1) Hemmerich et al. found that an Earth-fixed visual horizon (but not a non-horizon cue) significantly reduced cybersickness. ⁴ 2) Shahnewaz Ferdous et al. posited that Earth-stable cues introduced into VR or AR (via a partial virtual frame) should improve balance and lessen cybersickness. They discussed two small studies of balance-impaired VR/AR users. Their VR study detected a cueing difference for two balance measures and the Simulator Sickness (SSQ) Disorientation measure ⁵ , while their AR study (which allowed sight of the room) detected a difference in one balance measure but no SSQ measures. Benefits were seen only with balance-impaired subjects. While the findings were mixed, an appropriately-designed Earth-referenced cue should aid orientation. Expanded studies of this type should compare similar VR-versus-AR fields of view. Finally, 3) Cao et al. provided VR users with Earth-stable granulated peripheral cues that allowed some peripheral vision, which improved visual target searching better than restricting field-of-view (FOV), a typical countermeasure. Could this approach also mitigate cybersickness better than FOV restriction?

4) Stauffert et al. explored cybersickness implications of latency between the movement of a tracked object and its movement on a head-worn display. They provided information to assist in assessing latency, and stressed the need for comparable assessments. 5) Palmisano et al. posited that a key (and readily quantifiable) contributor to cybersickness is a large, temporally inconsistent difference between actual and virtual head position. Their findings are relevant to Moss et al. (2011), who found that varying head tracking latency was sickening. As many studies have observed that visually-moving fields elicit symptoms even when the head is still (e.g., Webb and Griffin, 2002), however, the contribution of visual field motion versus head position/motion conflict should be studied.

6) Kim et al. posited that linear head oscillations increase sensory conflict in VR devices that only track angular motion. While they failed to detect device-related differences in perceived scene stability, spatial presence, or cybersickness, this was a creative pilot study exploring implications of different tracking devices. 7) Wang et al. confirmed that vection (the illusion of self-motion) elicited by viewing a rotating dot pattern was stronger when concordant with expected graviceptive cues. VR/AR designers should know that when vection is desired, its direction should not contradict somatosensory/vestibular cues that would be present during real motion. Also, specific motion/orientation perceptions will tend to be altered to minimize sensory conflict (Young et al., 1975; Lackner and Teixeira, 1977; Dizio and Lackner, 1986; Howard et al., 1987; Golding, 1996; Tanahashi et al., 2012). The notion that vection can reduce sickening conflict is better supported than vection as a cause of sickness (Lawson, 2014a; Stanney et al., 2020b). Finally, 8) Hughes et al. evaluated head-worn versus tablet-based AR during tactical combat casualty training. They observed greater sickness with head-worn AR, but symptoms for both devices were mostly limited to the Oculomotor cluster of the SSQ, with little Nausea. Moreover, while subjects in the head-worn condition completed fewer training scenarios in the time allotted, they had more correct responses in completed scenarios. AR could be a less-sickening training approach, and solutions to mitigate oculomotor disturbances would make it even better.

9) Curry et al. evaluated participants in a head-worn racing game. They did not detect main differences in cybersickness between active drivers versus passengers. The reasons for this should be explored, as a difference has been observed in other contexts (Rolnick and Lubow, 1991; Stanney and Hash, 1998; Seay et al., 2002; Sharples et al., 2008). 10) Weech et al. found a correlation between visually-influenced body sway (reflected by the center-of- pressure [COP] ratio) ⁶ and SSQ Disorientation and Oculomotor sub-scores in a VR. It makes sense for the Disorientation score to be related to sway; expanded studies should determine if COP ratio correlates with SSQ Total Sickness or Nausea scores, as these are likely to predict quitting a training session. Finally, 11) Jasper et al. evaluated the efficacy of different cybersickness recovery strategies. Their study elicited sufficient cybersickness (Stanney et al., 2003). Greatest recovery was observed for resting with the VR off (real natural decay), while doing a virtual hand-eye task yielded the least recovery. We agree with the authors’ implication that administration of the SSQ during VR/AR should be explored further.

12) Golding et al. found that sickness severity in a moving visual surround is predicted by history of susceptibility to motion sickness, migraine, and fainting. They did not detect a relationship between sickness and vection, adding to the many studies failing to find this relation (Lawson, 2014a; Stanney et al., 2021). ⁷ Consistent with the literature (Lawson, 2014a; Stanney et al., 2020a), the aforementioned article #11 by Jasper et al. and #9 by Curry et al. observed mixed findings concerning sex as a factor in cybersickness susceptibility. Jasper et al. observed that women reported more cybersickness, but this was confounded by women having less experience with video games. The sex difference detected in Curry et al. was solely among the subset of subjects who discontinued participation early, wherein women quit earlier when driving, but not when passengers. Future studies of individual cybersickness differences should estimate variance accounted for by experience with motion sickness, driving, video games, and head-worn displays.