Classical Conditioning

A type of learning in which organisms learn to associate stimuli. It is also known as Pavlovian conditioning, after Ivan Pavlov (1849–1936), a Russian physiologist who incidentally discovered classical conditioning while studying the digestive system in dogs. Pavlov leashed his dogs in a harness and placed food in their mouths, after which he measured the saliva flow through a tube inserted into their cheeks. After several repetitions, Pavlov observed that his dogs started to salivate before the food was placed in their mouths. They would salivate merely by seeing the assistant in charge of bringing the food or listening to his footsteps approaching the cage. Pavlov realized that the dogs had learned to anticipate the food and to associate the food with, for example, the sound of approaching footsteps. Pavlov called the saliva the unconditioned response (UR) because it is a reflex naturally triggered by food, which he called the unconditioned stimulus (US). He then introduced a bell ring as a neutral stimulus and repeatedly rang the bell before presenting the food to the dogs. After several repetitions, the dogs were conditioned to salivate to the sound of the ring alone. The bell then became a conditioned stimulus (CS) and the salivation a conditioned response (CR). After this simple experiment, researchers started to condition different types of animals as well as humans to react to a variety of neutral stimuli. Classical conditioning often takes place without awareness.