Can eye-tracking technology move beyond niche applications and into the mainstream - and would you want it to?. Eye tracking has been around for decades, used by researchers studying the physiology and psychology of human vision. But with rapidly falling costs and recent technological advances, the tech is finally moving away from passive analysis and into the area of active interaction. People with disabilities use it to move the cursor on a computer screen, and there are trials to get them to control their prosthetic limbs just by using their gaze. Eye-tracking video gaming isstarting to take off, and many firms are beginning to explore the tech to understand how their customers react to adverts and shop displays using state-of-the-art headsets with integrated eye tracking. In the following decades this approach flourished, with a host of techniques that relied on recording reflections from light bouncing off the eye. Specifically, academics looked at how tracking the eye's endless sequence of fixations (pauses on a specific area) and saccades (rapid movementsbetween fixations) could help them better understand the visual system and even spot neurological disorders; as computers became widely available, they could even compute and analyse subtle differences in gaze patterns that are not noticed by humans.