Saturday, February 27, 2021

The Debate over Transgender Equality: Does Darwinian Natural Right Provide Any Standard?

 I have argued that the desire for sexual identity is one of the 20 natural desires of our evolved human nature.  If so, does that provide any natural standard for adjudicating the debate over transgender equality?  Most human beings easily identify their biological sexual identity as male or female.  But in a few cases, men desire to identify themselves as women, or women desire to identify themselves as men.  Does this show that gender identity is a social construction or mental experience that has nothing to do with the biological sex of the body?  Must we respect this gender identity by treating transgender women as women and transgender men as men?

So, for example, must we allow Caster Semenya to compete in the Olympics as a woman, even though she is a chromosomal male (XY) with the high testosterone levels typical for men, which gives her an advantage over other women in running events?  If we allow this, this would probably mean that chromosomal women (XX) will almost never win in Olympic running events competing with transgender or intersex women like Semenya?

Under present rules, Semenya will be prohibited from defending her 800m gold medal (won at the 2016 Summer Olympics in Rio de Janeiro), unless she takes drugs to reduce her testosterone to typically female levels.  Two days ago, her lawyers announced that they will be appealing to the European Court of Human Rights to ask that they overturn this rule as a violation of her human rights.

In a previous post, I have written about the controversy over Semenya, arguing that the science of sexuality confirms what we should know by common-sense experience that both the norm of sexual duality and the few exceptions to that norm are biologically real, and not just arbitrary social constructions.  We can respect Caster Semenya as an intersex individual with a partially male body and a female gender identity.  But we must also respect those many typically female athletes who want to compete with other biological females, so that they have a chance to display their athletic excellence.  To resolve this conflict of interests, the Olympic committees have properly ruled that intersex individuals like Semenya must either compete with men or reduce their testosterone levels to compete with women.

A similar dispute has arisen in the debate over the Equality Act, just passed by the House of Representatives, which would amend the Civil Rights Act of 1964 to prohibit discrimination on the basis of both sexual orientation and gender identity.  By passing this legislation, the Congress would endorse the interpretation of the Civil Rights Act adopted by the Supreme Court last summer in the Bostock case, where Neil Gorsuch (a Trump appointee) wrote the majority opinion that rejected the Trump Administration's claim that the sexual equality of men and women under the Civil Rights Act does not include the equal treatment of gays and transgender people.  I have written about this here and here.

President Biden has nominated Dr. Rachel Levine to be assistant secretary of health, who would be the first opening transgender federal official confirmed by the Senate.  In the first confirmation hearing, Senator Rand Paul questioned her about whether she supported genital mutilation, gender reassignment surgery, and hormone therapy for children.  Levine was evasive, replying that, "Transgender medicine is a very complex and nuanced field with robust research and standards of care."

Apparently, Paul's questioning was motivated by reports that Levine has endorsed a research study concluding that doctors should provide drug therapy for transgender adolescents to suppress puberty, because this would improve their mental health by bringing the sexual traits of their bodies into harmony with their transgender identity.  The study was published in the journal Pediatrics--"Pubertal Suppression for Transgender Youth and Risk of Suicidal Ideation," 145 (February 2020): e20191725.

Transgender people are known to suffer from high rates of suicidal thoughts--with about 40% having attempted suicide.  The claim of this new study is that pubertal suppression for transgender children would reduce this propensity to suicide, which would show better mental health for them.  This would be done by doctors prescribing gonadotropin-releasing hormone analogues that suppress puberty for adolescents 9 to 16 years old.

The method in this study was to conduct a survey of 20,619 transgender adults aged 18 to 36 years old, who were asked about their history.  Of this group, 3,494 individuals reported that they had at some time wanted to have puberty suppression therapy, but only 89 of these individuals reported that they had actually had the treatment.  These individuals were also asked about whether they had ever had suicidal thoughts or whether they had attempted suicide.  The researchers were able to show that those who reported receiving the puberty suppression treatment had a lower rate of suicidal thoughts and attempts than those who wanted the treatment but did not receive it.  The researchers concluded: "pubertal suppression for transgender adolescents who want this treatment is associated with favorable mental health outcomes."  And this is the conclusion that has been widely reported in the news media.

But if you read this study carefully, you will see some dubious features of their reasoning.  First of all, there's the fundamental methodological problem with all such survey research: they rely totally on the self-reporting of the people surveyed, although it is well known that people are often not accurate or honest in reporting what they have done or believed (see George Beam, The Problem with Survey Research, Transaction Publishers, 2014).

For instance, when some individuals report that they have had pubertal suppression treatment, and consequently they became less suicidal than they would been without the treatment, how do we know that this is true?  The research collected no medical records or observational data to confirm this self-reporting.  People who would report that they remained suicidal even after having the treatment would be confessing that their beliefs and behavior were mistaken.  Is it possible that they might be reluctant to admit that (even to themselves)?

Moreover, if you look at the actual raw numbers, they do not provide strong support for the conclusions of the article.  Only 16.9% of the people surveyed reported that they ever wanted pubertal suppression, so it seems that the great majority of transgender people do not believe this treatment would be good for them.  And those who actually received the treatment were only 0.43% of the total!

Of those who reported wanting to have the treatment, only 89 individuals (2.5%) reported that they had actually had the treatment.  And of those 89, 67 (75.3%) reported that they had thought about suicide, while 37 (41.6) reported attempting suicide.  41.6% attempting suicide is close to the 40% of transgender people generally who attempt suicide.  It's hard to see that the treatment has done much good.

Now, it is true that those who reported wanting the treatment but not having it have a higher rate of suicidality than those who wanted it and had it.  But the differences are not very dramatic.  Of the first group, 90.2% report suicidal thoughts, and 51.2% reported attempts at suicide--as compared with 75.5% and 41.5%, respectively, for the second group.

The most striking finding in these numbers is that regardless of whether transgender people report having puberty suppression or not, transgender people as a whole suffer depressingly high rates of suicidal behavior, much higher than for the general population.

There's another problem here.  Those who had puberty suppression treatment between the ages of 9 and 16 were minors.  That means that their parents agreed to this.  Did the parents force or coax their children into doing this?  Weren't these children too young to make a mature decision of this sort on their own?

Why shouldn't the law prohibit children from making this decision until they are young adults with enough moral and intellectual maturity to make this decision for themselves?

A popular explanation of transgender people is that they feel "trapped in the wrong body."  These people are said to have a personal gender identity that conflicts with the biological sexual identity of their bodies, and so they might seek hormonal and surgical treatment to change the sexual identity of their bodies to conform to their gender identity.  It has now become a standard medical treatment for "gender dysphoria" to provide procedures for changing one's sex to coincide with one's preferred gender, so that men can become women, and women can become men.

I agree with Melissa Moschella (a philosopher at Catholic University of America) who has argued against this "wrong body" narrative as based on a false dualist view of human nature that should be rejected in favor of an "animalist" view. Dualism is false because the body is intrinsic to our personal identity. Animalism rightly sees that our personal sexual identity as male or female is rooted in the biological identity of our body.  We are our animal bodies.  And therefore men are those with male bodies, and women are those with female bodies.  It's impossible to change one's biological sex, because biological sex is impressed on our body and brain early in fetal and neonatal life.

