LOS ANGELES - Off-price retailers such as Best Buy, Nordstrom Rack and Ross Dress for Less are slowly adopting a design secret that airlines and banks have known about for years: one single, snaking line makes impatient customers feel they are being treated more fairly than if they line up behind multiple cash registers.

"Personally, I like one line," said Gary Bickelman, a pharmacist in West Hills, Calif., out doing some last-minute Christmas shopping at Best Buy.

The electronics retailer adopted the snake line model at its stores a little more than a year ago, said Jenny Bohuslavsky, a spokeswoman for the company.

"With lots of lines you inevitably get stuck behind someone who's taking a long time," Bickelman said. "I was at Costco this morning, and it was like that. ... It gets a little frustrating."

"It looks really intimidating at first," said Pam Rubin in line at a Nordstrom Rack, which switched to a single line about a year ago when it remodeled its stores. "But once you get in, it moves pretty fast."

But does it? Wait times, which average from 1 1/2 to three minutes during nonholiday time, can depend on a lot of different factors, from the type of merchandise sold, to how many cashiers are working, to what the weather's like at the time.

What matters to retailers and to the bottom line is shoppers' perception of wait times, said Craig Childress, director of prototype design research at Envirosell, a New York-based consulting firm that analyzes the interaction between people and products.

"If a person comes in the front door and they see this 2,000-foot chain, they'll walk out - especially if it's near the door," Childress said. "The question is what you want this person to see."

Perhaps the most innovative attempt to hide a big scary line is on view at Fry's Electronics, which has turned its snake line into a labyrinth of what retailers call "impulse items."

These include everything from snacks and refrigerated sodas to CDs, DVDs and stuffed toys. Such direct marketing to captive consumers waiting in line is an old marketing technique that's still working, even on unwilling customers.

Todd Kaufman of Westlake Village, Calif., was so angry about the long line at Best Buy last week that he contemplated lodging a personal complaint to the manager. Despite his outrage, he ended up making an unplanned purchase of the film Amelie on DVD while waiting in the snake at the Canoga Park Best Buy.

"When I first got in line I was thinking, man, this [is terrible]," Kaufman said. "But it's working for Best Buy."

Regardless of which model a store chooses for its line design, there are some basic rules, said Childress, who adds he's amazed by how frequently these guidelines are broken.

For example, he said he often sees cash registers placed in the center of small boutique stores. Then, when lines build up, they effectively form a wall, cutting off customers from half the merchandise on sale.

Another no-no is to structure a single snake line directly down the center of the main aisle of a store. "People don't feel comfortable walking through a line," Childress said - unless they're unaware there is a line at all.

"People cut in front of you because they don't know it's one line," said Kim Railton, a longtime shopper at Nordstrom Rack. "People are rude."

Some retailers appoint line facilitators to clear up mix-ups. But there's also a disadvantage to that. If lines begin to lengthen, customers may start questioning the intelligence of store management in assigning a worker away from a cash register.

Indeed, any line at all is too much of a line for most shoppers, especially during the final shopping days leading up to Christmas. "The closer it gets, the more tolerance wanes," said Richard Giss, a retail consultant at Deloitte & Touche in Los Angeles.

Retailers can do little about a lack of patience. But there is something they should keep in mind as they continue to tinker with the design of their lines. "It's a lot easier to make the design fit the behavior than it is to change human behavior," Childress said. "People do what they do."