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Subscribe to RSSCari Nierenberg writes: If two hands are better than one, then imagine what you could do with three. In a new study, Swedish researchers were able to trick participants' brains into believing their body had an extra arm.
Brain scientists at the Karolinska Institutet in Stockholm conducted five different experiments on 154 healthy men and women, in the paper published in the February issue of the online journal PLoS ONE. To create the impression of having a third arm, participants sat with their right arm resting on a table and their left arm hidden from view, behind a screen.
A rubber prosthetic right hand was placed beside the person's real hand and a cloth was placed over the participant's right shoulder to hide everything but the forearms on both the real and fake right arms. If the volunteer glanced at their right hand, they appeared to have two of them.
Known to neuroscientists as "the supernumerary hand illusion," researchers used two different paintbrushes to stroke the skin on the index and middle fingers of the participant's real right hand and false one at the exact same time for a minute or two. During this process, participant's were told to look at the artificial limb.
After each brushing session, volunteers completed a questionnaire. Participants reported that they felt the touch of the brush on both the real and fake hand. They also described feeling as if they had two right hands and both limbs felt like a part of their body.
"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."
In another experiment, the researchers held a knife close to the volunteer's hand and the rubber hand as if it might pierce the skin. They wanted to see if the body and mind perceived the knife as a threat. The same stress response was seen in both the real hand and the prosthetic one. (The researchers measured the amount of sweat coming from the skin as a measure of emotional arousal of the nervous system; the same response to the threat of the knife was seen whether it was close to touching the real hand or the fake one.)
As for why the mind is so easily duped by the third-hand illusion, Guterstam explains that when a study participant sees a fake right hand next to his own, the brain wonders "Which right hand is mine?"
"Instead of choosing to experience only one hand as your own, we surprisingly found that the brain accepts both right hands as part of the body image, and the participant experiences ownership of an extra third arm," say Guterstam.
While some of these experiments might seem like fun parlor tricks, the results have practical applications.
They could be important in developing advanced prosthetics, suggests Guterstam. The findings, for example, may benefit stroke patients who need an artificial arm because one side of their body is paralyzed. Scientists would better understand how patients can control this extra arm and experience it as their own.
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Really?! Couldn't these scientists put their time to better use like solving a problem? Maybe they should try some card tricks while they're at it.
Hi there, perhaps you missed the last couple graphs:
I am Italian so if I were in this test group the 3rd arm would just be complimenting my 3rd leg.
bspurloc-
That was down right funny! LOL!
This is the biggest peace of crap study i've heard in a while! They WASTED all that research time and money for that! What a joke!!!
I think you mean piece of crap and I imagine that if you were someone in the need of a prosthetic (you know like a soldier or something) you would find this research valuable.
Yes Serious... why would understanding how the brain works have anything to do with anything... unless someone doesn't have a brain.
I'm all in favor of peace of crap. If there is one thing I hate, it's when feces go to war.
You didn't read the peer-reviewed paper, did you? In fact, it doesn't look like you even bothered to read the news report on it. If you had, you might have seen the part where it points out that this research can benefit stroke patients and patients with artificial arms. Not to mention the fact that anyone with a brain should want to understand something about how it works.
a House episode kind of dealt with this when he was trying to "befriend" another tenant who had lost an arm trying to save a child. the man was in constant pain because he was still trying to pull the child out. House used a box with a mirror to make the man's brain think he had two hands so that he was able to unclench his missing hand and relieve his pain.
This episode of House was based on preliminary work done by VS Ramachandran. For more information, consult his book "Phantoms in the Brain". This book contains pretty much everything you want to know regarding brain function and illusion as well as sensory perception.
That's an interesting idea. I wonder if they have actually researched this technique on people with phantom limb syndrome. It is common for people who lose limbs to feel excruciating pain in the missing limb, or to believe that it is in a painful and unnatural position. This kind of research could really help some people, so it's not a waste of time at all.
Yes, it has been researched and seems to be more effective than painkillers. For quite a while, actually. The problem seems to be that once a two way communication system is removed, the brain keeps sending signals that are never answered. For example... the right hand (which doesn't exist anymore) is being told to clench... clench.... clench... there is no response back, so the signals continue to fire in one direction. Since there IS no right hand anymore, there can't be any signal back. Unless you replace the signal stimulus with another stimulus. Enter the mirror, which provides a new stimulus (visual) to tell the brain that the "right hand" is clenching. Now, the phantom limb is no longer receiving signals relentlessly. The pain declines. Pretty cool stuff, indeed backed up by studies. Needs more than many other areas of research, but indeed mirror therapy is fairly well backed up.
As Mr. Spock would say... "Fascinating!"
The Bruce Willis movie Surrogates takes this concept to the limit. In the short term this research could lead to better prostheses. In the long term perhaps not true Surrogates but being able to send a human operated machine that can grasp and manipulate things as easily as we do in environments we can go into? Deep ocean exploration come to mind as a first use.
