Gaze determines a subjects current line of sight or fixation point. The direction of the eye gaze can express the interests of the subject and is a potential porthole into the current cognitive processes. Existing techniques for eye gaze tracking can be divided into video-based techniques and non-video-based techniques. However, non-video-based techniques are intrusive and interfere with the subject, while video-based techniques have significant shortcomings such as lacking sufficient accuracy and imposing physical constraints on the subject. This invention is directed to a system that enables eye and gaze tracking under natural head movement without the need for individual calibration. Unlike similar systems that require either static head positioning or bulky head mounting devices, this IR-based tracking system that is simple (requiring only one camera) and robust for tracking eye and gaze movements on a human.