Premack principle

A high-probability behaviour can be used to reinforce a low-probability behaviour. In other words, if an animal really wants to do something, the opportunity to do that thing can be used to reinforce something else first.

A horse who really wants to go back to the herd will work hard for the chance to do so. A dog who really wants to play tug will work hard for the chance to play tug. A parrot who really wants to fly to a particular perch will work for the chance to fly there. A child who really wants to play outside will eat their vegetables for the chance to do so.

The Premack principle, named after psychologist David Premack who formalised it in 1959, is one of the most useful additions to the trainer’s toolkit because it dramatically expands the range of available reinforcers. Trainers are not limited to food, scratches, and conventional rewards. Anything the animal wants to do can be used as reinforcement for doing something else first.

This is particularly useful for animals or moments where conventional reinforcers are not available or not effective. A horse who is not food-motivated in a particular context can be reinforced with the opportunity to graze, to return to the herd, or to stop work. A dog who is too aroused to take food can be reinforced with the opportunity to chase a toy or sniff a particular spot.

Identifying what an animal really wants in a particular moment, and using access to that as the reinforcer for the desired behaviour, is one of the most rewarding craft skills in applied training across species. It requires careful observation of the individual animal and willingness to use the animal’s own motivations rather than the trainer’s expected reinforcers.