The phantom touch illusion

It seems like every time researchers look further into our sensory-perceptive systems, we have another hole punched in our certainty that what we think we're perceiving is actually real.

We've looked at optical illusions -- and the fact that dogs fall for 'em, too.  We've considered two kinds of auditory illusions, the postdictive effect and the McGurk effect.  Sometimes we see patterns of motion in still objects -- and illusory "impossible" motion that our brains just can't figure out.  A rather simple protocol convinced test subjects their hands had turned to stone.  Stimulating a particular clump of neurons in the brain made patients see the doctor's face as melting.  We can even be tricked into feeling like we're controlling a second body, that just happens to be invisible.

As eminent astrophysicist Neil deGrasse Tyson put it, "The human brain is rife with ways of getting it wrong."  Honestly, at this point it's a wonder we trust anything we perceive -- and yet you still hear people say "I saw it with my own eyes" as if that somehow carried any weight at all.  Add to that all the problems with the reliability of memory, and you have to ask why eyewitness accounts are still considered the gold standard of evidence.

If you needed more proof of this, take a look at some research that came out last week from Ruhr-Universität Bochum into what happens when a person watches a virtual-reality avatar of their own body.  Participants were suited up in VR gear, and after a period of acclimation -- during which they got used to their avatar's arms and hands moving as their own did -- they were instructed to use a virtual representation of a stick to touch their avatar's hand.  Nearly all of the subjects reported feeling a sensation of touch, or at least a tingling, at the spot the virtual stick appeared to touch.

[Image licensed under the Creative Commons Samuel Zeller samuelzeller, VR (Unsplash VK284NKoAVU), CC0 1.0]

The researchers decided to check and see if the sensation occurred simply by drawing awareness to the hand, so they did the same thing only using a virtual laser pointer -- and no feeling of touch occurred.

Apparently all it took was convincing the subjects they were being touched to stimulate the sensation itself.

"The phantom touch illusion also occurs when the subjects touched parts of their bodies that were not visible in virtual reality," said study co-author Marita Metzler.  "This suggests that human perception and body sensation are not only based on vision, but on a complex combination of many sensory perceptions and the internal representation of our body."

The whole thing brings to mind a conversation I had with an acquaintance, a Ph.D. in philosophy, some years ago about the impossibility of proving materialism.  I'd always considered myself a hard-nosed materialist, but her stance was that no one could prove the external world was real.  I shot back with a snarky, "Well, that works until someone throws a rock at your head.  Hard to deny the rock isn't real after that."  She patiently responded, "No.  What is real are the sensations you experience -- the shock, the pain, the adrenaline rush.  Possibly a period of loss of consciousness.  You're still locked inside your own skull, and the only thing you have access to are your own thoughts and feelings.  Those are all you can be certain are real experiences -- and even those might well be false or misleading."

Well, it was a fair knockout (pun intended), and I still haven't really come up with a rejoinder.  Not that this is surprising; philosophers have been discussing the whole materialism vs. idealism thing for centuries, and haven't really settled it to anyone's satisfaction.  And since the time of that argument, I've found more and more evidence that we experience through our sensory-perceptive apparatus only the barest fraction of what's out there -- what neuroscientist David Eagleman calls our umwelt -- and even that part, we see inaccurately.

Kind of humbling, isn't it?  Think about that next time someone starts acting so all-fired certain about their own perceptions, memories, experiences, and opinions.  The more you know, they more you should realize that none of us should be sure of anything.

But after all, doubt isn't a bad place to start.  I'll end as I did yesterday, with a quote from the brilliant physicist Richard Feynman: "The first principle is that you must not fool yourself; and you are the easiest person to fool."

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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.

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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!]

Virtual immortality

I have lived through the deaths of people I was close to -- family members, friends, colleagues.  You can't spend 54 years on this Earth without having this experience.  And death can be many things -- peaceful, frightening, a release from suffering, the devastating tragedy of a life lost too young.

