125 participants in the experiment were made to stand up wearing a collection of head-mounted displays. Upon being asked to look down at their bodies, they realized that they could not see themselves, but rather empty space. In order to create the illusion, scientists touched their body in selected places with a large paintbrush, while simultaneously mimicking these movements with another paintbrush in their eyeline, according to NDTV.
Scientists trick people into thinking they have an invisible body
“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,” said Arvid Guterstam, study lead author and scientist at the Karolinska Institutet in Sweden.
Previous work by the same group of researchers showed that people could be tricked into thinking that their hand was invisible. “The present study demonstrates that the ‘invisible hand illusion’ can, surprisingly, be extended to an entire invisible body,” Guterstam noted.
In order to show that participants truly believed that their body was invisible, the scientists pretended to stab a knife into the empty space where the stomach of the invisible body was. Participants became stressed when they saw the knife under the illusion.
“It suggests that the brain interprets the threat in empty space as a threat directed toward one’s own body,” the authors noted.
Invisibility cloaking in the not too distant future
Another experiment involved the team investigating whether the perception of invisibility has any effect on social anxiety by placing participants in front of a group of strangers. “We found that their heart rate and self-reported stress level during the ‘performance’ was lower when they experienced the invisible body illusion,” Guterstam said.
It would appear that the perceived physical quality of the body can affect the way the human brain processes social cues, and that the feeling of invisibility changes our stress response to challenging social situations. Recent work in the field of materials science suggests that invisibility cloaking of relatively large objects, like the human body, may become possible sooner than previously thought.
The study was published in the journal Scientific Reports.