Handy to know.
July 17, 2004 1:02 AM   Subscribe

How do you know that the hand you see in front of you belongs to you? Now you know.
posted by snarfodox (17 comments total)
Vilayunar Ramachandran at the University of California, San Diego, U.S.A. has been doing well-publicized research on this for years -- I'm surprised the media are reporting this as new work. In 1994 he treated an amputee using an ingenious mirror setup.
posted by quarantine at 1:38 AM on July 17, 2004

Oliver Sacks, in his inimitable fashion, talks about being alienated from his unjured leg in "A Leg to Stand On"

Where was I just reading within the last two days about the early brain studies that localized body image and found that using a tool causes that internal representation to expand to include the tool?
posted by Ethereal Bligh at 3:46 AM on July 17, 2004

The salient point that differentiates this research is the functional localisation in the premotor cortex.
posted by snarfodox at 3:52 AM on July 17, 2004

Ramachandran, in his book, provides a couple of home experiments to trick the illusion of bounded self. Right now, I don't remember them exactly.
posted by Gyan at 4:03 AM on July 17, 2004

I think it would have been very interesting if after people had been convinced that the rubber hand is their own, the researcher had suddenly lopped off half of it with a cleaver.
posted by Jairus at 4:30 AM on July 17, 2004

I think it would be interesting if researchers regularly suddenly lopped off half of volunteers' hands with a cleaver. Then laugh manically.
posted by Ethereal Bligh at 4:32 AM on July 17, 2004

Jairus got at it :

Whenever there's a doubt in my mind, I just poke at the hand with a sharp knife.

That clarifies the issue.

(Leprosy and nerve damage-sufferers - don't try this one)
posted by troutfishing at 5:18 AM on July 17, 2004

Here's another of Ramachandran's mirror tricks - one of the more impressive experiments on this subject (from his book):

Robert Townsend is an intelligent, fifty-five-year-old engineer whose cancer caused him to lose his left arm six inches above the elbow. When I saw him seven months after the amputation, he was experiencing a vivid phantom limb that would often go into an involuntary clenching spasm. "It's like my nails are digging into my phantom hand," said Robert. "The pain is unbearable." Even if he concentrated all his attention on it, he could not open his invisible hand to relieve the spasm.
We wondered whether using the mirror box could help Robert eliminate his spasms. Like Philip, Robert looked into the box, positioned his good hand to superimpose its reflection over his phantom hand and, after making a fist with the normal hand, tried to unclench both hands simultaneously. The first time he did this, Robert exclaimed that he could feel the phantom fist open along with the good fist, simply as a result of the visual feedback. Better yet, the pain disappeared. The phantom then remained unclenched for several hours until a new spasm occurred spontaneously. Without the mirror, the phantom would throb in pain for forty minutes or more. Robert took the box home and tried the same trick each time that the clenching spasm recurred. If he did not use the box, he could not unclench his fist despite trying with all his might. If he used the mirror, the hand opened instantly.

The book is a fascinating compendium of prima facie intractable mental/psychological problems and ingenious, almost invariably low-tech solutions to them. I second the recommendations.
posted by louigi at 7:39 AM on July 17, 2004

Very, very nice linkage, all. This thread "is a fascinating compendium of prima facie intractable mental/psychological problems and ingenious, almost invariably low-tech solutions to them."
posted by moonbird at 8:13 AM on July 17, 2004

Another factor to consider is naturally induced insensitivity. That is, we produce a huge amount of endorphines so that we can *ignore* most of our body.

But what happens when you use an ex-junkie in such a study? Heroin replaces endorphines, and even when you stop using it, your endorphine production never climbs back to what it had been before. This leaves ex-junkies more nerve sensitive than ordinary people.

Some clinical paranoids are also extra sensitive, making them hard to sneak up on, for example, and helping them to overreact to things that ordinary people would ignore. They pick up on little details usually missed. Think of the character "Monk" as an extreme example.
posted by kablam at 4:40 PM on July 17, 2004

The faculty that encapsulates our self concept is obviously malleable, but it is this sort of research as well as visual or auditory illusion work that, for me, puts identity into sharp relief.
posted by snarfodox at 6:29 PM on July 17, 2004

Gates of Perception.
posted by troutfishing at 7:37 PM on July 17, 2004

Here's a scary one for you. In the 1970s, an antidepressant was created. Its chemical name is desipramine hydrochloride, but it was sold under the brand name Norpramine (noradrenaline).

It was really a shotgun solution to the b-b gun problem of depression, affecting a whole slew of brain chemicals; but it was the only game in town. After FDA approval, though it caused, routinely, every side effect in the book, it became one of the most widely prescribed medicines in the US.
Millions of people took, and still take it.

However, after approval, testing ended in the US. In Japan, however, experiments started noting very odd side effects, too subtle to be picked up in routine analysis at recommended dosage.

The strangest of these was that the drug tended to "soften" those mental parameters that mammals develop since birth. To demonstrate the power of this phenomenon, they sewed one eyelid of an adult housecat closed, then injected the drug in the optic center of the cat's brain.

In a week or two, the cat re-learned to see, but with only a single eye. When the stiches were removed, the eye still worked perfectly, and sent signals to the brain, where they were ignored.

Two functional eyes sending signals to the brain, but only monocular vision. And binocular vision did not return over time.

Now imagine what this drug has done, and is subtly doing, to millions of Americans, whose *entire brain*, not just their optic center, is being exposed to years worth of this chemical.
posted by kablam at 8:48 PM on July 17, 2004

It would seem — but I'm not sure, so I'm asking — that this would be related to the 6th sense, proprio sentia. Is that the case?
posted by silusGROK at 8:55 PM on July 17, 2004

look at your hands
posted by soyjoy at 9:21 PM on July 17, 2004

More about Ramachandran in a previous thread.
posted by crasspastor at 3:10 AM on July 18, 2004

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