Immersion in virtual reality (VR) is increasingly used in medicine, in the treatment of pain, addictions, phobias or OCDs or to help end-of-life patients. However, this promising use of VR may not be suitable for all patients. For while the existing evidence suggests that cybersickness is a different syndrome from motion sickness, a more common and better known condition, this Australian study results in relatively similar clinical pictures, both induced by pure visual or vestibular stimuli.
Initially, motion sickness is thought to be induced by motion. And this is obviously not the case for the "cyber-malaise" which does not involve any displacement. The objective of researchers from the University of Newcastle (Australia) was to clarify this question by directly comparing the subjective symptoms and physiological effects of motion sickness induced by physical movement and the physiological effects induced by immersion in reality. virtual, with the same participants.
Motion sickness is a common consequence of “sensory mismatch” which occurs when what a person sees, feels and senses does not match the sensory input associated with their orientation and position in space. A disconnection then occurs between the eyes and the vestibular system, which controls the functioning of the inner ear, general balance and orientation in space. Because motion sickness doesn't just involve the eyes, but other senses as well, blind people can experience motion sickness too.
Cybersickness has sometimes been likened to a type of motion sickness, with one important difference, however, is that it does not involve the vestibular system and was triggered only by visual stimuli.
However, the two conditions share a large number of symptoms, including nausea, sweating, dizziness, and fatigue.
The Australian researchers studied the physiological responses to motion sickness and cybersickness in 30 young adult volunteers, in 2 separate trials separated by more than 1 week. One trial consisted of exposure to a vestibular stimulus: blindfolded, on a rotating motorized chair and with tilting of the head at regular intervals. The VR Immersion Trial consisted of having participants ride a roller coaster in virtual reality. Both trials lasted a maximum of 15 minutes and the volunteers were instructed to continue for as long as they could tolerate the symptoms. During both trials, the researchers measured the participants' sweat rate using sensors placed on the skin of their foreheads. The volunteers completed questionnaires before and after the study, including a questionnaire rating the severity of discomfort. Experience shows that:
- Only 1 of the participants was able to complete the 15 minutes of either trial, suggesting that the majority of participants experienced motion sickness and cybersickness during the trials;
- the most common symptoms are nausea, dizziness, feeling hot and sweating;
- little difference is found between self-reported discomfort severity assessment and objective physiological measures between movement trials and VR, suggesting nearly similar clinical pictures between the 2 conditions.
The same clinical picture: conclusions that contradict previous studies, comment the researchers, who conclude that motion sickness and cybersickness can be considered as the same clinical condition. The implications are there because simple and inexpensive virtual reality technology is widely used today.
The authors thus cite the example of occupational pre-selection tests where motion sickness is an exclusion criterion or induces an occupational risk. We can also think of the therapeutic applications of VR, which are therefore not suitable for all patients.