New evidence on ghosts

The Skepbitch reports on the hilarious theories of "ghost hunter" Maryanna Chatelaine Moresby. Here are some stuff that I didn't know about phantoms:

"There is enormous evidence of “ghosts” in all parts of the world. And that fact that so many have believed that ghosts could attack a fetus is nothing new. But ghosts through history have had other reasons to enter a woman’s womb in many different cultures from reincarnation to vengeance. Even Dead Babies have been known to haunt their mothers wombs after a abortion or miscarrage.

When a person dies only his physical body ceases to exist. His subtle ghost body (consisting of the subconscious mind, intellect, ego and soul, i.e. minus the physical body) however continues to exist and moves on to the other regions of the universe. Or into someone else’s body through the Vagina in woman or the Anus in men.

Often a womb infested with a ghost is that of the ghost of loved ones, or to those of strangers, and the worst case possible Devils and Demons. Any woman’s womb can attract many different forms of a paranormal haunting at least that is the common belief amongst many. And so can men. The ghost that haunt men are often found living in their genitals, bowels or stomach. And the number of ghosts or demons and devil’s that can infect a person is said to be uncountable."

There's unfortunately much more over there.

Of course, there actually is good evidence for phantom wombs, phantom colons and phantom penises:

Dorpat TL. (1971). Phantom sensation of internal organs. Compr Psychiatry, 12(1): 27-35

Ovesen P, Kroner K, Ornsholt J, Bach K. (1991). Phantom-related phenomena after rectal amputation: prevalence and clinical characteristics. Pain, 44(3): 289-91.

Fisher CM. (1999). Phantom erection after amputation of penis: case description and review of the relevant literature on pnatoms. Can J Neurol Sci, 26(1): 53-6.

Ramachandran VS & McGeoch PD. (2008). Phantom penises in transsexuals: evidence of an innate gender-specific body image in the brain. J Consc Studies, 15(1): 5-16.

Erik Estrada: from CHIPS to CHUMP

I found a video where actor Erik Estrada remembers an interesting out-of-body experience he had in 1980, while recording an episode of CHIPS. Sorry, the film is dubbed in French (via this wonderful website with plenty of amusing woo woo videos).

So, briefly Estrada explains that during the shooting of an episode it was decided that he, Estrada, could do his own stunt on a motor-bike. He could not. What followed the terrible accident is that Estrada had an OBE with veridical perceptions of his surrounding. Interestingly, it's one of these OBEs that start with the subject not actually realizing that he is out of his body. Usually, it is the autoscopy, when they first see their own body standing or lying in front of them, that leads them to the striking realization that they see the world from a disembodied perspective. Well, that's what happened to Estrada. Also interesting is the apparent long duration of the OBE. Well anyway, the problem is that the actor is not interested in OBEs is the exact same way that I am, he simply believes that NDEs and OBEs are the real thing. That's where he begins wildly begging the question, by starting from the premise that having an OBE is de facto evidence that the center of one's consciousness can sometimes be shifted away from the physical body. And that God and Heaven exist.

For instance, at some point in the video, Estrada explains that he might very well have walked outside of his hospital room while out of his body, and might also have wandered around in the building without ever going "up or down". Erik Estrada takes for granted that people, when they die, go either "up" or "down". Otherwise, it means that they are cursed and have to wander aimlessly amidst the living. That's common sense, universally accepted knowledge, he thinks. Also, very interstingly, Estrada has all these thoughts about Heaven and Hell during his OBE. This means either that OBEs are brain induced hallucinations colored by the subject's own personal background and set of cultural expectations, or that during NDEs you really get to glimpse the afterworld but you retain your stupid earthly superstitions.

Alright, so at 11' he tells another story: at another point in his life, he saw a ghost in a French castle. How cool, he saw a ghost. In a castle. He gives some details also: it's a transparent apparition, of course. Unfortunately, he then proceeds to go through and repeat many times all of the uninteresting details of this ridiculous story. Estrada tries hard to understand his personal contacts with the paranormal, but of course only in terms of the paranormal. It never crosses his mind that there might be normal explanations. No, it is absolutely necessary that the apparition might have been the ghost of a lady from the 16th century, who had a child, and such. And he goes on with the idea that the OBE might have led his soul away from his body, like, forever. This is the hallmark of the gullible and the stupid.

I recommend especially you look at Estrada's face around 13'03, when he explains that the "apparition" might actually have been a "wandering spirit", you know, like we have so much evidence pointing to the existence of wandering spirits in the first place. But of course, he explains, only people that had no faith in their lives end up as wandering spirits, that's their punishment. Estrada really knows about stuff. Well, look at his face there: this is the face of stupidity, there's really no other way to put it.

