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Have you ever fantasized about waking up and becoming someone else? One study used visual images to "swap bodies", and found that this brought people's self-perception closer to the person who "swapped" their bodies with them, and that this process also affected memory.
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Source Cell Press
Compiled he Zichen
Edited by Qi Translation
In Makoto Shinkai's masterpiece "Your Name", the male protagonist Taki and the heroine Mitsuba exchange bodies across time and space, and when the two finally meet at dusk, the comet fragments once again strip their time and space.
In fact, the topic of exchanging bodies has also stirred up a small storm in the psychological community, and the core concept involved in this is self-concept, that is, the way we have a complete definition of the self. This definition answers one of the three ultimate questions of philosophical idealism— "who am I?" but when confronted with the proposition of exchanging bodies, it raises a series of questions: After switching bodies, am I still not the original "me"? How will my definition of "me" change?
"Even the way you express love / Fill your breath / Even the way you walk / Haunt your laughter." The interlude in the film describes how the two protagonists feel about their egos blending together. This description may actually be quite scientific: An Aug. 26 study by iScience suggests that when a pair of friends "swap their bodies" through optical illusions, their description of their personality becomes closer to their evaluation of their friend's personality.
Not only that, but the researchers also found that the physical and psychological connections in self-awareness are also involved in other functions such as memory: when our psychological self conflicts with our physical self, our memory can be damaged.
Bring fantasy into reality
It is widely accepted that our sense of self is influenced by childhood experiences, social interactions with others, and other events. But now, scientists have come up with another factor that can have an impact on self-perception: our bodies.
Pawel Tacikowski, a postdoc at the Karolinska Institute in Sweden and the paper's first author, said: "When I was young, I liked to fantasize about waking up in someone else's body one day. Many children may have this fantasy, and I may never get rid of it – and now, I have turned this fantasy into my job. ”
The brain, body, and Self Laboratory research team, led by Henrik Ehrsson of Karolinska Institutet, recruited several pairs of participants in friend relationships. Each pair was equipped with glasses that allowed the first view of another participant to be played in real time. To reinforce the illusion of exchanging bodies, the research team simultaneously applied stimulation to the same body part of each pair. Therefore, participants can see the other person's limbs being stimulated at the same time as they feel that the same part of themselves is also stimulated. These operations quickly had an effect: to verify that the subject was already immersed in the illusion, the researchers would threaten the friend's body with a prop knife, and the subject would begin to sweat sharply, as if they were the object of the threat. Tacikowski said: "The plot of exchanging bodies no longer exists only in science fiction movies. ”
Schematic diagram of the experimental setup. Image credit: Mattias Karlen
Here, to complete the entire process of limb exchange, the researchers used the "rubber hand illusion" in the body transfer illusion. In this classic hallucination experiment, the subject's hand is covered, but he can see a rubber glove that is receiving stimulation. If his own hand is stimulated with the same frequency at this time, the subject will hallucinate that the lifeless rubber gloves are the real part of his body. Interestingly, if the rubber hand or physical stimulus is just a virtual reality (VR) projection and does not exist in a real-world scene, the subject can also produce the rubber hand illusion.
Studies on this phenomenon have suggested that the necessary condition for the hallucination to occur is that both stimulus points are in the same relative position of the rubber glove or human hand: for example, in the palm of the hand or the tip of the index finger. This also shows that our awareness of the existence of the "self" in the body depends on the coordinate system with the body as the reference point, rather than the coordinate system formed by a stimulus and the external reference. In fact, there has been much in-depth research on the effects of the hallucination on the neural pathways that govern vision and movement, but the effects of the hallucination on the invisible and untouchable personality have yet to be revealed.
The great influence behind the illusion of simplicity
So what exactly did the researchers find in this latest article? Although participants were set to stay in the illusion of "waking up from someone else's body" for a short time, the results showed that this small period of time was enough to change the subjects' self-perception. Prior to the physical exchange, participants were evaluated for several qualities of their friends, such as chattiness, optimism, independence, and self-confidence. Compared with the baseline indicators set up at this time, their evaluation of these indicators during the body exchange tends to be closer to the indicators of their "body master".
As mentioned above, this hallucination also affects the subject's memory. Tacikowski notes: "There's been a well-established study that shows that people remember things more clearly about themselves. Therefore, we believe that if in hallucinations we can interfere with someone's sense of self, then their memory levels should be trending downward. ”
And the results were not surprising: subjects who were immersed in the illusion usually scored lower on memory tests. But a seemingly contradictory trend has also gained researchers' attention. They found that if a participant immersed herself in the illusion of exchanging bodies, that is, the greater the evaluation of her personality during the exchange of bodies, bringing her or her to a closer evaluation of her friend, his or her performance on memory tests would be better than those of those who claimed to feel "disconnected" from their own bodies. In response, the researchers speculate that these subjects, who are extremely susceptible to the illusion of limb exchange, may have lower "self-incoherence", that is, the psychological and physical understanding of the self remained relatively consistent during the experiment.
Go deep into the hearts of people with mental illness
It is worth mentioning that hallucination experiments, including the "rubber hand illusion", have also been questioned by some researchers. Particularly evident is the design of experiments, known as demand characteristics, in which participants have an idea of the results the team hopes to produce and are therefore inclined to respond accordingly. Therefore, the significant differences between the experimental data generated on this basis actually represent the gap in the expectations of researchers for different experimental groups. Information from the "rubber hand hallucination" experiment is easily searchable, so is it possible that the participants in the experiment wanted to see the results of the "limb exchange" and developed similar, biased perceptions and feedback? But the research team may have considered this possibility, and they wrote at the end of the paper that they interviewed all the participants after the experiment, and no one guessed the pattern of the results of the experiment.
Overall, these findings may have important implications for the treatment of depersonalization disorder and other mental illnesses, including depression. Among them, people with depersonalization disorder often feel that their mental state and limbs are separated, including feeling that their emotions are stripped away (depersonalization) and that their surrounding environment is imaginary (derealization). For these clinical applications, Tacikowski says, "Our results show that the concept of self-awareness has the potential to be rapidly changed. This brings us some interesting insights about potential applications. For example, people with depression often have stubborn negative opinions about themselves, which can have a devastating impact on their daily lives. However, if you can change this illusion a little, it may make them relatively flexible and positive in their evaluation of themselves. ”
Of course, based on the current results alone, Tacikowski's goal is to build a more universal framework for the physical and psychological construction of self-perception. He concludes: "Now my mind is filled with questions about why this illusion succeeded and how the neural mechanisms behind it worked. Once we've solved these questions, we can apply the model to more specific clinical practices to develop better treatments. ”
Thesis information
Tacikowski, P., Weijs, M. and Ehrsson, H., 2020. Perception of Our Own Body Influences Self-Concept and Self-Incoherence Impairs Episodic Memory.iScience, p.101429.
https://www.cell.com/iscience/fulltext/S2589-0042(20)30619-2
Reference Sources
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