Ivan Pavlov was a Russian physiologist known primarily for his work on developing the principles of classical conditioning. Pavlov’s classical conditioning has found numerous applications: in behavioural therapy, across experimental and clinical environments, in educational classrooms as well as in treating phobias using systematic desensitisation.


Pavlov looked at the digestive process in dogs, especially the interaction between salivation and the action of the stomach; thereby realising they were linked by reflexes in the autonomic nervous system. Without salivation, the stomach did not get the message to start digesting. Pavlov wanted to see if external stimuli could affect this process, so he rang a bell at the same time he gave the experimental dogs food. After a while, the dogs, which before only salivated when they saw and ate their food, would begin to salivate when the bell rang, even if no food were present.

The initial stage highlighting the US and UR, where in Pavlov's' case this was represented by the dog seeing food and then the dog salivates. This is a natural sequence of events. The US and UR are an unlearned stimulus response unit, called a reflex.

Food ---> Salivation

The next stage was the actual experiment, adding a second stimulus, the bell, would hopefully elicit the same response as the initial stimulus, the food. Pavlov was able to do this via repeated trials where the bell and food was made available simultaneously.

Bell with

Food ---> Salivation

After numerous trials, the second stimulus, the bell, elicited the desired UR from the dog, as the dog would associate hearing the bell with the appearance of food.

Bell ---> Salivate

In essence, Classical Conditioning is basically the connected relationship between two things, US (Food) and UR (Salivation), with the addition of a second thing CS (Bell) which eventually becomes strongly associated that it can produce old behaviour.

Food ---------------------> Salivation

Unconditioned Stimulus ---> Unconditioned Response


In regards to conditioned Stimulus (CS) and Conditioned Response (CR), Pavlov's experiment aimed to achieve this process via the experiment.

Conditioning Stimulus

Bell with

Food -----------------------> Salivation

Unconditioned Stimulus------> Unconditioned Response

Bell ---------------------> Salivation

Conditioned Stimulus ---> Conditioned Response


Ivan Pavlov Theory: Classical Conditioning

First discovered by Russian physiologist Ivan Pavlov (1849-1936), classical conditioning is a learning process governed by associations between an environmental stimulus and another stimulus which occurs naturally. 

All classical conditioned learning involves environmental interaction. For learning to occur, there must also be a ‘neutral stimulus’ which is then followed by a naturally occurring reflex. For instance, Pavlov’s dogs heard a tone (neutral stimulus) followed by salivating (naturally occurring reflex) in response to the arrival of food. Once the sound of the neutral stimulus became linked to the stimulus present in the environment (food arriving), it soon became possible to induce salivating just by sounding the neutral stimulus.     

The action of classical conditioning upon a subject is a three-phase process:


Phase 1: Pre-conditioned state

Classical conditioning demands a naturally occurring stimulus which will induce an automatic response. So at this stage, there is a UCS (unconditioned stimulus) linked to a UCR (unconditioned response) which occurs naturally. For instance, food produces salivating, or a stomach virus produces nausea.

At this point, the conditioned stimulus is still called the neutral stimulus because it currently has no effect.

Phase 2: Conditioning state

Next, a neutral stimulus is repeatedly introduced alongside the UCS. Soon, the neutral stimulus becomes linked with the UCS. Once this starts to happen, the neutral stimulus is transformed into a CS (conditioned stimulus) because the subject has now become conditioned to respond to the CS as if it were the natural UCR. For instance, you may associate a specific type of food with a stomach virus, or the bell ringing before getting food may be associated with receiving food.


Phase 3: Post-conditioning state

One the UCS and the CS are connected, the CS alone will trigger a response. At this final stage, the response has now become a CR (conditioned response). That means the subject has learned to produce the CR when triggered by the CS – which was previously just a neutral signal. So, the specific type of food now produces nausea (even if it wasn’t necessarily what caused the stomach virus), and the bell creates salivation.

In this way, you’ve unconsciously learned to associate the new stimulus (whether situation, object, person, etc.) with the response.

