Counter-conditioning (CC) is a type of classical conditioning used for behavior modification. The dog is exposed to something that usually causes him to become frightened or aggressive at a distance where he sees it, but the bad reaction is not triggered. As soon as the dog sees the trigger, he is given a food reward. The reward is not dependent on the dog performing any behavior. The aim of counter-conditioning is to change the dog’s emotional response to his triggers from negative to positive. A dog that feels positively about something will no longer feel the need to behave aggressively or fearfully towards it.
Counter-conditioning is often paired with desensitization because both happen at the same time during a successful CC setup. This is why trainers often use the acronym “DS/CC” to refer to this method of behavior modification.