CHICAGO — New supermarket carts equipped with touch screens will guide you to the tomatoes or toothpicks, let you order deli meat without standing in line and keep a running tally of your purchases.

What they won't do is tell you how many fat grams or calories are in your cart. The idea is to make it easier for consumers to buy, not induce second thoughts that maybe you should put something back on the shelf.

The touch-screen devices are on display at the supermarket industry's annual convention this week.

"It helps save you time, and it helps save you money. It's all about making it easy for you," IBM executive Ken Lawler said.

IBM's "Shopping Buddy" has been test-marketed at Stop & Shop stores in Massachusetts and is being rolled out this summer. A competing device called Concierge, made by Springboard Retail Networks, is being tested by Canadian stores in June and July.

"The whole model is driven by advertisers' need to get in front of consumers," Springboard spokesman Michael Alexandor said. "They're not watching 30-second TV ads anymore."

People can e-mail their shopping list from their home computer. At the store, they can use their customer card, or a key that fits on a key chain, to log into a system that will call up their list and organize their trip.

If you're looking for toothpicks, you type in the word or pick it from a list, and the screen will display a map showing where you are and where you can find them.

The Concierge and IBM's cart are equipped with the miniature equivalent of GPS, the global positioning satellite system. Sensors can track the location of your cart, so that as you turn into an aisle, the screen can show what's on your list in that aisle and which items are on sale.

The systems also keep a running tally of what you buy. Many stores do so already when shoppers use preferred-customer cards, but what's new is that the store can offer discounts based on your buying habits or tell you while you're in the store that one of your favorite products is on sale.

You scan the bar codes on your items as you drop them into your cart. When you're finished, the device figures your bill. You then swipe your card or key and hand it to the grocery checker, or insert it into a self-checkout stand and pay. All that's left is bagging the groceries.

The buddy won't advertise things that don't fit with a shopper's buying habits, Lawler said: "We don't want it to become a yakky box, or customers will tune out in a heartbeat."

There are differences between the Concierge and the shopping buddy. The Concierge is mounted on the handle of a shopping cart. With the buddy, shoppers get their carts first and then pick up a buddy as they walk into the store. It fits into a holder on the cart.

The Concierge has a bar-code scanner on the bottom of the panel, while the buddy has a detachable wand to scan items.

Shoppers say they like using the self-checkout stand, said Michael Sansolo, senior vice president of the Food Marketing Institute. It's fast as well as entertaining — a mom can have her children help bag the items, he said.

FMI research indicates self-checkouts will outnumber checkouts with grocery clerks in the next 10 years, he said.

Like self-checkouts, a smart grocery cart is a way to help stores make shopping trips more convenient, which, along with discounts and other incentives, can cultivate loyalty, Sansolo said.

That's vital in an industry that has slim profit margins and intense competition, from traditional supermarkets to supercenters, discount stores, limited-assortment stores and warehouse clubs, as well as natural or organic stores and convenience stores.

The new computerized shopping assistants don't come cheap. It will cost the average store about $160,000 to buy and install the devices, Lawler said.

Alexandor said the Concierge will cost stores about $500 each.