What is an Unconditioned Stimulus? (Explained in 3 Minutes)

An unconditioned stimulus (US) in classical conditioning is a stimulus that naturally and automatically triggers a response without prior learning. For example, food is an unconditioned stimulus for a hungry animal because it elicits a natural, unlearned response, like salivation. This response occurs automatically and is known as the unconditioned response (UR). The concept is central to understanding how certain stimuli can produce innate reactions.