Classical Conditioning

Modified: 2024-07-01 12.22 PM CDST

• Ivan Pavlov was a Russian physiologist.
  • During the early 20th century he worked on describing the process of digestion.
  • He developed techniques of collecting saliva from dogs.
  • He did so because salivation is the first step in digestion.
• He presented meat powder to his dogs, and then collected the saliva.
  • However, he soon noticed that as the dogs became familiar with the experimental routine they began to salivate before they received the meat powder.

  • That observation led Pavlov to investigate the process whereby dogs learned to associate the experimental routine with the meat powder.
  • That decision marked the time that Pavlov's research became psychological instead of physiological.
  • He systematically presented stimuli, e.g., metronomes, lights, buzzers, to his dogs and then followed those with meat powder.
  • He soon found that the dogs easily learned to salivate to the presentation of any stimulus associated with the meat powder.
• He called the meat powder the unconditioned stimulus or UCS, because dogs did not need to learn that association.
• It was already "built-in" to each dog.
• He called the stimulus he chose to present first the conditioned stimulus or CS.
  • He called it the conditioned stimulus because the dogs would not salivate to it at first.
  • They would only salivate to it after it had been associated with the UCS.
• When the dog salivated to the meat powder, Pavlov called that response the unconditioned response or UCR.
  • He called it that because it occurred to the UCS.
• When the dog salivated to the stimulus Pavlov chose and presented prior to the UCS, he called that the conditioned response or CR.
  • Again, he called it that because it occurred to the CS.
  • Although the UCR and CR are very similar, they are not identical.
• So, Pavlov's discovery was that a new stimulus can lead to a new response similar to a naturally occurring stimulus and response.
• The keys to classical conditioning are the temporal (time) relationships of the CS and the UCS, and also, how well the CS predicts the likelihood of the UCS.
• Let us review. Pavlov's discovery is now called classical or respondent conditioning.
  • The UCS-->UCR relationship is naturally occurring; it is not learned.
• Salivation in dogs occurs to the presentation of meat powder because that is part of the biology of being a dog.
• A similar example in humans is an air puff to the eye following the presentation of a light.
  • Humans will blink if air is blown gently into their eye. (UCS->UCR)
  • The CS (the light) at first leads to no observable behavior.
  • But, as the CS is followed by the UCS over and over, do humans start to salivate when the CS is presented,; they blink to a light when that light (a CS) is presented prior to the puff of air.
• So, one can think of classical conditioning as the pairing of a CS and a UCS in time, with the CS occurring first, or, CS-->UCS.