If you see a shoe billboard, will you buy a shoe? Advertisers around the country are starting to get some answers to that question.
Clear Channel Outdoor Americas, a massive billboard company controlled by iHeartMedia Inc. with thousands of displays across the country, is debuting a new kind of consumer tracking technology the company is calling "RADAR." The system taps into mobile phone signals to track how well ads are doing their jobs, answering questions like who's really buying a product, looking up a brand, or talking about it with friends after they see an ad.
Get Data Sheet, Fortune’s technology newsletter.
Andy Stevens, senior vice president for research and insights at Clear Channel Outdoor, told The New York Times the concept "does sound a bit creepy."
But Clear Channel says the company can't really see who you are and where you're going. The system is designed to anonymously track traffic patterns about who's passing ads and what they do next. Clear Channel's partnering with AT&T, ad analytics company Placed, and PlaceIQ to analyze the data.
Toms recently tried out the new system in Orlando. The company learned how likely people were to talk about its shoes with their friends or look up the company online after they saw an outdoor ad. Clear Channel said people who saw the Toms ads were 44% more likely to buy a pair of shoes.
For more on advertising, watch:
The tracing comes as TVs and computers around the world are starting to watch consumers. The BBC recently conducted an experiment looking at how people's faces respond to ads on their computer screens, while TVision tracked thousands of people watching Super Bowl 50 in Boston and declared a "most smiled at" ad (it featured Alec Baldwin). Facebook's Mark Zuckerberg recently announced the company is also working on virtual reality technology that would more precisely trace where people are looking on-screen to deliver faster, higher-quality resolution virtual reality.
So here's looking at you, consumer.