According to Learning Theory there are four important messages that the handler can send the dog:
Reward or release marker
Correct behavior. You have earned a reward.
Keep going signal
Correct behavior. Continue and you will earn a reward.
No reward marker
Incorrect behavior. Try something else.
Punishment marker
Incorrect behavior. You have earned punishment.
Using consistent signals or words for these messages enables the dog to understand them more quickly.
It is important to note that the dog’s reward is not the same as the reward marker. The reward marker is a signal that tells the dog that he has earned the reward. Rewards can be praise, treats, play, 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.