Gender dysphoria, she has argued, is not a medical problem requiring physiological or surgical treatment but a psychological problem requiring psychiatric counseling.  Those with gender dysphoria are suffering from the mental delusion that their mental sexual identity differs from the sexual identity of their body.  So doctors who try to help them undergo a biological sex change are not curing them but rather supporting their delusional disorder.  This explains why although patients often feel better initially after sex-change procedures, later on they often become depressed, anxious, and suicidal.

Moschella mades a comparison with anorexia. The cure for anorexia is not liposuction, although the patient might initially feel better, because the problem is not obesity but the psychological delusion of being too obese.

Moschella has also pointed out the incoherence in the "wrong body" idea.  It is said that a person's gender identity is in the mind not in the body.  But then it is said that the sex of the body must be changed to be in harmony with the true gender identity of the person, which concedes that the sex of the body really is essential for sexual identity.

Moschella seems to be agreeing with Dr. Paul McHugh at Johns Hopkins University Hospital, who was responsible for shutting down the sex-change treatment program that had once been supervised by Dr. John Money.  Money was the one who invented the idea of "gender identity" as different from "sex identity," with the thought that "gender" is a mental or social construction that need not conform to biological nature.  This has supported the claim that while animals have "sex," only humans have "gender."  Moschella's animalism seems to deny the gender/sex dichotomy started by Money.

It should be said, however, that biological nature does sometimes throw up anomalous cases that cannot be clearly identified as male or female--the most obvious case being those who are born as true hermaphrodites, who combine male and female traits.  In response to a question about such cases of intersexuality, Moschella has conceded that these cases show a biological disorder creating confusion about biological sex identity, but gender dysphoria is not an intersexual anomaly of nature like this.

For Moschella to sustain this claim, she would have to refute the "developmental mismatch" theory of gender dysphoria.  According to this theory, in utero the sexual differentiation of the genitals occurs separately and earlier than the sexual differentiation of the brain, so that it is possible for the sexual identity of the body to differ from the sexual identity of the brain.  This is not a dualist theory that denies animalism, because both the body and the brain are biological realities of the human animal.

My argument here is that the central tendency of animal biology is to distinguish the sexual identity of males and females as determined by their complementarity for reproduction.  But while this holds for the most part, there are exceptional cases in nature where the bipolarity of male and female becomes confused.

Some of my other posts on intersexuality and gender dysphoria can be found herehere, and here.

Wednesday, February 24, 2021

Disowning One's Own Body: Somatoparaphrenia and the Bodyguard Hypothesis for Bodily Self-Awareness

Oliver Sacks told the story of a man who woke up in a hospital bed, and when he moved, he felt someone's leg in his bed.  He thought the nurses were playing a cruel joke on him by putting a severed leg in his bed while he slept.  He threw the leg out of the bed.  But when he did this, he somehow came after it.  Falling on the floor, he was shocked to discover that the leg was attached to his body.  He began punching the leg and trying to tear it from his body.  When Sacks arrived, he told the man he shouldn't be punching the leg like that.  "And why not?" the man exclaimed.  "Because it's your leg," Sacks answered.  "Don't you know your own leg?" The man insisted that this was not his leg.  Sacks then asked him, "If this is not your left leg, then where is your own left leg?" The man turned pale.  "I don't know," he said.  "I have no idea.  It's disappeared.  It's gone.  It's nowhere to be found . . ." (Sacks 1985, 53-55).

Ever since I read that story, I have wondered how to explain those bodily disorders in which people lose their sense of bodily self-ownership.  If we can explain what they have lost, this should help us explain that normal sense of bodily self-awareness that most of us most of the time take for granted.


SOMATOPARAPHRENIA

Recently, I have been studying some of the research on one of the strangest of those disorders of bodily disownership--somatoparaphrenia.  The man described by Sacks was probably a somatoparaphrenic patient.

The term somatoparaphrenia is derived from three Greek words: soma (body), para (next to, in addition to), and phren (mind, the locus of thought).  So it denotes "body outside the mind."  People who have suffered strokes in the right hemisphere of the brain often suffer through a period in which they deny that their left leg or arm belongs to them--it doesn't feel like their body.  And in many cases they identify that body part as belonging to someone else (Feinberg et al. 2010; Vallar and Ronchi 2009).

When somatoparaphrenic patients are asked to identify their left hand, they are confused.  They will say: "How am I supposed to know whose hand is this?  It's not mine" (Gandola et al., 2012, p. 1176).  They can see that their left hand or left leg is attached to their body, but it doesn't feel like it's part of their body.  One patient said: "My eyes and my feelings don't agree, and I must believe my feelings.  I know they look like mine, but I can feel they are not, and I can't believe my eyes" (Vallar and Ronchi 2009, 545).

One person reported: "I woke up last night and called the nurse because there was this hand here, and I thought that Nadia forgot it.  I wanted to give it back to her.  She cannot work without it.  Poor Nadia" (Gandola et al. 2012, 1177).

Asked about her left hand, another person said: "It's my niece's hand.  She is so kind, she left it here to keep me company."

In one study of stroke patients admitted to a New York City hospital over a 5-year period, the doctors found that the misidentification of one's own limb after right hemisphere stroke was common but transient.  They saw that 61% (22 of 36) of right middle cerebral artery stroke patients could not identify a left limb within the first 36 hours of stroke.  But this declined quickly to 44% at 3 days and 15% at 1 week.  Of those who could not identify a limb, 77% (15 of 22) said that the limb belonged to someone else.  The doctors concluded: "Spontaneous biological recovery begins in the first hours and days after stroke" (Antoniello and Gottesman 2017).  So it seems that the brain has evolved to be resilient in response to damage to restore the normal sense of bodily self-ownership.

This research by Antoniello and Gottesman included brain scanning (MRI and CT) of these patients.  They found that damage to the right supramarginal gyrus in the inferior parietal lobe was associated with those who misidentified their limbs.


This agrees with the report of Feinberg et al. (1990).  But other studies have identified damage to other regions of the brain as associated with stroke patients who misidentify their limbs.  Antoniello and Gottesman explain this disagreement by saying that in these other studies, the examinations of the stroke patients occurred 3 to 9 days after the onset of the stroke; and since limb misidentification is so transient, their control groups were contaminated with false negatives.


THE BODYGUARD HYPOTHESIS

So what is required for the sense of bodily ownership?  What has gone wrong when people feel that their own body parts are alien to them?  

Comparing the studies of somatoparaphrenia, other bodily disorders, and illusions such as the rubber hand illusion provides evidence for what Frederique de Vignemont (2020) calls the Bodyguard Hypothesis: the brain has evolved to protect the body through neural circuits that have a protective body map that creates a sense of bodily ownership and affective motivation to behave in ways that protect the body identified in the body map.  Disownership syndromes occur when the body map does not represent a limb that feels alien.  Illusions of body ownership occur when the body map mistakenly represents something as a body part.

As long as that neural body map is functioning normally, we feel a sense of owning our bodies, and we show an emotional response to threats to our bodies.  That protective emotional response can be measured by skin conductance responses. When we see an image of a knife thrust toward a body part, we show increased skin conductance responses.

By contrast, a somatoparaphrenic patient can feel that his left leg is alien, that it does not belong to him.  And if he sees that leg threatened by a knife, he will not show an increased skin conductance response.

