Monthly Archives: May 2012

MYSTERIES OF THE BRAIN Part 22: Classical conditioning and beyond

Veritas Readers,


                This is the 22nd part of The “Mysteries of the Brain” series.  All earlier episodes are available on the VERITAS blog site(  Look at the “Mysteries of the Brain” tag).

                Most of us have read or heard about Pavlov conditioning. However there are some lesser known experiments that he did and these experiments give some very interesting insights as to how our mind works. In this VERITAS we will study Pavlov’s experiments and their very interesting insights.

                Ivan Petrovich Pavlov was not really researching about how the brain works. He was more interested in digestion. In the 1890s he was doing experiments on digestion using dogs at the university of Saint Petersburg. He observed that the dogs started salivating whenever they saw the lab technician who usually fed them even if he arrived without any food. Pavlov wanted to understand this association and devised a series of experiments which hugely increased our understanding about our minds and our behavior.

                Pavlov started preceding the feeding of the dogs by the ringing of a bell. So first a bell rang and a few moments later the dogs were given food. After a few days of doing this Pavlov saw that the dogs started salivating as soon as they heard the bell. So the dogs had formed an association between the bell and the food. After a few days the bell was sounded without the food being given immediately afterwards. But the dogs continued to salivate at the sound of the bell. So the bell that now had nothing to do with food still triggered a salivating response in the dogs. This phenomenon is called conditioning( some people call it classical conditioning or Pavlov conditioning). Note that this is an subconscious effect.

                A few technical terms to help you understand other articles on Pavlovian conditioning using the above example

1)      Food: Unconditioned stimulus

2)      Salivation on seeing food: unconditioned response

3)      Bell: First this is a neutral object but after  the dog makes an association between the bell and the food this becomes conditioned stimulus.

4)      Salivation on hearing the bell: Conditioned response. This is not a natural response but has been learnt by association.

                A lot of our behavior is based on Pavlov conditioning. Sometimes a particular song may take you into a different time and induce a mood that you felt when you had  heard that song in the past. Let’s take the example of mathematics. We have millions of people with a fear of mathematics even in adulthood. Why? Because mathematics is associated in childhood with unpleasant feelings of fear, worry, and lowering of self esteem by “not-so-well-versed in psychology” teachers and parents. Let’s take another example: young children who suffer from cancer are sometimes given an ice cream before chemotherapy as a reward for agreeing to undergo the painful experience. Now chemotherapy induces nausea. Even when such a child grows up the association between ice cream and nausea remains causing them to feel sick even at the sight or smell of ice cream.

                Pavlov conditioning is a very powerful effect and can have a permanent effect on a person’s brain. Its proper use can be used to improve education in our schools. Of course, schools sometimes(!) end up accidently using it in a negative manner causing kids to hate studies. Pavlov conditioning has been used to cure phobias and in behavior therapy of criminals. In case of criminals, Pavlov conditioning is used to associate physical discomfort with their criminal thoughts. For example sexually deviant people are made to smell unpleasant substances when they are describing their deviant fantasies. This causes a permanent aversion to whatever they were thinking. Such methods have, in recent years come under attack from rights activists.

                Now let me describe a lesser known but very interesting experiment conducted by Pavlov. Before we proceed further I must stress once again that conditioned response comes from the subconscious. The conscious brain has no control on it. Pavlov showed some images to the dogs: whenever he showed the image of a circle it was followed by food. When the image shown was an ellipse, the dogs were given a small electric shock afterwards.  The dogs quickly learned to differentiate between the two images. When the image of the circle was shown, the dogs would start salivating and wag their tails. When the image of the ellipse was shown, the dogs would start whining and would try to run away. After a few days of doing this, Pavlov decreased the eccentricity of the ellipse( made it less longer and more circular) by a small amount. The dogs had no problem differentiating between the ellipse and the circle and the respective reactions to seeing them stayed. Pavlov continued to decrease the eccentricity of the ellipse but the dogs continued to differentiate the ellipse from the circle and their reaction of fear at seeing the ellipse and salivating when seeing the circle continued. However when the eccentricity of the ellipse was made about 9:8( nearly a circle but not exactly) the dogs were not able to differentiate- and their reactions suddenly became completely unpredictable and weird. They did not know how to react. They became very anxious and would whine and even defecate on seeing the image. And they now gave the same reaction on seeing the circles. Some of them became so disturbed to see the circle or ellipse they had a nervous breakdown. So the dogs had the nervous breakdown because they were no longer able to differentiate a happy stimulus from an unhappy one and their subconscious minds did not know how to react. Thus when the subconscious mind experiences a conflict that it cannot resolve, it causes anxiety, nervousness and at times even mental breakdown. Note that after showing the ellipses of 9:8 eccentricity, the dogs lost all differentiation of even normal circles and ellipses. The earlier conditioning was lost and a new behavior of mental disturbance set in.

