Using its PageRank technology, Google (Mountain View, Calif.) has been able to collect revenue from advertisers based on the number of ads on which people are clicking.

With Eyebox, brick-and-mortar advertisers can determine which billboards or products people are looking at in mall corridors or on store shelves, and count them in the same manner that Google counts clicks for online ads.

The Eyebox consists of a palm-sized video camera surrounded by infrared light-emitting diodes and a Universal Serial Bus interface. Software running on an attached computer can determine whether someone is looking at the camera by recognizing the "red eye" spot, which only appears when a viewer is looking directly at the camera.

It is possible to track eye movements today, but the laboratory setups to do so cost $25,000 and up. In addition, the viewer must be no more than 2 feet away and must remain stationary, and the setup must be calibrated for each individual.

Xuuk (Kingston, Ont.) claims to have extended the range of the Eyebox to 32 feet and to have eliminated the need for personal calibration. People walking by don't have to stop in order to be counted.

Because the light is infrared, users are unaware of being observed. Xuuk emphasizes that no data on the identity of the user is collected. Instead, the device simply counts how many people per day have looked at an ad or product. By using a separate Eyebox for each billboard or product on a shelf, advertisers can be charged on a "per-look" basis.

Xuuk was founded by Roel Vertegaal, director of the Human Media Laboratory at Queen's University (Kingston) and Xuuk's CEO. Vertegaal invented the Eyebox as part of the Attentive User Interfaces project in the Human Media Laboratory. The research project aimed to make computers attentive to their users by sensing when to interact with them.

In addition to the advertising application, the project also aims to make computers, cellphones and household appliances more attentive to users.