What follows then at 13'15 is also astonishingly idiotic. Estrada explains, in all seriousness, that when he dies he's "not gonna come back on the surface". No no no. Not him. Like we care. But anyway, he immediately changes his mind, and adds, again like we should care, that he would only "come back" as a "force" in order to help and protect someone or save a life. "That I could shoot for, you know", he says, hoping anyone will think he's a hero for holding such a courageous opinion. God, the man is stupid. Obviously, he believes he is Poncerello.

Now, notwithstanding the cognitive abilities of the man, his OBE is actually quite interesting. Of course, given the way he talks in the documentary, the stupid and ridiculous things he says, and the low-brow re-enactment that has been made, I don't trust any of his story. Nevertheless, I like the idea of an OBE so well construed and so convincing that the subject is surprised to realize that he is actually not in his body. The level of surprise in OBEs is rarely reported and not at all studied as such in the literature on the topic.

Now for something completely different. I wonder if Estrada's paranormal experiences might explain this:

Frégoli delusion and erotomania.

S Wright, A W Young, and D J Hellawell (1993). Frégoli delusion and erotomania. J Neurol Neurosurg Psychiatry, 56(3): 322–323. (paper available here).

We describe a further case for whom the Fregoli delusion arose in the context of the form of erotomania known as de Clérambault's syndrome, in which patients suddenly arrive at the delusional belief that someone (usually of higher social standing) is in love with them. Although this patient had other delusions, the Fregoli and de Clerambault delusions dominated the clinical picture, and were strongly held and persistent.
The patient was a 35 year old, divorced, unemployed woman who lived on her own. She had a psychiatric history from the age of 16, and was diagnosed as suffering from chronic paranoid schizophrenia. She stopped medication 6 weeks before admission. She was agitated and verbally hostile, and reported auditory hallucinations of famous actors who she said were her friends. She claimed to be telepathic, saying her actor friends put their thoughts into her head, and that her thoughts were broadcast to them. She showed grandiose delusions, believing she could arrange to stop all television and radio communications by telling her actor friends to go on strike using her "telepathic powers".
The patient believed that she was the girlfriend of Erik Estrada (an American actor and pin-up), with whom she communicated across the Atlantic via telepathy. She also believed that Erik Estrada visited her home city regularly, disguised as acquaintances or her current boyfriend. She stated that she knew her actual boyfriend was Erik Estrada in disguise due to the absence of a previous scar on his face. She was convinced that Erik Estrada was in love with her and planned to marry her one day.
Past medical history revealed childhood epilepsy until the age of 9 years, phenobarbitone being stopped at the age of 11 years. There was no family history of mental disorder. Routine haematological, biochemical and serological examinations were normal. Physical examination revealed no abnormality. An EEG showed a moderate excess of mixed irregular and rhythmic slow activity at 2-6 HZ and 10-30uV in the central and post-central regions. She refused neuroimaging. The patient was able to recognise photographs of emotional expressions
(happy, angry, sad, etc) without significant difficulty. She was impaired at recognising photographs of familiar faces, but showed no tendency to misidentify unfamiliar faces as familiar (20/20 correct rejections of unfamiliar faces). In this face recognition test, she did not claim that any of the photographs showed Erik Estrada, in disguise or otherwise. She performed at the borderline of the impaired range on the Benton Test (which requires matching of unfamiliar faces) and was very poor at matching unfamiliar faces when they were masked by various disguises. On the Warrington Recognition Memory Test, she showed normal recognition memory for words but severely impaired recognition memory for faces.
The patient was started on a fluphenazine depot and her mental state improved considerably. Twelve months later, however, she still believes she is to marry "Erik" and that he continues to visit her regularly, albeit in disguise. (...)
Her pattem of impairment on face processing tests was comparable to that found for another case we investigated, in which the Fregoli delusion arose in the context of cerebral infarction of the right hemisphere." (...) She thought that she was being pursued by her cousin and a female accomplice, both of whom adopted different disguises. It was later found that some years previously the patient had a long love affair with this cousin (lasting over 20 years, and leading to the birth of her only child).

Here's my theory. This patient isn't crazy at all, what she keeps seeing is the astral double that fled from Estrada's body during his hospital OBE.

Phantom of the escalator

Very cool paper with the awesomest title ever given to a scientific report:

Fukui T, Kimura T, Kadota K, Shimojo S, Gomi H (2009) Odd Sensation Induced by Moving-Phantom which Triggers Subconscious Motor Program. PLoS ONE 4(6): e5782. (it's a free access journal)

Odd sensation? Induced by moving-phantom? Which moreover triggers subconscious motor program?? You got to be kidding me, that's a Nobel prize winner!

So let's check it out. The premise is extremely simple: have you ever stepped onto a stopped escalator? How did it feel? Yeah, I'm sure you know what I mean. I also have it. Well, that's what the authors of this paper set out to understand. They call it an "odd sensation". (One of the charms of the paper, I should mention, is that it is written in Japanglish).

