An unconditioned response is a natural and automatic reaction to an unconditioned stimulus. It is a reflexive and involuntary response that occurs reliably every time an organism comes across biologically significant stimuli. In classical conditioning, an unconditioned response is an unlearned response that occurs naturally in reaction to the unconditioned stimulus. For example, in Pavlovs experiment, the dogs salivating for food is the unconditioned response, which is triggered by the unconditioned stimulus of food. Unconditioned responses are innate responses that organisms have from birth and do not require prior learning. They are often contrasted with conditioned responses, which are learned responses that are provoked by a conditioned stimulus.