Classical Conditioning (Ivan Pavlov): This type of learning was first investigated by Ivan P. Pavlov. His interest was mainly in the physiology of digestion. During his study he observed that the dogs on which he was conducting his experiments started salivating at the sight of an empty plate in which food was served. As you should know, secretion of saliva is a reflex reaction to food or something in the mouth. Pavlov designed an experiment to understand this process in detail, again using dogs.

In the first phase, a dog was placed in a box and harnessed. The dog was left in the box for some time. This was repeated several times on different days. Meanwhile, a simple surgery was performed and one end of a tube was inserted into the dog’s jaw and the other end of the tube was put into a measuring glass.

The experimental setup is shown in Figure 3.2. In the second phase of the experiment, the dog was kept hungry and one end of the tube was placed in the jaw and the other end was kept in a glass jar. The bell was rung and immediately thereafter food (meat powder) was served to the dog. The dog was allowed to eat it. For the next few days, whenever meat powder was presented, a bell would be rung. After several such trials, a test trial was introduced in which everything was the same as in the previous trials, except that no food was eaten after the bell was rung. The dog was still salivating upon hearing the sound of the bell, expecting the presentation of meat powder because the sound of the bell was associated with it. This association between the bell and food resulted in the dog developing a new response, i.e. salivation to the sound of the bell. This is called conditioning.

You must have noticed that all dogs drool when they are given food. Thus food is an unconditioned stimulus (US) and salivation that follows it is an unconditioned response (UR). After conditioning, salivation began in the presence of the bell sound. The bell becomes a conditioned stimulus (CS) and saliva secretion becomes a conditioned response (CR). This type of conditioning is called classical conditioning. The process is shown in the figure.

Principles Of Classical Conditioning

Extinction It was noted by Pavlov that if the conditioned stimulus (ringing of the bell) is presented alone a number of times without the food, the magnitude of the conditioned response of salivation begins to decrease, and so does the probability of its appearing at all. This process of gradual disappearance of the conditioned response or disconnection of the S. R association is called extinction.

Spontaneous Recovery It was also discovered by Pavlov that after extinction, then a controlled response is no longer evident. The behavior after reappears spontaneously but at a reduced intensity. This phenomenon of the reappearance of an apparently extinguished conditioned response (CR) after an interval in which the pairing of conditional stimulus (CS) and unconditional stimulus(CS) has not been repeated is called spontaneous recovery.

Stimulus Generalisation Responding to the stimulus is such a generalized way was termed as stimulus generalization with reference to a particular stage of learning behavior in which an individual once conditioned to respond to a specific stimulus is made to respond in the same way in respond to other stimuli of similar nature.

Stimulus Discrimination Stimulus discrimination is the opposite of stimulus generalization. Here, sharp contrast to responding in a usual fashion the subject learns to react differently in different situation.

Implication of Classical Conditioning

Our behavior in the form of interests, attitudes, habits, moods and dispositions of experiment or criticism is formed through conditioning. The process of conditioning, not only helps in learning what is desirable but also helps in eliminating, avoiding or preventing the learning of undesirable habits, unhealthy attitudes, superstitions, fears and phobias through de-conditioning. A person who hates a particular person or thing may be induced to enjoy their company. Another person who thinks it is a bad sign if a car crosses his path may be asked to give up his superstition.