Golda used to really enjoy potato salad, and at a family reunion she ate a large helping. Unfortunately, the potato salad had not been kept cold, and Golda became quite ill after eating it. Now she finds that even the sight of potato salad in the school cafeteria can make her feel sick to her stomach. In this example of classical conditioning, the sight of potato salad in the school cafeteria is:_________.
a. an unconditioned stimulus
b. a conditioned stimulus
c. an unconditioned response
d. a conditioned response

In classical conditional, conditioned stimulus is defined as a previously neutral stimulus that has become associated with an unconditioned stimulus and, eventually, begins to trigger a conditioned response. The sight of potato salad was a neutral stimulus for Golda. However, after eating a bad one, she has associated it with with having food poisoning. When she had food poisoning, she had an unconditioned response, which was feeling ill after eating it. Now that the two things have become associated, the sight of potato salad has become a conditioned stimulus that causes the conditioned response of feeling sick to her stomach, even without eating it.