This post is part of the HBR Forum, The Future of Retail.

A couple of months ago, I found myself, of all places, in the research lab of one of the largest shopping cart manufacturers. I had been invited to preview a prototype for the future. It was a whole new area of study for my ongoing investigation into the psychology of brands. Until this visit, I’d never so much as given a thought to the shopping cart’s design. To me, they have looked much the same since forever.

The head of the research lab — I’ll call him Anders — opened his presentation with an interesting fact: the bigger the cart, the more we buy. In fact, if the cart is double the size of our regular one, we buy an astounding 40 percent more than we usually do. It’s not as if we need the extra items, but larger carts tap in to our primordial need to hoard food. We’re still operating with our primitive brain and, ultimately, we’re primed to guard against starvation. Evolutionary speaking, we’re hardwired to store food in times of plenty. So, if our shopping cart looks half-empty, we’ll fill it.

The humble shopping cart made its first appearance in 1937 at the Piggly Wiggly supermarket chain in Oklahoma City. Two baskets, one above the other, were wheeled around on a simple metal frame. Evermore sophisticated checkout systems allowed retailers to tally each purchase, maintain stock control, and see what was being purchased when.

The new shopping cart that Anders wheeled out looked much the same, except for one small significant detail; each comes with a small computer that can be programmed to understand the shopper’s buying patterns. It reveals the speed of the shopper, how long it takes to make a selection, the preferred route, and the order in which items are placed in the cart.

The mini device, equipped with a GPS, plugs into the supermarket’s mainframe computer, making it possible to pinpoint, within inches, exactly where the shopper is, all the while building up a personal shopping profile. In return for this behavioral data, the shopper is promised specially customized discounts, available only to them. All that’s required is a quick swipe of a loyalty card on a display, positioned beside the shopping cart’s handle. This is bound to change the nature of the regular supermarket shop, because for the first time ever, each customer can be tracked in real time. The consumer profile can be matched with the consumer’s actual behavior, and thus can be matched with the advertising messages most likely to attract the shopper.

So, armed with all this new data, the question is — where should a supermarket shopper’s journey begin? What category will best predispose her hoarding instincts to be sparked? Retailers are looking for their own version of the domino theory. The first product should lead to another, to another, and by the time the shopper’s reached the checkout, she’s bought more than she intended.

For three years, Anders and his team had worked on this project. They studied millions of data points along the shoppers’ path, from barbecue sauces to cat food, back to toilet paper. They’d analyzed walking speeds and times taken from first pause to actual selection. They’d discovered that if the first product they buy seems cheaper than they expected, there was a tendency for the shopper to be more trusting and, thus, purchase more, regardless of the subsequent prices.

One can only assume that mobile technology will be Anders’ next assignment. It’s entirely probable that as smart phones become increasingly integrated into our daily lives, wireless advertising will link directly to the shopping data.

The digitized shopping cart will undoubtedly give rise to a more flexible retail store — one which constantly adapts to the ever-changing moods and trends of the shoppers. That aside, it will also open up entirely new revenue channels: retailers will be able to sell their customer insights to manufacturers, and when online, wireless and in-store shopping carts are linked, it’s entirely likely that each platform will present new advertising opportunities.

As I left the factory, I saw hundreds of shopping carts all lined up to have their mini-computer installed. I couldn’t help but think of the consequences these devices will have on our lives, our privacy, and the future of retailing. After years of retailers trying to second guess the behavior of consumers, now this little black box on the side of the handle will transform the supermarket. It will invade our privacy, or what’s left of it. It will make use of contextual marketing, targeting our already strained hip pocket. Contextual marketing will increase the sell, store revenues will rise, and it is likely to become the most accurate source of consumer insight for manufacturers looking for more effective packaging design, line extensions, and pricing. All this because of a device attached to the simple shopping cart, which somehow doesn’t seem quite as simple any more.