The EyeLink 1000 eye tracker attached to a CRT monitor. The chin/head rest is adjusted to an appropriate height for the participant and they use the controller to make responses throughout the experiment.
The EyeLink 1000, which records the eye position every millisecond and has an accuracy of 0.25º – 0.5 º of visual angle. By using infrared light directed at the participant and a camera to record the light reflected back, the eye position can be calculated. The eye position is calculated by asking the participants to look directly at points on the screen and recording the position of the pupil and the position of the corneal reflection (the first Purkinje image, which is the reflection from the outer surface of the cornea) when looking at these points . An algorithm is then used to calculate the eye position across the entire display.