Three’s The (Ch)Arm

Submitted by Mark Esposito, Guest Blogger

Think reality is self-evident. Neuroscientists at Stockholm’s Karolinska Institutet aren’t so sure. Seems recent testing reveals it is quite easy to convince the human mind that it’s body has three arms.

A February article in the online journal, PLoS ONE, reports on a study in which participants were asked to test the “supernumerary hand illusion.” The subjects were asked to place their right hand on table and a prosthetic rubber arm was placed next to it. The left arm was hidden from view by a screen. A drape was placed over the right shoulder so that only the forearms of the real and prosthetic arm were visible.

When a paintbrush was applied to the index finger of the real and the fake arm, the subject noted “feeling” sensation in both the real and the fake arm. They even noted the sense that both the real and fake arms were attached to their bodies. A similar result was obtained when a knife was place close to both arms in a simulated threatening gesture.

“Our study shows that the human brain has the ability to experience an extra third arm,” says Arvid Guterstam, the study’s lead author and a neuroscience doctoral student. You might think that being born with two arms and two legs would limit your body image to this idea, he says. “But within less than a minute, you can fool the brain into believing it has an extra arm, which is quite fantastic.”

Besides being “fantastic” the study holds promise for developing new artificial limbs and helping stroke victims who’ve lost the use of a limb. It might also explain why so many seemingly reasonable folks watch Glen Beck. Self-delusion, it appears, has a genetic origin.

Source: msnbc

~Mark Esposito, Guest Blogger

41 thoughts on “Three’s The (Ch)Arm”

  1. Buddha Is Laughing: “Speaking of which, my mom has an odd brain/eye issue. She has about a one second delay in the light hitting her eyes and her brain perceiving it.”

    !

    I once heard someone say that we all live in the past and mistake it for the present. That the time delay between seeing something and actually processing it to understanding, while short enough to make it generally immaterial, still puts us behind the timeline of actual events. Our perception of reality is actually an internal movie of the very recent past. We are divorced from absolute, external reality by just that tiny sliver of time. It sounds like your mother is selectively removed even more so.

    Does your mother live in a world that appears to be poorly synched, where the difference between sounds and the visual cues for them don’t correspond?

  2. Blouise: “The doctors told her that this was because the brain had been trained to see 1 1/2 and would always do so even if she lost complete vision in one eye.”

    ——
    We had a friend that was blinded in one eye due to trauma. He stopped driving a few months after that because his ability to perceive depth faded. It didn’t end abruptly with his loss of vision but lessened over a few months thereafter. It is amazing to me (and was to him) that he retained a working semblance of depth-of-field for a time even when he no longer had stereo vision.

  3. J Brian Harris: “Alas, my third and fourth hands got loose and are tapping keyboard keys without my permission?”

    That’s OK, mine do that all the time 🙂

  4. Buddha Is Laughing
    1, February 28, 2011 at 12:10 am
    Blouise,

    Let me get this straight. See didn’t see 1 1/2 before the surgery? If so, I find that particular odd and interesting. Is she able to drive? And I don’t mean that sarcastically either. I’d think that sort of visual impairment would make something with a continual shifting depth of field very difficult if not very dangerous. It sounds like a recipe for perpetual headaches from eye strain.

    =========================================================
    No, she did not have double vision before the operation as the lazy eye drifted to the far right corner of the right eye. The 1 1/2 vision began when the eye was moved to the center.

    No, she has no problem driving in that she started to adjust to the problem of 1 1/2 vision shortly after the bandages were removed. She was born in 1945 so the operation at the age of 12 was in 1957. By the age of 16 she had learned to compensate though she drives carefully and slowly. She has received 1 speeding ticket and had 1 fender bender in all her 50 years of driving.

    She has trouble playing tennis but can manage badminton as the birdie moves slower and after 1 games she has adjusted and can be competitive from game 2 on.

    She is prone to spilling glasses of liquids in that if she reaches quickly for the glass she sometimes misjudges it’s placement and hits the side of the glass with her fingers or hands … aiming for the 1/2 object rather than the whole. She has trained herself to reach slowly for items.

    Before the operation she only used the one strong eye so lacked “depth” … bringing the other eye to the center did not really help depth perception as it created that additional 1/2 view rather than the full focus of 2 eyes working together. For instance, she closes her right eye (weaker) and holds up a pencil so that it appears to be in the middle of two distant objects when viewed with only the strong eye. Keeping the pencil in the same position, she closes the left eye (stronger) and views the pencil with just the right (weaker) eye. The pencil changes position and appears to be to the left of the two objects … yet, no matter which eye she is using, there is always 1/2 of the object (in this case the pencil)just to the right of the actual object.

    She says she gets occasional eye strain but doesn’t suffer from regular headaches. She can not draw a straight line without the aid of a ruler.

    She likes to joke that she understands people who have visions as every minute of everyday she sees things that literally aren’t there … or at least 1/2 that isn’t there.

  5. And while I’m in a wonderin’ mood . . . I wonder if one can get phantom headaches after losing their mind? Does one hear phantom jokes if they lose their sense of humor? These are the kinds of things I think about when drinking beer and taking cold medicine; the great mysteries of life.

  6. lol

    Yeah, but drunk without the woozy?

    Eh, I might feel inclined to feel a little cheated!

    I wonder what would happen if she smoked marijuana?

    It does change the pressure within the eye.