Similarly, those who suffer from xenomelia, who might want to have their left leg amputated, do not feel that leg is really theirs, and they will not show any protective response when it is threatened.

The opposite mistake occurs in the rubber hand illusion and in the experience of phantom limbs.  People can momentarily have the feeling that a rubber hand is their hand, and they show a protective response when they see it threatened.  Similarly, those who are missing one of their limbs--either from congenital deformity or from amputation--can feel that the missing limb is really a part of their body, and they will show a protective response when it is threatened.   

In a French podcast, Frederique de Vignemont has conveyed her Bodyguard Hypothesis in one senstence: Je me protege donc je suis.  I guard myself, therefore I am.  

Evolution by natural selection favors those psychological propensities rooted in the brain that enhance our chances for self-preservation, which includes a sense of personal identity expressed in our identifying and protecting our bodies.


REFERENCES

Antoniello, Daniel, and Reena Gottesman. 2017. "Limb Misidentification: A Clinical-Anatomical Prospective Study." Journal of Neuropsychiatry and Clinical Neuroscience 29: 284-88.

Feinberg, Todd E., Annalena Venneri, Anna Maria Simone, Yan Fan, and Georg Northoff. 2010. "The Neuroanatomy of Asomatognosia and Somatoparaphrenia." Journal of Neurology, Neurosurgery, and Psychiatry 81: 276-81.

Gandola, Martina, Paola Invernizzi, Anna Sedda, Elisa R. Ferre, Roberto Sterzi, Maurizio Sherna, Eraldo Paulesu, and Gabriella Bottini. 2012. "An Anatomical Account of Somatoparaphrenia."  Cortex 48: 1165-1178.

Sacks, Oliver. 1985. The Man Who Mistook His Wife for a Hat, and Other Clinical Tales. New York: Summit Books.

Vallar, Giuseppe, and Roberta Ronchi. 2009. "Somatoparaphrenia: A Body Delusion.  A Review of the Neuropsychological Literature." Experimental Brain Research 192: 533-551.

de Vignemont, Frederique. 2010. Mind the Body: An Exploration of Bodily Self-Awareness. Oxford: Oxford University Press.

Saturday, February 20, 2021

The Claremont Institute Repudiates Trump. So What Took Them So Long?




Yesterday, when I received the winter 2020/21 issue of the Claremont Review of Books, I expected to see a series of articles defending Trump, because the Claremont Institute has been doing that since the fall of 2016.  So I was shocked to see three articles criticizing Trump--by Andrew Busch, William Voegeli, and Charles Kesler--and only one offering a tepid defense--by Michael Anton.

For four and a half years, I have written posts disagreeing with the Claremont Institute's support for Trump (hereherehereherehereherehere, and here,)  I am pleased to see that they have now been persuaded by my arguments.


VOTE FRAUD?

Busch, Voegeli, and Kesler agree that Trump lost the election and that it was not stolen from him.  Anton tries to claim that fraudulent voting was common, but he offers no proof.

Busch, Voegeli, and Kesler agree that Trump has never been popular, that his core of supporters has always been a minority, and that Trump did nothing during in his first term or in the 2020 campaign to win over a majority of voters.  In 2016, he lost in the popular vote by 3 million votes, although Clinton was a weak candidate.  During his term in office, Trump was "the most consistently unpopular president since polling began" (10).  In the election of 2020, he did win 75 million votes, but Biden won more, and perhaps a third or more of Trump's votes were from people voting against Biden rather than for Trump (34).

The fundamental problem is not just that Trump is unpopular, but that the Republican Party generally is unpopular.  As Anton says, "a national popular vote guarantees a Democratic win in every presidential election henceforth" (26).  The Republican Party has become a permanent minority party at the national level.

This points to the strange incoherence of Trump's unpopular populism.  Populist rhetoric depends on the claim that there are only two groups--the Elites and the People--and that the Populist demagogue speaks for the People.  But this makes no sense if the Populist leaders speaks for only a minority of the People.  I made this point at a Claremont panel at the 2017 American Political Science Convention, and the panel members dismissed this with disdain.  But now it seems the people at the Claremont Institute are conceding this problem.

Of course, Trump and his supporters say he really does speak for the great majority of the people, but that the Democrats stole the election from him.  Anton tries to say that the election was probably fraudulent, but his reasoning for this is confusing.  He refers his readers to Claes Ryn's "Memorandum: How the 2020 Election Could Have Been Stolen" as "the single-best summary of the irregularities" (25).  But if you read Ryn's essay, you will see that he simply repeats Trump's claims about fraudulent voting without offering any supporting evidence, while remaining silent about the evidence against those claims.

For example, Ryn writes: ". . . There, on the evening of Election Day, counting was suddenly stopped.  Election observers and most others wee sent home.  CCTV captured what happened then a a voting place in a convention center in central Atlanta, Georgia.  A few election workers stayed behind, pulled out suitcases with ballots from under a covered table and, without the legally required election observers, fed them into the voting machines into the early morning."  Ryn says nothing about the fact that this was investigated by the Republican Secretary of State in Georgia, who found that if you looked at the entire video tape, you could see that nothing illegal occurred, and that the tape presented by Rudy Giuliani on the Hannity show and elsewhere had been edited to distort what happened.

Similarly, Ryn repeats the wild claims about the Dominion voting machines changing votes from Trump to Biden, without even mentioning that these claims have been debunked, and that Dominion is now suing those who promoted these false claims.  Oddly enough, Anton admits that Trump and his supporters made "extraordinary claims" about vote fraud, and "extraordinary claims demand extraordinary evidence, of which none was provided" (25).


TRUMP'S CHARACTER AND JANUARY 6

I have insisted that Trump's extraordinarily bad character--his lack of any moral or intellectual virtues--is enough to render him unfit to be President.  Now it seems that the people at the Claremont Institute agree.

Busch says that "Trump gave Democrats plenty of ammunition to run a campaign against his character and temperament" (12).  And after November 3, Trump "gave vent to his most narcissistic and demagogic impulses" (15).  Voegeli says that Trump's bad character created "Trump Fatigue": people were just tired of four years of daily displays of his mean-spirited narcissism, lying, and boorishness (20-21).

One of the many bad consequence of Trump's bad character was the rioting in the Capitol Building on January 6.  Kesler admits that "Trump was reckless" in calling the rally for January 6 that led to the riot (32).  But he tries to defend Trump against the charge of incitement to insurrection by claiming that his speech of January 6 provides no clear evidence of his intending to incite a riot (31).

In making his argument, however, Kesler is silent about the evidence that Trump intentionally refused to stop the riot after it began.  For over two hours, people begged him to say something to stop it, and he refused, even while watching the television coverage of the violence.  During this time, Chris Christie said publicly: "The president caused this protest to occur.  He's the only one who can make it stop."


TRUMP'S POLICIES

Many of Trump's supporters have objected that his bad character does not matter as long as his policies are good.  But a president who lacks moral and intellectual virtues like self-discipline, honesty, prudence, and wisdom is unlikely to intelligently formulate and promote good policies.  Voegeli suggests this when he notes the chaotic disorder in Trump's policy reasoning.  Kesler says "the Trump agenda was never well prepared and thought through" (34).  Isn't that because due to his bad character, Trump was never well prepared, and he never thought through anything?

