A mechanic for Otis Elevator Company, who regularly services downtown Washington department stores, was shopping with his wife on his day off.

The store's woman elevator operator, who had never seen him out of uniform, greeted him with, "Hello, George. I didn't recognize you with your clothes on."

Result: One red-faced mechanic, one stammering elevator operator, several bemused passengers, and one peevish wife.

If nothing more, a rule of elevator etiquette had been broken, says a social psychologist who has spent more time than most studying people on elevators.

The rule: Don't talk to people you know if people you don't know are on the elevator.

Layne Longfellow of the Health Education Institute at Phoenix (Ariz.) Baptist Hospital believes that just as we have rules for expected behavior in libraries, movie theaters and supermarkets, we have them for elevators.

They are unwritten rules, he says, but they exist. Here they are:

Keep your face forward.

No eye contact.

Keep your hands folded in front of you, except when the elevator is crowded.

Then keep your hands at your side.

No touching.

No talking to strangers.

Stop talking with acquaintances when strangers get on.

And why is there a need for rules?

"Elevators," says Longfellow, "put us physically closer to strangers than we want to be."

If you don't believe these rules exist, he suggests trying this experiment the next time you get on an elevator:

Face the rear, establish eye contact, stand right next to another person and start a conversation. You're now forcing intimacy, says Longfellow, and your elevator companions will back off.

Those are just the basics. There's more, says Longfellow, who once was asked to discuss lift logic on a radio talk show. The interview took place in an elevator. Some of his other observations:

Numbers: Most of you keep your eyes glued to the lighted row of floor numbers because: 1) It helps you know where you are and in which direction you are going. 2) It enhances your peripheral vision, allowing you to keep an eye on elevator companions without looking at them directly. 3) You think it wills the elevator faster to your destination.

Division of Space: When you are the only person on board, you stand either near the control panel, or with your back to the rear wall. When there are two on board, you divide the space in half; each takes a side wall. When there are three, the space is divided in thirds; two claim a side wall, the third gets the back wall. If you are the fourth person to enter, you will look around, size up the situation and put yourself in the center, but forward near the door. If you are fifth on, you will see those on the two sides move to the back wall on either side of the other back-wall person. The fourth person shuffles to a side wall, and you take the other side or stand front center.

Pets: "Pets create a feeling of discomfort for fellow passengers unless they are cute pets. When cute pets and/or babies are on board, people are allowed to break the rules and talk to the pets, the babies and their owners."

Romance: If you meet your true love on an elevator, you are living out a popular fantasy. While it's against the rules of human behavior to talk to strangers on board, if you want to start something, this could be the place.

Control: If you are a take-charge personality, you may go out of your way to stand near the control panel. But don't be surprised if another passenger reaches across -- no matter how awkward -- to press his own floor button rather than risk a breach of rules by asking you to do the honors.

Constant Button Pushing: Unnecessary. The heat from your hand the first time you press is enough to signal the car to your floor. Yet some keep at it, thinking it relieves the frustration created by waiting or the embarrassment of standing around doing nothing.

Women and Elevators: Etiquette may dictate by tradition that women enter first and leave first, but forget the rules if the woman happens to be standing at the rear of the car. Adds Letitia Baldrige, who has revised and expanded "The Amy Vanderbilt Complete Book of Etiquette" (Doubleday), "This is ridiculous in this new world where women are out for the same jobs."

Smoking on Elevators: In 37 states and Washington, D.C., it is against the law to light up a cigarette, cigar, pipe or other flame-carrying device in an elevator. In D.C., it's punishable by a $300 fine or 10 days in jail if someone prosecutes. (It's not yet restricted in Arkansas, Connecticut, Delaware, Idaho, Indiana, Kentucky, Louisiana, Maine, Mississippi, Oklahoma, Utah, Vermont or Wyoming.)

For etiquette commentary here, Longfellow defers to Baldrige, who says, "It's a serious breach of health safety, as well as a breach of manners to smoke on elevators, but if you're going to point this out to an elevator companion, wait until you are off.

"You don't want to be confined with someone who may not like this speech and could turn on you."