Five ways shops are spying on youData gathered via Wi-Fi, phone signals and cameras

22 March 2015

Shopping privacy

Shops are using new technologies to monitor and analyse your behaviour while you're in their stores, Which? research has discovered.

We’ve found that shops are using advanced – and sometimes creepy – technology to find out more about you, the customer: where you’ve come from, how often you shop, which items you’re picking up and more.

We've laid out five ways that shops are doing this below. For more detail on how these technologies work and which shops are using them, Which? members can read our full article on shops spying on you.

How shops are spying on you

1. Information collected via in-store wi-fi

Any information you provide when signing up to use free in-store wi-fi, such as your name and email address, can typically be shared with the shop – and sometimes even third parties – and used by them for marketing. Some wi-fi providers track customers’ locations within the store, and cross-reference this with any demographic information you’ve provided. In some cases, the sites and apps you use over the wi-fi are recorded and fed back to the store.

2. In-store movement tracking cameras 

Cameras can measure how many people are going in and out of a store, which areas of the shop you’re spending time in and for how long, and even the items you’re picking up off the shelf. Companies say that this data is collected in order to improve the store, that it’s all anonymous and that images of you aren’t stored.

3. Mobile phone tracking 

Your mobile phone is constantly communicating with nearby phone masts and wi-fi networks, and in doing so it’s sending out unique IDs called TMSI/IMSI numbers and MAC addresses. Some shops can pick up these IDs, and use them to measure how often you visit the store, how long you spend in there and how you move around. They can even track people who are just walking past the store.

4. Advertising based on face scanning 

Digital video screens showing adverts can scan your face and determine whether you’re male or female and which age bracket you fall in to, just by examining facial characteristics. Advertisers look at the demographic data for particular times and places, and use it to tailor the ads they show.

5. Location-specific messages sent to your phone 

Shops can send vouchers, offers and other messages to your phone via their apps – and these can change depending on where you are in the store. They can even be personalised further, if they’re combined with information from shops’ loyalty schemes about what you normally buy. Small devices are placed around stores and send messages when your smartphone is nearby via Bluetooth, email or text.

More on this...

  • Tell us what you think of this technology in our Which? Conversation post on shops spying on you
  • Find out who Which? members ranked as the best and worst shops
  • Asda, Sainsbury's Tesco and more rated in our supermarkets review