Pavlovian Conditioning

Sometimes, a discovery seems too simple to believe its applications. This is the case with Pavlovian conditioning named after the doctor Ivan Pavlov. He was a doctor and besides his research  on the secrets of digestive system, he was interested in knowing what signals triggered the related phenomena such as secretion of saliva.

We know that saliva is secreted whenever food is presented before animals. This is called drooling. In us humans, an enzyme called Amylase is present in the saliva which breaks down the starch we eat into lower sugars which are sources of energy for sustaining our bodies. Similarly, dogs begin to drool whenever food is presented before them. But what strange thing he observed was that dog also began to drool whenever it saw the doctor’s coat. He concluded that dog formed an association with lab coat and associated it with food. He did more experiment of different kind. He will ring a bell and immediately present food to dog. After some days, he observed that dog began to secret saliva on ringing the bell even if he was not presented with food. This time dog has formed an association between ringing of bell and presentation of food. Pavlov’s discovery was that the environmental events that previously had no relation to a given reflex (such as a bell sound) could, through experience, can be made to trigger a reflex (salivation). This kind of learnt response is called conditioned reflex, and the process whereby dogs or humans learn to connect a stimulus to a reflex is called conditioning.

Animals generally learn to associate stimuli that are relevant to their survival. Food aversion is an example of a natural conditioned reflex. If an animal eats something with a distinctive vanilla taste and then eats a tasteless poison that leads to nausea, the animal will not be particularly eager to eat vanilla-flavoured food the next time. Linking nausea to taste is an evolutionarily successful strategy, since animals that failed to learn their lesson did not last very long.

This work has great spin off studies and changing of behavior.  An important principle in conditioned learning is that an established conditioned response (salivating in the case of the dogs) decreases in intensity if the conditioned stimulus (bell) is repeatedly presented without the unconditioned stimulus (food). This process is called extinction.

In order to treat phobias evoked by certain environmental situations, such as heights or crowds, this phenomenon can be used. The patient is first taught a muscle relaxation technique. Then he or she is told , over a period of days, to imagine the fear-producing situation while trying to inhibit the anxiety by relaxation. At the end of the series, the strongest anxiety-provoking situation may be brought to mind without anxiety. This process is called systematic desensitization.

Pavlovian conditioning is used in effective commercial advertising.  An effective commercial should be able to manipulate the response to a stimulus (like seeing a product’s name) which initially does not provoke any feeling. The objective is to train people to make the “false” connection between positive emotions (e.g. happiness or feeling attractive) and the particular brand of consumer goods being advertised.


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