Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Friday, August 28, 2020

The body exchange

When we think about our own bodies, we tend to externalize them.  It's subtle, but ponder it for a moment; when I say "this is my hand," where is the "me" who is the hand's owner?  We usually put our "selves" in our heads (or hearts), so the rest of the pieces belong to whoever that "self" actually is.

As support of this, consider the unpleasant possibility of losing a limb, a sense, the ability to walk.  Something huge and devastating.  Even with such a major change, most of us feel that our "self" would remain intact.  Switch brains, though (if such a thing were possible) and you wouldn't be you any more -- there's something about that sense of self that resides there, in what my neurophysiology professor called "the meat machine."

René Descartes's illustration of mind-body dualism

Predictably, the reality may be more complex than that.  In a fascinating experiment run at the Karolinska Institutet of Sweden, researchers used virtual reality headsets to give two friends lying near each other the sense that they'd switched bodies.  In "Perception of Our Own Body Influences Self-Concept and Self-Incoherence Impairs Episodic Memory," by Pawel Tacikowski, Marieke Weijs, and Henrik Ehrsson, which came out in iScience this week, we find out that the sense of who we are is much more intimately connected to our bodies than we might realize.

The researchers did personality assessments prior to the swap.  Each participant ranked both him/herself and the friend on a number of characteristics.  While wearing the headsets, they were asked to re-rate both themselves and their friends -- and across the board, while they were in the body swap they ranked themselves as closer to what they had previously ranked their friend!

Another interesting feature was that both before and after the swap, participants were given memory tests.  They were also asked how convincing the illusion was -- how real it seemed that they were inhabiting their friend's body while the headset was on.  Last, how comfortable were they with the illusion?  Did they find it intriguing, exciting, scary, disorienting?  Curiously, the people who were the most comfortable and curious about being "inside a friend's body" did significantly better on the memory tests, leading to the conjecture that a skew between your bodily awareness and your sense of self can interfere with cognitive activity.

"We show that the self-concept has the potential to change really quickly, which brings us to some potentially interesting practical implications," said study lead author Pawel Tacikowski, in an interview with Neuroscience News.  "People who suffer from depression often have very rigid and negative beliefs about themselves that can be devastating to their everyday functioning.  If you change this illusion slightly, it could potentially make those beliefs less rigid and less negative."

The authors write:
[Our findings extend] previous knowledge in several important ways.  First, it challenges a common assumption that self-concept is relatively fixed over time and emphasizes the role of the body in the continuous construction of our sense of who we are; this role has been largely neglected in past social psychology research.  Second, this result shows that perceptual aspects of the bodily self dynamically shape multiple, abstract beliefs that constitute our conscious self-concept rather than only selected aspects of self-representation that are perceptual, body-related, or implicit.  Third, this finding clarifies that the illusory ownership of another person's body not only modifies attitudes toward this person or toward a social group to which this person belongs but also, and perhaps predominantly, modifies beliefs about the self.
What this immediately made me think of is people with body dysmorphia -- often at the root of not only disorders like anorexia, in which a person who is thin to the point of emaciation looks in a mirror and sees him/herself as overweight, but in trans individuals, who often describe the feeling as "not being in the right body."  It's no wonder both conditions are devastating, and linked to depression and suicidal ideation.  What the Tacikowski et al. study showed is that our sense of self is deeply connected to our own bodies -- and a disconnect between the self and the body has profound cognitive and emotional effects.

Naturally, the next step is to find out what's actually happening in the brain during the illusion.  "Now, my mind is occupied with the question of how this behavioral effect works — what the brain mechanism is,"  Tacikowski said. "Then, we can use this model for more specific clinical applications to possibly develop better treatments."  I'm also curious to find out how long-lasting the effects were.  Did this trigger a long-term change in how the person sees his/her friend?  Or did the change evaporate as soon as the headset was turned off and the participant was "back in your his/her own body?"

No question, though, that it's a fascinating result, and worthy of a lot more inquiry.  It gives some new insight into the age-old "mind-body problem" that has plagued philosophers since the time of Plato.  Perhaps the mind and the body aren't as independent of each other as it seems -- and our sense of self is much more tied to our physical flesh-and-blood presence than was apparent.


This week's Skeptophilia book recommendation of the week is a brilliant retrospective of how we've come to our understanding of one of the fastest-moving scientific fields: genetics.

In Siddhartha Mukherjee's wonderful book The Gene: An Intimate History, we're taken from the first bit of research that suggested how inheritance took place: Gregor Mendel's famous study of pea plants that established a "unit of heredity" (he called them "factors" rather than "genes" or "alleles," but he got the basic idea spot on).  From there, he looks at how our understanding of heredity was refined -- how DNA was identified as the chemical that housed genetic information, to how that information is encoded and translated, to cutting-edge research in gene modification techniques like CRISPR-Cas9.  Along each step, he paints a very human picture of researchers striving to understand, many of them with inadequate tools and resources, finally leading up to today's fine-grained picture of how heredity works.

It's wonderful reading for anyone interested in genetics and the history of science.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

No comments:

Post a Comment