The reactions of mkeMike and SeriousTalker shouldn't be surprising. They're the product of a country that no longer values science.
And they're not capable of reading the article to the very end.
And the technique only helps for appendages you can see...
Maybe this will have some practical application for lonely nights in bed.
Or when you're with three chicks at the same time
They already believe I have a third arm. :-), It's holding an apple.
vdancer
- Best...post...ever
Terrific.
How's that cure for cancer coming along scientists? Put that on the back burner have we?
Some scientists do cancer research and some scientists do other kinds of research. Is that too difficult to grasp?
Yes because every single scientist in the entirety of the world is studying this one single piece of research.
What's a matter Matt only able to do one thing at a time?
If you can walk and chew gum at the same time I guess scientists can actually do research on more then one problem at a time.
The cure for cancer has certainly been found by now, but right now cancer is too important to the G8 as a worldwide population thinner. It's the perfect disease. It does not discriminate. Old, young, black, white, etc.
The wars of the future will be over fuel, food and water. Why the hell would they want to release the cure for cancer right now? Also, do you have any idea how much money is involved in cancer research? If you were making BILLIONS annually "looking" for a cure, would you every really want to find it???
Paranoid much? Perhaps you should actually, I don't know... research a bit about what you are talking about, Chris? If anyone had a mass applicable cure, it'd be exploited for riches via pharma, NOT research. I suppose it is more entertaining for you to bury your head into the sand and listen to entertaining (but false) conspiracy stories, no?
Ah heck, Corporations through madison avenue have doing this to consumers for years!
Not to mention political party's...........
"An extra third arm"? Wouldn't that be a fourth arm?
You either did not read the entire article, or you cannot comprehend. Studies like this one, done in Sweden, have absolute potential for all sorts of applications --- prosthetics; remote surgery, etc. I suppose all scientists should check with YOU to determine which areas of study they can pursue.
They should try the experiment on amputees with artificial limbs.
Three arms. Big deal. Guys have three knees. Left knee, right knee, weenie.
They should have chosen a few members of the U. S. Republican party as subjects instead of so many gullible Democrats and socialists who will believe almost anything..............
That was discussed but decided against, as a brain is needed in order to conduct research on it.
Funniest quip of the day!
I bet some of the participants in this, ahh, research are easy to hypnotize too.
Yeah they were Glen Beck viewers.
clinpsych,
That is one of the strange features of proprioception, one of our internal 6th senses. One would need to see the limb, or the body schema, in order to receive the feedback loop from the limb (or phantom limb) to the brain. It's all fascinating stuff, and Oliver Sacks writes often about this and kinesthesia in many of his great books.
On another note: I wonder, unless I missed something, what the left arm and hand were doing in all this. They didn't seem to mention it, unless you can just chalk it up to yet another case of the left side being utterly useless.
Well I think that may have something to do with the left and right half hemispheres of the brain, one side that stores memories and the other that creates imagination? Not entirely sure but something I'd look into? Not saying this research is productive or not, but certainly worth a try since we're not paying for it if it turns out bogus...
oddly enough, my penis sometimes feels like a 3rd arm.
There's way more than 5 senses, be careful calling anything a 6th sense (obvious layman connotations there... balance [with an entire dedicated system], temperature, motion... all are senses, the list actually approaches 20ish I'd say without a list in front of me... with much debate... but still). If you refer to left hand in reference to my example of a missing right hand (not going back to article to see if they specifically said the fake arm was always right handed, in a hurry :P ), the left hand is the hand clenching in the mirror so that the brain gets visual "evidence" the the right hand can be left alone.
This only proves that some scientists that "believe" that global warming is real just keep trying to make us beleive that there is man made global warming when this is further proof of their lies and deciet that they create. Just like politicians try to tell us that we should go green...never trust either one...I don't.
Don't trust science! It's all lies and make-believe! Trust only what you see on fair and balanced news outlets because everyone else is a liberal socialist! Why are we wasting money on science when all the answers are readily available from Fox News? <sarcasm>
zgomer - Global warming is not a belief, its a theory backed up by multiple sources of data that all point to the fact that the planet is getting warmer, faster. While the earth goes through natural warming and cooling cycles, the most recent warming cycle we are in is happening alot faster than any warming period in the past. CO2 is a known greenhouse gas and we are releasing millions of tons of it into the atmosphere every year.
To those that think that funding scientific research is a waste of money, you're apparently just not smart enough to understand the benefits or your attention span just isnt long enough to read the whole article.
Well, at least no animals were harmed in THIS scientific experiment =D !!
This is a fascinating experiment! The human brain is amazing!
Yall stupid, I got 3 legs , 8 eyeballs and a bush of cactus in my pockets full of sunshine, yall retarded people
This is an awesome discovery and the experiment has tremendous implicatons! Way to go Sweden! If some of you who wrote such pathetic comments, would take just a little of your time to read educational materials, such as Scientific America or Discovery you would not make such cynical and ignorant remarks. What a pity for us, Americans!