Dogs do not communicate with verbal language. They communicate on a much more fundamental and physical level than us humans. They express themselves with eye contact, or lack of eye contact and through body language. Actually we humans also communicate this way, but rely on speech to convey more complex ideas and opinions. It is because of our complex verbal system that we sometimes complicate dog training by using too many words and not being consistent with our actions. Ideally, we would like to use language as a training tool, but to do so effectively, the words must be conditioned to have meaning to the dog.
For instance, when your dog jumps up on you, pushing it and saying "off" can discourage this bad behaviour. However "pushing" in dog terms is playing...so if you are saying "off", make sure your body is communicating the same message. When you say the word, "off" or whatever you want to use for stopping unwanted jumping up, you should calmly walk into the dog and claim your space. Often times with more excitable dogs a collar correction is needed. I like to pull the dog into a sit, then reward it for compliance. To ensure you are not re-inforcing bad behaviour by giving attention for jumping up, ask yourself what your body language is say. Is it calmly and clearly giving the dog the message that you don't enjoy this behaviour? Some dogs just crave all attention and are rehearsing old habits that resulted in attention, bad or good. In addition to claiming your space, another good aversive is to withdraw all attention.When the dog calms down and offers appropriate behaviour then give it a verbal and physical cue that it has done well. "Good-boy!" followed by a pat or a treat. Body language is more useful than words in communicating with our dogs.
Rewards are really important in defining things for dogs. They are more likely to repeat behaviour that brings about positive outcomes. Reward systems are not just food based; although most dogs will work well for food. Some dogs don't care about treats and will do anything for a ball or a game of tug with you. Play driven dogs can be the easiest to train because unlike food, play drive doesn't usually decrease or become satiated. Also, playing with your dog doesn't result in weight gain. The other reward that is common is social acceptance and praise. Many dogs will work for praise and just to please you. When using verbal praise to train a dog, it must be conditioned to have meaning. Saying "Good Boy!" and following it with a bum rub or a pat will give the clear communication that you are happy with the dogs performance and a socially driven dog will often work simply for your approval.
Purely positive re-inforcement is a modern trend in dog training and it can bring about really great results, as well as build a strong bond between you and your dog. Nonetheless, punishment can also be conditioned to have meaning and clearly communicate to your dog when you are not happy with his performance. The word "NO" has no meaning to a dog, yet when coupled with an aversive, like a collar correction, the dog quickly realizes that NO indicates something unpleasant will follow and will associate this corrections with the thing it is doing at the time, thus reducing the behaviour. Properly administered correctives do work and are often necessary in clearly defining what is unacceptable.
I would also like to touch on the idea of conditioned interrupters as well as markers. Cesar Milan comes to mind, with his infamous "CHUCHT!" If you have ever watched how he interrupts a behaviour, makes this noise and follows it with a poke or a little nudge to the dog's side. He is essentially conditioning the dog to associate the sound with being poked or nudged with his foot. He also is interrupting the behaviour and getting the dog's attention. Dogs are physical and when conditioning a word or a sound to have meaning as a corrective, you must follow the word with some aversive. Anything that the dog doesn't like is an aversive...even petting can be a punisher if it is not enjoyable for the dog! Eventually, just the sound preceding the interrupter acts as the correction on its own.
When using markers, like clickers, we can also condition the dog to understand exactly when it has gotten something right. The verbal equivalent to a clicker is the use of a word or sound like "YES" and following it with a treat or reward. Eventually, the word "YES", or the click indicates to the dog that something good is coming. In addition, when the dog is not complying to what is being asked of him, the word or sound "UH-AH!" can be paired with withholding that reward to clearly communicate non-compliance. We can shape a dogs behaviour by simply rewarding or withholding rewards until he gets it right. Using interrupters and markers are a clear way of letting the dog know when it is doing something right or wrong.
It is important to keep it simple and make sure that your dog is understanding what you are trying to say. Work on developing clear communication by using verbal cues that have been conditioned to have meaning and let your dog know when he gets things right. Basically, through reward and corrections you can teach your dog words or sounds for indicating it got it and a reward is coming, or if necessary, that it has gotten it wrong and a corrective action is coming. Even withholding a reward is an effective aversive. The key is being very clear and consistent. Reward all good behaviour as well as interrupt and redirect all unwanted behaviour and a large portion of your training will be done! Remember, dogs will repeat behaviour that brings about positive results and will be less likely to repeat things that bring about unwanted results. Most of all I can't stress enough that dogs learn through repetition. Repetitive behaviour becomes learnt behaviour, so don't get lazy and let your dog repeat bad behaviour!
Be consistent and don't give up on your dog!
