When retailers tell shoppers they have their eyes on them – they soon won’t be kidding. This is because new technology will be able track consumer eye movements while people shop. It has already been developed by Lancaster University (UK) researchers, as well as one scientist from Germany.

Called “Sideways” it employs software “to locate faces and eye movements of shoppers captured on camera,” the BBC reported. “It could allow for video screens which change adverts depending on what you look at in a shop.”

Researchers predict the technology could be found in retail settings within five years, the BBC said.

“The system uses a single ordinary camera that is placed close to the screen," one of the scientists, Andreas Bulling, who works at the Max Planck Institute for Informatics (News - Alert) in Saarbrücken, Germany, told the BBC. "So we don't need any additional equipment. The system detects the faces of people walking by and calculates where the eyes are relative to the eye corners."

What makes this technology unique is that it can track as many as 14 shoppers at the same time.

“SideWays uses a conventional video camera and a computer vision program the team developed, which finds your pupils by recognising the corners of your eyes and where they sit relative to your face,” The New Scientist explained in a recent report. “The process only causes a short delay, after which it begins tracking your gaze.”

The prototype was shown at the recent Conference on Human Factors in Computing Systems in Paris. One current challenge is people wearing glasses. It is also better at tracking horizontal rather than vertical eye movement. Legal and ethical questions could arise about the use of the device, too.

There are other eye-tracking applications – and many more are on the way. For example, Samsung (News - Alert) recently launched the Galaxy S4, which can tell if the user is looking at the phone by tracking movement of the eyes. Further, Tobii Technology, will offer its technology to PC users with a consumer eye-tracking PC device. It is about the length of a pen and fits under the monitor of any Windows 8 PC, TMCnet reported. Called the “REX,” it is expected to be launched this fall.