There is an excellent post by Crystal at Reactive Champion about the difference between Classical and Operant conditioning, and how to use both in a training program.
When I first got Fozzie, I used to post to positive training listserves in search of advice about his leash reactivity. One suggestion I got was to have him sit behind me as another dog approached. This sounded like a great idea at first, but I wondered for a while why it just seemed so...impossible.
The person who suggested this, while well-intentioned, was not aware that Fozzie was way too over threshold at these times to do anything requiring presence of mind. But as Crystal from Reactive Champion reported from the Kathy Sdao seminar she attended, a strong foundation of classical conditioning is what allows a reactive dog to get in a space where operant conditioning is possible:
In other words, what classical conditioning does is give you the foundation on which to build those operant behaviors. It helps your dog relax enough to think. It gives you enough time to intervene. It gives you the space you need to begin training the behaviors you want instead of constantly focusing on the ones you don't.
Fozzie, and any dog who is above threshold, can't handle the expectations of performing a particular behavior until he's been brought below his threshold through classical conditioning. This is the same principle that prompts some really good shelters to have their visitors treat dogs even when they're barking.
I've seen this work with Lamar, as he is now looking at me when he sees another dog since we've trained him for many months with a click as soon as he so much as glances another dog's way (Crystal, thanks for the clarification that this is indeed an operant success!)
Fozzie is making progress too--if we're far enough away from another dog and I've shoved enough "free" treats in his face, he will sometimes offer a sit!
I love my fellow dog bloggers for explaining tricky concepts so well--you are my continuing education!