  7. You could be correct buddha, but if the incorrect focusing was caused by the doctors, there may be a case. That would be one tough situation to get used to. It would be like be drunk all the time! Wait a minute…that doesn’t sound so bad after all!:)

  8. Speaking of which, my mom has an odd brain/eye issue. She has about a one second delay in the light hitting her eyes and her brain perceiving it. It’s the result of a blow to the head she got in a car accident with her brother as a kid. I find the whole optical system very interesting considering how much of the brain is dedicated to processing visual stimuli.

  9. Maybe, raff. But if the defect is in the eye’s focusing mechanism itself, not so much. Tortfeasors take claimants as they find them, to their detriment or not.

  10. Blouise,

    Let me get this straight. See didn’t see 1 1/2 before the surgery? If so, I find that particular odd and interesting. Is she able to drive? And I don’t mean that sarcastically either. I’d think that sort of visual impairment would make something with a continual shifting depth of field very difficult if not very dangerous. It sounds like a recipe for perpetual headaches from eye strain.

  11. I have a friend who, at the age of 12, had an operation to cosmetically correct a lazy eye. The surgeons cut the muscle to bring the eye in from the right corner to the center. The 2 eyes do not focus together and the result was correct for cosmetic purposes but resulted in my friend seeing 1 1/2 of everything … not quite double vision. After a few years she noticed that if she closed one eye, it mattered not which, she still saw 1 1/2 of everything. The doctors told her that this was because the brain had been trained to see 1 1/2 and would always do so even if she lost complete vision in one eye.

  12. RE: Nal, February 27, 2011 at 8:30 am

    The implications of this are extremely interesting. For the skeptic it is another example of the fact that our perceptions of reality are constructed. This means that seeing (and experiencing) is not believing. What we experience is largely a fiction. It works well enough most of the time – but not all the time. It can be tricked into incorrect perceptions that we cannot distinguish from accurate perceptions – it all seems really real to our brains.

    ####################################

    My first and second hands decided to not type anything, hence the empty prior comment of mine.

    Alas, my third and fourth hands got loose and are tapping keyboard keys without my permission?

    What better description of what may be the basis of intractable belief in the Adversarial Principle could ever I seek?

  13. if there are any researchers reading LK’s post please keep in mind i have no known drug allergies.

  14. “For the skeptic it is another example of the fact that our perceptions of reality are constructed. This means that seeing (and experiencing) is not believing. What we experience is largely a fiction.”

    This was a topic explored in a movie I saw last night titled “The Spirit Molecule”. It was a movie that recounted a scientific study, the Strassman study, of DMT, N,N-Dimethyltryptamine. I recommend it to everyone.

    From Wikipedia: “(DMT) is a naturally occurring hallucinogenic compound of the tryptamine family. DMT is found not only in several plants,[3] but also in trace amounts in humans and other mammals, where it is originally derived from the essential amino acid tryptophan, and ultimately produced by the enzyme INMT during normal metabolism.[4] The natural function of its widespread presence remains undetermined. Structurally, DMT is analogous to the neurotransmitter serotonin (5-HT), the hormone melatonin, and other psychedelic tryptamines, such as 5-MeO-DMT, bufotenin, and psilocin.”

    It’s a fascinating movie and I’m sorry I didn’t have the opportunity to try the drug it but it wasn’t available when I was 🙂

    The point that is made as an introductory explanation of the structure of DMT is as above, it’s a simple molecule and present in plants, other mammals and people. It’s also a molecule that has 2-3 openings that readily accept other, plant derived triptamines in the psychedelic realm.

    Naturally occurring in the brain DMT can be mobilized and potentially active under great stress such as sexual ecstasy or events giving rise to spiritual experiences. The fact that it is present in humans and plants and is easily stimulated and augmented by other plants indicates that it is probably a very old molecule and that it and humans have had a long, productive relationship on some levels. Very little is actually known about what it does in the brain.

    From Wikipedia: “Injected DMT produces an experience that is similar to inhalation in duration, intensity, and characteristics.

    In a study conducted from 1990 through 1995, University of New Mexico psychiatrist Rick Strassman found that some volunteers injected with high doses of DMT had experiences with a perceived alien entity. Usually, the reported entities were experienced as the inhabitants of a perceived independent reality the subjects reported visiting while under the influence of DMT.[11] In a September, 2009, interview with Examiner.com, Strassman described the effects on participants in the study: “Subjectively, the most interesting results were that high doses of DMT seemed to allow the consciousness of our volunteers to enter into non-corporeal, free-standing, independent realms of existence inhabited by beings of light who oftentimes were expecting the volunteers, and with whom the volunteers interacted. While “typical” near-death and mystical states occurred, they were relatively rare.” ”

    Listening to the medical subjects as well as the scientists involved in the test it is unmistakable that the mind is capable of exploring realms that we are in the main divorced from. The question of weather such a drug allows entry into another level or dimension of actual being we normally don’t have access to, or creates another state of being as a projection is also explored.

    In either event it is astonishing what the brain/mind is capable of and speaks to how little we currently know about the brain/mind. I have read of work being done (with some success) to make computers responsive to brainwave signals to assist people that cannot speak and do not have use of their limbs. Also, my uncle was an amputee and years after the event would feel his missing leg on occasion, painfully, but none the less. We need a lot more research into the working of the brain/mind. And a lot more trippy drugs.

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