Here's how the problem is stated in the introduction:

"When we encounter an escalator that is out of service, we recognize the escalator is certainly stopped and is not going to move; have the definite intention to step onto the stopped escalator (action to peculiar physical dimensions of stairs, see Fig. 1A), not a moving one (very familiar action); and then step onto it. After doing so, despite the proper awareness and intention, we frequently feel clumsy, as if our posture is awkward, our bodies heavier, and the steps are sometimes hard to climb. This clumsiness is associated with some kind of odd sensation." (emphasis added)

If you have no idea at all what these guys are talking about or what this "odd sensation" is supposed to be, then the paper will make no sense at all to you. It's really one of these things you have to experience firsthand to understand what it's all about. But still, even if you're like me and had this "odd sensation" dozens of times, you might ask why this is interesting at all. Well, the crucial point with this peculiar illusion resides in the interaction between top-down and bottom-up processes involved in visuo-motor integration. As the authors put it:

"...when we step onto a stopped escalator even with perfect knowledge that it is stationary, we are often surprised by the strange feeling accompanied by our own action. This feeling implies the involvement of subconscious processes against conscious awareness in the emergence of the odd sensation. Thus, this phenomenon raises an intriguing question as to how implicit motor programming escapes from conscious top-down control and offers an opportunity to study it."

In other words, it is definitely most interesting that such an effect should exist even when people know full well that the escalator is stopped. Why does it feel still feel so weird? What's going on, and how can we study this?

The authors decided to use an actual escalator to investigate this "escalator illusion". They set out three hypotheses that might explain it:

1) the effect is merely due to our unfamiliarity with stopped escalators. It coincides with specific body movements, of course, but the "odd sensation" only comes from "unfamiliarity" and that's it.

2) the effect is primarily due to the specifics of the escalator: it is true that an escalator's steps are deeper and higher than most normal stairs, and when it is stopped we have to accomplish nonuniform movements to climb it, which induce clumsiness (i.e. the first step taken is notably shorter than the following ones)

3) the effect emerges against our will, as our brain somehow triggers the motor program required to step onto a moving escalator even as it is perfectly evident that it is a stopped one. (in their words: "the subconscious emergence of the habitual escalator-specific motor program leads to the inappropriate motor behavior, which leads to the odd sensation".

To differentiate these 3 hypotheses (and it is clear that they favour the third one), they tested 3 conditions: subjects had to step onto either a moving escalator, a stopped escalator, or a wooden stair not looking like an escalator but having the same physical dimensions. There were only 7 subjects, and during all trials they wore movement trackers on their back and their heels. The kinematics of upper and lower body was the main measure studied, and after each trial they also were asked to rate on a 1 to 5 scale "the extent to which they felt some kind of odd sensation".

I will spare you an account of the detailed results of this study, which are quite elaborate. The analyses I must say are very original and smart, but I wonder how many journals have turned down this study before it was published in PLoS One. I have the feeling that many reviewers would have been put off by the overkill nature of all these kinematic data and path analysis statistics for the sole purpose of investigating an "odd sensation". Well, you ask me, this should be published in Science or Nature, no less.

The discussion is a little bit redundant, but it can be conveniently summarized as follows:

"the prerequisite for the emergence of the odd sensation is an inappropriate motor behavior against the current situation resulting from the habitual motor behavior for a moving escalator. People may not be able to suppress this behavior despite completely understanding the current stopped escalator situation.

(...)

The conflict between the motor intention and the sensory outcome would be the important factor for the emergence of some kind of strange/peculiar feeling."

Well, this is the trouble with habits. They only work insofar as the context doesn't change too much. But the authors cannot really explain where this "subconscious" motor program specialized for escalator climbing comes from in the first place. How many escalators do you have to use in a lifetime to acquire the "subconscious motor program" leading to this "odd sensation"? What is more, it is clear to me that the "sensation" is there as well when you have to climb down a stopped escalator, and when you walk on one of these very long airport treadmills that happen to be nonfunctional. Does the interpretation based on the kinematics of climbing up still hold? I would also like in the future to know more about exactly what the "odd sensation" is. In the introduction, they mention clumsiness, heaviness, and awkwardness. Are these all synonymous, or different dimensions of the sensation? Can these be dissociated, for instance if we modulate the speed of the escalator (very slow instead of stopped, and so forth)? Finally, I'd like to ask why the word "phantom" is used in the title, but not at all in the text? This is very bizarre and disappointing, as it appears also in the abstract:

"moving escalator-specific motor actions emerged after participants had stepped onto the stopped escalator despite their full awareness that it was stopped, as if the motor behavior was guided by a ‘‘phantom’’ of a moving escalator"

Well, as a self-proclaimed phantomologist, I can only say that I perfectly agree with the use of the word (although it is not clear if we're talking of a "phantom moving escalator" or "phantom self on a moving escalator"), but it really boggles the mind that the concept should be brought about in the title and the abstract, and then be entirely forgotten. Another case of vanishing phantoms, I guess.

