The idea of classical conditioning was first proposed by Ivan Pavlov(1849 – 1946) who discovered that dogs could be conditioned to salivate to thesound of a bell, if that sound was repeatedly presented at the same time as theywere given food. Originally Pavlov studied the digestive system, heexperimented on dogs by strapping them in a harness and placed different typesof food in their mouths, and through a tube that was surgically inserted intheir cheeks, measured the flow of saliva. However, after repeated sessions thedogs would salivate before the food was put in their mouths which was aphenomenon Pavlov labelled as ‘Psychic salivation’.
Pavlov’s studies of digestion demonstratedthat salivating when food is presented is a basic neural reflex which requiresno learning, in classical conditioning terms this is known as the unconditionedresponse (UCR), the food is the unconditioned stimulus (UCS), this is astimulus that triggers the unconditioned response. The bell is the neutralstimulus as initially before conditioning, the bell produced no response in thedog. After repeated pairings of the food being presented whilst the bell wasrung eventually, the dog salivated at the sound of the bell alone. Therefore,the bell became the conditioned stimulus (CS) and the dog’s salivation inresponse to the bell was the conditioned response (CR).