Google has been awarded a patent that will allow the company to charge advertisers if a user looks at an advert using a technology called "pay per gaze".
The filing does not specifically mention Google Glass, the search giant's wearable technology that is currently undergoing developer-only testing, but the description of the device the technology would be used with is very similar to Glass.
Companies could be charged for offline advertisements in the same way as online advertisements.
"The head mounted gaze tracking device comprises eyeglasses including side-arms that engage ears of the user, a nose bridge that engages a nose of the user, and lenses through which the user views the external scenes ... with at least one forward facing scene camera disposed on the eyeglasses," the filing states.
The patent also allows the technology to generate "latent search results" based on "at least a portion of the items views by the user" including items that are in the user's peripheral vision.
Search requests can then be cached for later use automatically without the user's active permission.
Furthermore, the technology not only tracks pupil movement, but also pupil dilation, which is a commonly acknowledged involuntary reaction to interest in a subject of attention or sexual arousal, as well as light conditions.
The patent suggests companies could be charged for offline advertisements in the same way as online advertisements for Glass, i.e. if the user looks directly at the ad and how long for. It is also suggested more could be charged for analytical data collected by the device.
Google has previously been criticised for its attitude to privacy with regard to Glass, particularly by the Information Commissioner's Office.