So what are Trump's policies?  Anton suggests: "secure borders, fair trade, a modest foreign policy" (26).  Kesler suggests: "economic protectionism, 'internal improvements' or infrastructure spending, immigration reduced and tied to assimilation, a modest foreign policy mindful of the national interest, low taxes, judges willing to enforce the constitutional limits of legislative power, and a patriotic civic culture" (34).  Kesler rightly points out that this largely coincides with the old-fashioned Republic Party policies that prevailed from Lincoln to Coolidge.

If these are good policies, they need intelligent and prudent proponents to defend and implement them.  There is no reason to believe that a person like Trump has the character traits to do that.


 THE LIBERTARIAN ALTERATIVE

All of this points to the alternative in 2016 that was ignored by both the pro-Trump Republicans (like the Claremont Institute) and the anti-Trump Republicans (like Bill Kristol et al.). They could have supported the Johnson/Weld ticket of the Libertarian Party.  Certainly, many voters thought they were being presented with a bad choice between two bad candidates.  In retrospect, the failure of the Republican Party leaders to support a libertarian alternative to Trump now seems like a big mistake. 

Friday, February 19, 2021

The People Who Desire to Amputate Their Healthy Legs: The Neural Correlates of Body Ownership



People with Body Identity Integrity Disorder (BIID)--also called Body Identity Dysphoria--feel that their legs or arms are so alien to them that they obsessively think about their need to amputate them, although their limbs are perfectly healthy.   For half or more of these people amputation is sexually arousing, and they seek out amputees for sexual relations.  Most of them are men, although a few are women.  

The feeling of estrangement from one of their legs or arms begins when they are children and lasts throughout their life.  For most of them, it's the left leg that they want to be rid of.  And there's a clear line on the leg where they want the amputation--perhaps just below or above the knee.  Below that line, they have sensation and control over the leg, but they feel they won't be "complete" until that part of their leg is removed.

A few of them have found surgeons willing to amputate a healthy leg, and they report that they feel fine about themselves after the amputation.  There are some reports, however, that even after an amputation, those will BIID might then become unhappy with other limbs that they want to amputate.  Most surgeons refuse to do this because it seems to be a clearly unethical form of medical malpractice.  Some of those with this disorder will find ways to intentionally mangle their leg so badly that a surgeon will agree that amputation is necessary.

For most of us this is incomprehensible, because we identify with our whole bodies as belonging to us; and the idea of amputating one of our healthy limbs is horrifying.  We all normally have a sense of bodily self-ownership.  But why and how do we have that sense of self-embodiment?  If we could explain what the people with this disorder lack, that might explain what normal people have that sustains their identification of self and body.

Thinking about this disorder also raises questions about my account of the 20 natural desires, particularly the desires for sexual identity, sexual mating, and bodily health.  Are the people with this disorder expressing these natural desires in their desires for amputation and the sexual satisfaction associated with amputation?  Or are their desires unnatural because they are abnormal?  Or are they natural in the sense that they have natural causes?  If the good is the desirable, would it be good for them to satisfy their unusual desires?  In a free society, should they be free to have surgeons amputate their healthy limbs if this is what they need to be happy?  (I have written about the 20 natural desires here and here.)

Body Identity Dysphoria is so rare that there was little public knowledge of it until about forty years ago.  But in recent years, there has been a growing body of scientific research--psychological and biological--studying this condition (Sedda and Bottini 2014). 

The first public recognition of this disorder was in 1972 in a series of letters published in the men's magazine Penthouse.  The writers described their erotic obsession with having their healthy limbs amputated.  Some of them reported that they had succeeded in doing this.  For some of the readers this was so unbelievable that they thought it was a prank.


PSYCHIATRIC/PSYCHOLOGIAL EXPLANATIONS

In 1977, the famous "sexologist" John Money of Johns Hopkins University and Hospital published the first scientific report about this disorder (Money 1977).  In 1965, Money had established the Gender Identity Clinic at Johns Hopkins.  In 1966, the Johns Hopkins Hospital began performing sexual reassignment surgeries for transsexuals who wanted to change their bodies through surgery and hormone treatment to conform to their gender identity--men becoming women or women becoming men.  Money had actually coined the term "gender identity" in the 1950s.  (I have written posts on Money, intersexuality, and the desire for sexual identity herehere, and here.)

Money's article was about two men who had come to Johns Hopkins asking for the amputation of a healthy limb.  Having heard about the sex change surgeries for transsexuals at Hopkins, they assumed that they could find surgeons there willing to amputate their limbs to satisfy their sexual fantasy of being an amputee.  Money offered them psychological counselling, but he refused to refer them for surgical amputation.

He identified their condition as a paraphilia that he called apotemnophilia.  Using words derived from Greek words, he had popularized the term paraphilia--"love (philia) beyond (para) the usual"--as a non-pejorative substitute for words like "sexual perversion." He coined the word apotemnophilia to denote "amputation love"--"away from" (apo), "piece cut off" (temno), "love" (philia).  The American Psychiatric Association adopted Money's term paraphilia for the Diagnostic and Statistical Manual of Mental Disorders, in which the "paraphilic disorders" include sexual conditions like voyeurism, exhibitionism, masochism, sadism, pedophilia, and transvestism.  But the DSM has never included apotemnophilia as one of the paraphilic disorders. 

Money has a long list of over 30 paraphilias, which include asphyxiophilia (self-strangulation), autoassassinophilia (own murder staged), autonepiophilia (diaperism), narratophilia (erotic talk), and zoophilia (animals) (Money 1986, 441).

Money tried to explain apotemnophilia as caused by a psychological or psychiatric condition of unusual erotic obsession.  He noted that both of his cases were men, which was not surprising since all of the paraphilias occur predominantly in men.  He saw this desire for amputating a limb as related primarily to eroticization of the stump and secondarily to an erotic imagery of overachievement, in which visualizing an amputee surmounting a physical handicap became an erotic turn-on.

In the years following Money's article, psychologists followed Money's lead in looking for psychiatric/psychological causes for this disorder.  But then in 2005, Michael First moved this research in a different direction.  He interviewed 52 people who desired amputation (all but four were men).  The six who had obtained amputations reported that they were satisfied, because without the foreign limb they "felt complete" for the first time in their lives.

First noted that sexual arousal was only a secondary motivation for most of these people, and so he suggested that Money was wrong about this being a paraphilia.  The primary motivation seemed to be identity--the desire to "feel complete" in one's body without an alien limb.  To replace the term apotemnophilia, he proposed Body Integrity Identity Disorder (BIID), which would suggest the parallel to Gender Identity Disorder.  Others have proposed that a better term for this would be xenomelia ("foreign limb") (McGeoch et al. 2011).


NEUROLOGICAL EXPLANATIONS

Over the past 20 years, there has been a move away from psychological or psychiatric explanations of this disorder to neurological explanations.  Neuroscientists have pointed to the neural correlates of BIID, which indicate how this disorder is rooted in the brain.  But as is so often the case with research like this, correlation is not necessarily causation:  given the plasticity of the brain, we cannot be sure whether the neural correlates of BIID are the causes or the effects of the disorder.  Do abnormalities in the structure and functioning of the brain cause BIID?  Or does living with this disorder create these abnormalities in the brain?  Or do we need to see a complex interaction of multiple causes--mind, brain, and society?

