If you have ever tried virtual reality (VR) and wondered why did it feel so real then this blog-post is for you!
Although presence is an everyday phenomenon of being in the here and now, alive in a real world, the same concept is applied to the feeling of being inside VR. Here we will concentrate only on the experience of presence inside VR.
Last summer, me and my friend while walking down a crowded seaside boulevard in Georgia, suddenly noticed a weird bench looking like a part of a wrecked roller coaster, emitting irritating noise. We got closer and to our surprise, we read – “Experience Virtual Reality- for only 5 Gel”. I got excited, so decided to open “The Doors of Perception” of VR. A nice lady renting the device put huge goggles and headphones on my head and fastened me tightly on the bench. “Goggles?” – “ok!”, “Headphones?”- “ok!”, but what the hell is a belt needed for? Soon after, I was frankly thankful for being tightly fastened. As the lady finished with belting, she turned some buttons on and the bench started swinging and vibrating. The funny noise started roaring in my ears. In goggles, I was watching at somebody rushing down on a roller coaster. That’s all ok, but suddenly I realized, that I was crawling back on the bench trying to keep myself from falling. It was me on the roller coaster and I was really scared not to fall down from it. My brain was tricked and so was my body: increased heart rate and pulsation, sweating hands – perhaps all the symptoms that would have actually accompanied a real experience with a roller coaster.
So what happened with my brain on that funny VR bench?
I’d like to use this blog-post as an opportunity to answer this question. To investigate what is already known about how VR tricks our brain, and consequently why does it feel so real.
Presence in VR
First two terms I came across while digging into scholarly articles about VR were “presence” and “immersion”. Although sometimes these terms are used as synonyms, I’d prefer to share a viewpoint of those theoreticians who differentiate between them. Immersion deals with how technically developed a VR equipment is, while presence in VR, on the other hand, is defined as a psychological and physiological sensation of a user of actually being into VR. There is a considerable body of research, suggesting that more immersive a VR environment is (i.e. a good sound system, large 3d screen, a possibility of active navigation) the level of experienced presence increases.
Although cognitively you know very clearly that what you see is not real, still cannot help a feeling that you are actually there, in an environment that does not exist. Like that weird feeling when suddenly in your dreaming you realize that this all is just a dream, but still can not wake up.
Well, now we can feel more relaxed knowing that this feeling has a name and it is called presence. Moreover, there even exists a whole international society interested in studying this concept.
Actually, the term (tele)presence was first used by Marvin Minsky while speaking about the perspectives of human- technology interaction back in 1980 : –
“The biggest challenge to developing telepresence is achieving that sense of “being there.” Can telepresence be a true substitute for the real thing? Will we be able to couple our artificial devices naturally and comfortably to work together with the sensory mechanisms of human organisms?“
Brain substrates of VR presence
Until now, there are widely used subjective and just developing objective measures of presence. The first implies self-report ratings during actually being in VR, and after experience questionnaires. These ratings might differ by their effectiveness. Some studies indicate that ratings during the experience are more effective compared to post presence questionnaires as feelings are livelier and memory effects play no negative role in evaluating an actual experience. But still, they are both subjective, thus provide no perfectly reliable data for measurement.
Thanks to technological development, it is now possible to measure presence more objectively. It can be done either by observing bodily reactions of users (measuring heart rate or skin conductance) or by different brain imaging techniques. Following our aim to find out how brain is tricked by virtual reality, let’s concentrate on the latter.
