It used to be that advertisements were designed to lure you into the stores. Today, however, the stores themselves are fast becoming an advertising medium.

Two area grocery chains -- Safeway and A&P -- have joined a number of other food retailers across the country in using their stores as a place where national food companies and local firms can promote their wares.

In shopping baskets, on the child seats of carts, on store directories above each food aisle -- and even on cash-register tapes -- advertisements are prominently displayed to tout diapers, coffee, candy bars, cough drops, detergents, local eateries and dry cleaners, among other things.

"We've got advertisements everywhere," said Charles Cushman, store manager of the Georgetown Safeway.

The promotions, Safeway officials say, are a boon not just to the store (which collects revenue from the ads) but also to consumers and national advertisers.

"The objective is to cut our costs, provide greater customer service and hopefully make a profit," said Ernie Moore, Safeway's public affairs manager for Washington-area stores.

"We save by not having to install aisle markers ourselves," Moore said; rather, Actmedia Inc., the Connecticut-based company that posts the ads, is responsible for maintaining the markers. Moore said the consumer also benefits because some of the basket promotions contain a store directory that makes it easier to shop.

Safeway has been installing the promotions for the past four months in its Washington stores; A&P will begin installing similar advertisements in 56 stores here today.

Giant Food Inc. is not joining the advertising bandwagon, however. "It was a management decision not to go ahead with it," said Barry Scher, Giant's director of public affairs.

"Very few companies have not elected to use our program," said Jeffrey Sturgess, vice president of sales for Actmedia, which leads the nation in installing ads in supermarkets.

Giant declined "principally for the reason that they strongly push their own private lines" and don't want to promote national products at the expense of their own goods, Sturgess added.

Advertisements in supermarkets can make a critical difference in what a consumer buys, contends Actmedia and the Point-of-Purchase Advertising Institute (POPAI). According to a POPAI study, two-thirds of all purchasing decisions are made on the spot, so last-minute advertising can significantly affect a consumer's buying habits, said John Kawula, a POPAI vice president.

Actmedia says its tests have shown that in-store ads can increase sales of an item by about 8 percent.

"Point-of-purchase advertising is an old medium that is increasing quite heavily," Kawula said. "One reason is the high cost of other media such as television and magazines. Then advertisers can also get right down into the store level and sell to the people right there. Nowhere else does an advertiser have a consumer, a product and money all together in the same spot."

As a result, Kawula predicted point-of-purchase advertising will grow to include more than ads on shopping carts and aisle directories. Some stores, including 10 Safeway units here, already have experimented with electronic digital billboards at their delicatessen counters to promote products by Hormel and other deli companies.

Meanwhile, A&P is testing another in-store promotional campaign in New York, in which consumers are given manufacturers' coupons as they walk in the stores. Additionally, the chain is looking at installing television monitors at strategic spots to display manufacturers' advertisements for their products. "From the point of view of a retailer, we are asking whether these ads can bring in revenue, keep our costs down and, on the whole, be helpful to the consumer without being obtrusive," said Michael Rourke, A&P's vice president of marketing and corporate affairs.

"There's a myriad of ways" under study, Kawula said. For example, he said, one firm is offering to redo a store's floors with tiles that have advertisements on them.

For the grocery chains, the in-store advertisements offer a new source of revenue. Actmedia, for example, gives the stores 25 percent of the advertising revenue it receives. "We're providing the stores with a share of our advertising revenue; ABC and CBS don't share with the retailer any of their revenue" from network commercials, Sturgess said.

"It's just another way for us to get revenue," said A&P's Rourke. "If you consider that supermarket margins are 1 percent, the opportunity to get additional revenues" is very enticing.