A device that tracks the eye movements of users of a Google Glass-like product and identifies what the users happen to look at through the glass. One notable purpose of the system is the tracking of which advertisements users looked at and how often while using Google Glass. The technology can also measure a Google Glass user's emotional response (such as readings of pupil dilation etc.) to an advertisement or advertised item and sending that information to advertisers for a premium fee. This form of advertising is also known as "pay per gaze."