Classical conditioning

Theory of Classical Conditioning

Pavlovian conditioning is also known as classical conditioning.  It is the learning through association and was discovered by Ivan P. Pavlov, a Russian physiologist. In other words, two stimuli are linked together to produce a response in a person or animal. John Watson recommended the practice of classical conditioning based on Ivan Pavlov work’s and was able to describe all the aspects of human psychology.

There are three stages of classical conditioning. At each point the stimuli and responses are given special scientific terms:

Stage 1: Before conditioning: This stage states that, the unconditioned stimulus (UCS) produces an unconditioned response (UCR) in an individual, which means that a stimulus in the environment who has produced a behavior/ response which is unlearned (i.e., unconditioned) and therefore it is a natural response which has not been taught. In this case, no new behavior has been learned yet.

According to Pavlov, this stage also involves another stimulus which has no impact on a person and it is called as neutral stimulus (NS). A person, object, place could be a neutral stimulus.

The neutral stimulus in classical conditioning does not produce a response until it is connected with the unconditioned stimulus.

Stage 2: During this stage, a stimulus which produces no response is associated with the unconditioned stimulus due to which it is known as conditioned stimulus (CS). In order to make classical conditioning effective, the conditioned stimulus should occur before the unconditioned stimulus, rather than after it, or during the same time. Thus, the conditioned stimulus acts as an unconditioned stimulus.

At this stage, the UCS must be associated with CS on a number of occasions, or trials, for learning to take place. However, learning can happen on certain occasions when it is not necessary for an association to be strengthened over time.

Stage 3: After conditioning: once the conditioned stimulus (CS) has been associated with the unconditioned stimulus (UCS) to create a new conditioned response.

Pavlovian Experiment:

Pavlov came across food conditioning unintentionally during his research into animals’ gastric systems. He wanted to observe and measure the salivation of the dog. This is a normal reflex response which humans would expect to happen as saliva plays a role in the digestion of food.

The procedure of the Pavlov experiment was that dog was placed in an isolated environment and restrained in a harness, with a food bowl in front of them and a device was used to measure the rate at which their saliva glands made secretions. These measurements were important so that Pavlov could monitor salivation rates throughout the experiments. He found that the dogs would begin to salivate when meat powder was served in front him. He repeated the trials and measures the salivation in dog. Then Pavlov decided to associate the sound of the bell with the meat powder in order to observe the learning of the dog and to measure the amount of saliva produced by the dog. This association could be created through repeating the neutral stimulus along with the unconditioned stimulus, which would become a conditioned stimulus, leading to a conditioned response, salivation. In order to test variety of neutral stimuli this would otherwise be unlinked to the receipt of food.  These included precise tones produced by a buzzer, the ticking of a bell.

Pavlov then started presenting the meat powder in front of the dog with a sound of the bell, and repeated the same thing for many days, so later he observed that dog salivated on the sound of the bell as dog learned that whenever the sound the bell triggers, meat powder is served in front of him.

The dogs would establish a related relationship between these events and the food that followed. Then Pavlov decided to present the dog with the sound of the bell which they would come to associate with food. He then played the sound of the bell but decided not to present food in front of the dog. After he made the sound without food numerous times, the dog produced less saliva as the conditioning underwent experimental extinction- a case of ‘unlearning’ the association.

Pavlov's experiment on dog

Criticism of Pavlov’s Experiment:

Pavlov used “internal inhibition” as an explanatory concept for the decrement in response in experimental extinction of conditioned responses, and negative, differential, delayed and trace conditioning and trace conditioning. Disinhibition is attributed to its removal by distraction, and sleep to its irradiating effects. It is argued that at least one of the factors causing the so-called gradual irradiating cortical inhibition is the relaxation of muscular tonus which may result from factors extraneous to the conditioning process itself, but involved in the experimental sett-up. Similarly, so –called “disinhibition” may result from experimentally included hypertension, or reinstatement of tonus. But relaxation does not account, for Wendt showed that experimental extinction and delayed, trace, and differential conditioned responses can develop without it. He interpreted it in terms of competition, or the reciprocal innervation of competing systems. Wenger summarizes his position in the form of four principles and a postulate, as follows: There are at least two forms of inhibition: a)reduction of proprioceptive facilitation, and b) shift of dominance to a competing reaction.” Certain deductions from the postulate are verifiable, as the effect of depressing and exciting drugs on experimental extinction, etc. Most of Pavlov’s work on inhibition and conditioning must be repeated, with drowsiness eliminated.  

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