unconditioned stimulus (UCS)
occurs naturally without teaching/associating. produces unconditioned response (UCS)
An unconditioned stimulus (UCS) is a stimulus that naturally, automatically and consistently triggers a response without any prior learning. The response evoked by the unconditioned stimulus is known as the unconditioned response (UCR). Examples of unconditioned stimuli include food, water, pain, loud noise, and bright light. These stimuli elicit a reflexive response from an organism without the need for learning.
For instance, when we smell food, the odor serves as an unconditioned stimulus that triggers hunger (the unconditioned response). Similarly, when a person is subjected to a sudden loud noise, the sound acts as an unconditioned stimulus that triggers the startle response (the unconditioned response). In classical conditioning, an unconditioned stimulus is paired with a neutral stimulus to create a conditioned response.
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