Classical Conditioning

Classical Conditioning
Pavlov's dog


Classical conditioning was accidentally discovered around the beginning of the 20th century by Russian physiologist Ivan Pavlov. ††Pavlov was studying digestive process in dogs when he discovered that the dogs salivated before they received their food.In fact, after repeated pairing of the lab attendant and the food, the dogs started to salivate at the sight of the lab assistants. Pavlov coined this phenomena ďpsychic secretions."He noted that dogs were not only responding to a biological need (hunger), but also a need developed by learning.Pavlov spent the rest of life researching why this associate learning occurred, which is now called classical conditioning.

To experiment on classical conditioning, Pavlov utilized a tuning fork and meat powder. He hit the tuning fork and followed the sound with the meat powder.Pavlov presented the sound (tuning fork) with the meat powder at the exact same time increments.In the beginning, the dog salivated only to the meat powder, but after this was repeated, salivated at the sound of the tuning fork.Even when Pavlov took away the meat powder, the dog continued to salivate at the sound of the tuning fork.

In classical conditioning, an organism learns to associate one stimulus with another.The organism learns that the first stimulus is a cue for the second stimulus.In Pavlovís experiment above, the tuning fork cued the dogs that food might be coming. Following is an example of classical conditioning.

Classical Conditioning In technical terms, the food is an unconditioned stimulus (UCS) and the salivation is the unconditioned response (UCR).The bell is a neutral stimulus until the dog learns to associate the bell with food. Then the bell becomes a conditioned stimulus (CS) which produces the conditioned response (CR) of salivation after repeated pairings between the bell and food.

John B. Watson was interested in how classical conditioning could be applied to humans.In 1921, Watson and his research assistant Rosalie Rayner experimented on a 11-month-old infant named Albert.The goal was to condition Albert to fear a white rat by paring the white rat with a loud bang (UCS). Initially, Albert showed no fear of rats, but once the rat was repeatedly paired with the loud noise (UCS), Albert developed a fear of rats.The noise (UCS) induced fear (UCR).After pairings between the loud noise (UCS) and the rat (CS), Albert started to fear the rat.Watsonís experiment suggested that classical conditioning could cause some phobias.

Baby Albert


  • Unconditioned Stimulus (UCS)
    A stimulus that elicits a response without conditioning

  • Unconditioned Response (UCR)
    Automatic response elicited by the unconditioned stimulus

  • Conditioned Stimulus (CS)
    A neutral stimulus that when paired with an unconditioned stimulus (UCS) elicits a similar response
  • Conditioned Response (CR)
    A response that is learned by pairing the originally neutral conditioned stimulus (CS) with the
    unconditioned stimulus (UCS)

  • Acquisition
    The acquisition phase is the consistent parings of the CS (bell) and the UCS (food) that produces a CR (salivation).In the example above, this phase occurs when the dog begins to salivate at the sound of the bell.Conditioning occurs more rapidly when the food follows the bell by a half a second.

  • Extinction
    The extinction phase is when the conditioned response no longer occurs after repeated pairings without the unconditioned stimulus. The dogís response to the bell can be extinguished by repeatedly presenting the bell (CS) without the food (UCS).The dog has not completely forgotten the association between the bell and the food.If the experimenter waits a day, the dog may have a spontaneous recovery of the conditioned response and salivate again to the bell.

  • Generalization
    Occurs when there is a small difference in the presented stimulus and the original conditioned stimulus.If Pavlovís dog heard a bell of a similar tone, the dog would still salivate.

  • Discrimination
    The opposite of generalization, discrimination happens when a conditioned response does not occur when there is a difference between the presented stimulus and the original conditioned stimulus. † If Pavlovís dog heard a bell with a different tone and was not awarded the unconditioned stimulus (food), the dog would learn not to salivate to the second tone.

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Operant Conditioning

Ivan Pavlov
John B. Watson
B.F. Skinner