Fear of death is pretty much universal, and it's the unknown aspect of it that terrifies most people.  Will there be an afterlife, or just... nothing?  If there is an afterlife, what will it be like?  Despite the similarities between many near-death experiences, the cultural imaginings of the afterlife vary tremendously, from the benign to the horrifying.  And, of course, some afterlives are benign for some (the true believers) and horrifying for everyone else (nonbelievers and devotees of other religions).  So I think it's safest to say that no one has the slightest idea what, if anything, we'll experience after we die.

This explains why the search for immortality has been around for a long, long time.  There are scientific approaches -- usually involving the protection of the telomeres, end-caps on the chromosomes that shorten with the years and seem to have a role in age-related illnesses.  And, of course, there are the legends of people who supposedly achieved immortality by magical means, including the Comte de St.-Germain, Nicolas Flamel, and... Keanu Reeves.

So I suppose it's no surprise that there are people who want to cheat death using technology.  And a company called Paranormal Games claims that they are taking the first steps down this road with a virtual-reality software called Project Elysium, that supposedly can make an interactive 3-D computer model of a deceased love one.

The company hasn't released how it plans to accomplish this -- the software is an entrant in the Oculus VR Jam 2015 contest, where it is rumored to be a favorite for the grand prize.  Presumably the bereaved would provide photographs of the dearly departed, along with other personal details, perhaps even voice recordings, if such are available.  Project Elysium has provided screenshots of people being turned into virtual-reality characters, like the one below:

The company will be releasing promotional videos as early as next week.

Now, it stands to reason that any such facsimiles of real people, especially if they are created from still images, will be pretty rudimentary.  At first.  But as we've seen over and over, once something becomes technologically possible, it becomes sophisticated and streamlined fast.  (Consider how digital music storage and retrieval has changed, from the days of CDs to now, when you can have thousands of songs stored on a device smaller than a matchbox.)  Even if Project Elysium is not very authentic-looking at first, all it has to do is demonstrate that software designers can make it work on some level.

After that, it'll be off to the races.

My general sense is that this crosses some kind of ethical line.  I'm not entirely sure why, other than the "it just ain't right" arguments that devolve pretty quickly into the naturalistic fallacy.  Especially given my atheism, and my hunch that after I die there'll be nothing of my consciousness, why would I care if my wife made an interactive computer model of me to talk to?  If it gives her solace, what's the harm?

I think one consideration is that by doing so, we're not really cheating death.  The virtual-reality model inside the computer isn't me, any more than a photograph or a video clip is.  But suppose we really go off the deep end, here, and consider what it would be like if someone really could emulate the human brain in a machine -- and not just a random brain, but yours?

There's at least a theoretical possibility that you could have a computerized personality that would be completely authentic, with your thoughts, memories, sense of humor, and emotions.  But even given my opinions on the topic of religion and the existence of the soul, there's a part of me that simply rebels at this idea.  Such a creation might look and act like me, but it wouldn't be me.  It might be a convincing facsimile, but that's about it.

But what about the Turing test?  Devised by Alan Turing, the idea of the Turing test for artificial intelligence is that because we don't have direct access to what any other sentient being is experiencing -- each of us is locked inside his/her own skull -- the only way to evaluate whether something is intelligent is the way it acts.  The sensory experience of the brain is a black box.  So if scientists made a Virtual Gordon, who acted on the computer screen in a completely authentic Gordonesque manner, would it not only be intelligent and alive, but... me?

In that way, some form of you might achieve immortality, as long as there was a computer there to host you.

This is moving into some seriously sketchy territory for most of us.  It's not that I'm eager to die; I tend to agree with my dad, who when he was asked what he wanted written on his gravestone, responded, "He's not here yet."  But as hard as it is to lose someone you love, this strikes me as a cheat, a way to deny reality, closing your eyes to part of what it means to be human.

So when I die, let me go.  Give me a Viking funeral -- put me on my canoe, set it on fire, and launch it out into the ocean.  Then my friends and family need to throw a huge party in my honor, with lots of music and dancing and good red wine and drunken debauchery.  And I think I want my epitaph to be the one I created for one of my fictional characters, also a science nerd and a staunch atheist:  "Onward into the next great mystery."

For me, that will be enough.