From our experience, humans say the word “No" to their canine companions often. “No!” to jumping on people, “No!” to counter surfing, “No!” to this, “No!” to that. “No!” “No!” “No!” But what does it really mean to our dogs? We find, as canine behavior consultants, when you use a word for everything, it means nothing. Sure, most dogs respond to it because people typically yell it or say it in a stern “I really mean business” voice. It is usually that to which the dogs are responding. If you said the word “Apple!” in the same voice, I am sure your dogs would respond the same way as if you said “No!”
We have never taught our dogs the word No. Why have a cue for something we don't want to happen? We believe it is far better to teach dogs “Yes” to a few things than to teach “No!” to the millions of things out there we do not want our dogs to do. If we teach them what to do, they will more likely do that than find something we don't want them to do on their own. Even when we catch them in the act of something we do not want, instead of saying “No!” we ask them to do something we do want. If a dog jumps on you, instead of saying “No!” (what does that really mean anyway?) we say “Sit” to ask the dog to sit instead. A dog cannot jump on you in the sit position. This is just one example of what is called an Incompatible Behavior. Can you think of other behaviors you can turn from a “No!” to a "Yes?"