Today’s Eye Tracking systems measure what’s called the ‘Point-of-Regard’ by a technique called the ‘Pupil Center, Corneal Reflection’ method. The equipment consists of a matrix of LEDs emitting non-dazzling infra-red light, which is directed into the subject’s eyes. The light enters the retina and is reflected back as a bright disc.
These reflections are detected by an infra-red camera and the data processed by software, which, once calibrated with registration points, resolves the information into specific x and y coordinates that record the position of the subject’s gaze. It does this by identifying the centre of the pupil and the position of the corneal reflection in the field of view and then, using trigonometry, it’s able to calculate a precise point-of-regard position.
The data acquired during an extended eye tracking session can, for example, be overlaid on the original visual stimulus so that insights can be gained from the subject’s interaction with the material. [...]
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