Despite these very few caveats, I'd like to repeat that this is a very delightful paper. And I'd like now to share with you something it reminded me about. The authors have this to say in the introduction:

"when going up or down stairs, we sometimes extend the foot in expectation of an additional step at the end of the stairs, which causes us to stagger."

This they say is entirely different from the escalator illusion because in this case we realize that we made a mistake, "a self-prediction error caused by our thinking there was an additional step", whereas in the escalator case there is no error, we know and see that it is stopped. Well, this brought to my mind a very peculiar account from a very peculiar book. It allows me to demonstrate that the use of the word "phantom" by the authors of the escalator study was perfectly appropriate, as there could be a nice continuity from the "odd sensation" they talked about, to the situation where we lose our footing while climbing down the stairs as we expect an additional step that is not there, and then onto the full-blown "phantom" projection, meaning disembodiment as in out-of-body experiences. This is in my opinion all part if phantomology.

The demonstration is found in the account by a man named Sylvan Muldoon of his repeated out-of-body experiences (see Blackmore's account of this interesting fellow). In his main book, The Projection of the Astral Body, Muldoon explains in some excruciating details the many ways and situations to induce an "astral projection". Of particular interest here is a subsection of chapter 2 that explains how an OBE can be induced by mistakenly expecting an additional staircase step.

A projection caused by a mis-step

Here is an example of how an unexpected jar will throw the phantom out of coincidence. One night, a few years ago, I was coming down the stairs of my home. I had been sleeping, and was still quite drowsy. There were fifteen steps, and I had trodden up and down them hundreds of times, having lived in the house all my life. Just why I do not know, but, as I reached the bottom step, I tried to take one step more (many of us have done this), and the impetus jarred me vigorously.
A breath-taking sensation shot through the pit of my stomach, and even before the physical dropped to the floor, I found myself projected from it, in a perfectly conscious state. (...) I both saw the physical mechanism fall to the floor and also felt it fall, while standing several feet from it. Let me analyse this, and see what actually happenened, for by doing so we shall discover the fundamental law of astral projection.
It must be understood that it is not the conscious mind which causes projection, but it is the subconscious Will.
(...)
Which brings us to the bed-rock rule of astral projection: IF THE SUBCONSCIOUS WILL BECOMES POSSESSED OF THE IDEA TO MOVE THE BODY (COINCIDING BODIES) AND THE PHYSICAL COUNTERPART IS INCAPACITATED, THE SUBCONSCIOUS WILL MOVES THE ASTRAL BODY INDEPENDENT OF THE PHYSICAL." (The Projection of the Astral Body, Chap. 2, p.64)

There goes some "odd sensation", isn't it? Note how he calls the OBE a "phantom thrown out of coincidence", which is actually a wonderful and accurate way to put it from a cognitive perspective I think. Note also how Muldoon uses almost exactly the same terminology than the Japanese authors of the escalator study, positing a conflict between the "subconscious will" (the "motor programs") and the physical outcome of the event. In modern words, we would say that the body schema and the body image are not coinciding, hence the induction of an "odd sensation", which could perhaps manifest itself in more extreme situations (and possibly quite rare individuals) as an OBE.

Ok, I refrain to talk here about similar effects found in elevators. Remind me to discuss someday the wonderful paper by Schilder on the topic (Parker, S. & Schilder, P. (1930). Das Körperschema im Lift. Zeitschrift für die gesamte Neurologie und Psychiatrie, 128: 777-783).

Also, if he agrees to let me do so, I might also discuss in the future a nice idea for a project that my colleague Pär Halje proposed in less than 5 minutes when he was pressed to come up with something for a PhD class. He called it "The trampoline after-effect", and I think the idea is just too wonderful to be left alone. More phantomology induced by cool artifacts.

And one last word about escalators: French readers might want to learn more about the international plot of escalator repairmen. We know what you are doing, bastards, so stop it already.

Michael's phantom body

Allright, I guess as the "phantomologist" I have to say something about this video that's all over the webz right now. Well, there are tons of rational explanations for this interesting effect, and also many explanations as to why this is even a topic for discussion between adults in the 21th century. I just want to reproduce here what a commenter (n°47) said on the Pharyngula thread to this ridiculous topic:

Posted by: Greymalkin | July 7, 2009 2:16 AM

If that 'ghost' would have been moonwalking in the background, I would actually be impressed (not to be confused with convinced).

