People often like to think they control their behaviour. But the truth is, external forces often condition our reactions, sometimes without us even being aware of it. Suppose you are scared of thunder. Every time you see a bolt of lightning, you might wince in expectation of thunder noise. That conditioned response is what’s called in psychology classical conditioning.
The Russian physiologist Ivan Pavlov discovered classical conditioning. Pavlov’s dogs inspired his experiment (1897) when he noticed the dogs salivating as soon as his assistant opened their cage doors because they associated open doors with receiving food.
Pavlov (1897) decided to test this hypothesis by conducting a new experiment in which each time the dogs were given food (stimulus 1), a bell sounded (stimulus 2), and the dogs slowly learned that the ringing of a bell was synonymous with food (new learned response). He observed and investigated the factors that can influence the strength and speed of learning by association and how they can provide explanations for some behaviours in humans, such as neurosis.
What is classical conditioning in psychology?
First, let's untangle the definition of classical conditioning.
Classical conditioning involves the association of two stimuli to elicit a new learned response in animal and human behaviour. It can also be referred to as learning by association or learning by conditioning.
According to John Watson (1913), classical conditioning explains all aspects of human psychology based on Pavlov’s findings and observations.
Pavlov's classical conditioning research
In the 1890s, Pavlov studied salivation in dogs as an expectant response to being fed. He placed a small tube in each dog’s cheek to measure the amount of saliva when they were being fed. He expected the dogs to salivate at the sight of food, but instead, they salivated at the sound of the footsteps of his assistant, who was in charge of feeding them. He found that the dogs elicited a similar response to anything (lab assistant) paired with food. Pavlov researched this scientific discovery for many years.
Key terms in classical conditioning
A neutral stimulus is an event that does not elicit a response.An unconditional stimulus is an event that produces a natural or innate response.An unconditional (innate) response is an unlearned natural response to an unconditioned stimulus.The conditioned stimulus is an event that elicits a learned response.The conditioned response is a learned response elicited by conditioned stimuli.
Pavlov’s classical conditioning experiment
Pavlov based his study on the idea that some responses in dogs are innate and not learned. For example, dogs salivate naturally at the sight of food; they do not learn this response because it is naturally wired into them. Pavlov concluded from this observation that the unconditioned stimulus is the food, which leads to an unconditioned response, the dog’s salivation.
The unconditioned stimulus is food → The unconditioned response is salivation.
Pavlov strapped the dog into a harness attached to an apparatus that measured the rate and amount of salivation in three stages.
The dog’s salivation was measured once when only ringing the bell.
Neutral stimulus (bell) → No conditioned response.
He again measured the saliva when giving food to the dog.
Pavlov measured saliva when he rang the bell and presented the food at the same time.
These steps were repeated several times to condition the dogs to learn this association. The dog’s saliva levels were high after this conditioning with just the ringing of the bell, but without food. This step was crucial to measure the strength of the learned response. The neutral stimulus now became the conditioned stimulus.
Conditioned stimulus (bell) → Conditioned response (salivation).
According to Pavlov, a conditioned response can only be learned if both stimuli occur at the same time. If there is a large time difference between the occurrence of the conditioned stimulus (bell) and the unconditioned stimulus (food), the association cannot be learned. This time difference is called temporal contiguity.
Pavlov greatly contributed to the theory of classical conditioning, which many researchers replicated after him. Although Pavlov’s theory formed the basis of classical conditioning, researchers who came after him added some important arguments for and against this theory.
- The theory of classical conditioning is considered scientific because Pavlov showed that it provided empirical evidence through a controlled experiment.
- John Watson (1913), in his Little Albert experiment (little Albert was conditioned to fear a rat), showed that classical conditioning explains all aspects of human psychology based on Pavlov’s findings and observations.
- Pavlov’s experiment supports the claim that our learning depends mainly on our environment. He rules out the possibility that we can learn some behaviours through the interaction of nature (biological) and the environment (cultivated).
- Classical conditioning is easily tested in a controlled laboratory setting. However, it may not apply to and explain complex human behaviours such as problem solving and memory.
- Classical conditioning is deterministic, however, in that it constrains the individual’s free will with respect to the response to be learned, just as little Albert had to learn to fear a rat in John Watson’s experiment (1913).
Classical Conditioning - Key takeaways
The Russian physiologist Ivan Pavlov discovered classical conditioning in 1897.
In classical conditioning, two stimuli are combined to elicit a new, learned response in animal and human behaviour.
Pavlov based his study on the idea that some responses in dogs are innate and not learned.
Pavlov (1897) found that each time dogs were given food (stimulus 1) and heard a bell ring (stimulus 2), they slowly learned that a ringing bell was equivalent to food (new learned response).
The theory of classical conditioning is considered scientific because it is a lab-controlled experiment with empirical evidence.
