单项选择题

In America alone, tipping is now a $16 billion-a-year industry. Consumers acting rationally ought not to pay more than they have to for a given service. So why do they The conventional wisdom is that tips both reward the efforts of good service and reduce uncomfortable feelings of inequality. The better the service, the bigger the tip.
A paper analyzing data from 2,547 groups dining at 20 different restaurants shows that the relationship between larger tips and better service was very weak. Customers who rated a meal as "excellent" still tipped anywhere between 8% and 37% of the meal price.
Tipping is better explained by culture than by economics. In America, the custom has become established; it is regarded as part of the accepted cost of a service. In a New York restaurant, failing to tip at least 15% could well mean abuse from the waiter. Hairdressers can expect to get 15-20%, the man who delivers your groceries $2. In Europe, tipping is less common; in many restaurants, free tipping is being replaced by a standard service charge. In many Asian countries, tipping has never really caught on at all.
How to account for these national differences Look no further than psychology. According to Michael Lynn, the Cornell paper’s co-author, countries in which people are more outgoing, sociable or neurotic (神经质的) tend to tip more. Tipping relieves anxiety about being served by strangers. "And," says Mr. Lynn, "in America, where people are outgoing and expressive, tipping is about social approval. If you tip badly, people think less of you. Tipping well is a chance to show off." Icelanders, by contrast, do not usually tip—a measure of their introversion (内向) and lack of neuroses, no doubt.
While such explanations may be crude, the hard truth seems to be that tipping does not work. It does not benefit the customer. Nor, in the case of restaurants, does it actually encourage the waiter, or help the restaurant manager to monitor and assess his staff. The cry of mean tippers that service people should "just be paid a decent wage" may actually make economic sense.
Michael Lynn is most probably ______.