Dog Training part III - Communicating with the dog

Fundamentally, dog training is about communication. From the human perspective the handler is communicating to the dog what behaviors are correct, desired, or preferred in what circumstances. From the canine perspective the handler must communicate what behaviors will give the dog the most satisfaction to his natural instincts and emotions. Without that inner satisfaction a dog will not work well.
A successful handler must also understand the communication that the dog sends to the handler. The dog can signal that he is unsure, confused, nervous, happy, excited, and so on. The emotional state of the dog is an important consideration in directing the training, as a dog that is stressed or distracted will not learn efficiently.
According to Learning Theory there are a four important messages that the handler can send the dog:
Reward or release marker
Correct behavior. You have earned a reward. For example, "Free" followed by a reward.
Bridge
Correct behavior. Continue and you will earn a reward. For example, "Good".
No reward marker
Incorrect behavior. Try something else. For example, "Uh-uh" or "Try again".
Punishment marker
Incorrect behavior. You have earned punishment. For example, "No".
Using consistent signals or words for these messages enables the dog to understand them more quickly. If the handler sometimes says "good" as a reward marker and sometimes as a bridge, it is difficult for the dog to know when he has earned a reward.
Rewards can be treats, play, praise, or anything that the dog finds rewarding. Failure to reward after the reward marker diminishes the value of the reward marker and makes training more difficult.
These four messages do not have to be communicated with words, and nonverbal signals are often used. In particular, mechanical clickers are frequently used for the reward marker. Hand signals and body language also play an important part in learning for dogs.
Dogs usually do not generalize commands easily; that is, a dog who has learned a command in a particular location and situation may not immediately recognize the command to other situations. A dog who knows how to "down" in the living room may suffer genuine confusion if asked to "down" at the park or in the car. The command will need to be retaught in each new situation. This is sometimes called "cross-contextualization," meaning the dog has to apply what's been learned to many different contexts.
Next: Dog Training part IV - Reward and punishment