What does VR with the brain?

marktforschung.de: How did you come to researching the effects of Virtual Reality on the brain?

Paul MacNeilage: I started working with Virtual Reality because it is a very useful tool to investigate questions I am interested in. In the real world all the different sources of information about self-movement are in agreement – at least most often. But in VR you have the chance to dissociate the influence of different stimuli, because the visual movement stimuli do not match with the actual movement of the head. This happens all the time with VR and can even lead to sickness.

marktforschung.de: Is this some kind of motion sickness then?

Paul MacNeilage: The most generic name is motion sickness, but there are different kinds of it. One subclass is simulator sickness or cyber sickness. To distinguish between these is hard, we just don’t know enough yet. 

marktforschung.de: Can sickness be prevented?

Paul MacNeilage: That depends on what you’re presenting inside the VR-goggles. There is a chance that the visual stimuli that you get from a head-mounted-display can cause dizziness or loss of balance. VR can affect the equilibrium, so it’s definitely possible to get sick even when just sitting. For example when you watch a high-speed car chase in a head-mounted-display, some stimuli suggest that you’re moving through the environment when in reality you are just sitting at your desk. This can lead to conflict in the brain and therefore to sickness.

marktforschung.de: Where does the discrepancy come from? Is it mainly due to the ear-eye-connection or is it caused in the brain?

Paul MacNeilage: This is something that I am actually researching. I just published a paper on this topic in the journal “Current Biology”. The title of the article is “Visual-Vestibular Conflict Detection Depends on Fixation”. In it I am discussing how the brain detects conflict. We don’t really know how this works yet. In this paper I am trying to come up with a model or a framework that would allow us to actually study and quantify how the brain detects conflicts. The model consists of two estimates: a visual estimate of self-motion and a non-visual, for example a vestibular estimate. The brain then compares those two estimates and does some form of statistical T-Test to see if both estimates are in agreement or not. But: The ability to make this comparison depends on how reliable the signals are. If you have both a reliable visual and a vestibular estimate you are going to be quite sensitive to conflict. But if it is dark outside and the visual estimate is not very clear you are going to have a harder time detecting conflict. Bottom line: The ability to detect conflict depends on the reliability of those signals.

marktforschung.de: Are estimates the only factor or does it also depend on the way the brain functions? Every human works differently, right?

Paul MacNeilage: Certainly, there would be some aspect of that. We know that there are large individual differences as to who is more or less susceptible to motion sickness. But we don’t really know what causes those individual differences. So one hypotheses would be that some people have very reliable estimates of visual-vestibular-movement and are therefore more sensitive to conflict. That is something we could investigate moving forward. 

marktforschung.de: Is the parameter gender influencing those conflicts?

Paul MacNeilage: There is evidence claiming that females are more susceptible to simulator sickness. This is obviously a concern to the VR-industry, since it affects half of the potential consumer market. But I think the science on that is not so clear cut. When you see these differences, you don’t see what’s causing them: Is it really a difference in the peripheral physiological function? Is it a difference in more sensual processes, where these comparisons are made? Is it a difference in the way the comparison processes are translated into feelings of sickness? Or is it a difference in actual reporting, that women are more likely to stop and to say that they are uncomfortable, whereas men are more likely to continue? We just don’t know where this gender difference comes from. 

marktforschung.de: What about age?

Paul MacNeilage: We know that with age the vestibular system and its functions are compromised; it becomes less reliable. There are claims in literature that older people are less likely to get motion sick. This may be due to the decreased vestibular function. But I don’t know if there is a scientific consensus. 

marktforschung.de: Let’s go back to simulator sickness caused through VR. Do you think the conflict in the brain depends on the VR-instrument? So to say: Are people wearing goggles more likely to get sick than if they were being tested in a simulator?

Paul MacNeilage: We know from studies on motion sickness that people, who are susceptible to getting sick, are less likely to actually get sick when they are driving the car themselves. It has something to do with being in control of the motion. And perhaps being able to anticipate what motions are coming next can help prevent motion sickness. I would expect that you would observe something similar in Virtual Reality. On that note you can take this hypothetical control signal as another source of information in addition to vision and vestibular estimates. This additional control signal can help evaluate and perhaps resolve conflicts.

marktforschung.de: What happens in the rest of the body?

Paul MacNeilage: From literature on motion sickness I know that there are other physiological responses than feeling dizzy and nauseous, such as sweating, changes in heart rate or nervousness.

marktforschung.de: Mr. MacNeilage, thank you very much. It was a pleasure talking to you.