I used classical conditioning on my dog Jenny a few minutes before writing this post. She is in the process of developing an ear infection, but she hates to have her ears cleaned. I’m using classical conditioning to change her emotional reaction to the ear cleaner from fear or stress to anticipation and enthusiasm.
The unconditional stimulus (UCS) is the ear cleaner. When I show it to her, she has a natural response (fear, demonstrated by her sudden flight from my vicinity). I could pair this UCS (ear cleaner) with a neutral stimulus (a bell). The animal learns to apply its emotional response to the second stimulus (fear of the ear cleaner) to the first stimulus (the bell). In other words, the bell comes to predict the ear cleaner, and eventually, the dog would learn to run away when she heard the bell, as if she were afraid of the bell.
That’s not useful either. What I am doing is pairing something to which Jenny has a positive natural response (cheese) with the ear cleaner. The first thing she sees predicts the second thing, so I show her the ear cleaner first, then give her cheese. Over time, the ear cleaner comes to predict cheese, and eventually she will greet the ear cleaner with the enthusiasm previously reserved for cheddar. Of course, I have to build slowly up to actually cleaning her ears, but after one session she is enthusiastically touching her nose to the bottle when I show it to her instead of leaving the room. I expect the process to take several sessions, so I’m starting before I actually need to clean her ears.
Classical conditioning is also used frequently in behavior modification, to change the emotional response (fear) of dogs to a stimulus (strange people, strange dogs) into a new emotional response (enthusiasm). Again, pairing food with the approach of the stimulus works well, with a sufficiently gradual approach. This counter-conditioning approach is frequently used in the behavioral treatment of dogs who erupt into enraged barking at the sight of other dogs.
It is important to remember that the first stimulus predicts the second. If you get things backwards, you can break your dog! I have heard stories of people teaching their dogs to flee the room upon smelling peanut butter, because peanut butter had been overused as a lure before a variety of unpleasant stimuli (ear cleaning, nail clipping...). So remember, bad thing first, good thing second.
Go, try it if you have trouble cleaning your dog’s ears or clipping their nails!
[ETA: There is some very interesting discussion about the definition of classical conditioning in the comments. -DZ]