measured based on which response was more probable for each individual child. Some of the children preferred one activity over the other. In the second phase of the experiment, the children were tested with one of two procedures. In one procedure, eating was the reinforcing response, and playing pinball served as the instrumental response. This means that children had to play pinball in order to eat candy. The results were consistent with the Premack principle, only the children who preferred eating candy over playing pinball showed a reinforcement effect. In another test, the roles of responses were reversed, and the results were identical to the first procedure. Only children who preferred playing pinball over eating candy showed a reinforcement effect. This study shows that the power of the Premack principle is that any high-probability activity can be an effective reinforcer for a response that the subject is less likely to perform, only if the subject prefers the high-probability activity (Domjan, 2010).

Further information[edit]

This psychological principle can be used effectively in certain controllable situations to dramatically affect the behaviors of individuals.

In behavioral terms Premack's principle states that any high-frequency activity can be used as a reinforcer for any lower-frequency activity. This common statement made by most mothers easily show us how Premack's principle is used "You have to finish your vegetables (low frequency) before you can eat any ice cream (high frequency)" (Wenning, C., no page).

The term behavior change has replaced the term behavior modification because in operant conditioning, one does not modify behavior but instead one modifies the environment (antecedents and consequences) that then results in behavior change.

Some researchers believe that response deprivation theory is better than Premack's principle. Response deprivation theory is actually a refinement of Premack's principle. It may be a bit more difficult to understand than Premack's principle, but it is the most reliable predictor of a reinforcer's effectiveness. This theory allows us to predict whether an activity will serve as a reinforcer by observing the probability of that behavior (and of the behavior to be reinforced) in a baseline situation. An experiment that tested this theory was done by Konarski in 1987, which set up different contingencies between two behaviors in a population of adults with mental retardation, and this allowed him to make a direct comparison of the predictions of Premack's principle and response deprivation theory. The predictions of Premack's principle succeeded in some cases and failed in others, but the predictions of response deprivation theory proved to be correct almost 100% of the time.


  1. ^ Jon E. Roeckelein (1998), Dictionary of Theories, Laws, and Concepts in Psychology, Greenwood, ISBN 0-313-30460-2 p. 384
  2. ^ Tony Ward, D. Richard Laws, and Stephen M. Hudson (2003). Sexual deviance: issues and controversies. SAGE. p. 66. ISBN 978-0-7619-2732-7. 

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