Krulwich Wonders...
11:02 am
November 22, 2010
November 22, 2010
Try this: Put a blindfold on someone, take them to a park or a beach or a meadow and ask them to walk for as long as they can in a straight line. Then watch what happens:
Credit: Benjamin Arthur, Robert Krulwich, Jessica Goldstein, Maggie Starbard, Mike Ruocco
So why, when blindfolded, can't we walk straight? There is still no good answer. Jan Souman, a research scientist in Germany, co-wrote a paper last year about this human tendency to walk in circles.
Jan Souman/ Max Planck Institute for Biological CyberneticsLike Asa Schaeffer in our animation, he blindfolded his subjects (if you can call what he did to them "blindfolding"; it's more like head wrapping) and told them to try to walk straight for up to an hour.
They did this in the Sahara Desert. They did it on a beach. As usual, the blindfolded subjects could not keep to a straight line.
Jan Souman/Max Planck Institute for Biological CyberneticsSouman also ran the experiment in Bienwald forest in Germany, apparently without blindfolds. As the subjects walked, Jan mapped where they went. Here's a sample of his results.
Those two red dots mark the start of several walks. He ran these experiments over a series of days.
The Weather Matters
When the sky was cloudy and visibility low (blue lines), the walkers (labeled KS, PS and RF) were unable to stay straight and began to turn.
When it was sunny (yellow lines), the walker (labeled SM) was able to keep a steady and rather lengthy straight line.
Humans, apparently, slip into circles when we can't see an external focal point, like a mountain top, a Sun, a moon. Without a corrective, our insides take over and there’s something inside us that won't stay straight.
But Why?
In our radio broadcast, Jan and I explore (just hit the "Listen" button on this page) possible explanations for this tendency to slip into turns. Maybe, I suggest, this is a form of left or right handedness where one side dominates the other? Or maybe this is a reflection of our left and right brains spitting out different levels of dopamine? Or maybe it's stupidly simple: Most of us have slightly different sized legs or slightly stronger appendages on one side and this little difference, over enough steps, mounts up?
Wrong, wrong and wrong, Jan says. He's tested all three propositions (the radio story describes the details) and didn't get the predicted results. There is, apparently, no single explanation for this phenomenon. He is working on a multi-causal theory.
So like walking in circles, we finish where we started: with Asa Schaeffer's very simple field studies, his graceful pencil lines (especially when our animator Benjamin Arthur gives them beautiful motion) posing the puzzle: How can we be turning and turning and not know it?
These "Turning" field studies appear in Chris McManus' book, Right Hand, Left Hand, The Origins of Asymmetry in Brains, Bodies, Atoms and Cultures (Phoenix, 2002)
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Suzanne Benninghoff (osmfac) wrote:
Has anyone thought that maybe we walk in circles on purpose. It seems to me that "instinctually" it would have helped earlier humans out hunting and gathering to stay in close proximity to their families and not get lost as easily... just a thought...
Mon Nov 22 2010 08:10:59 GMT+0000 (GMT Standard Time)
Stephen Oliveri (SO2) wrote:
Why should a human being, or any animal for that matter, have an innate ability to walk (or run or fly or even crawl) in a straight line? I can think of no reason why this ability should ever have evolved in living things that inhabit a non-linear world. From a biological or evolutionary standpoint, what possible purpose could moving in a straight line serve?
Mon Nov 22 2010 07:41:07 GMT+0000 (GMT Standard Time)
Suzanne Young (suroyo) wrote:
If they can't hear does that make a difference? Seems like the inner ear and balance could have something to do with it?
Mon Nov 22 2010 07:07:56 GMT+0000 (GMT Standard Time)
Richard Johnston (RichardUWS) wrote:
An obvious line of further inquiry is whether someone blind from birth or someone who became blind after being sighted exhibits the same behavior. Surely someone has already looked into this.
In what the French in the 18th century called the "Cas Molyneux" philosophers discussed whether someone born blind who had handled objects such as cubes, spheres and pyramids, then was given sight, would be able to recognize them solely from visual cues. There were some instances of this happening, and now we know the answer.
Mon Nov 22 2010 06:54:24 GMT+0000 (GMT Standard Time)
Joel Silbert (kandinsky2) wrote:
Quite apart from the fascinating content of this article, Benjamin Arthur's animation is beautiful and brilliant.
Mon Nov 22 2010 06:46:10 GMT+0000 (GMT Standard Time)
I am (Bob_Marley) wrote:
Circles and curves appear in nature all the time, straight lines rarely do.
Mon Nov 22 2010 06:46:00 GMT+0000 (GMT Standard Time)
Jyuyoung Lee (the_jyu) wrote:
I laughed so hard at the swimmer going off course.
That's exactly me, when I was young and in the Minnows Swimming class.
It's also, precisely the reason why I could never graduate from Minnows level to Seal (the animal)...I just went in circles - hah!Mon Nov 22 2010 04:01:07 GMT+0000 (GMT Standard Time)
Michael Spencer (Stomper88) wrote:
I think the problem is based on equilibrium. Our equilibrium is not very accurate, so our brains uses the other senses (visual markers, muscle feedback) to boost the information from it for a sense of direction and location. My guess is when blindfolded, the equilibrium's "noise" apparently provides a slight bias to left or right and since you cant correct it based on visual information, you're helpless to follow its bias.
Mon Nov 22 2010 02:00:48 GMT+0000 (GMT Standard Time)
Ian Lesser (JazzPhilosopher) wrote:
Now we need a study that explains the phenomenon of two people trying to follow one another and still somehow going in a direction with some kind of goal...
Mon Nov 22 2010 01:11:20 GMT+0000 (GMT Standard Time)
Mr Z (filigree) wrote:
I think it's simpler than described. We trust our senses in differing strengths. We might trust our right foot more and not consider a misstep with it as out of line. When we have ONLY tactile feedback to recon with, our trust has to go to something, even if it is wrong. With no visual feedback for correction, we will continue on trusting what we perceive as straight forward foot steps. This can change from moment to moment. With a sun to give heat and light indications, we have additional feedback. Likewise, audio feedback would work. It's a natural process which is not handled in the conscious mind so we are 'unaware' of our choice of what to trust as we step forward over and over again... it's simply guessing and we'll trust our 'sure' foot more often than the unsure foot. Some people skateboard with right foot forward, others with left. This preference of orientation will give us a natural bias which will drive us in circles without additional feedback. There is no mystery to this. It's a natural thing. Similar problems are found in hobby robots. When one motor is more efficient than the other it will go in circles without feedback.
Mon Nov 22 2010 01:07:56 GMT+0000 (GMT Standard Time)
2010-11-22
A Mystery: Why Can't We Walk Straight? : Krulwich Wonders… : NPR
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