Eye tracking is an interesting way of connecting the Qualitative and the Quantitative method of measuring. It also allows us to go beyond “just” asking the users, with eye tracking we can actually see what the users are looking at. You can use eye tracking for research in a consumer study. Eye tracking can help understand the usability of a product.
See introductory slides here: http://www.slideshare.net/pederrudbeck/eyetracking-metrics-uxstoriesdk