Ivan Petrovich Pavlov




Classical Conditioning

Higher-order Conditioning

Explanations for Classical Conditioning - Timing

Basic Processes in Classical Conditioning

Classical Conditioning in Everyday Life





'I would prefer to remain a pure physiologist, that is, an investigator who studies the functions of separate organs, the conditions of their activity, and the synthesis of their function in the total mechanism as a part or in the whole of the organism; and I am little interested in the ultimate, deep basis for the function of an organ or of its tissues, for which primarily chemical or physical analysis is required.'

I.P. Pavlov cited in Dean Calsbeek, 1999

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Despite his personal identification as a physiologist Pavlov became one of the best-known figures in the history of psychology.
Being born on September 14, 1849 in a small village, called Ryazan in central Russia, Ivan Petrovich Pavlov was the first born of 11 siblings. His father, Peter Dimitrievich Pavlov was the local village priest. Due to an accident Pavlov's primary education at the church school in Ryazan was delayed (Dean Calsbeek, 1999).
Following in his fathers footsteps he entered the Ecclesiastic Seminary in Ryazan, where he planned to pursue a career in theology.

However, after being introduced to the work of Charles Darwin and Ivan Sechenov, Pavlov's interest in natural science made him abandon his religious career. He decided to transfer to the University of St. Petersburg, where he studied animal physiology and medicine. After obtaining his medical degree (doctorate) in 1883 Pavlov intensified his studies in Germany at the University of Leipzig.

Two years later he returned to St. Petersburg and worked as an assistant in a physiology laboratory until he was appointed Professor of Pharmacology at the Military Medical Academy in 1890. In 1895 he was further appointed to the Chair of Physiology which he held until 1925 (Nobel Lectures, 2001).

Also in 1890 Pavlov became head of the Department of Physiology at the Institute of Experimental Medicine. This is where he conducted his research on physiological topics, such as digestion and blood pressure, using dogs as experimental animals.
At the age of 50 Pavlov began to study Classical Conditioning which he continued for the next 30 years ( Lefrancois, 1999).
The experiments provided also an income for Pavlov as he sold the 'gastric juices' collected, which were back then in high demand for the cure of stomach ailments (Kentridge, 1995).

In 1904 Pavlov received the Nobel Prize in Physiology and Medicine for his work on the physiology of the digestive glands.
In 1925 he founded the Pavlov Institute of Physiology of the Russian Academy of Science, where under his guidance from 1925 to 1936 problems of physiology, pathology and genetics of the higher nervous activity were intensively investigated (Pavlov Institute of Physiology of the Russian Academy of Science, 2001).
Pavlov died in 1936 in Leningrad.

For a detailed Biography go to Nobel e-Museum

For a short overviw visit 'A Science Odyssey'

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Classical Conditioning

'Classical Conditioning is a type of learning in which a stimulus acquires the capacity to evoke a response that was originally evoked by another stimulus' (Weiten, 1995).
Pavlov discovered this form of learning almost accidentally, while conducting his research on the digestive system of dogs. By surgical means he had implanted a tube in a dogs salivary gland which collected the salvia produced after placing food powder in the dogs mouth. Pavlov observed that some of his dogs began to salivate before they were fed. And he noticed further that this occurred only in dogs that were used to the laboratory surrounding (Lefrancois, 1999).
Fascinated by his findings Pavlov decided to investigate further. In order to clarify what was happening, he paired the presentation of the meat powder with an auditory stimulus. Pavlov used a tone and presented it together with meat powder. After having presented the meat powder paired with the tone for a number of trials, the tone was presented alone. Results showed that the dogs now salivated as a reaction to the tone without receiving any meat powder.
In his demonstrations Pavlov referred to the food as an unconditional stimulus (US). Being called a stimulus, because it is an environmental event that affects the organism and unconditional, because it leads to an natural, unlearned response.
The initial salivation to the food is called unconditional response (UR), as it is a response that occurs without learning.
In contrast, the bond between the tone and salivation was established through conditioning. Therefore the former neutral stimulus (NS) is called conditional stimulus (CS) and the learned reaction to a conditional stimulus is called conditional response (CR) (Lefrancois, 1999).
Experimental arrangement similar to this is typically used in demonstrations of classical conditioning although the original setup (inset and above drawing) was much simpler. The dog is restrained in the harness. A tone is is used as the (CS) and the presentation of meat powder is the (US). The tube inserted into the dog's salivary gland allows precise measurement of its salivation response. The pen and rotating drum of paper on the left are used to maintain a continuous record of salivary flow. Pavlov originally colected the saliva on each trial (Weiten,1995).

