The science of associating something with an activity is known as classical conditioning. The best example is the experiment conducted by Pavlov. Whenever he served food to his dog, he used to ring a bell. In the beginning, the dog used to salivate by looking at the food. Later he began associating the bell with the food and at a point of time, he used to salivate at the sound of the bell.

This doesn't mean that the actual noise of the ringing bell made him salivate. The dog associated the ringing of the bell with the food and that food or even the thought of it made him salivate.

Classical conditioning cannot actually make the dog to sit or jump at the command, but it does change the way the pet feels about a particular situation in which it is right now. Classical conditioning gives explanation about the behavior relating to a particular place, object or event. It explains how the emotional response is developed. The responses can be developed in the animal either wontedly or by chance. Also the trainer must remember that the change in the behavior is irreversible most of the times.

One of the most common behaviors dealt with in conditioned emotional response is fear. The fear can be instinctive, learned or unknown. For example, if a cat gets scared upon seeing a dog, this is instinctive fear.

If the cat backs off upon seeing a raised hand, this is learned fear. This can happen in the case of an abused cat. If there is fear because of lack of exposure to a particular situation before, this is known as fear of unknown.

The conditioned emotional responses, which are dislikeable, can be reduced with the help of classical conditioning. Classical conditioning further has two concepts namely desensitization and counter-conditioning. Desensitization is reducing the sensitivity of the animal towards a particular unavoidable situation.

The bad situation is created again and again until the animal becomes insensitive or doesn't feel about it any more. For example, if the animal is given crate training, it is locked inside the crate again and again, till he gets used to staying locked inside the cage.

In counter-conditioning the animal is exposed to a lower degree of extremity. The intensity is less and as well a positive thing is presented to the animal. By doing this pet begins to like the nasty situation.

The pet is made to respond in such a way, which contradicts the current or previous reaction. For example, a pet doesn't like to be locked up in the crate all the time. But this undesirable situation can be made to look pleasant if the pet is fed with a treat from time to time as long as it stays calmly inside the cage.

Negative counter conditioning is another technique, but it is used very rarely. For example, if the cat likes to bite the hand of the owner very frequently, the person can rub something distasteful on the hand. When the animal bites the hand, it will taste the distasteful substance and then associate the bad taste with the hand and will not bite again, if done repeatedly.

Classical conditioning is used to alter the way of reaction of the animal in a particular situation. With classical conditioning it can be made to like an unpleasant situation and even dislike a pleasant condition.