Eh! Indeed, that's exactly what I thought when I saw the video for the first time!

Creating phantom fingers

The Phi phenomenon (or Phi effect, or Phi movement, of Phi illusion, or apparent motion...) is a classic demonstration of how the brain just makes up stuff in your mind that are actually not out there. Typically, you see one dot flashing on your left, and when it turns off, another dot appears on the right. Given the right circumstances, and these are pretty accomodating anyway (i.e. it works under a lot of conditions), what you see are not two stationary flickering dots, but a single dot moving back and forth. It is indeed quite hard not to perceive the nonexistent intermediary dots in between the flickering ones: they are, as it were, phantom dots.

The effect was discovered by Max Wertheimer, one of the founders of Gestalt psychology, and first published as: Experimentelle Studien über das Sehen von Bewegung. Zeitschrift für Psychologie 1912, 61, 161-265, 1912. (see a list of Wertheimer's publications, and much more, in this excellent website).

Now, this simple effect as been hugely influential and useful for theories of movement perception, and vision and cognition in general. There are hundreds of variations that you can think of (and that have been most probably already studied, make no mistake), as well as thousands of papers on the phenomenon. It has become quite hard to do anything original in this field, at least since Shiffrar and Freyd's excellent study on "apparent motion of the human body" [1], which I plan to discuss someday in the context of phantom limbs. One of the questions raised by the Phi phenomenon is of course its mechanisms: is it primarily a bottom-up thing, based on mindless "motion detectors", or is it modulated by top-down factors, like beliefs, knowledge, expectancies, etc.?

Well, I now see that the journal Perception has a short and intriguing piece [2] that might bring something new to the topic. Whereas Shiffrar and Freyd focused on the perception of apparent motion for other person's body parts, Ekroll and Scherzer, the authors of this new paper, propose a demonstration of the Phi illusion for one's own body. Here's their abstract:

We describe how illusory apparent motion of one’s own fingers and other body parts can easily be experienced in spite of grossly conflicting proprioceptive signals. This simple illusion may be used to shed light on the crossmodal integration of visual and proprioceptive signals. Our preliminary observations suggest that the visual and proprioceptive signals do not merge into a common crossmodal percept. Instead, mutually inconsistent visual and bodily sensations are experienced simultaneously.

So, how do you induce apparent motion using your own body? Here's what the authors say:

To experience the phenomenon, hold one of your hands with the fingers pointing
away from you (...). Only the index finger should be stretched out and visible from your point of view. Then lower the index finger and lift the middle one instead. Keep the hand steady while alternating swiftly and cyclically between these two finger positions, ie move the two fingers up and down in counterphase. When this is done swiftly enough, you will have the visual impression of a single finger tip moving horizontally instead of two fingers moving up and down. (...) One may initially find it difficult to move the fingers swiftly enough while preserving the appropriate coordination of the two fingers. (...) The effect seems to be more easily experienced
when the fingers are viewed monocularly with a half-closed eye. (...) Furthermore, viewing the fingers in peripheral vision, say, by looking at the wrist instead of directly at the fingers, also seems to enhance the effect.

Taken from Perception's website, the figures below of a hairy hand illustrates the idea. From my experience, you have to do this rather fast, and it's not so easy to be consistent (it is very important that you always see the same "amount" of finger sequentially, otherwise it seems to me that any effect there might be is destroyed).































The animation can be seen here. It is really a matter of subjective opinion whether there is a strong feeling of apparent horizontal motion or not while looking at this (I mean, looking at the animation, i.e. not doing it yourself). The authors also recommend trying this with the feet, as in the follwing figures:


































The animation can be seen here. This works even less, I think, but try it anyway.

Ok, good. Neither these effects work so well for me, but I accept the general idea (and maybe I should practive a little bit more, while trying I did have brief glimpses of a quite effective phi, but this was very transient). Theoretically, when this works, it should induce the perception of intermediate phantom fingers in between the real fingers, just like phantom dots are created by the brain in between two flickering dots. I'll keep trying.

Well ok, this is all fun, and makes for a very cool classroom demonstration. But one might ask, from a theoretical point of view, what's the point? Well, the authors valiantly present three theoretical perspectives arising from this funny experience:

1) "proprioceptive signals from the hand could have dominated over visual motion signals, making the subject perceive the veridical vertical finger motion, although a second passive observer perceives illusory horizontal motion"

Well that's a good idea. The problem is that it will be hard to gather good data from this illusion, as subjects have to do it themselves, and therefore it can hardly be controlled, plus the feeling is by definition subjective, and so forth. What is more, if you want a "second passive observer", then this guy would have to see the fingers from someone else's point of view, hardly a practical experimental setting. Another approach to test hypothesis 1) would be to induce in the fingers some kind of proprioceptive disturbance, to see if this enhances the perception of phi. But I have no idea how to do this without disturbing motor processes. It seems we reached an experimental dead-end. But proprioception is not the only thing getting in the way of vision here. As I said, it is very difficult to produce consistent, identical and repetitive finger movements while looking at them from a specific angle, so the visual information itself is quite unstable, which might be enough to reduce any phi effect.