In 2006, the first EEG study was conducted with a group of children and adults watching a roller coaster in VR with different immersive conditions in order to detect the neurophysiological underpinnings of presence. Although children reported a stronger sense of presence, the results indicated that in both groups strong presence experience was correlated with higher activations in the parietal brain areas (known to be involved in spatial processing, navigation, body-centered representation of space and visuomotor control). Another important finding was that in comparison to youngsters, adults showed stronger activation in the prefrontal areas (known to be responsible for a control of executive functions). This might be explained by an assumption that activation in the frontal brain regions causes critical evaluation of VR stimuli in adults. The same pattern is not observable in children as the prefrontal brain areas are not yet fully developed at their age. Results indicated also the important role of the insula in experiencing presence. Insula, the brain region placed deep between the parietal, frontal and temporal lobes, is known to be involved in modulating body related sensations, attention, and self-awareness. Another brain structure associated with the parietal lobe that showed significantly increased activation during a strong sense of presence was the posterior cingulate gyrus (among different functions involved in processing emotional stimulus, episodic memory, spatial attention). The authors state that increased activation in the parietal cortex while experiencing presence can be explained by stimulating emotional centers through different pathways, including the cingulate gyrus, which generates emotions like fear and joy. This consequently might lead to an increased presence experience in VR.
Since presence can be defined as a body-centered spatial experience in VR, it can be assumed that the parietal cortex plays a crucial role in experiencing it. In other words, it would be logical to think that the parietal brain regions modulate body-centered perspective of VR by gathering information from different sensory systems and thus form a comprehensive representation of space.
2 years later, the same authors repeated their study this time using fMRI. The results indicated that the prefrontal brain regions, namely Dorsolateral Prefrontal Cortex (DLPFC) inhibit the sense of presence in adults. Again, similar to the previous study, this pattern was not observable in youngsters. DLPFC unites brain areas that are known to be involved in attention modulation, cognitive control and is highly interconnected with the parietal brain regions. In comparison to children, adults have fully developed prefrontal brain regions, thus their DLPFC manages to control activities in the parietal lobe more effectively. Hence, the authors assume that it can inhibit the sense of presence in VR by critically evaluating VR stimuli.
More recent findings add credibility to the previous ones. The study from 2013, also reports an increase in activation in the parietal lobe and in insula during the strong experience of presence. While another one stresses the relationship between an increase in the presence experience and a decrease in an activity of DLPFC, that is responsible for controlling attentional recourses. Hence, it can be stated that a strong sense of presence is accompanied by accumulating attentional recourses towards VR environment at an expense of ignoring the outer real world.
Another evidence that insula plays one of the key roles in experiencing presence comes from an interesting theory, where presence is viewed as an everyday phenomenon and is studied in line with schizophrenia and Depersonalization Disorder (DPD). Here these mental disorders are described as the states of “disturbed presence”. According to the model, the crucial phenomenon for presence is a continuous prediction of emotional states generated in the insula. E.g. when a frightening stimulus is anticipated, the innate prediction of the organism is anxiety, accompanied by an adequate bodily reaction. When an actual frightening stimulus is present, organism compares between an anticipated state and actual bodily state. The author argues that there will always be a mismatch between predicted and actual state, however, a strong sense of presence is the result of “successful suppression of this mismatch between the predicted and actual interoceptive state”. The assumption of the author that the insula is the basic brain region generating a sense of presence can be validated by the data that insular activity in DPD is abnormally low.
And still, why does it feel so real?
Well, deriving from the literature the answer to our question why VR seems so real might be that immersive VR technology causes increased parietal and insular activity and inhibits the frontal brain activity. In other words, it can be assumed that a strong sense of presence is in a positive relationship with the parietal brain activity that forms the body-centered perspective of VR by accumulating information from different sensory systems. The positive relationship is also present with an insular activity that is responsible for successful repression of perceiving error between predicted and actual bodily state. While, on the other hand, the sense of presence is likely to be in a negative correlation with activation of DLPFC what causes impaired cognitive control and attention modulation. However, besides above mentioned, there still remain number of questions, like e.g. individual differences in experiencing presence, unanswered, what makes it obvious that studying presence or VR is in its infancy and there is a huge need for continuing research towards this direction.
Finally, the crucial point here is that combining VR and brain-imaging techniques provide the possibility to simulate real-world situations, induce actions and emotions under a full control of an experimenter, and at the same time to measure the underlying brain processes. Hence, considering presence as being a “fundamental property of consciousness” studying it in VR provides the unique possibility to study our sense of being in the here and now, being alive in the real world.
Brainy Sundays 