Final answer:
After extinction and a rest period, the conditioned response in a dog can reappear through spontaneous recovery. This illustrates the resilience of learned associations.
Step-by-step explanation:
After a dog has undergone extinction and no longer salivates to the sound of a bell, if given a period of rest and the bell is presented again, the dog might exhibit what is known as spontaneous recovery. This term refers to the return of a previously extinguished conditioned response after a rest period. In Pavlov's experiments, the dogs, after a rest from extinction training, began to salivate again when the bell was rung, even though the meat powder (unconditioned stimulus) was no longer presented. Similarly, if Tiger the cat heard the sound of an electric can opener after not hearing it for several months, she would likely recall the association with food and exhibit excitement.
Pavlov's work also revealed that not all conditioned responses are permanent; they can weaken and disappear when the unconditioned stimulus is no longer coupled with the conditioned stimulus. However, after a rest period, the conditioned response can re-emerge, demonstrating the resilience of learned associations, even after a period of extinction.