When Nordstrom posted a sign telling customers it was tracking them, shoppers were unnerved. http://www.nytimes.com/2013/07/15/business/attention-shopper-stores-are-tracking-your-cell.html?pagewanted=all  Nordstrom wanted to learn more about its customers — how many came through the doors, how many were repeat visitors — the kind of information that e-commerce sites like Amazon have in spades. So last fall the company started testing new technology that allowed it to track customers’ movements by following the Wi-Fi signals from their smartphones.
Nordstrom’s experiment is part of a movement by retailers to gather data about in-store shoppers’ behavior and moods, using video surveillance and signals from their cellphones and apps to learn information as varied as their sex, how many minutes they spend in the candy aisle and how long they look at merchandise before buying it.

All sorts of retailers — including national chains, like Family Dollar, Cabela’s and Mothercare, a British company, and specialty stores like Benetton and Warby Parker — are testing these technologies.

Consumers seem to have no problem with cookies, profiles and other online tools that let e-commerce sites know who they are and how they shop, some bristle at the physical version, at a time when government surveillance — of telephone calls, Internet activity and Postal Service deliveries — is front and center.

RetailNext, based in San Jose, Calif., adds data from shoppers’ smartphones to deduce even more specific patterns. If a shopper’s phone is set to look for Wi-Fi networks, a store that offers Wi-Fi can pinpoint where the shopper is in the store, within a 10-foot radius, even if the shopper does not connect to the network.
The store can also recognize returning shoppers, because mobile devices send unique identification codes when they search for networks. That means stores can now tell how repeat customers behave and the average time between visits.
RetailNext also uses data to map customers’ paths; perhaps the shopper is 70 percent likely to go right immediately, or 14 percent likely to linger at a display.

Brickstream uses video information to watch shoppers. The company, based near Atlanta, sells a $1,500 stereoscopic camera that separates adults from children, and counts people in different parts of a store to determine which aisles are popular and how many cash registers to open.

Cameras have become so sophisticated, with sharper lenses and data-processing, that companies can analyze what shoppers are looking at, and even what their mood is.

Realeyes, based in London, which analyzes facial cues for responses to online ads, monitors shoppers’ so-called happiness levels in stores and their reactions at the register.

Nomi, of New York, uses Wi-Fi to track customers’ behavior in a store, but goes one step further by matching a phone with an individual.

When a shopper has volunteered some personal information, either by downloading a retailer’s app or providing an e-mail address when using in-store Wi-Fi, Nomi pulls up a profile of that customer — the number of recent visits, what products that customer was looking at on the Web site last night, purchase history. The store then has access to that profile.

Nomi then uses Wi-Fi signals to follow the customer throughout the store, adding to the information it maintains. “If I’m going and spending 20 minutes in the shoe section, that means I’m highly interested in buying a pair of shoes,”