The primary reason for believing that there must be neural correlates for BIID was that for over a hundred years neurologists had studied the loss of body ownership--mostly on the left side of the body--after damage to the right hemisphere of the brain, which suggested that the sense of bodily self-ownership is largely based in the right cerebral hemisphere.

For example, in 1914, the French neurologist Joseph Babinski introduced a new neurological term anosognosia, coined from three Greek words--a (without), nosos (disease), gnosis (knowledge)--for a disorder suffered by some patients with extensive damage to the right hemisphere of the brain: the left side of their body was paralyzed, but they were unaware, or seemed to be unaware, of this paralysis.  Later, this term was broadened to include a broad range of disorders in which people fail to recognize the presence or the severity of their neurological deficits from brain damage (Jenkinson 2014).

Anosognosia is now seen as one of a long list of bodily disorders (including BIID) in which some dimension of bodily awareness has been disrupted by an abnormality in the brain, often caused by damage from stroke to the right cerebral hemisphere of the brain (Case et al 2020).  A list of such neurological and psychiatric bodily disorders compiled by Frederique de Vignemont (2020, pp. 212-14) numbers over 50.

This list includes:

Autoprosopognosia.  Inability to recognize one's own face.

Cotard syndrome.  Delusional belief that one is dead, does not exist, is putrefying, or has lost one's blood or internal organs.

Delusional parasitosis.  Tactile hallucination associated with the delusion that small creatures are infesting one's skin.

Embodiment delusion.  Feeling another individual's left arm as being one's own.

Heutoscopy.  Seeing a double of oneself at a distance.

Negative heutoscopy.  Inability to see one's reflection in a reflecting surface.

Out of body experience.  Visual awareness of one's own body from a location outside the physical body.

Phantom limb.  Awareness of a non-existing limb, often after amputation.

Somatoparaphrenia.  Denial of ownership of one's own body part.

As de Vignemont notes, bodily disorders like this are not rare.  There is one report that over half of the stroke patients in a neurological department has some kind of impairment in bodily awareness (Denes 1990; Schwoebel and Coslett 2005).  If these disorders seem rare, it's because often they appear for only a few days or weeks and then disappear.

Since the most common pattern is damage to the right cerebral hemisphere causing bodily disorder in the left side of the body, those looking for the neural correlates of BIID have suspected that they are most likely to be found mostly in the right hemisphere.  And, indeed that seems to be the case.

One thorough examination through brain imaging of 15 males with a strong desire for amputation of one or both legs found predominantly right-sided cortical abnormalities in the parietal lobe and the right anterior insula (Berti 2013; Hilti et al. 2013).  A recent brain imaging study of 16 men desiring the amputation of the left healthy leg found structural and functional abnormalities in the target limb sensorimotor area and in the right superior parietal lobe (rSRL).  The greater the atrophy in the rSPL the stronger was the desire for amputation (Saetta et al. 2020).  

This suggests that the brain has evolved to have a neural network to establish and maintain a sense of body ownership, but that a disruption in this network can break down this normal bodily ownership in a way that inclines people to feel a desire for amputating healthy limbs that feel alien to them.

Neural abnormality might also explain the erotic connotations of BIID.  Although it is a speculative explanation, these erotic fantasies "may have their roots in the proximity of primary somatosensory cortex for leg representation, whose surface area was reduced in the participants with xenomelia, with that of the genitals."  Or "the spatial adjacency of secondary somatosensory cortex for leg representation and the anterior insula, the latter known to mediate sexual arousal beyond that induced by direct tactile stimulation of the genital area, might play a role" (Hilti et al. 2013, 318).  

Some of the same areas in the brain that are associated with the xenomelic/BIID disorder partially overlap with the brain areas that are damaged in the disorder known as somatoparaphrenia, in which people deny the ownership of their left legs or arms and often say these limbs belong to someone else.  While somatoparaphrenia is an acquired abnormality from severe lesions in the right hemisphere, xenomelia might arise from a congenital abnormality in the brain.  Even if there is some uncertainty as to whether the abnormal neurocircuitry of xenomelia is cause or effect, it is clear that the desire for amputating one's healthy limb is imprinted in one's brain.

In the next post, I will say more about somatoparaphrenia, and how it illuminates the neural basis of bodily ownership.


REFERENCES

Berti, Anna. 2013. "This Limb Is Mine But I Do Not Want It: From Anatomy to Body Ownership." Brain 136: 11-13.

Case, Laura K., Marco Solca, Olaf Blanke, and Nathan Faivre. 2020. "Disorders of Body Representation." In K. Sathian and V. S. Ramachandran, eds., Multisensosry Perception: From Laboratory to Clinic, 401-422. London: Academic Press.

Denes, Gianfranco. 1990. "Disorders of Body Awareness and Body Knowledge." In F. Boller and J. Grafman, eds., Handbook of Neuropsychology, 2: 207-228. Amsterdam: Elsevier.

First,  Michael. 2005. "Desire for the Amputation of a Limb: Paraphilia, Psychosis, or a New Type of Identity Disorder?"  Psychological Medicine 35: 19-28.

Hilti, Leonie Maria, Jurgen Hanggi, Deborah Vitacco, Bernd Kraemer, Antonella Palla, Roger Luechinger, Lutz Jancke, and Peter Brugger. 2013. "The Desire for Healthy Limb Amputation: Structural Brain Correlates and Clinical Features of Xenomelia." Brain 136: 318-329.

Jenkinson, Paul M., and Aikaterini Fotopoulou. 2014. "Understanding Babinski's Anosognosia: 100 Years Later." Cortex 61: 1-4.

McGeoch, Paul D., David Brang, Tao Song, Roland R. Lee, Mingxiong Huang, and V. S. Ramachandran. 2011. "Xenomelia: A New Right Parietal Lobe Syndrome." Journal of Neuroscience, Neurosurgery, and Psychiatry 82: 1314-1319.

Money, John. 1977. "Apotemnophia: Two Cases of Self-Demand Amputation as a Paraphilia." The Journal of Sex Research 13: 115-125.

Money, John. 1986. Venuses Penuses: Sexology, Sexosophy, and Exigency Theory. Buffalo, NY: Prometheus Books.Schwoebel, J., and H. B. Coslett. 2005. "Evidence for Multiple, Distinct Representations of the Human Body." Journal of Cognitive Neuroscience 17: 543-553.

Saetta, Gianluca, Jurgen Banggi, Martina Gandola, Laura Zapparoli, Gerardo Salvato, Manuela Berlingeri, Maurizio Sherna, Eraldo Paulesu, Cabriella Bottini, and Peter Brugger. 2020. "Neural Correlates of Body Integrity Disorder." Current Biology 30: 2191-2195.

Schwebel, J., and H. B. Coslett. 2005. "Evidence for Multiple, Distinct Representations of the Human Body." Journal of Cognitive Neuroscience 17: 543-553.

Sedda, Anna, and Gabriella Bottini. 2014. "Apotemnophia, Body Integrity Identity Disorder or Xenomelia? Psychiatric and Neurological Etiologies Face Each Other." Neuropsychiatric Disease and Treatment 10: 1255-1265.

de Vignemont, Frederique. 2020. Mind the Body: An Explanation of Bodily Self-Awareness.  Oxford: Oxford University Press.

Friday, February 12, 2021

Happy Darwin/Lincoln Day!

