In classical conditioning, extinction refers to which phenomenon?

• A. Extinction occurs when the conditioned stimulus is presented without the unconditioned stimulus, causing the conditioned response to fade.
• B. Extinction occurs when the unconditioned stimulus is strengthened.
• C. Extinction is the strengthening of a learned response to a new stimulus.
• D. Extinction refers to increased sensitivity to a stimulus.

Answer: (A)

Extinction in classical conditioning is the process where the conditioned response fades when the conditioned stimulus is presented without the unconditioned stimulus. Imagine a dog that salivates to a bell because the bell once predicted food. If the bell rings repeatedly without food following, the salivation response gradually weakens and may disappear. This shows the association is weakened by nonreinforcement. It’s also worth noting that extinction doesn’t erase the original learning; the association can reappear later through spontaneous recovery or be reacquired quickly if training resumes.

So, the described phenomenon—presenting the conditioned stimulus without the unconditioned stimulus causing the conditioned response to fade—is extinction. The other options describe different processes, like strengthening a stimulus or response or increased sensitivity, which are not extinction.