Here's how: While a consumer looks at images of print ads or billboards projected on a screen, a camera underneath the screen sends an invisible beam of light off the consumer's pupil.
The camera flashes 60 times per second, and documents exactly where on the screen the person was looking at that instant. The result is a series of pictures of exactly what the person saw, time-coded to show how long the person spent looking at each area of the ad.
Users may not even be aware that their eye movements were recorded-they're never told, and there's no headgear or goggles involved.
PRS, Fort Lee, N.J., follows up the procedure with a more traditional Q&A session, asking consumers what they remember about the message of the ad and the image of the brand.
After the data are integrated and analyzed, PRS provides a report about what consumers are really looking at when they see ads. Often, it has little to do with the advertiser's message. People are too busy staring at the girl in the bikini to notice what brand of beer she's holding in her hand.
"Usually, the lesson is to embody the call to action and the branding into the primary visual," says PRS President Scott Young. That's the message that Visit Florida, the state's tourism-marketing agency, found when using PRS's programs.
"Our ads are designed to set the stage for why Florida's such a great place to vacation, and show how to get more information about planning a Florida vacation," reports Barry Pitegoff, VP-research for Visit Florida.
"The testing showed we needed to get the logo, the phone number, the Web-site address more prominent. There was a big drop-off between the visuals and the call to action," she says.
In a typical PRS campaign, the company speaks with between 100 and 150 people to test an ad concept. Marketing clients pay between $25,000 to $30,000 for the research.
Technology marketers, which need to gauge the reaction of harder-to-find IT managers, pay more.
PRS has been providing its PRS Eye-Tracking services for print and billboards since the early 1970s for clients including Ralston Purina, IBM Corp., General Motors Corp. and Visit Florida.
Now, the company has adapted its efforts to analyze Web pages. By placing the camera behind a computer monitor, PRS can observe how a user looks at an Internet site. When users are done, PRS clients such as Visa USA and Walt Disney Co.'s ABC News receive videotapes of each person's experience-both where their eyes went as well as where their mouses moved.