ABSTRACT
Development of instruments for tracking eye movements has been under way for over 25 years (Cornsweet & Crane, 1973; Young & Sheena, 1975). Early eye trackers were cumbersome devices in which the user wore uncomfortable gear, such as bulky helmets or other equipment affixed to the head. Except under the most controlled conditions, these devices were not capable of maintaining their calibration because it was difficult to maintain strict positioning of the devices on the head. More recently, eye trackers have been developed that attempt to overcome these shortcomings. Ultralight headband-mounted trackers have been developed that reduce slippage. Also, newer devices, based on a tracking system mounted on the display screen rather than the head, permit the user to roam relatively freely over a comfortable region of space.
