Classical conditioning (Pavlov – 1899, 1927)

Pavlov’s original experiments

• Pavlov was measuring the amount of saliva produced by dogs when they ate.

• He found that the sight or sound of the lab technician feeding the dogs also produced salivation.

• Salivation had become associated with a new stimulus (the technician) and not just the original stimulus (food).

Key Terms

• Classical conditioning– Refers to a form of learning that occurs through the repeated

association of two (or more) different stimuli.– Learning is only said to have occurred when a particular stimulus

consistently produces a response that it did not previously produce.• Stimulus

– Any event that elicits (produces) a response from an organism (eg, food)

• Response– A reaction by an organism to a stimulus (eg, salivation)

• Conditioned reflex– An automatic response that occurs as the result of previous

experience.

Unconditioned stimulus (UCS)

• Any stimulus which produces an unconditioned response (UCR).– Food (UCS) causes salivation (UCR)

Unconditioned response (UCR)

• The response which occurs automatically as a result of the unconditioned stimulus (UCS).

• A reflexive, or involuntary, response is an UCR as it is predictably caused by an unconditioned stimulus (UCS).– Dogs salivate (UCR) at food (UCS)

Conditioned stimulus (CS)

• The stimulus which is ‘neutral’ at the start of classical conditioning and does not normally produce the unconditioned response (UCR) but eventually becomes associated with the unconditioned stimulus (UCS).– Sound of bell causes no response– Sound of bell (CS) after being “paired” with

food (UCS) produces saliva (UCR)

Conditioned response (CR)

• The learned or acquired response to the conditioned stimulus.– The sound of the bell (CS) leads to

salivation (CR) without the food (UCS)

Process of acquisition

• The overall process during which the organism learns to associate two events (the CS and the UCS).

Stimulus discrimination

• The ability to distinguish between two (or more) different stimuli, even if the stimuli are similar.

Stimulus generalisation

• The tendency for similar stimuli to produce the same, but not necessarily identical, response.

Extinction and Recovery

• Process of extinction The gradual decrease in the strength or rate of a CR that occurs when the UCS is no longer presented.

• Spontaneous recovery: The reappearance of a conditioned response after its apparent extinction.

Real-life application

• Some animal training such as hand signals or clickers

• Aversion therapy– one-trial learning