Neuroscientists Simulate Feeling of Being Invisible in Human Subjects

A team of scientists found a way to trick the human brain into perceiving its body as invisible, pulling off one an especially tricky optical illusion.

According to the Washington Post, authors of a study published in the journal Scientific Reports used virtual reality devices in their experiment. The researchers, neuroscientists from the Karolinska Institutet in Sweden, previously induced phantom limb syndrome with people who never had an amputation.

"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," study lead author Arvid Guterstam said in a press release. "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."

The new study is a step forward from the previous one.

"We wondered if it was possible to generalize this sense of an invisible limb to an entire invisible body using the same psychological trick," Guterstam told the Post.

With their subjects wearing the virtual reality headset, the researchers set up cameras to control what they saw. Not only did they make the subjects feel as though they were looking at themselves and seeing nothing, but they poked the empty space with a paintbrush at the same time as they did the person's body (see photo above).

Then the researchers used the headset to put their subjects in stressful states of mind, finding the brain is less susceptible when it thinks its body cannot be seen.

"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," Guterstam said in the release. "These results are interesting because they show that the perceived physical quality of the body can change the way our brain processes social cues."