                Pavlov now tried to train the dogs to differentiate the circles from the ellipses again. Once again he started using normal eccentricity ellipses and followed them with electric shocks, and he used images of circles and followed their images with food. This time the dogs had a much more difficult time learning how to differentiate between ellipses and circles compared to the first time. So he observed that once the differentiation was lost, it was difficult to create again. So in a sense the dogs had become less sensitive to external stimulus. These experiments show us that there is a difference between the first experience of something and subsequent experiences- the first experience will always make the mind condition to the stimulus much faster and better than subsequent experiences.

                Based on Pavlov’s findings, Eysenck formed his theory of extroversion and introversion. An introvert is more sensitive to external stimulus and easily conditioned. An extrovert is less sensitive and his subconscious brain is more difficult to condition. The reason for extroversion may be natural or acquired- maybe that person has been through that experience earlier and similar experiences do not cause the same conditioning and differentiation- much like Pavlov’s dogs shown the circles and ellipses after they had lost the differentiation.

                I think Pavlov’s experiments tell us a lot about how we learn things and how experience the world around us.  I don’t think we really understand how we can apply classical conditioning to enhance the learning experience of students and make studies less stressful and confusing. Also classical conditioning can give us extremely important insights into why people behave the way that they do and how socially beneficial behavior can be learnt not just by individuals but also by the whole society if we think of society as a collective conscience.

Pavlov received the Nobel Prize in 1904. But that was not for his contributions to psychology- that was for his studies on the digestive system.  

                After Pavlov’s experiments, a lot of psychologists started thinking about conditioning and its impact on behavior. They began to expand the scope of conditioning beyond classical conditioning. In general, Conditioning is an learnt association of things with each other at a subconscious level. When I say learnt I mean that this association is not natural but is acquired by a constant association which we experience in our lives. We have studied Classical conditioning. Now lets briefly look at Evaluative conditioning and social conditioning.

                Evaluative conditioning is the association of likes or dislike towards something related to something else that you may like or dislike. Lets take an example: if we strongly dislike someone say A . And a different person, B always is found with A, then we may start disliking B as well. This kind of conditioning is the basis of a lot of advertisements. You may like a celebrity and if he or she appears to like a product, you will start associating that celebrity’s characteristics with that product and will start liking it. That is why advertisers are very conscious about the brand value of celebrities. When a celebrity gets involved with a controversy( as they so often do), suddenly they start getting less advertisements.

                A very interesting experiment demonstrating evaluative conditioning was done some years back: a set of people were treated to a delicious free lunch and during the course of the lunch, a set of political slogans were shown to them. Another set of people were taken to a room filled with bad odours, and in the room they were shown the same political slogans. It was found that the free lunch subjects had a much more favourable opinion of the slogans compared to the people who saw the slogans in the bad odour filled room. This is evaluative conditioning.

                Another example which I am sure a lot of you would be familiar with. Sometimes during the naming of a new born child, parents tend to disagree with each other a lot on the choice of names. Why? Because they have associated names with characteristics of people who had those names! A husband may have had a favourite teacher named Suresh in childhood. So for him the name Suresh stands for love for knowledge, patience and kindness. However the wife may have met a uncouth, ill-mannered person named Suresh. And for her Suresh is a very bad name for a child. This is conditioning. Remember, all this is happening at a sub-conscious level!

                Now, lets talk about social conditioning. Society tends to favour certain behaviours and disapprove others. This causes a subconscious conditioning in the minds of individuals who grow up in that society. It may be related to what choice of professions are “better”,  what “kind of people” are to be liked or disliked. Even, the concept of physical beauty is related to social conditioning. The society floods us with images and messages of what is beauty and what is not. And people’s minds get conditioned to it. For example, why do Indians associate fairness with beauty? Social conditioning. Come to think of it, even patriotism is an example of social conditioning. Why should your love for humanity stop at the border? Because society wants you to think that the people on this side are our people and the people on the other side of that artificial line side are not ours- and not so nice. Social conditioning.



Go wondrous creature, mount where science guides

go measure earth, weigh air, state the tides,

instruct the planets in what orbs to run

correct old time, regulate the sun