'Not science fiction anymore,' a body swap study reveals important clues about the concept of self

Pairs of friends were given the illusion of switching bodies as part of a new study and when individuals became convinced their friend's bodies were their own, they began to describe their personality like their friend's personality. The researchers concluded that beliefs about our personalities are flexible and perceptions of our physical and mental selves help encode our memories.

The study examined two hypotheses. The first one is that our body image shapes our personality, or perception of self, and the second is that the interaction between our perception of self and our body image helps shape and encode memory. 

In the experiment, pairs of friends laid down in the same position, wearing goggles that showed live video feeds of their friend's body as if it were their own. To further convince the mind of an actual body swap, "simultaneous touches to both participants on corresponding body parts" were applied, which each participant could see through the goggles. 

For example, one subject was threatened with a fake knife, eliciting an anxious response from the other friend who experienced the "attack" through his glasses. According to researchers, this indicated that the two friends had become convinced the other person's body was their own.

"As a child, I liked to imagine what it would be like to one day wake up in someone else's body," Pawel Tacikowski, a postdoctoral researcher at Sweden's Karolinska Institutet and one of the study's co-authors, told Cell Press. "Many kids probably have those fantasies, and I guess I've never grown out of it – I just turned it into my job."

Participants were made to feel like they woke up in someone else's body for a brief time – just enough time, researchers said, to alter their perception of themselves. 

Prior to the virtual body swap, the pairs of friends rated each another on different personality traits such as cheerfulness, talkativeness, independence and confidence. After the swap, each individual rated their own personality traits closer to those of their friend's, researches said.

"Body swapping is not a domain reserved for science fiction movies anymore," Tacikowski told Cell Press.

The encoding of memory was also affected during and after the body swap, researchers said. Those more readily connected to the body of their friend performed better at memory tests than those reporting a feeling of disconnection from the body. 

Tacikowski and the team say those who performed better had less "self-incoherence," meaning that their mental and physical self-representations still aligned. They explain that this is because we are better at remembering things related to ourselves. 

The study may further illuminate depersonalization-derealization disorder, which according to Mayo Clinic is when someone consistently or repeatedly has the feeling that they are observing themselves from outside their body or they have a sense that things around them are not real. This mental state can be akin to the feeling of constantly living in a dream. 

It is common to experience both mental states from time to time, researchers say, but when the feeling becomes persistent it becomes a disorder. The disorder is usually brought on by some traumatic experience and, over time, can interfere with relationships, jobs, life and memory.

The study may also illuminate other disorders such as depression and lead to more effective treatments.

"People who suffer from depression often have very rigid and negative beliefs about themselves that can be devastating to their everyday functioning," Tacikowski told Cell Press. "If you change this illusion slightly, it could potentially make those beliefs less rigid and less negative." 

Tacikowski plans to continue to focus on the brain mechanisms of self in relation to psychological and body image. 

"Then, we can use this model for more specific clinical applications to possibly develop better treatments," he said, as reported by Cell Press.