Once again, it's time to celebrate the birthday of Abraham Lincoln and Charles Darwin, who were born on February 12, 1809.

I have commented on some of the many points of comparison for the two in previous posts here and here, which include links to many other posts.

In those posts, I have explained the eight points of similarity between Darwin and Lincoln.

Both saw the universe as governed by natural laws, which included the natural laws for the evolution of life.

Both were accused of denying the Biblical doctrine of Creation.

Both were accused of being atheists.

Both spoke of God as First Cause.

Both appealed to the Bible as a source of moral teaching, even as they also appealed to a natural moral sense independent of Biblical religion.

Both abhorred slavery as immoral.

Both were moral realists.

Both were classical liberals.

Wednesday, February 10, 2021

"I Felt As If the Rubber Hand Were My Hand." Was this the Immaterial Soul Speaking?

"I felt as if the rubber hand were my hand."  That's what many people have said when they have participated in the rubber-hand experiment, which is designed to test the conditions for the sense of bodily ownership.

In the first report of the rubber-hand illusion, Botvinick and Cohen (1998) describe two experiments.  In the first one, ten subjects were seated with their left arms on a table and a screen beside the left arm to hide it from the view of the subject.  A life-sized rubber hand and arm was placed in the middle of the table in full view of the subject.  While the subject looked at the rubber hand, the experimenters used two small paintbrushes to gently stroke the hidden hand and the rubber hand, timing the brushing so that it was synchronous.


Manos Tsakiris Speaks About the Rubber Hand Illusion

After ten minutes, subjects answered a questionnaire about their experience.  Many of them reported that during the experiment there were times when they seemed to feel that the rubber hand had sensed the touch of the brush.  "It seemed as though the touch I felt was caused by the paintbrush touching the rubber hand."  "I found myself looking at the dummy hand thinking it was actually my own."

To provide a control condition, some subjects experienced asynchronous brushing of the real hand and the rubber hand--the brushing was not done simultaneously.  These subjects did not report the illusion of feeling the brush stroke in the rubber hand.

The experimenters inferred that the rubber-hand illusion here shows that bodily self-identification arises from the interaction of at least three sensory modalities--vision, touch, and proprioception.  Vision monitors where the limbs are in space.  Touch monitors body conformation and its contact with external objects.  Proprioception is the sensation of the body's position and movement, relying on mechanosensory neurons distributed throughout the body, which are called proprioceptors (Tuthill and Azim 2018).  The illusion arises because the brain's attempt to reconcile the visual inputs from the rubber hand and the tactile inputs from the hidden hand distorts the proprioceptive sense so that in the brain's representation of the body, the rubber hand takes the place of the real hand.

The experimenters tested this hypothesis of proprioceptive distortion in their second experiment.  Subjects were put into the conditions of the prior experiment for a prolonged period (30 minutes).  Then, with their eyes closed, the subjects were asked to move the right index finger under the table until it was in alignment with the left index finger, which was still on top of the left side of the table.  The subjects' reaches were displaced toward the rubber hand, and the magnitude of the displacement was proportional to the reported duration of the hidden-hand illusion.  Thus, their proprioceptive sense of the location of their left hand had been moved in the direction of the rubber hand. 

Something similar to the rubber-hand illusion can be induced in experiments with phantom limb patients.  Some patients who had had their left arm amputated were put into an experiment in which a mirror was placed in front of them, so that when they looked at the stump of their left arm, they saw the reflection of their intact right arm.  When they saw their right arm being touched, they reported feeling that their phantom left arm was touched (Ramachandran and Rogers-Ramachandran 1995).

A similar illusion can occur when an experimenter simultaneously strokes an amputee's stump, which is out of view, and a visible rubber hand located near the stump: the patient starts to feel that the rubber hand is part of her body, so that the rubber hand becomes her phantom hand (Ehrsson et al. 2008).  This is an important finding for neuroprosthetics, where it's important to develop artificial limbs that feel like real parts of the body.

This experimental study of the rubber-hand illusion has been replicated many times (Blanke et al. 2015; Longo et al. 2008; Moseley et al. 2012; Tsakiris 2010, 2017).  The later studies have been able to use improved neurophysiological technology--such as functional neuroimaging--to identify the neural correlates of the sense of body ownership.  These studies have identified a network of areas in the brain--including premotor, temporopariental, and occipital areas, as well as the insula.  The insula is known as the hub of the interoceptive system of the brain, but it is also engaged in the experience of bodily ownership during the rubber-hand illusion.  

I have written previous posts on Bud Craig's account of how interoception in the insula supports bodily self-ownership here and here.

Interoception arises from sensations coming from inside the body and the visceral organs that signal physiological states such as thirst, hunger, need for air, heartbeat, coolness, warmth, distension of the bladder, sexual arousal, and other internal states.  Interoceptive signals arise from the cardiovascular, respiratory, gastrointestinal, and urogenital systems.

This indicates that our sense of our bodily self depends on the multisensory integration in the brain of the exteroceptive body (the body as viewed from the outside) and the interoceptive body (the body as viewed from the inside) (Tsakiris 2017).


HYPNOTIC SUGGESTIBILITY?

Over the past year, the research on the rubber-hand illusion has been challenged by psychologists studying hypnosis who say that these reports of illusory body ownership might be the product mostly of hypnotic suggestibility (Florio et al. 2020; Lush 2020; Lush et al. 2020; Makin 2020; Seth et al. 2020).  Peter Lush and his colleagues at the University of Sussex have said that the experiments with the rubber-hand illusion have been confounded by what psychologists call "demand characteristics" or "suggestibility effects."  That is to say, when people are recruited to be subjects for experiments like this--and it's often college students--they can many times figure out what is expected by the experimenters, and if so, many of the subjects will tend to say whatever they think the experimenters want them to say.  They will think: Oh, if they want me to say that I feel as though this rubber hand is really my hand, then that's what I will say.

This propensity can be measured by hypnotic suggestibility:  some people are more easily hypnotized than others, and the researchers who study this can rate people for their suggestibility.  Lush and his colleagues conducted experiments in which they found that those subjects who were more suggestible were more likely to report an intense feeling of the rubber-hand illusion.  This seemed to be a lot like the placebo effect: people can show a beneficial effect from a drug or therapy, even though they were not given the real drug or therapy, because they believed they had. 

I have had an exchange of emails with Manos Tsakiris, a neuropsychologist at the Royal Holloway University of London, who is one of the leading researchers on the rubber-hand illusion.  When I questioned him about the work of Lush and colleagues, he said that if you look at their data, you will see that it does not deny the reality of the rubber-hand illusion.  Their data shows that both those who are highly suggestible and those who are low in suggestibility report feeling the rubber-hand illusion.  There is only a difference of degree, in that the highly suggestible subjects feel the illusion more intensely.  There is nothing surprising in this, he observes, because there will always be individual variability in psychological experiments like this due to individual differences in personality.

I accept this response.  But I still think Tsakiris and others in RHI research need to answer the argument of Lush and colleagues that even if the RHI is a real subjective experience, it is very weak, and so it does not show that our ownership of our body is easily malleable.  When subjects have undergone the RHI experiment, they do not leave with a permanent or enduring illusion that the rubber hand is really their hand.  Even if they have had a fleeting feeling of the illusion--a few seconds or minutes--they have no trouble realizing that this has been only a momentary feeling, and that the rubber hand is not their real hand.  