By Dr. Saul McLeod, updated 2021
Like many great scientific advances, Pavlovian conditioning (aka classical conditioning) was discovered accidentally. Ivan Petrovich Pavlov (1849–1936) was a physiologist, not a psychologist.
During the 1890s, Russian physiologist, Ivan Pavlov was researching salivation in dogs in response to being fed. He inserted a small test tube into the cheek of each dog to measure saliva when the dogs were fed (with a powder made from meat).
Pavlov predicted the dogs would salivate in response to the food placed in front of them, but he noticed that his dogs would begin to salivate whenever they heard the footsteps of his assistant who was bringing them the food.
When Pavlov discovered that any object or event which the dogs learned to associate with food (such as the lab assistant) would trigger the same response, he realized that he had made an important scientific discovery. Accordingly, he devoted the rest of his career to studying this type of learning.
Pavlovian Conditioning
Pavlov (1902) started from the idea that there are some things that a dog does not need to learn. For example, dogs don’t learn to salivate whenever they see food. This reflex is ‘hard-wired’ into the dog.
In behaviorist terms, food is an unconditioned stimulus and salivation is an unconditioned response. (i.e., a stimulus-response connection that required no learning).
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Pavlov's DogsUnconditioned Stimulus (Food) > Unconditioned Response (Salivate)
In his experiment, Pavlov used a metronome as his neutral stimulus. By itself the metronome did not elecit a response from the dogs.
Neutral Stimulus (Metronome) > No Conditioned Response
Next, Pavlov began the conditioning procedure, whereby the clicking metronome was introduced just before he gave food to his dogs. After a number of repeats (trials) of this procedure he presented the metronome on its own.
As you might expect, the sound of the clicking metronome on its own now caused an increase in salivation.
Conditioned Stimulus (Metronome) > Conditioned Response (Salivate)
So the dog had learned an association between the metronome and the food and a new behavior had been learned. Because this response was learned (or conditioned), it is called a conditioned response (and also known as a Pavlovian response). The neutral stimulus has become a conditioned stimulus.
Pavlov found that for associations to be made, the two stimuli had to be presented close together in time (such as a bell). He called this the law of temporal contiguity. If the time between the conditioned stimulus (bell) and unconditioned stimulus (food) is too great, then learning will not occur.
Pavlov and his studies of classical conditioning have become famous since his early work between 1890-1930. Classical conditioning is "classical" in that it is the first systematic study of basic laws of learning / conditioning.
Summary
To summarize, classical conditioning (later developed by Watson, 1913) involves learning to associate an unconditioned stimulus that already brings about a particular response (i.e., a reflex) with a new (conditioned) stimulus, so that the new stimulus brings about the same response.
Pavlov developed some rather unfriendly technical terms to describe this process. The unconditioned stimulus (or UCS) is the object or event that originally produces the reflexive / natural response.
The response to this is called the unconditioned response (or UCR). The neutral stimulus (NS) is a new stimulus that does not produce a response.
Once the neutral stimulus has become associated with the unconditioned stimulus, it becomes a conditioned stimulus (CS). The conditioned response (CR) is the response to the conditioned stimulus.
Classical conditioning is learning through association and was first demonstrated by Ivan Pavlov. Pavlov showed that dogs could be conditioned to salivate at the sound of a bell if that sound was repeatedly presented at the same time that they were given food.
First the dogs were presented with the food, they salivated. The food was the unconditioned stimulus and salivation was an unconditioned (innate) response. Then Pavlov sounded the bell (neutral stimulus) before giving the food.
After a few pairings the dogs salivated when they heard the bell even when no food was given. The bell had become the conditioned stimulus and salivation had become the conditioned response.
The dogs had learnt to associate the bell with the food and the sound of the bell and salivation was triggered by the sound of the bell.
Pavlov showed that classical conditioning leads to learning by association. Watson and Rayner showed that phobias can be learnt through classical conditioning in the “little Albert” experiment.
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How to reference this article:
McLeod, S. A. (2018, October 08). Pavlov's dogs. Simply Psychology. www.simplypsychology.org/pavlov.html
APA Style References
Pavlov, I. P. (1897/1902). The work of the digestive glands. London: Griffin.
Pavlov, I. P. (1928). Lectures on conditioned reflexes. (Translated by W.H. Gantt) London: Allen and Unwin.
Pavlov, I. P. (1927). Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex. Translated and edited by Anrep, GV (Oxford University Press, London, 1927).
Pavlov, I. P. (1955). Selected works. Moscow: Foreign Languages Publishing House.
Watson, J.B. (1913). Psychology as the behaviorist Views It. Psychological Review, 20, 158-177.
Download this article as a PDF
How to reference this article:
McLeod, S. A. (2018, October 08). Pavlov's dogs. Simply Psychology. www.simplypsychology.org/pavlov.html
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