“Two-thirds of what we buy in the supermarket we had no intention of buying,” says consumer expert Paco Underhill, author of Call of the Mall (Simon & Schuster, $14, www.amazon.com) and founder and managing director of Envirosell, a behavioral market-research and consulting company headquartered in New York City. Supermarkets not only rely on such behavior; they encourage it. Every aspect of a store’s layout — from the produce display near the entrance to the dairy case in the back to the candy at the register — is designed to stimulate shopping serendipity. To explain how store geography influences your spending, Real Simple enlisted a team of merchandising experts to map out a typical supermarket, identifying the booby traps to help you emerge with exactly what you need and want, and not a single potato chip more.

Store Layout
Are supermarkets all alike? In important ways, yes. This blueprint shows a typical layout. Experts in store design explain why this setup is so common and share some smart-shopping secrets.

Entry

Flowers

Why They're Here: “Flowers can enhance the image of a store,” explains Wendy Liebmann, founder and president of WSL Strategic Retail, a consulting firm in New York City that publishes the consumer studies How America Shops. “Consumers walk in to something that is pretty, smells great, and builds the notion of ‘fresh.’”
Shopping Tip: Buy supermarket flowers for convenience, not value. The prices may be low, but the flowers are seldom as fresh as local florists’.

Produce

Why It's Here: To create a tempting sensory experience. “Stores need to communicate to shoppers that produce is fresh, or else people won’t buy anything,” says Liebmann.
Shopping Tip: Reach to the back and dig for the freshest items. “The smart retailers always have the oldest merchandise in front or on top, since they need to get rid of it quicker,” says Mike Tesler, instructor of retailing at Bentley College, in Waltham, Massachusetts, and president and founder of Retail-Concepts, a consulting firm located in Norwell, Massachusetts. Also, buy produce during theweek. “Most deliveries come in Monday through Friday,” Paco Underhill says.

Bakery

Why It's Here: “The bakery gets your salivary glands going,” Underhill says. This makes you feel hungry, and “the hungrier you are when you shop, the more food you will buy.”
Shopping Tip: Shop after a meal, or have a snack first.

Grab-and-Go Items (Milk, Bottle Water, Snacks)

Why They're Here: “To get back business lost to convenience stores, supermarkets started adding sections up front for grab-and-go items,” Tesler says.
Shopping Tip: If all you need is a quart of milk, get it here to avoid the temptations lurking along the way to the dairy case at the back of the store.

Bank

Why It's Here: “To get more money into the hands of the shopper, so she will spend it,” Tesler says.
Shopping Tip: Set a budget before you shop, and bring a calculator to keep a running tally, says William Schober, editorial director of P-O-P Times, a publication of the In-Store Marketing Institute, in Skokie, Illinois.