Scientists Create the Invisible Man?
Well, not exactly. But a team of neuroscientists has created the perceptual illusion of having an invisible body, and shown that the feeling of invisibility changes our physical stress response in challenging social situations.
The power of invisibility has long fascinated society, and inspired the works of many great authors and philosophers. This includes well-known literature such as the myth of Gyges' ring in Plato's dialogue The Republic and the science fiction novel The Invisible Man by H.G. Wells. And let's not forget Harry Potter's invisibility cloak.
And while these ideas are the work of fiction, recent advances in materials science indicates that invisibility cloaking of large-scale objects, such as the human body, may soon become a reality.
In this latest study, published in the journal Scientific Reports, the Swedish team describes a perceptual illusion of having an invisible body, bringing us one step closer to the dream of invisibility. The study examined the illusion experience in 125 participants, all wearing a set of heat-mounted displays. To evoke the feeling of having an invisible body, the researchers touched the participant's body in various locations with a large paintbrush while, with another paintbrush held in the other hand, they exactly imitated the movements in mid-air in full view of the participant.
"Within less than a minute, the majority of the participants started to transfer the sensation of touch to the portion of empty space where they saw the paintbrush move and experienced an invisible body in that position," lead author Arvid Guterstam explained in a statement. "We showed in a previous study that the same illusion can be created for a single hand. The present study demonstrates that the 'invisible hand illusion' can, surprisingly, be extended to an entire invisible body."
But was this illusion actually real? To demonstrate that it was, the researchers would make a stabbing motion with a knife toward the empty space that represented the belly of the invisible body. The participants' sweat response to seeing the knife was elevated while experiencing the illusion but absent when the illusion was broken. This suggests that the brain thought the threat in empty space was a threat directed toward one's own body.
Until now, it was unknown how invisibility would affect our brain and body perception.
"We found that their heart rate and self-reported stress level during the 'performance' was lower when they immediately prior had experienced the invisible body illusion compared to when they experienced having a physical body," added Guterstam. "These results are interesting because they show that the perceived physical quality of the body can change the way our brain processes social cues."
This research could potentially bring us one step closer to making the "Invisible Man" a science-fiction reality.
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