I am lunching with a four-year-old, her mother, and her aunt. When the mother comes back to the table with a small cup of soup and a small cup of cut fruit, it is the fruit that causes excitement. "Fruit!" the child exclaims, as if greeting a long absent friend.

Nevertheless, she is obliged to eat her soup first. "Finish your soup," her mother says, "and then you can have your fruit salad." The child ponders this for a moment and then says "Um...I'll just have the fruit. I don't eat salad."