Running VR sessions safely

VR can be temporarily disorientating and affect perception of reality afterwards, so HVS strongly recommends that participants, especially after long or repeated trials, do not drive or operate machinery until re-adjusted, and that you put your own risk procedures in place. The treadmill base is low-friction: with lubricant and treadmill overshoes participants must hold the frame with both hands when stepping in until used to sliding; change shoes on a mat beside the treadmill (overshoes are not for hard floors). Without overshoes, wear non-slip shoes such as running shoes. Treadplate users need non-slip shoes and a supervisor who can help them balance. Put procedures in place for anyone with balance difficulties.

Going deeper

Both closure-gate clips on the metal-framed treadmill must be locked whenever a participant is immersed. Participants hold the rail initially while getting used to moving in VR. Treadmill motion matching visual motion reduces motion sickness; very low frame rates or lag between optical and vestibular input increase it.

Position the participant where the headset was set up. Explain that they can look around using the headset and turn their body; in the water maze, looking slightly upwards shows the distal cues and looking around on the platform helps learn its position. Fit the headset, adjust for the clearest image, then fine-tune with the lens slider. Click 'Run HVS 6D VR', wait for the default scene, then press the function key for your experiment; the participant appears at the pre-trial location. With hand controllers: left thumbstick forward to move, right thumbstick to turn. On the treadmill, stepping on the spot is usually recommended; overshoes allow slide-step or scoot actions (practise without the headset first; very slippery); use the same motion for all participants in an experiment; hold the rail initially.

Going deeper

Glasses wider than 142 mm or taller than 50 mm, or touching the headset lenses, should be removed. Key-press and head-tilt navigation are easiest to explain and practise inside VR. Mobility-limited participants can use arrow keys or walk in an open space or wheelchair, depending on the system.

Let the participant practise looking around, stopping, starting and turning at the pre-trial location. Ask them to stop moving before you press Enter, otherwise they could 'escape' and land on the pool rim, lab floor or featureless plane rather than in the pool. Enter places them at the trial start point. In case of disruption (for example a fire drill), Escape stops the trial and Enter re-runs it; the series then continues, the re-run is labelled 'rerun' and the original is saved as far as it got. Shift+Escape closes the program, saving the cancelled trial. vrScript errors show an error log; the bottom names the lines to correct. Pressing a function key with no matching file runs default.vrScript.

Going deeper

Consecutive trials with identical start directions keep the participant's view from the end of the previous trial; build in an inter-trial interval if they need to turn back to the calibrated direction: start rotation is set relative to the calibrated real-world facing direction, so a participant facing away from it starts facing the other way in VR.

Walking through the pool wall and starting outside the pool both point to the headset position not matching the participant's real position: recentre or reset the view with the participant standing exactly where they take part. Ask them to stop moving before you press Enter, otherwise they can 'escape' and land on the pool rim, lab floor or featureless plane; Escape stops the trial and Enter re-runs it. They should also not step or lean forward just before you press the function key. Keep start and target points within about 7/9 of the pool radius (draw a 9-unit circle for the pool edge and a 7-unit circle inside it; anything on or within the inner circle is fine), so the virtual body doesn't overlap the wall when the next trial starts. If the participant slides towards the wall on the treadmill, turn off Sticky Keys in Windows accessibility settings. A grey or empty scene means the start coordinates are outside the scene.

Going deeper

If it continues after these checks, please contact HVS with the vrScript and a description of when it happens.

Check for motion sickness by asking about symptoms before, during and after the session, using a standard questionnaire. The Simulator Sickness Questionnaire is the established measure [Kennedy 1993]. Symptoms can persist and become more apparent hours after use [manufacturer safety instructions].

Going deeper

Very low frame rates, or lag between what participants see and what their sense of balance feels, increase sickness; treadmill motion that matches the visual motion reduces it. Keep the frame rate high and close other programs on the VR PC.

Set up a clear, safe play area and clean the headset between participants. Allow a roomscale space of at least 2 × 2 m; clean between uses with skin-friendly, non-alcohol wipes; no liquids on the lenses; replace a worn facial interface; do not share with anyone with a contagious eye, skin or scalp condition [manufacturer safety instructions].

Going deeper

Your institution's infection-control rules take precedence.