After all, if the RHI experiment really did induce an enduring feeling that the rubber hand had replaced their real hand, this would be an unethical experiment that would never be approved by any Institutional Review Board for Protection of Human Subjects!  I assume that whenever Tsakiris submits a proposal for a RHI experiment, he tells his university review board that the experiment is harmless--that it will not induce any enduring state of confusion about body identity.

In contrast to the transient feeling of the RHI, people with certain kinds of brain damage can completely lose their sense of body ownership in a limb, and they can even believe quite strongly that one of their limbs actually belongs to someone else (Vallar and Ronchi 2008).  Some people with xenomelia ("foreign limb") even have an obsessive desire to amputate a healthy limb because it seems alien to them (Hilti et al. 2013).  The RHI does not show this kind of serious disruption in the sense of bodily self-ownership.

There is another problem here that runs through all of this research on the psychology and neuroscience of subjective experience:  the researchers cannot observe directly the inherently private experience of subjective feelings and thoughts that are invisible to the researchers; they have only an indirect access to this invisible world through the introspective self-reporting of their subjects.

Can this invisible world of subjective experience be reduced to the visible material world of the body and the brain?  Or is this subjective world of conscious self-awareness the activity of an immaterial soul?


TRICKING THE IMMATERIAL SOUL?

If one's highly suggestible mind is easily tricked into believing that a rubber hand is one's real hand, even if only momentarily, does that manifest the power of the immaterial soul to change the material body and brain?  That's the conclusion drawn by Denyse O'Leary (2020) in her assessment of the debate over the RHI.

O'Leary has often argued that natural science supports both the dualistic reality of an immaterial soul and material body as opposed to materialist reductionism and the truth of Intelligent Design Theory as opposed to Darwinian evolution.  Not surprisingly, then, she has criticized some of my arguments; and I have responded to her.

She sees the RHI as similar to the placebo effect in that it shows how our subjective mental expectations have effects on the body and the mind.  This is the kind of evidence she cites in her book The Spiritual Brain (2007)--coauthored with neuroscientist Mario Beauregaard--arguing that neuroscience provides evidence for the existence of the soul as an immaterial and immortal spirit.

She is correct in pointing to the mystery of consciousness and to the failure of neuroscience to resolve that mystery in materialist terms by explaining exactly how the brain creates the mind through purely material causes.  Nevertheless, she herself has not resolved this mystery by asserting that the immaterial soul has been created supernaturally by God, but without explaining exactly how God does this.  This is the fallacy of explaining a mystery with a mystery.

I will say more about this in a future post on Thomas Willis and the neuroscience of dualism.


REFERENCES

Blanke, Olaf, Mel Slater, and Andrea Serino. 2015. "Behavioral, Neural, and Computational Principles of Bodily Self-Consciousness." Neuron 88: 145-166.

Bolvinick, Matthew, and Jonathan Cohen. 1998. "Rubber Hands 'Feel' Touch that Eyes See."  Nature 391: 756.

Ehrsson, H. Henrik, Birgitta Rosen, Anita Stockselius, Christina Ragno, Peter Kohler, and Goran Lundberg. 2008. "Upper Limb Amputees Can be Induced to Experience a Rubber Hand as Their Own." Brain 131: 3443-3452.

Fiorio, Mirta, Michele Modenese, and Paola Cesari. 2020. "The Rubber Hand Illusion in Hypnosis Provides New Insights into the Sense of Body Ownership."  Scientific Reports 10:5706.

Hilti, Leonie Maria, Jurgen Hanggi, Deborah Ann Vitacco, Bernd Kraemer, Antonella Palla, Roger Luechinger, Lutz Jancke, and Peter Brugger. 2013. Brain 136: 318-329.

Longo, Matthew R., Friederike Schuur, Marjolein P. M. Kammers, Manos Tsakiris, and Patrick Haggard. 2008. "What is Embodiment? A Psychometric Approach." Cognition 107: 978-998.

Lush, Peter. 2020. "Demand Characteristic Confound the Rubber Hand Illusion." Collabra: Psychology 6:22.

Lush, Peter, V. Botan, R. B. Scott, A. K. Seth, J. Ward, and Z. Dienes. 2020. "Trait Phenomenological Control Predicts Experience of Mirror Synaesthesia and the Rubber Hand Illusion." Nature Communications 11:4853.

Makin, Simon. 2020. "Hypnosis Experts Cast Doubt on Famous Psychological Experiments." Scientific American Blog, October 21.

Moseley, G. Lorimer, Alberto Gallace, and Charles Spence. 2012. "Bodily Illusions in Health and Disease: Physiological and Clinical Perspectives and the Concept of a Cortical 'Body Matrix.'" Neuroscience and Biobehavioral Reviews 36: 34-46.

O'Leary, Denyse. 2020. "Is There Really a 'Rubber Hand' Illusion?" Mind Matters blog, April 19.

Ramachandran, V. S., D. Rogers-Ramachandran, and S. Cobb. 1995. "Touching the Phantom Limb." Nature 377: 489-490.

Seth, Anil, Warrick Roseboom, Zoltan Dienes, and Peter Lush. 2020. "What's Up with the Rubber Hand Illusion?" NeuroBanter blog. November 9.

Tsakiris, Manos. 2010. "My Body in the Brain: A Neurocognitive Model of Body-Ownership." Neuropsychologia 48: 703-712.

Tsakiris, Manos. 2017. "The Multisensory Basis of the Self: From Body to Identity to Others." The Quarterly Journal of Experimental Psychology 70: 597-609.

Tuthill, John C., and Eiman Azim. 2018. "Proprioception." Current Biology 28: R187-R207.

Vallar, Giuseppe, and Roberta Ronchi. 2009. "Somatoparaphrenia: A Body Delusion.  A Review of the Neuropsychological Literature." Experimental Brain Research 192: 533-551.


Monday, February 08, 2021

How (and Why) Do You Know Your Body Is Yours?

I remember well reading Rene Descartes' Discourse on Method in one of my first college philosophy classes.  I couldn't believe that he was serious in separating his self from his body--arguing that while he could doubt the existence of his body, he could not doubt the existence of his self as a thinking being, because in the very activity of doubting, he would be thinking and thus showing his thinking self: I think, therefore I am.  But, surely, I thought, our thinking self is always situated in our bodily self.

Years later, however, I learned from Oliver Sacks that some people can become so estranged from their bodies that they feel that some parts of their body are not really theirs, so that they might think their left leg is not theirs, but someone else's.  In some rare cases, from a young age, people might obsessively want to amputate a healthy leg that seems alien to them.  In such cases, there must be some malfunctioning of those parts of the brain that support our feeling of bodily self-ownership.

Over the past 30 years, neuroscientists who believe that the evolved purpose of the brain is to serve the survival and wellbeing of the body have studied how the brain creates our sense of owning our bodies.  In recent years, I have become interested in this research as possibly providing neuroscientific confirmation for John Locke's principle of self-ownership as grounded in the body. 

There have been four major approaches to the neuroscientific study of bodily self-ownership: mirror self-recognition, studies of the changes in corporeal awareness after brain damage, experiments inducing bodily illusions in healthy individuals, and studies of aberrant bodily experience in otherwise healthy people.  I will briefly survey each of these areas of research.

