The sequence of experiments described in Section 5.2 made use of a pair of Lucas Products Corporation white ``Super Sunnies'' goggles, of the kind commonly used in tanning booths. These are worn directly over the eyes, and therefore fit easily under an HMD. The 1.27 cm diameter central ultra-violet protector in front of each eye was removed: this had the effect of providing clear vision in an FOV limited to a central circle. As the goggles rest close to the eyes, translation of the pupil during eye rotation results in a difference between ``direct FOV'' (the range one can foviate on by turning the eyes but not the head) and ``peripheral FOV'' (the total range one can see using peripheral vision while looking straight ahead without turning the head). We measured direct FOV for the foreground occlusion at 40, peripheral at 60.
To avoid infection, in all experiments the goggles were washed with rubbing alcohol between participants.
To compare the foreground occlusion condition (i.e., the condition in which the participants wore the tanning goggles) to the same FOV without the foreground occlusion, black construction paper was placed over the HMD screens with holes corresponding to what was visible through the tanning goggles.