2) vision may dominate over proprioception, and the active subject may have the
bodily sensation of a horizontally moving finger.

Sure. I mean, this is sort of trivial, for if the illusion that is described works at all, then it implies that vision does indeed, somehow, dominate over proprioception.

3) "proprioceptive and visual information may fail to merge into a coherent crossmodal percept. In our experience, the latter seems to be the case."

I'm not sure what this last hypothesis means. In the author's words: "one experiences a visual illusion of horizontal motion although the fingers are felt to move vertically". What would it feel like if a "coherent crossmodal percept" between proprioception and vision was achieved? How is hypothesis 3) different from hypothesis 2)? If vision dominates over proprioception, well then they have not "merged" appropriately, right? On the other hand, it might be a sort of figure-ground phenomena, akin to what happens during binocular rivalry or the Necker cube: there are times, when doing this illusion, where you perceive either proprioception, or vision, but not both at the same time (and when vision is in the foreground, then phi is experienced). But again, it's close to impossible to actually test this thorougly. It gets also quite confused in the conclusion, where the authors write:

"the proprioceptive and visual signals, which in many other cases of proprioceptive/visual conflict merge into a common percept, fail to do so in the present case. A possible explanation for this would be that the horizontal apparent motion is so discrepant from the vertical motion that would be expected on the basis of the efferent motor commands that the visual percept is more plausibly attributed to an object not belonging to the observer's own body."

This they link to the literature on experimental disturbances of agency (of the Jeannerod type). But obviously this goes a step too far. I'm of course speaking on my own experience (or lack thereof) of this illusion, but it certainly does not feel like the moving fingers, whether they seem to move vertically or horizontally, are someone else's! I don't think there's any disturbance of agency or ownership in this illusion, as far as I'm concerned I think this is the wrong approach.

But then I don't really have anything better to propose, and I think overall that the publication is very cool and intriguing.

[1] Shiffrar M & Freyd JJ (1990). Apparent motion of the human body. Psychological Science, 1 (4): 257-264.
[2] Ekroll V, Scherzer T R, 2009, "Apparent visual motion of the observer’s own limbs" Perception 38(5) 778 – 780

Borje Cronholm: a pioneer in the modern study of phantom limbs

Phantom limbs are endlessly fascinating. I will post regularly about this phenomenon in this blog, for there is so much more to learn about phantoms than is generally realized. Phantom limbs certainly are the first building blocks for a serious phantomology - a science of human bodily consciousness - to emerge. Not only there is much much more to learn, but most of what we do know was actually discovered long ago.

You might have heard of so-called referred sensations in amputees. This refers to the peculiar experience some amuptees have to feel their non-existent limb when certain parts of their bodies are touched. The excellent VS Ramachandran is usually credited with this beautiful observation, which he showed to behave in a strikingly ordered somatotopic fashion (see the now classic review here). It turns out you can literally draw a hand on the ipsilateral cheek an upper limb amputee, delineating as it where the receptive fields that have been rearranged in the somatosensory cortex. Well, that was a brillant rediscovery and extention of an old observation.

I don't know for sure who wrote first about referred sensations in amputees, but the best treatment to have been given to the topic has certainly been published in 1951.

Cronholm B. Phantom limbs in amputees: a study of changes in the integration of centripetal impulses with special reference to referred sensations. Acta Psychiatr Neurol Scand Suppl 1951; 72: 1–310

(A review of this remarkable monography can be found here (The Journal of Bone and Joint Surgery 1953; 35-B (2): 332))

Some information about the author of this work, Börje Cronholm, can be found on the swedish Wikipedia [1]. He was born on 1913 August 28 in Lund and died in Stockholm in 1983, October 11, from a brain tumour. Cronholm spent much of his professional career as a psychiatrist and professor of psychiatry at the Karolinska Institute. He did his PhD on phantom experiences in amputees, which I guess is the work contained in the superb monograph I'm about to present. Cronholm had 3 children, one of which (Tomas) became also became a professor at Karolinska. One of his grand-daughter is apparently a famous artist in Sweden (Ellén Cronholm). Apart from his work on phantom limbs, Cronholm was very interested in the links between art and medicine. He wrote on the artistic expressions of schizophrenic patients (among them one Ester Hennings, whom he met during a temprary position he held at Beckomberga, the mental Institute in Stockholm. Cronholm contributed to the saving of Henning's works, which are now kept and visible at the National Museum). In his later years, Cronholm focused on "psychological measuring methods", meaning he devised clinical tests for assessing memory disorders, the effects of brain damage and aging, as well as depression (I don't know any of these works). He was of course member of numerous boards and associations (which is something I'm afraid I'll never be able to brag about). Intriguingly, it seems that Cronholm was appointed to hold the speech for the Nobel Prize acceptance of Konrad Lorenz. I might investigate a little bit on this, I don't see the connection between these two guys. Well, that's pretty much it for his biography. Let's look now at what I take to be his magnum opus, of which I proudly own one copy. See the cover below, and I ask you to take a good look at the dedication in the upper right corner (see the magnification right below):

