Dog behavior is complex, intricate and occasionally difficult to understand. When attempting to modify canine behavior, trainers and behaviorists fall back on the industry-standard "four quadrants of operant conditioning." Simply put, there are four options a trainer can utilize to reinforce or discourage a dog's behavior. Positive reinforcement, negative reinforcement, positive punishment and negative punishment all provide avenues to changing behavior, and while interconnected, each is quite different from the others. Positive punishment utilizes added stimulus to decrease the chances of a behavior happening.
When it comes to operant conditioning, "positive" simply means something is added, not that it's good. Punishment is utilized to decrease the chances of a behavior happening again. Therefore, positive punishment uses added stimulus to discourage your dog from performing an action for a second (or third, or fourth) time.
Almost any introduction of pain, force or physical correction is positive punishment. If your dog pulls on the leash and you yank back on a prong collar, the yank on the prong collar is positive punishment. You have added stimulus (the prong collar correction) directly after your dog's behavior (pulling on the leash) with the goal of preventing pulling on the leash in the future. If your dog barks and you squirt her with water, you've introduced an aversive in order to teach her not to make so much noise or something unpleasant will happen.
Positive punishment works quickly to teach your dog what not to do. The lesson is quite simple: "Do what I want you to do, or else." The measured application of force can ensure steady performance, solid distraction proofing and obedience in most circumstances. It's simple to utilize and understand and the results show with only a couple sessions.
While positive punishment teaches your dog what not to do, it doesn't teach him alternative behaviors. When your dog doesn't know what to do instead of the behavior you're eradicating, it becomes a constant cycle because he always reverts back to the pattern he knows. Additionally, the use of pain and force in behavior modification introduces anxiety and fear into the equation, which degrades your dog's trust in you.