Over the years, I'm sure that you have noticed that most everyday items bear a Universal Product Code (UPC). This symbol--a series of numbers and vertical bars of varying thicknesses--is shorthand for product information. When a cashier passes the UPC symbol over an electronic scanner, a computer decodes the symbol and sends the price to the register. The price appears on a display screen and on your printed receipt.

    Retailers say scanner technology has several advantages: speeding checkout time, lowering labor costs, and improving sales and inventory records. They also say that scanning results in fewer pricing errors than manual entry.

    Scanning errors can result in overcharges and undercharges. Some studies show that, overall, overcharges are balanced by undercharges. Overcharges can cost the individual shopper money, especially if the shopper doesn't speak up when they occur. They also can be frustrating for time-conscious consumers, who may have to stand in line for a refund, or worse, return to the store.

    Savvy consumers--those who are aware of prices, who check scanner charges for expensive items or items they know are on sale and who are willing to shop else where if price corrections aren't made--will encourage retail stores to police the accuracy of their checkout scanners.

    Electronic scanning is not foolproof. The reasons: human error, pricing difficulties, management problems. As a result, consumer advocates and regulators are concerned about inconsistencies between advertised or posted prices and prices stored in the computer; inaccurate prices throughout a chain of stores because of an error in the central computer; and problems for shoppers who may not remember posted prices or special promotions when they check out.

    Although the UPC symbol has replaced the traditional readable price tag, it's still possible for consumers to spot pricing errors at the register. Here's how:

(1) Watch the display screen for prices. If you think you're being overcharged, speak up. Ask about the store's policy on pricing errors, and ask the cashier to make the adjustment before you pay. Although some stores simply adjust the price, others deduct an additional amount. Still others offer the mispriced item for free.

(2) Bring a copy of the store's flyer or newspaper ad to the checkout counter. Some advertised specials--15 percent off an item for two hours, for example, or a two-for-one promotion--may not be in the computer and must be entered manually by the cashier.

(3) Consider jotting down prices or special sales as you wend your way through the store. In grocery stores, you may want to use a pen to note the product prices on the packages.

(4) Check your receipt before you walk away. If you notice an error, ask the cashier to adjust the total. If you've already left the cashier's lane, see the store or department manager or the customer service department to correct any mistakes.

    The Department has a list of store policies for certain grocery chains in the state. For written policies at other stores (grocery/merchandise) contact them directly. If you notice a pattern of electronic scanning errors in a particular store, talk to the customer service department or the store manager. Sometimes the retailer may not realize a problem exists until it is pointed out.