I guess to most people this doesn't mean much, but it turns out that the copy I own belonged to JM Nielsen, a neurologist in Los Angeles that produced quite a few inspiring and important papers on disorders of the body schema, back in the 1930's. For example this one, from 1937 in the obscure Bulletin of the los Angeles Neurological Society (and long before people started using the horrible and misleading word "asomatognosia"):







It seems to me that Nielsen deserves to be rediscovered (see some publications here). He wrote numerous papers on a wide range of subjects, and also the influential textbook: Nielsen, JM, Agnosia, Apraxia, Aphasia. 2nd Ed. New York: Hoeber, 1946; as well as A Textbook of Clinical Neurology. New York: Hoeber, 1941. Here's what Joe Bogen, the famous surgeon of the split-brains, had to say about Nielsen:

I remember one of his brain cuttings relevant to this paper: After someone had read the history, he said, "Let's look at the anterior commissure." He held the brain with one hand and that big knife in the other (as you know, the anterior commissure is shaped like a handlebar mustache) and he made one curving sweep through the brain; then he lifted off the top half, and there was the full extent of the commissure.

Not impressed? Bah, you've never been to a brain cutting demonstration. Anyway, enough of memorabilia, and let's examine some of the book's content. First, as the title indicate, the book is really focused on the phenomenon of referred sensations. It is quite extraordinary that Cronholm devoted such a meticulous work to a phenomenon that, when you think about it, does not immediately strike you as even remotely interesting. Amputees must have noticed for centuries that when certain parts of their body are touched, they "feel" another touch in the location of the phantom limb. Ramachandran ended up with the sexy "remapping" explanation, in the light of the mid-eighties mounting evidence for massive cortical plasticity in the monkey's somatosensory cortex (Kaas, Pons, Merzenich [2]), but before that it took Cronholm to investigate systematically, and I mean really systematically, how these sensations work. He painstakingly interviewed 122 amputees and did all sorts of tests, mostly on tactile perception, with them. The monograph is replete with fantastic illustrations and numerous tables. The table of contents itself tells a whole story (chapter 13: Voluntary movements in a Ph[antom]; chap. 28: changes in the length of a Ph[antom] on stimulation of the stump; chap. 34: Referred sensations assigned to a Ph[antom] or the stump percept when the bladder is expanded, on miction or defecation; chap. 39: The experience of leg amputees when walking with a prothese; etc.)

So below is an illustration of referred sensations in one patient, clearly showing that face-to-phantom referrals where abundantly described before Ramachandran. This is patient n°13, a male born1906, amputated from the right upper limb in 1944 and first examined in 1945. I'm telling you, this is a meticulous study. In 1944, n°13 got "his right arm caught in a conveyor belt and torn off just below the shoulder. The nerves were torn off at the plexus". Shit happens. "Ever since amputation the patient had experienced the entire lost limb percept from within, the Ph-hand most clearly, the the Ph-elbow. The Ph-arm was of normal length and volume. it usually hung down his right side with the elbow slightly flexed and the fingers flexed. He demonstrated this posture with his left arm in exactly the same way at examinations in 1945 and 1949." Note how Cronholm is a smart little guy. One of the only ways to test for the "reality" of phantom limbs is indeed to check its consistency across trials. He continues: "The Ph-arm was experienced as "less real" than the left arm percept - "no life in it" - but just as solid. The patient could not make any voluntary movements in the Ph. Attempts to move the Ph-fingers merely led to increased "tingling" and sometimes to a mild feeling of cramp in the Ph-hand. The Ph-arm always felt numb, he had an "icy" feeling in it and a "tingling", "like when one hits one's funny bone, but not so strong". Well, it goes on and on like this. The level of detail is astonishing. (nowadays you can read papers describing fMRI studies of amputees, including having received a human limb graft, with no mention whatsoever of the mere presence or not of a phantom).
Let's look at the figure for patient n°13.

