Eye tracking is a design evaluation method used to visualize eye movement of a person. During usability tests, eye tracking enables moderator and further spectators to trace where participants are looking or not looking, and how long they are looking at particular locations. This way observers are able to better understand participants’ actions.
Using a special analysis software, the gaze point data of several participants can be superimposed after the test. Thereby, it is possible to state how the tested object has exactly been perceived. Eye tracking results are visualized as heatmaps, opacity maps or gaze plots.
Find a more detailed description of the method here: Eye Tracking