The following graphics depict classical conditioning while using (UCS) for (US) and (UCR) instead of (UR).

For further graphical illustraction have a look at 'Behavioral Conceptions'

or at this side

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Higher-order Conditioning

In Higher-order conditioning a (NS) comes to elicit a (CR) by being paired with an already established (CS) (Weiten, 1995).
In the 'dog-case' the (CS), the tone would for example be paired with a (NS) like a red light or as shown below a ball. After a number of trials the dog will salivate in response to the red light or the ball.

Tom Creed has created an animated illustration of the red light experiment.

Now Conditioned Stimulus

Random Object (NS)
The dog salivates when he/she hears the bell and sees the random object.

Neutral stimulus
The neutral stimulus has been modified to make the dog salivate.

(Taken from 'Behavioral Conceptions')

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Explanations for learning - Timing

Contiguous events usually occur at the same time and place. Not so in classical conditioning where Contiguity does not necessarily mean that the (CS) starts and ends at the same time as the (US) does (Lefrancois, 1999).
Precise timing has a great influence on whether the (CS) can be reliably conditioned to produce the (CR) (Kentridge, 1995).

Simultaneous conditioning occurs when (CS) and (US) begin at the same time. The conditioning in this temporal arrangement is rather weak (Lefrancois, 1999).

Delayed conditioning is a far more effective temporal arrangement. The (CS) is presented before the (US) and continues during presentation of the (US). It is called 'delayed' pairing due to the time lag between the presentation of the (CS) and the beginning of the (US) (Lefrancois, 1999).

InTrace conditioning the (CS) starts and ends before the (US), so that there is a very brief time laps between both stimuli. In cases where the time laps is longer than half a second or so, trace conditioning is not very effective (Lefrancois, 1999).

In Backward conditioning the (US) has already been presented and removed before the presentation of the (CS). Backward conditioning is controversial because many psychologists argue that it does not work (Exploring Psychology, 2001).

For an more info go to 'Temporal Relationship of Stimuli'

Reinforcement is a more complex concept, referring to the effects of a stimulus.
One kind of reinforcement for example, is positive reinforcement, in which an effect like the satisfaction of hunger leads to learning (Lefrancois, 1999). This understanding is more relevant in operant conditioning.
For classical conditioning reinforcement is simply the repetition of (US) and (CS) (Stratton & Hayes, 1999).

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Basic Processes in Classical Conditioning

Acquisition is referred to the phase in which a response is learned or strengthened. In laboratory experiments, a single pairing of the (CS) with the (US) is not usually sufficient for learning to take place. But with increasing number of pairings, the (CR) occurs more frequently and more strongly. The strength of the (CR) is not only influenced by timing of (US) and (CS) but also by the intensity of the (US). Speaking in general, the stronger the (US), the more quickly will (CR) reach its peak (Lefrancois, 1999).

Extinction refers to the elimination of a response due to repeated presentation of the (CS) without the (US). If, for example a bell being the (CS) is presented to a dog without food, the dog will eventually stop salivating.

Spontaneous recovery describes the phenomenon that occurs when after an interval of time a previously extinguished response reappears, although at a lower intensity.
To completely extinguish the response, it would be necessary to present the (CS) without the (US) again and repeat this procedure a number of times. Eventually, there would no longer be evidence of spontaneous recovery (Lefrancois, 1999).

The following graph is taken from 'Pavlovian Conditioning' by T. Creed.

