Some supermarkets in the U.S. can now establish the “closure rate” of products – how many consumers bought a product as a percentage of those who passed by, reports Telegraph.co.uk. Called Prism, the surveillance system uses infrared devices (sensors) similar to those used on automatic garage doors. They are placed in aisles around the perimeter of a store in what is known a "racetrack" formation, emit infrared light and record the number of times the beam is broken by a shopper, the direction the person is heading and the exact time. A number of companies including Proctor & Gamble, Coca-Cola and Kellogg have joined forces with retailers, including Wal-Mart, to test the project in 166 stores. Wal-Mart and Procter & Gamble hope to introduce the system internationally within a couple of years and believe it will have a profound impact on the industry's ability to predict the behavior of shoppers, determine product placement on shelves for most successful sales, and indicate how marketers’ campaigns are resonating. Early trials have already found valuable information for retailers, including the fact that two thirds of shoppers who visit snacks aisles make a purchase and those with children put more in their shopping baskets.