What punishment is.
The confusion that comes from trying to understand punishment relates to a misunderstanding in the definition. According to the Merriam-Webster Online Dictionary punishment refers to "suffering, pain, or loss that serves as retribution" or "severe, rough, or disastrous treatment". With these definitions it is easy to see how so many trainers can claim that they do not use punishment when training dogs. However, when referring to behavior and learning, punishment has a very different definition. In this case, punishment simply means anything that causes a behavior to stop or become less likely. Notice that there is no mention that the punishment has to be harsh, painful, or severe. It does, however, need to be something the dog finds unpleasant. There are two types of punishment. Positive punishment, which means something is added to reduce the likelihood of a behavior, and negative punishment, which means something is removed to reduce the likelihood of a behavior. The remainder of this article will discuss positive punishment, as it is the most frequently misunderstood and misused.
What punishment is not.
Punishment must be contingent on the dog's behavior. Lashing out at a dog in anger, getting revenge or retribution, or otherwise treating a dog harshly "because he deserved it" are not forms of punishment. These acts do not teach the dog anything(except that humans are scary and unpredictable) so are therefore not punishers in the technical sense. To be considered punishment has nothing to do with how harsh or severe it is, and everything to do with whether it diminishes the target behavior.
Problems with punishment.
There are a number of reasons why punishment may not be the best way to train dogs. Here are just a few examples.
When trying to stop a problem behavior punishment must be administered immediately following the behavior, every single time. This can be somewhat challenging for pet owners. Punishment delivered too late runs the risk of punishing a completely different behavior and causing confusion and frustration in the dog. When punishment is used inconsistently on a behavior, many dogs will learn to gamble in the hopes that this time they won't be punished.
While there are forms of punishment that do not hurt the dog physically(such as spray bottles, shake cans, etc.), all punishment is unpleasant to the dog being trained. Many times the effects of the punishment are not outright obvious. Fear, mistrust and frustration can result from using punishment in dog training. This can be damaging to the relationship between pet and owner.
Using punishment can have other unintentional side effects. Dogs will often create negative associations with other things in their environment at the time the punishment was delivered. For instance, a dog that is given a leash jerk every time he looks at another dog may learn to hate the presence of other dogs. For all he knows, those other dogs are the cause of the punishment.
Punishment can actually inhibit learning in some cases. A dog that is punished every time it makes a mistake often becomes reluctant to try anything new. This can make things difficult when trying to teach a new behavior.
Most importantly, punishment does not teach the dog what you want him to do. While you may have stopped that particular behavior, unless you train an alternative behavior to replace the old one, the dog is left trying to figure out what to do instead.
Is there a better way?
Yes! There are many ways that problem behavior can be solved without the need for punishment. Check out this article for two very effective options for dealing with behavior problems without using punishment.
If you are having a behavior issue with your dog that you are finding difficult to solve, you should not hesitate to contact a professional trainer that practices positive and humane methods. Two good resources are the Karen Pryor Academy and the Association of Pet Dog Trainers.