For graphical support see The classical conditioning paradigm

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Classical Conditioning in Everyday Life

Phobias are one example where certain objects or situations are classical conditioned to elicit a irrational fear. Being stuck in a hot, overcrowded elevator with a group of frightened and sweating fellow passengers might lead to a fear of elevators or perhaps produce a phobia of elevators.

Anxiety responses are less severe compared to phobias but can also be products of classical conditioning. Some people for example cringe when they hear a dentist drill. The pain experienced as a cause of the dentist drill is functioning as a (UR). The pain has been paired with the sound of the drill, which became a (CS), eliciting the cringe. For a 'self-test' go to this side

Further examples of classical conditioning in everyday life can be found among emotional responsesor in advertisement. The following examples have been taken from a side called 'Classical conditioning'.


This type of influence is extremely common. If you have pets and you feed them with canned food, what happens when you hit the can opener? Sure, the animals come running even if you are opening a can of green beans. They have associated the sound of the opener with their food.

Classical conditioning works with people, too. Go to K-Mart and watch what happens when the blue light turns on. Cost conscious shoppers will make a beeline to that table because they associate a good sale with the blue light. (And, the research proves that people are more likely to buy the sale item under the blue light even if the item isn't a good value.)

And classical conditioning works with advertising. For example, many beer ads promeniently feature attractive young women wearing bikinis. The young women (Unconditioned Stimulus) naturally elicit a favorable, mildly aroused feeling (Unconditioned Response) in most men. The beer is simply associated with this effect. The same thing applies with the jingles and music that accompany many advertisements.

Perhaps the strongest application of classical conditioning involves emotion. Common experience and careful research both confirm that human emotion conditions very rapidly and easily. Particularly when the emotion is intensely felt or negative in direction, it will condition quickly.

For example, when I was in college I was robbed at gun point by a young man who gave me The Choice ('Your money or your life.') It was an unexpected and frightening experience. This event occurred just about dusk and for a long time thereafter, I often experienced moments of dread in the late afternoons particularly when I was just walking around the city. Even though I was quite safe, the lengthening shadows of the day were so strongly associated with the fear I experienced in the robbery, that I could not but help feel the emotion all over.

Clearly, classical conditioning is a pervasive form of influence in our world. This is true because it is a natural feature of all humans and it is relatively simple and easy to accomplish ('Classical Conditioning',1996).

A variety of advertisments can be found here

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Concluding it can be stated that Pavlov's discovery of conditional reflexes while studying digestion in dogs led to a systematic investigation of learning processes, and established the principles of classical conditioning. These were taken as a foundation of behaviourism by J.B. Watson and so influenced the development of psychology.

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the formation of a new conditioned response tendency.
Classical Conditioning
a type of learning in which a neutral stimulus acquires the ability to evoke a response that was originally evoked by another stimulus.
Conditional Stimulus
a previously neutral stimulus that has, through conditioning, acquired the capacity to evoke a conditional response.
Conditional response
a learned reaction to a conditioned stimulus that occurs because of previous conditioning.
the occurrence of things both simultaneously and in the same space.
in classical conditioning, the cessation of a response following repeated presentations of the CS without the US.
Interoceptive Conditioning
the conditioning of actions involving glands or involuntary muscles.
Operant conditioning
The process of changing behaviour by manipulating its consequences.
a simple unlearned stimulus-response link, such as salivating in response to food in one's mouth.
Spontaneous recovery
spontaneous reappearance of a response that had previously been extinguished.
the effects of a reinforcer, specifically, to increase the probability that a response will occur.
Unconditional stimulus
a stimulus that evokes a unconditional response without previous conditioning.
Unconditional response
an unlearned reaction to an unconditioned stimulus that occurs without previous conditioning.

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Lefrancois, G.R. (1999). Theories of human learning. Belmont: Wadsworth.

Weiten, W. (1995). Themes & variations 3/e. (3rd ed.). Pacific Grove: Brooks/Cole

Stratton, P. & Hayes, N. (1999). Psychology. (3re ed.). London: Arnold

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This side was composed by Judith Mönter; ID 98101292
for Massey University, Paper: 175.202