Читать книгу Eye Tracking the User Experience - Aga Bojko - Страница 42

Head box indicates the freedom of head movement that a remote eye tracker allows (see Figure 3.8). As long as the participant’s head remains in this imaginary box, the eye tracker can do its job and track the position of the eyes.

FIGURE 3.8 Eye tracker head box indicating the allowed range of head motion.

It is impossible for people to be completely motionless during eye tracking sessions and, in UX research, you typically don’t stabilize participants’ heads using chinrests or other contraptions. Therefore, the larger the head box, the less data will be lost due to head movement. The size of the head box depends on the eye tracker, but the typical ranges are 12–17 inches (~30–44 cm) in width, 7–9 inches (~17–23 cm) in height, and 8–12 inches (~20–30 cm) in depth.

Wearable eye trackers don’t have a specified head box. Because the eye tracker moves with the participant’s head, there are no movement restrictions.