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Classical Conditioning
Classical conditioning is the acquisition of a response to a new
stimulus by association with an old stimulus. It involves coupling a
stimulus with an innate behaviour or physiological response. Most
laboratory based classical conditioning studies focus on
physiological responses. The most famous, of course, involved Pavlov
and his dogs. Ivan Pavlov was a Russian physiologist who trained
dogs to salivate at the sound of a bell ringing. Indeed he went on
to win the Nobel prize in 1904 for research in which he measured the
saliva production of dogs in response to a variety of stimuli and
many workers in this field still refer to this sort of learning as
Pavlovian conditioning.
Pavlov had spotted his experimental dogs salivating when they heard
his technician tinkling a bell as he approached the kennels to feed
them. To determine how accurately a dog could build such
associations, he decided to replace the sound of the bell with more
easily varied sounds made by a buzzer and then a metronome. He
surgically implanted a tube to collect saliva and measure its rate
of production using the apparatus shown. A second hole in the dog's
cheek was used blast meat powder into its mouth.
Pavlov coupled a novel external stimulus to a physiological stimulus
and response. The dog learned to respond to a new stimulus, the
buzzer, which had previously been irrelevant or neutral. Because its
effect was the product of learning, Pavlov called the buzzer a conditioned stimulus. The salivation response to the
conditioned stimulus
is called the conditioned response.
Before the learning experience, only meat powder, the
unconditioned stimulus, produced salivation as an
unconditioned response. Crucially, in classical conditioning,
the sound of a buzzer was followed by the delivery of food to the
mouth, regardless of what the dog might have done when it heard the
buzzer. Classical conditioning enables the animal to associate
events over which it has no control. This increases the
predictability of an environment.
The classical conditioning procedure is as follows:
So that
Learning about sex seems especially likely as a consequence of
classical conditioning. Stallions get aroused when they hear the
sound of the bridle used to control them in the service pen. Dog
breeders capitalise on a similar effect to ensure reliable
performance of stud dogs. If they observe the same routine before
taking the dog to the same room prior to every mating, these stimuli
condition a response that supersedes the attractiveness of a
particular bitch.
Another useful example of this sort of learning is seen in cows that
let release milk when they hear calves calling because they have
formed an association between this sound and subsequent suckling of
teats. On dairy farms an analogous phenomenon arises when the
unconditioned stimulus of being milked by a human, linked to a
milk-let down response, is replaced by simply being in the milking
parlour or sometimes even the collecting yard. The involuntary milk
let down shown by dairy cows when they hear the milking apparatus
becomes a conditioned physiological response.
The interesting footnote to Pavlov's study was that he recorded that
his dogs would race ahead of their handlers to get to the
experimental area. They wouldn't just hang around waiting for a
stimulus that made their mouths water, they would try actively to
put themselves into situations and perform activities that led to
rewards. This was a result of trial and error learning and brings us
neatly to the other important category: operant conditioning.
Context specificity
Pavlov's dogs knew that the lab was where they received meat powder.
The ropes that held them in place may well have caused great
resentment in a different context such as a park. Their effect was
context specific in the same way that some cats seem to know that
white coats represent danger, but only at the veterinary clinic.
Household visitors can wear white coats without provoking a panic
response. Because these animals learn to expect individual cues with
specific outcomes in certain places, their learning is said to be
context specific. Learning to behave in different ways that are
entirely dependent on the context is what accounts for a puppy
giving appropriate responses to cues in a training school and yet
apparently forgetting everything when out on a walk. Good trainers
do their best to break down context specificity. This is why, for
instance, one of the most time consuming elements of guide dog
training, after a dog has been taken through basic training with
artificial obstacles, is the process of repetition in other contexts
to eliminate any dependence on the training ground's environmental
cues.
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