The general conclusion from all of this research is that the brain has evolved neural networks for representing peripersonal space and body ownership that allows planning and executing movements that are good for the body, because they protect the body from external threats (physical and social), because they support social cooperation that benefits the body, and because they sustain the internal homeostatic health of the body (Barrett 2020; Craig 2015; Moseley et al. 2012; Tsakiris 2010, 2011).


SELF-RECOGNITION

One way to study bodily self-awareness is to devise experiments in which people look at body-parts, and the test is whether they can judge correctly whether this belongs to their body or not.  One of the most common techniques is mirror self-recognition, in which individuals are tested to see if they can recognize their faces in a mirror.  If they can recognize their face as their own, this indicates self-awareness (Gallup et al. 2011; Jeannerod 2003; Keenan et al. 2003).

Not only humans but also other animals have been tested in this way for mirror self-recognition.  One common way to do this is to put a spot of brightly colored dye on the foreheads of some individuals.  Then, when they see their faces in a mirror, they can show self-recognition by touching the colored spot and exploring it with the mirror.  

Most animals cannot do this, because they react to their faces in a mirror as if these were the faces of others.  I often see this in the spring, when a robin is staking out his territory around my house, and he repeatedly flies into the picture window of my house, because he sees his reflection and mistakes it for another robin invading his territory who needs to be driven away.  

Among primates, monkeys can perceive faces, but only some of the great apes can recognize their own face in a mirror. About 75% of chimpanzees between the ages of 8 and 15 years can pass the mark test.  

Most children can pass the test beginning sometime between 18 months and 2 years old.  But some humans cannot recognize themselves in mirrors.  Children younger than 18 months react to themselves in mirrors as if they were seeing other children.  Some mentally disabled and autistic children do not show self-recognition.  The same is true for some schizophrenics, for some people with brain damage, and some people with advanced Alzheimer's disease.

Self-recognition indicates the self-awareness that is a necessary condition for "mind-reading"--making inferences about mental states in others.  To know what other people are thinking, we must build from our awareness of mental states in ourselves.  Consequently, those who lack a deep self-awareness--such as severely autistic people--find it hard to read the minds of others, which impedes their understanding of and engagement in social interaction.

This self-awareness of our own minds and bodies that allows us to imagine the minds of others is the essential condition for what Locke presents as the natural understanding of the law of nature that dictates the equal liberty of all people.  If I naturally desire to receive good from other people, then I should understand that other people have the like desire to receive good from me; and as I would desire to punish anyone who would injure me, then I should understand that anyone I would injure would have the like desire to punish me for injuring him.  And just as I desire ownership of my own body and my natural rights to my life, liberty, and property as the necessary conditions for my body's survival and wellbeing, I can imagine that others have the like desire that I cannot frustrate without provoking their resentment and retaliatory punishment (Second Treatise, pars. 4-13).  In this way, Locke suggests, reasoning from what we know from self-recognition about our own desires, we recognize others as having similar desires; and we then can understand why the mutual satisfaction of those desires requires that we respect those natural rights and duties that make peaceful social cooperation possible.

Since it secures the benefits of social cooperation, the mental capacity for self-recognition would have been advantageous for our evolutionary ancestors; and so we might expect that the human brain would have some evolved neural mechanisms for self-recognition.  And indeed there is extensive evidence for a neural network in the human brain that enables self-recognition (Keenan et al. 2001; Platek et al. 2004; Gallup et al. 2011).

Early in this research, studies of split-brain patients made it clear that the right cortical hemisphere was more important for self-face recognition than the left hemisphere.  Later research confirmed this through measuring reaction times in identifying one's own face as opposed to other faces.  Left hands had faster reaction times than right hands in responding to self-faces but not to other faces.  Other evidence came from patients with right hemisphere damage that makes it hard for them to identify their faces.  Brain imaging studies showed that during the identification of self-faces, there was greater activation in the right frontal lobes, the right inferior parietal lobe, and the right insula.

Self-recognition, mental state attribution, and autobiographical memories share similar brain regions.  One might expect this if self-awareness and mental state attribution are linked.  

This is also connected to the neural correlates for contagious yawning--to tendency to yawn when one sees--or even thinks about--another person yawning.  People who show contagious yawning recognize their own faces more quickly and score high on tests for mental state attribution (the ability to infer the mental states of others) (Platek et al. 2003).  Brain imaging studies show that seeing someone yawn activates the posterior  cingulate and the precuneus, which are areas of the brain related to self-awareness, theory of mind, and autobiographical memories (Platek et al. 2004).

Chimpanzees who are capable of self-recognition show contagious yawning (Anderson et al. 2004).  Autistic children who show little self-recognition or mental state attribution do not show contagious yawning (Senju et al. 2007).

I will be writing more posts on the neuroscience of bodily self-ownership.


REFERENCES

Anderson, J. R., Myowa-Yamakosh, M., and Matsuzawa, T. 2004. "Contagious Yawning in Chimpanzees." Proceedings of the Royal Society B 271: 468-70.

Barrett, Lisa Feldman. 2020. Seven and a Half Lessons About the Brain. New York: Houghton Mifflin Harcourt.

Craig, A. D. (Bud). 2015. How Do You Feel? An Interoceptive Moment with Your Neurobiological Self. Princeton, NJ: Princeton University Press.

Gallup, Gordon G., James R. Anderson, and Steven M. Platek. 2011. "Self-Recognition." In Shaun  Gallagher, ed., The Oxford Handbook of the Self, 80-110. Oxford, UK: Oxford University Press.

Jeannerod, Marc. 2003. "The Mechanism of Self-Recognition in Humans." Behavioural Brain Research 142: 1-15.

Keenan, Julian Paul, Aaron Nelson, Margaret O'Connor, and Alvaro Pascual-Leone. 2001. "Self-Recognition and the Right Hemisphere." Nature 409: 305.

Keenan, Julian Paul, Gordon Gallup, and D. Falk. 2003. The Face in the Mirror: The Search for the Origins of Consciousness. New York: HarperCollins/Ecco.

Moseley, G. Lorimer, Alberto Gallace, and Charles Spence. 2012. "Bodily Illusions in Health and Disease: Physiological and Clinical Perspectives and the Concept of a Cortical 'Body Matrix.'" Neuroscience and Biobehavioral Reviews 36: 34-46.

Platek, Steven M., Samuel R. Critton, Thomas E. Myers, and Gordon G. Gallup. 2003. "Contagious Yawning: The Role of Self-Awareness and Mental State Attribution." Cognitive Brain Research 17: 223-27.

Platek, Steven M., Julian Paul Keenan, Gordon G. Gallup, and Feroze B. Mohamed. 2004. "Where Am I? The Neurological Correlates of Self and Other." Cognitive Brain Research 19: 114-122.

Senju, A., Maeda, M, Kikuchi, Y., Hasegawa, T., Tojo, V., and Osanai, H. 2007. "Absence of Contagious Yawning in Children with Autism Spectrum Disorder."  Biology Letters 22: 706-708.

Tsakiris, Manos. 2010. "My Body in the Brain: A Neurocognitive Model of Body-Ownership." Neuropsychologia 48: 703-712.

Tsakiris, Manos. 2011. "The Sense of Body Ownership." In Shaun Gallagher, ed., The Oxford Handbook of the Self, 180-203. Oxford: Oxford University Press.