The key elements of classical conditioning:

1. Acquisition

Acquisition requires a neutral stimulus to become linked with an unconditioned stimulus. This must then be repeatedly reinforced to ensure strong learning takes place.

2. Extinction

Extinction (the opposite of acquisition) occurs when a conditioned response weakens or ceases to exist. For a conditioned response to be maintained, the unconditioned stimulus must be re-introduced occasionally to ‘top up’ the desired conditioned response. 

3. Generalisation of stimulus

Once a conditioned response has been created, it can tend to emerge as a response to other stimuli which appear similar. For instance, if a particular bell tone is the conditioned stimulus, similar sounding bell tones can elicit the same response.

Teachers can use classical conditioning to help children overcome some anxiety-provoking contexts. For instance, providing consistent reassurance and support may help a child who is anxious about reading aloud start to feel more calm and comfortable.

Based on his observations, Pavlov suggested that the salivation was a learned response. The dogs were responding to the sight of the research assistants' white lab coats, which the animals had come to associate with the presentation of food. Unlike the salivary response to the presentation of food, which is an unconditioned reflex, salivating to the expectation of food is a conditioned reflex.

Pavlov then focused on investigating exactly how these conditioned responses are learned or acquired. In a series of experiments, Pavlov set out to provoke a conditioned response to a previously neutral stimulus. He opted to use food as the unconditioned stimulus, or the stimulus that evokes a response naturally and automatically.

The sound of a metronome was chosen to be the neutral stimulus. The dogs would first be exposed to the sound of the ticking metronome, and then the food was immediately presented.

After several conditioning trials, Pavlov noted that the dogs began to salivate after hearing the metronome. "A stimulus which was neutral in and of itself had been superimposed upon the action of the inborn alimentary reflex," Pavlov wrote of the results.

"We observed that, after several repetitions of the combined stimulation, the sounds of the metronome had acquired the property of stimulating salivary secretion." In other words, the previously neutral stimulus (the metronome) had become what is known as a conditioned stimulus that then provoked a conditioned response (salivation).

Terms to know


Application: In Everyday life and Psychotherapies.

·       Now for an interesting part of Classical Conditioning; its part in a our day to day life, and the related methods that are used for therapy - counterconditioning.

·       Everyday life: Classical Conditioning can help to explain the simple things in life such as a person's reaction to a particular song, or smell as well as larger emotional problems such as fear and anxiety. Pavlov's dogs have explained why cats run to the kitchen simply at the sound of a Can Opener. Likewise, the family dog knows that he/she is going to be taken for a walk by the answer phone being switched on or the owner walking to where the leash is kept. Classical Conditioning also illustrates why a person may react in a peculiar way when a particular song is being played. Further investigation may find that a good or bad experience may have occurred for that person when the song was playing.

·       Psychotherapy:Classical Conditioning helps us to understand some fears and anxiety and points the way to finding a solution. For example, if a person associates the experiences of being bitten by a dog with going outside, the person my develope agoraphobia (fear of open spaces). This can be especially intense if the person keeps re-living the dog bite in his/her mind. Joseph Wolpe developed a technique called Systematic Desensitization, which is based on the process of pairing a new response with an old stimulus. Desensitization is developed to associate relaxation with the stimulus that had once induced fear and anxiety. Wolpe taught anxious clients to be physically relaxed then to slowly imagine themselves closer and closer to approaching the anxiety - provoking stimulus - all the while the client is to stay relaxed. The next step in Wolpe's process is for the person to move closer to the stimulus in real life.

·       Another technique of counterconditioning is Aversion Therapy. This is a behavior therapy with which an aversive stimulus is paired with a stimulus that induces an undesirable response (Weiten, 1998 p.617). For example, in therapy, alcoholics have their drinks paired with an emetic drug which causes nausea and vomiting. A conditioned response is created of aversion to alcohol through this pairing. Other behaviors which have been eliminated successfully with this method are drug abuse, sexual deviance, gambling and over eating.