You, Mr. or Mrs. So-and-So, might have noticed a hot trend at retail establishments.

You're about to travel merrily on the road to checkout anonymity when an eager clerk flips up your credit card and wishes you -- personally, by first or last name -- to have a nice day.

It's a strategy extolled by many customer service experts, who argue that such personalization makes customers feel important, perhaps even pampered.

And it's being practiced nowhere more noticeably than at several branches of PNC Financial Services Group, which are practically daring customers to demand personal service.

At the Forbes Avenue branch of PNC in Squirrel Hill, buttons reading "I.O.U. $5 if I don't use your name during this transaction" adorn the teller booths.

The buttons are part of a pilot program intended to emphasize the friendly and respectful manner in which PNC employees treat their customers, said Alan Trivilino, a PNC regional manager and senior vice president.

But why pick out names as especially important? As Shakespeare once pondered, "What's in a name?"

Carnegie Mellon University Professor George Loewenstein notes that, if nothing else, our own name gets our attention. In studies on the "cocktail party effect," he said, people will pick out the sound of their own names even when they are spoken in a noisy room.

"We're on a hair trigger to hear our own name," he said.

A 2006 survey by BAI, a professional organization for the banking industry, found that 31 percent of people liked being called by name at a bank branch, 55 percent were indifferent, and 14 percent did not like it.

"Many customers do like to be recognized, if not by name, at least for the business they bring or the tenure they've had," said Paul McAdam, BAI's senior managing director. "This is an attempt to provide some of that."

And research by a Cornell University professor showed that waiters and waitresses received bigger tips when they addressed their customers by name.

Different uses of names can convey different messages from a business. Addressing a customer by "Mr." or "Ms." might establish a posh tone for the business. "If we move to hotels as an analogy," said Peter Boatwright, a CMU marketing professor, "the upscale, premium hotels, the Four Seasons type, are going to use your name. By association, if I know that and I walk into a bank, I might put that bank at a premium level of service."

By contrast, the use of a customer's first name conveys a more casual, intimate environment.

"They don't want you to perceive them as a faceless, cold, bureaucracy," said Mr. Loewenstein. "They want you to perceive them as a warm, organic entity. We're used to situations where the only people who address us by first names are our family and friends, so if people are addressing us by our first names, they must be my family or friend."

At PNC, tellers are allowed to use their discretion to use first or last names, depending on the customer. The pilot program started last month and will be in effect through June.

So far, said Mr. Trivilino, tellers at the approximately 15 branches participating have paid out less than $50.

He said that the buttons promising $5 have been good conversation starters, and been well received by customers.

But there are a few dangers in the name game. Customers might be offended by a teller mispronouncing a name, for example, or resent a grocery clerk obviously reading a name off a credit card.

"Some people feel like they as individuals are treated as individuals," said Mr. Boatwright. "Others might feel like it's an intrusion of privacy, and privacy is on people's minds right now."

Mr. Boatwright and fellow Carnegie Mellon Professor Rahul Telang recently did a study in which they tested how people responded to being addressed by name in e-mail correspondence from a company that they had done business with in the past.

Overall, said Mr. Telang, the reaction to the use of "name-based personalization" in the e-mails was negative.

However, "many of the customers responded positively, and they bought more," said Mr. Boatwright. "It was quite shocking how there were two groups on these types of personal messages."