Eye tracking as a quantitative method for collecting eye movement data, requires the accurate knowledge of the eye
position, where eye movements can provide indirect evidence about what the subject sees. In this study two eye tracking
devices have been compared, a Head-mounted Eye Tracking Device (HED) and a Remote Eye Tracking Device (RED).
The precision of both devices has been evaluated, in terms of gaze position accuracy and stability of the calibration. For
the HED it has been investigated how to register data to real-world coordinates. This is needed since coordinates
collected by the HED eye tracker are relative to the position of the subject's head and not relative to the actual stimuli as
it is the case for the RED device. Result Results show that the precision gets worse with time for both eye tracking
devices. The precision of RED is better than the HED and the difference between them is around 10 - 16 pixels (5.584
mm). The distribution of gaze positions for HED and RED devices was expressed by a percentage representation of the
point of regard in areas defined by the viewing angle. For both eye tracking devices the gaze position accuracy has been
95-99% at 1.5-2° viewing angle. The stability of the calibration was investigated at the end of the experiment and the
obtained result was not statistically significant. But the distribution of the gaze position is larger at the end of the
experiment than at the beginning.