Motion sickness in VR can cause general discomfort for certain users. It depends on the person, but users can experience disorientation, vertigo, drowsiness, sweating and in extreme cases vomiting.

There are several theories as to why motion sickness occurs: sensory conflict, eye movement and evolutionary instability. This article will give you a good understanding of why our bodies can react adversely to VR, what’s causing motion sickness, and what we can do to minimize these effects.

Sensory Conflict

According to the Sensory Conflict Theory, motion sickness can occur as a result of a sensory mismatch between expected and actual motion.

In VR, expected motion is simulated by visual and auditory cues, whereas our actual motions are still detected by our vestibular system. This is our sensory system that is responsible for providing our brain with information about motion, head position and spatial orientation.

So, when our visual system would sense motion and our vestibular system would not, then this can cause a mismatch that may result in motion sickness.

Eye Movement

Motion sickness can also occur when unnatural eye motion is required to keep the scene’s image stable. A conflict can happen when the image moves differently than expected. Our eyes must then move and react in unusual ways to compensate for the unstable image. This can cause motion sickness.

Evolutionary Instability

Evolutionary, it has been critical for our survival to properly perceive the motion of our body and of the world around us. If we get conflicting information from our senses, it means something is not right. Our bodies have evolved to instinctively protect us from these irregularities.

Such protection mechanisms are the reason why we lay down until we recover, or why we sweat, vomit or have nausea when we have toxins in our body. This is in order to discourage us from ingesting similar toxins in the future.

Motion sickness may occur because the brain interprets sensory mismatch as a sign of intoxication, and triggers nausea/vomiting as a self-defence mechanism.

How to minimize the effects?

With these theories in mind, at Rhinox, we pay a lot of attention on what we can do to minimize the effects of motion sickness. This includes:

• Adding motion platforms and haptics to match the physical body movement with visual movement.
• Using teleportation as the preferred method of locomotion to minimize sensory conflict.
• Striving for a minimum of 90FPS in all our applications.
• Striving for a maximum latency of 40ms in all our applications.
• Advising users on how to correctly align the lenses.
• Reducing virtual rotations and angular velocity in our applications.

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