Tokyo has a new shop with no price tags, no cash registers or no paying customers- what's it all about?

At first glance, all looks as it should be in the Sample Lab, a bright, airy store in the heart of Tokyo's trendiest shopping district: products on one side, eager customers on the other, and in between, the polite, immaculately turned-out staff that comes as standard these days in Japanese retail.

But then you notice odd details. For a start, most of the products lined up around the shelves have no price tags, and there are no cash registers. Then there are the shoppers, who line up quietly in numbered lines before dashing for the shelves. Rather than assist, the staff get out of the way.

Oddest of all, customers walk home with their newly acquired products absolutely free.

A shop that gives everything away doesn't sound very lucrative, but Sample Lab is a major success story, claims Melposnet, the company that runs it.

"We're delighted at the reaction," says company spokeswoman Erika Awata, who proudly boasts that over 40,000 people have come here to grab everything from sake to nylon tights since the shop opened in the Harajuku district four months ago. Think of it as legaliSed daylight robbery.

What's the catch? Melposnet is a marketing agency that set up Sample Lab to harvest feedback and generate interest in new products for corporate clients. The Lab is membership only and customers can be asked to fill out questionnaires on what they've taken, which are then sent to the companies that have donated freebies. The system has been dubbed "tryvertising."

Consumer trends company trendwatching.com, which claims to have coined that awkward term, says behind the new approach lies a dramatic loss of consumer faith in traditional advertising. "So introducing yourself and your products by letting people experience and try them out first is a very civilised and effective way to show some respect," explains the firm's website.

Sample Lab's visitors, over 80 per cent of whom are young women, seem happy to take part in the experiment. "Most of the stuff doesn't even have a questionnaire attached," laughs Yoko Hashitate, a university student on her fifth visit to the shop. She is clutching a basket containing bottled water, canned coffee and bath salts. "You don't have to pay for anything. At first I thought it was a trick."

Her friend Emiko Amano says they drop into the shop on their way home from college. "I wear contacts, so contact-lens cleaner and make-up are my favorite products, but sometimes there are really surprising things on the shelves, like nice food. But you have to be quick to spot them."

How does the shop work? First-time visitors pay a 1000 yen (about €6) annual membership fee and a 300 yen (€1.84) registration, earning them a two-dimensional barcode on their phones, which is scanned when they come to shop. Customers must be over 15, able to read Japanese and own a cell phone, say the rules, published on the shop's website (http://samplelab.jp).

Once here, they wait in line for one of seven daily grab sessions, and they can only take five items at a time. Feedback is rewarded by a points system, which accumulate to allow more samples to be taken home: the more you come, the more you can take . . . within limits. "We try to keep visits to two a week," said a store assistant.

We called during a brief lull in the shopping, as the assistants restacked shelves with cans of green tea, foundation cream, packs of honey, fruit granola and Swiss marshmallows, bottles of sake and even cigarettes. Some of the products were new and unavailable in conventional shops. Others are expensive, such as a 11,550-yen (€70.85) box of moisturising cream.

The customers hovered off the shop floor. On a signal from the staff, they rushed the shelves and grabbed everything in sight. That night cream was among the first to go. "The only problem is the queuing," lamented one middle-aged woman who declined to give her name. "But I have lots of time, so I come often."

A key ingredient of the whole enterprise is creating buzz about new products, explains Awata. "The companies rely on word of mouth and internet blogging to get the word out about what they're selling. Young women in particular often tell their friends about stuff they like."

She points to two rooms at the back of the store for interviews and product sampling, where visitors can sit and try on makeup in front of mirrors. "Customers in department stores usually feel under some pressure to buy when they're trying on products, but here they can relax and enjoy themselves. We feel they give better feedback in this environment," she says.

Melposnet came up with the idea for the Sample Lab after growing tired of trying to survey people on the street. Shoppers disliked being stopped and asked for their opinions, say the firm, and the product data mined was often unreliable. Many companies routinely distribute samples, so Malposnet approached them for a steady supply, offering detailed feedback.

Malposnet's clients say they are more than satisfied with the results. "The merit is that the questionnaires are answered by targeted people actually trying samples," a spokesperson for mayonnaise-producer QP Corporation recently told the Japan Times.

"The results of questionnaires from information-sensitive people who have become members by paying fees are extremely precise," said alcoholic drink maker Takara Shuzo.

Feedback like that has encouraged Malposnet to expand its Harajuku operation into Osaka and Nagoya. So, could tryversiting be the wave of the future? "We don't see any reason why this idea can't spread far and wide," says Awata.