Eye tracking is a method which records a subject's glances. This is how it works:

The subject is sitting in front of the image that is to be tested. The person puts on eyeglasses with a built-in camera. This camera records the eye movements.

After the collected data is analysed, a composite image is created which shows the points wher the eyes stopped and how long they stopped at each point. It also shows where they just flew over, and gives information on the sequence - e.g. what elements first catched the subject's eye.

Such tests are also used for ads etc. The customers should notice all important elements, the slogan, and especially the logo - and this test can tell if this is the case.