eyetrackers

Eyetrackers are devices that measure eye positions and movements to determine where a person is looking, or the gaze point. They are used in research, product testing, and accessibility applications, and can be mounted on the head or positioned remotely in front of a user.

Most contemporary eyetrackers operate with video-based infrared illumination. A camera records the eye while infrared light casts reflections on the cornea; software detects the pupil center and a corneal reflection and estimates gaze direction. A calibration procedure links eye measurements to screen coordinates, enabling the device to report gaze points in real time or from recorded sessions. Outputs typically include raw gaze coordinates, pupil size, and derived metrics such as fixations and saccades.

Form factors include remote or desktop devices that watch a user’s eyes from a distance, and wearable systems such as eye-tracking glasses. Some devices are integrated into VR or AR headsets. Eye-tracking data can be synchronized with other modalities such as mouse, keyboard, or video.

Key metrics are gaze points, fixation duration, fixation count, saccade amplitude and velocity, and dwell time. Visualizations include gaze heatmaps, scanpaths, and area-of-interest analyses. Data are used to infer attention, cognitive load, and information processing.

Applications span usability testing, human–computer interaction, cognitive psychology, marketing research, driver monitoring, and assistive technology for people with limited mobility.

Limitations include sensitivity to lighting and head movement, calibration drift, occlusions from glasses or eyelids, and variability across users. Privacy and consent are important, as gaze data can reveal sensitive information about attention and intent; data handling should comply with relevant regulations.