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How Retailers Use Smartphones To Track Shoppers In The Store


Now, from tracking you where you work to where you shop. This doesn't just happen when you shop online, but in actual brick-and-mortar stores, too. And for more on this, I'm joined now by Latanya Sweeney. She's chief technology officer for the Federal Trade Commission, and she has written about how this works. Dr. Sweeney, welcome to the program.

LATANYA SWEENEY: Thank you. Thank you for having me.

SIEGEL: And you've actually written on your own blog. This isn't in your official capacity with the FDC.

SWEENEY: Right. The views that I have are not in my - are not of the FTC or any of its commissioners. They allow me to blog on the site solely to open up discourse in the topic.

SIEGEL: OK. So how are retailers able to track me, a consumer, when I'm in a store?

SWEENEY: Well, one of the ways they might do that is using your mobile phone. So what a lot of people may not realize is that, in order for your phone to make a connection on the Internet, it's constantly sending out a unique number that's embedded in that phone, called the MAC address, to say, hey, any Wi-Fis out there? I'm number, say, 124 - though the numbers are a little longer and more complicated. Will you connect with me?

And by using these constant probe requests by the phone looking for Wi-Fis, you could actually track where that phone has been, how often that phone comes there, down to a few feet. Which is much finer than, say, the GPS location that your phone might be giving.

SIEGEL: So how is this helpful to companies, and to what extent are companies doing this?

SWEENEY: Well, you know, I'm not an expert about marketing, but one could easily understand that knowing where customers might move throughout the store is very helpful for designing the store and putting the kinds of products the store might want to sell in particular pathways of the customer. You could also imagine a future in which they might use your location to deliver just-in-time ads. I'm not saying that any of the stores are doing that, but we could easily see how that could be done.

SIEGEL: When this is done, to the extent that it's done, is the customer notified? And in your view, should the customer be notified that this store tracks your whereabouts on the premises?

SWEENEY: Well, that's one of the most interesting aspects - is that this can be done actively by the store without the consumer ever knowing. And why might you care? Well, it could be the case that knowing where you are in a point in time or knowing where your phone has been in a point in time can be an issue. You could imagine future lawsuits in divorce proceedings. Wants to know, oh, were you with MAC address number blah, blah, blah, for example.

SIEGEL: In the jewelry department.

SWEENEY: (Laughing) Right. Were you in the jewelry department someone else? And so these kinds of unforeseen consequences that can cause real harms to consumers, without consumers knowing that that tracking is happening, is something that one should be a little concerned about.

SIEGEL: Is it something that, as a consumer, I can easily opt out of? You know, flick a switch on my smart phone?

SWEENEY: Right. Well, my background is in computer science. And a lot of times, what I do is look at how the design of the system fits in with policy or consumer expectations. And this is a really good issue - is suppose I did know it was happening, but I didn't want to be party to it. What do I do then? A lot of times, you can put it in airplane mode - the phone - which would turn off the Wi-Fi. But if you turn on the Wi-Fi after that, then the Wi-Fi stays on. And so that can be a little confusing. There are some apps that allow you to change the MAC address that address that's sent out in the probes, so that you could sort of masquerade as someone else, if you wanted to.

SIEGEL: And is there anything that I could see on the settings of my smart phone that would tell me whether or not I'm being tracked?

SWEENEY: No. There's nothing you can see. All you could do is turn the ability for them to do the tracking off or leave it on. But there's nothing that you would know that someone actually listened to a probe that was being emitted by your phone.

SIEGEL: Well, Dr. Sweeney - Professor Sweeney, thank you very much for talking with us about it today.

SWEENEY: Thank you.

SIEGEL: Latanya Sweeney is chief technology officer with the Federal Trade Commission. Transcript provided by NPR, Copyright NPR.

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