Nordstrom is well-respected among U.S. retailers – but its shoppers could soon be edgy as they walk from department to department.

That’s because 17 Nordstrom and Nordstrom Rack stores are using a tracking service from Euclid Analytics to track shoppers’ movements in the store.

Dallas’ CBS 11 TV I-Team recently reported how the chain monitors its shoppers’ time spent in specific departments and which departments they visit.

Tara Darrow, a Nordstrom spokeswoman, confirmed to the Dallas TV station, “Sensors within the store collect information from customer smart phones as they attempt to connect to Wi-Fi service. The sensors can monitor which departments you visit and how much time you spend there,” according to a news report.

No personal information is released to the store – and all information is kept anonymous. The tracking has been ongoing since October.

“This is literally measuring a signal. You are not connected to the signal,” Darrow said in a statement.

The data will help the store monitor “customer foot traffic.” Such data could lead to a specific store adding more employees in periods of higher consumer traffic, or may lead a store to change the design of a department. So far, none of these events took place. But they are possible in the future.

Also, at some point the service could notify willing customers to go to merchandise of interest – based on the data.

Shoppers can opt out of the tracking by turning off their smartphones.

Also, John Fu, marketing director at Euclid, says his firm provides service to a "variety of different kinds of retail stores, ranging from mom and pop stores and coffee shops to large department stores."

Home Depot also uses the service provided by Euclid Analytics, according to the Huffington Post.

Privacy advocates are concerned about the practice, however.

"I think it's outrageous," John Soma, executive director of the University of Denver (News - Alert) Privacy Foundation, told Denver's ABC7 TV station. "What are they going to do with that data? Are they going to keep it forever? Are they going to aggregate it? Are they going to sell it to 'affiliates’? We just don't know. That's what's so troubling to me."

Also, a future practice involving eye tracking of multiple consumers could be used in retail stores in five years, TMCnet reported. Called “Sideways,” it has already been developed by Lancaster University (UK) researchers, as well as one scientist from Germany.