Unconditioned Stimulus

An unconditioned stimulus (US) is a natural, unlearned trigger that automatically causes a response. For example, food is an unconditioned stimulus because it naturally makes a dog salivate without any prior learning. It’s something that instinctively prompts a reaction. In classical conditioning, it serves as the original stimulus that elicits a response before any learning occurs. Essentially, it’s a stimulus that consistently and automatically produces a specific reaction in an organism.