In Classical Conditioning, what is typically the unconditioned stimulus in Pavlov's experiment?

In Pavlov's classical conditioning experiment, the unconditioned stimulus is food. An unconditioned stimulus is a stimulus that naturally and automatically triggers a response without prior conditioning. In this case, the food presented to the dogs elicited the natural reflex of salivation, which is an unconditioned response.

Pavlov used food to demonstrate how a neutral stimulus, such as a bell or a metronome, could be associated with the unconditioned stimulus (food) through repeated pairings. Over time, the dogs learned to associate the sound of the bell or metronome with the food, eventually leading them to salivate in response to these previously neutral stimuli. This fundamental principle underlines how classical conditioning can establish new behavioral responses.