Black dots in (A) indicate the location where the experimenter touches the patient. Each trial is numbered, and the resulting tactile feeling in the phantom arm is shown in (B). Note how touches on the chest elicit feelings in the phantom forearm (with quite large receptive fields), and touches on the stump elicit feelings in the fingers, or rather across several fingers. Note also that here Cronholm didn't check for the face, this will come in the next figure. Cronholm had almost all the cards in his hands to make a point about the somatotopy of these referred sensations and how they could relate to the somatosensory homunculus. The only problem, of course, is that Penfield's homunculus wasn't fully described at the time, or at any rate Cronholm didn't have the required mental framework to draw the connection with the information on somatotopy available in his time (Penfield published with Rasmussen The Cerebral Cortex of Man in 1950, while Cronholm was busy pin-pricking his patients during the 1940's). In any case, it boggles the mind to see that it took 40 more years for Ramachandran to come up with the simple and elegant explanation of cortical maps invading the brain areas left deprived by the peripheral amputation. Well, that's a nice story, as always with Ramachandran, but it turns out that reality is often less spectacular than the textbooks. Cronholm followed-up on patient n°13, and here's in (C) what he obtains 3 years later:

Numbers refer to the same loci of stimulation than 3 years earlier, from the previous figure (Cronholm was a well organized man). Referred sensations from the cheek ipsilateral to amputation elicited wide areas of sensations in the forearm and the wrist. This is rather unlike the classic "hand on the face" of Ramachandran. See also that touches on the chest, this time do elicit sensations in the fingers, whereas touches in the stump produce feelings in the forearm! What the hell? This is the exact reverse pattern from 3 years ago! How does one account for that in terms of cortical remapping? You see, phantom limbs are much more complicated and fascinating than many people acknowledge, including people well versed into neurology and bodily consciousness.

And there are even more bizarre things. Look at the following figure, which shows the phantom forearm of patient n°6, amputated at the elbow in the right arm (this male patient was amputated when he was 7 years old and examined at 17). In (A), Cronholm stimulated the ventral side of the stump, in 13 locations drawing a straight line from the inside of the elbow to the apex of the stump. Doing this, the patient indicated on his healthy arm where the feeling was felt in the phantom, and it turns out that the somatotopy is very reliable: all the phantom sensations were isolated tactile sensation drawing a straight line on the ventral side of the phantom forearm. Now, look at (B). Stimulating the dorsal side of the stump elicited feelings in the dorsal side of the phantom. Right away, this seems to indicate that the phantom has some kind of a volume, or spatial existence. But this is not the most interesting with this figure. You have to read the fine print to see what is really intriguing here. Stimulation n°13 in the apex of the stump, in (A), is not represented on the phantom chart. Why? Well, that because, as Cronholm indicates, "when point 13 was stimulated the patient felt a sensation "in space" distal to the Ph-fingertips"). That's right, exosomesthesia! This patient, quite clearly, makes a difference between a phantom limb and empty space. Think about what this means, I just love this observation.

There is much more to say about Cronholm, so stay around for future posts on this classic, but poorly known, research on phantom limbs. What I can say right away, however, is that where Cronholm is excellent in observation, he's rather weak on theory. But reading this painstakingly documented monograph, one gets the impression that he wanted to give the best possible picture, with any single detail that might turn out later to be relevant or not, for others to study.


[1] Thanks to Pär Halje for express translation (with ever so honey-coated voice)
[2] Animal activists out there behold: these guys simply chopped off monkeys fingers and limbs to see what would happen in their brains. Well, they usually made up some story about the animal "losing" "spontaneously" its body parts in some fight, but it's clear that this sort of neuroscience is by now over (or at least I hope so).

The Phantomologist is just born

Welcome to the Phantomologist, my new blog. My name is Sebastian Dieguez, I am a PhD student working on the cognitive neuroscience of self-awareness, I live in Lausanne (Switzerland), I am Spanish, and if you come back here you will perhaps learn more about me.
Here's some info about what I plan to do here: the phantomologist will be a bilingual (french-english) blog mostly about my opinions on science, beliefs, the neurosciences, the human body, religion, politics, local affairs, AND SO FORTH.
Why the "Phantomologist"? Well, following the prophetic Stanislaw Lem and its current guru Peter Brugger, "phantomology" can be defined as the science "whose aim [it] is to study the virtual reality of bodily awareness - from phantom limb to phantom body". This seems a bit over-specialized stuff, but when you get to the bottom of the idea you realize that it encompasses pretty much anything remotely associated with the human mind and human behaviour, which is extremely convenient when you plan to discuss phantom limbs, out-of-body experiences, and doppelgangers, but also pseudoscience, art, politics and stupidity in general.
I will try to balance the number of posts in english and in french, but it might very well turn out that the choice of language will depend on the topic adressed. Well, in any case I think that this is an interesting experiment, as I don't know of any other bilingual blog (but then I haven't really looked for one).

Good, so that was my introduction. Stick around for the upcoming display of arrogance and sarcasm, this should be fun.