Apr 24, 2015 10:43 AM By
Scientists from Sweden's Karolinska Institutet created the sensation of invisibility (sorry, no real invisibility yet) in a group of participants and found follow-up performance tasks were less anxiety-producing if the subjects had just gone invisible. The team published their study in the journal Scientific Reports, in which they suggest the findings could hold great use for people with social anxiety disorder.
One of the study’s more fundamental findings was how the brain makes sense of the body. In prior tests, the same team used head-mounted displays to simulate an invisible hand. Within minutes, subjects began feeling light touches on the invisible hand as their own. Now, with whole-body sensations, the brain reacted just as quickly.
“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 paint brush move and experienced an invisible body in that position,” said Arvid Guterstam, lead author of the study, in a statement.
In the latest experiments, Guterstam and his colleagues equipped subjects with the same head-mounted display from the prior hand study. Though the subjects looked down at their own bodies, the goggles projected an empty space a few feet away from them. An experimenter then used a paint brush to lightly touch both the subject’s stomach and a similar area in the empty space.
In another case, the experimenter swapped the brush for a knife, to which the subjects showed an increased sweat response. When they weren’t wearing the goggles, however, the knife elicited no such response. This signaled something unique about the experience of being “invisible,” as if the brain really was sensing the threat of getting stabbed.
While novel, the experiment also has clinical significance, the researchers argue. A follow-up test showed that simulating a crowd in front of the participant was stressful only for the people who weren’t made invisible. Seemingly, with all the typical human flaws and vulnerabilities on display, people receded into their normal physiologic response. But invisibility took away that pressure.
Anxiety disorders, according to the Anxiety and Depression Association of America, are the most common mental illness in the U.S., affecting some 40 million adults age 18 and older. Traditionally, people find treatment in cognitive behavioral therapy. They visit counselors to acclimate themselves to the source of their anxiety through exposure, similar to the treatment of other phobias. “This illusion could be incorporated so you stand in front of a virtual crowd so you are invisible, then increase transparency so you feel you are standing in front of them,” Guterstam told Discovery News.
Up next for the researchers are tests aimed at understanding the moral decision-making involved with invisibility. Many of us, at one time or another, have fantasized about getting away with something under the cover of darkness — or absence. As science progresses, the team wrote, these moral questions grow in importance.
“This issue is becoming increasingly relevant today,” they explained, “because of the emerging prospect of invisibility cloaking of an entire human body being made possible by modern materials science.”
Source: Guterstam A, Abdulkarim Z, Ehrsson H. Illusory ownership of an invisible body reduces autonomic and subjective social anxiety responses. Scientific Reports. 2015.