It’s too soon to know whether The Public Option, a new brewpub set to open in D.C. by early fall, will serve good beer, but it does promise patrons a less awkward experience than its competitors: Customers won’t have to fret over how much money to add to the bill, because waiters won’t accept tips. The Public Option may be part of a trend: Earlier this month, Manhattan’s Restaurant Riki joined a growing list of New York restaurants that don’t take tips. The Public Option’s founder says he hopes the no-tipping policy will encourage a better dynamic among waiters, kitchen staff and customers.

There's a fairly long library of scholarship that has gone into this very subject. Defenders of tipping, traditionally, have argued that it gives waiters an incentive to provide good service. But over the years, research has shown that what customers actually reward often doesn’t have much to do with service. Here are a few things that actually elicit bigger tips.

Touching the customer

For a 1984 paper in Personality and Social Psychology Bulletin, April Crusco and Christopher Wetzel had waitresses at two Mississippi restaurants randomly divide their customers into three groups. One group of diners wouldn’t be touched; one group would be touched on the shoulder once for about a second and a half, as the waitress returned the change at the end of the meal; and one group would be touched on the palm of the hand twice for half a second each time. Crusco and Wetzel found that touching had a significant effect on tip size, and the double-hand touch was the most effective: Customers left an average tip of 12 percent when they weren’t touched, 14 percent when they were touched on the shoulder and 17 percent when touched twice on the palm of the hand.

Having blond hair

In a study of 432 waitresses, Lynn found that waitresses with blond hair received larger tips than waitresses with any other hair color.

Drawing a smiley face on the check—but only if you’re a woman

In 1995, psychologist Bruce Rind and marketing researcher Prashant Bordia recruited a waiter and a waitress to take part in an experiment at a Philadelphia restaurant. Rind and Bordia randomly assigned the servers to draw a smiley face on the check of about half the 89 groups that dined at the restaurant over the course of a three-day period. It turned out that the waitress raised her average tip size from 28 to 33 percent when she drew a happy face, but the opposite effect held for the waiter: Drawing a smiley face decreased his tip from 21 to 18 percent. Rind and Bordia hypothesized that customers thought the smiley face was cute when women did it but effeminate when men did.