The psychological principle every parent has already discovered

Some of the most powerful observations in science, the ones that grand theories are built on, are the ones that cause people to say, “I could have told you that!” The Premack Principle is undoubtedly one of these observations. It’s a simple idea that’s been used forever, but was only spelled out in the 1950s.


The Premack Principle started out as an idea in the mind of David Premack when he decided to perform a little experiment with Cebus monkeys. Obviously, experiments had been performed with monkeys before – generally by gaining the monkey’s participation by offering it some desired object. Premack gave the monkeys access to four different toys, and noted how much time they spent playing with each. Then he started limiting their access to the toys. He gave the monkeys longer access to the toys they chose to play with most frequently, but only if they first played with the toys they chose less frequently. Sure enough, the monkeys caught on and started playing with the less desirable toys longer in order to get access to the more desirable toys.

Premack then graduated to humans, specifically human children. As with the monkeys, he gave the kids their choice of behaviors. In phase one of the experiment, he let them spend a certain amount of time either eating candy or playing pinball, and noted which activity each child preferred. Phase two was no more Mr. Nice Guy. Premack split the group into two halves. In one half of the experiments, if the kids wanted to eat candy, they had to play pinball. In the other half, they earned their pinball by eating candy. How the kids reacted depended on their established preference. If the kids generally played pinball anyway, the lure of candy had no effect on their behavior. If, on the other hand, candy was always their choice, they adapted and played pinball to get what they wanted. No matter what the preference or what the group, the same principle played out.


This became known as the Premack Principle. People who are free to do anything they want are more probable to engage in some behaviors (eating potato chips and chocolate) than others (exercising). More probable behaviors can be used to reinforce less probable behaviors. Less probable behaviors are not going to do a thing to motivate people to engage in more probable behaviors. This is also known as Grandma’s Rule. You can only eat dessert if you eat your greens first. No grandmother gets mixed up and says a kid can only eat their broccoli if they eat a sundae first. It wouldn’t work, and we all know it.


It seems like David Premack took a long walk to get to an obvious conclusion, but his work did form the foundation for a lot of later psychological treatment, although some of it was, arguably, not the kind of treatment we'd like to be subjected to. If patients don’t respond to any rewards, it’s always possible to use the Premack Principle to take away their most desired activity, even if it’s only sitting in a chair and being left alone, until they cooperate. On the other hand, the Premack Principle eliminates the need to make an experimental subject choose between some great reward and some terrible punishment in order to elicit a desired behavior. All they really need is a choice between a greater and lesser reward.

More importantly, the Premack Principle requires scientists – or anyone who wants to use it – to learn about the people they want to use it on. Premack stopped scientists from seeing rewards as objects and started them seeing rewards as preferred individual behaviors. Every parent knows that what motivates one kid will be a punishment to another, but when we deal with people whose points of view are far outside our own, we don’t always realize that. Thinking about what people, and patients, actually want to do helped groups, like anorexics and schizophrenics, that doctors previously didn’t know how to work with. Even in everyday life, actually observing what people like to do, and giving them the possibility of doing more of it, is both a kinder and more efficient way of managing others than assuming there's some kind of universal carrot that works for everyone. Sometimes, applying basic common sense is, in itself, a big idea.


Top Image: Elisa Azzali

Monkey Image: Arthur Chapman

Pinball Image: Joan Vega

Via NCBI, Adaptive Dynamics, Principles of Learning and Behavior.


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