In an enormous grocery store in northern France, the lights above the aisles aren’t all they seem to be. They look ordinary—more than a mile and a half of fixtures exuding bright light, folded into a grid overhead—but they’re actually flickering faster than the human eye can see. The unique patterns each individual section of lighting emits are a 21st-century twist on Morse code, meant not for people, but for the cameras on their phones.
If shoppers grant the store’s app access to their smartphone’s front-facing lens, the phone can watch for the lights and use the pulses to pinpoint its location. Doing so allows the app to plot the best routes for shopping lists, tracking people as they travel through the store. (The guidance might come in especially handy for first-time visitors to the 84,000-square foot Carrefour “hypermarket,” the French equivalent of a Walmart.)
Location information is one of the most valuable types of data a retailer can gather from its customers, says Joseph Turow, a professor of communications at the University of Pennsylvania. (I interviewed Turow about the future of retail surveillance last month.) If a retailer knows where you spent most of your time inside of a store, it can follow up with discounts for a product you looked at but didn’t buy—either after you’ve left the store, to encourage a return trip, or even right as you’re lingering in the aisle, to nudge you to buy it now. In the U.S., Target and Walmart are rumored to use lighting technology to locate smartphone-toting shoppers, but aren’t forthcoming about their plans.