Classical Conditioning

     Classical conditioning or learning through association is a theory that was accidentally discovered by a Russian physiologist named Pavlov. He worked on the mechanism of digestion and the role of glandular secretions. By measuring the amount of gastric juices in dogs, he noticed that animals do not just salve while eating, but also at the sight of the food or even the person who brings them. This made Pavlov and his co-worker lead a series of works to elucidate what is called the classical conditioning.

  1. Major concepts

      This theory has 4 major concepts if you understand them you will understand the whole theory. Let me introduce these concepts to you briefly; we have the unconditioned stimulus: it is a natural stimulus in the environment and it produces a behavior or a response that is unlearned this response is called unconditioned response. Next to that we have the conditioned stimulus and it is a neutral stimulus that has no effect on our behavior but after being associated with the unconditioned stimulus it gives us a response that we call conditioned response.

     Still not clear then let us say for example that you use a leash every time you want to take your dog out so your dog gets excited every time he sees the leash. However in that case the real reason behind the dog’s excitement is not the leash but rather getting out. Well in that example the unconditioned stimulus or the natural stimulus was getting out that stimulus created a natural response which the excitement. However the dog gets used to the fact that you always use a leash when you want to take him out so the unconditioned stimulus “getting out” was associated with conditioned stimulus “the leash” which created a conditioned response which is getting excited when he sees the leash even if you are just holding the leash to put it in a different place.    

2. Stages of classical conditioning

       We can see in the example above that there are three stages of classical conditioning:

       1. Before conditioning: in this stage the unconditioned stimulus “getting out” creates an unconditioned response “excitement”.

      2. During conditioning: in this stage the conditioned stimulus “the leash” is associated with the unconditioned stimulus “gettingout”. For classical conditioning to work the conditioned stimulus need to be presented before the unconditioned stimulus “the leash needs to be present before getting out” this is called forward conditioning if the conditioning is presented backward “backward conditioning” it is generally unsuccessful. This stage is an important step in classical conditioning because if the association does not occur repeatedly during this stage the learning will not be successful.

       3. After conditioning: in this stage the association has been completed successfully and the conditioned stimulus “the leash” has the ability to create a conditioned response “the excitement”.

   3. Laws of classical conditioning

         After discovering this theory Pavlov presented some laws that control the process of learning by association like:


  • Extinction:

this law explains how the association disappears. Presenting the conditioned stimulus repeatedly without the unconditioned stimulus leads to the extinction of the conditioned response.

  • Generalization:

this law explains how the association can extend to stimuli that are similar to the conditioned stimulus. For example the dog may give the same response of excitement even if you change the leash and bring a new one. We see evidence of stimulus generalization in phobia. For instance if a child is bitten by a large dog, he is liable not only large dogs but also small dogs.

  • Discrimination:

this law explains how an animal can learn to differentiate between two similar stimuli. For example if you ring a bell each time you give your dog food your dog will learn to associate between the food and the bell. That way the dog will run towards you to have food each time you ring a bell but if you change the bell and use a gong your dog will not give you the same response.

  • Spontaneous recovery:

After extinction and a period of rest, presenting the conditioned stimulus without the unconditioned stimulus will again elicit a weak conditioned response.

   4. Pavlov’s experiment

       In his experiment Pavlov used food as a natural stimulus and the salvation of the dog as the unconditioned response. Whenever he feed the dogs, he always rang a bell (neutral stimulus).  After repeating this procedure a number of times, he only rang the bell without bringing the food. Like expected, dog’s salivation level increased when Pavlov rang the bell. The dog had learned an association between the bell and the food and developed a new behavior. Because this response was conditioned to learn, it is known as the conditioned response.

Before Conditioning:

Food (unconditioned stimulus)                                                         

salvation (unconditioned response)

Bell (neutral stimulus)

No response

During Conditioning:

Food + Bell

salvation (unconditioned response)

After Conditioning:

Bell (conditioned stimulus)

Salvation (conditioned response)  



  • Pavlov, I. P. (1928). Lectures on conditioned reflexes: Twenty-five years of objective study of the higher nervous activity (behavior) of animals (W. H. Gantt, Trans.)

  • SCIENCES HUMAINES N°3 - SEPTEMBER 2000- 48 F. P (26-27)

See Also:


Operant Conditioning

Trial and error

Conditioning Watson and little Albert

Behavior therapies