Why can't blindfolded humans walk a straight line?

Travis

Misanthrope of the Mountains
Travis
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Mar 31, 2007
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So I'm up late tonight for reasons that would take too long to explain and I ended up watching last week's episode of Mythbusters. In it they rather definitely confirm that at least Adam and Jaime cannot come close to walking in a straight line while blindfolded and cut off from sound. With blindfolds and earmuffs on they were let loose in a huge field trying to walk straight for a target they saw prior to being deprived of stimuli and then immediately proceed to start walking huge corkscrews all the while talking about how they feel they are doing a pretty good job of sticking to a straight path.

They then repeat this experiment while swimming and driving a vehicle with the same results.

But the "why" of this phenomenon is something they only briefly touch on. They speculate that when deprived of outside stimuli the brain creates a fictional topography and then you react to that sort of intuitively. However their one experiment to try and counter that doesn't work.

So does anyone here have any ideas?

I would speculate that minute changes within the inner ear get exacerbated when the brain loses all visual and auditory clues.
 
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...or that most people favour one side of their body, perhaps? After how long did they start veering? Were they able to stay straight for any distance at all? I often walk into the person walking to the left of me even with my eyes open and my mom is even worse.
 
Strangely their turns seemed to always be in the same direction per try. But from try to try they would favor different directions. For instance in his first test Adam did a huge horseshoe to the left. In his next test Adam started corkscrewing to the right and just kept doing that until he was almost to a nearby road.

Jaime tended to execute rather sharp turns while unaware and went off course even faster than Adam. And, like Adam, seemed to alternate which direction he would veer off in.

In the last test they bound themselves to each other with a ladder to see if they could self correct each other with a mechanical stimulus. But this didn't work either. They actually did a 180 and almost ended up back at their starting point while narrating how they thought they were doing better with the rig.
 
This doesn't seem odd to me. Most open-loop systems tend to drift because of internal irregularities and external disturbances.

In this case differences in leg length and muscle strength would bias the direction of travel, as would the slope of the ground and wind direction. The reason for the different paths on subsequent attempts were probably caused by under and over compensation for these factors.
 
I don't think any explanation is needed other than a directional bias in locomotion. A toy car, driven by independent rear wheels (no common axle) and a separate motor on each wheel and with no mechanism to self-correct its direction, will have the same problem. Attempts to consciously compensate for the bias will undercorrect or overcorrect and still end up circling. One might expect alternating undercorrection and overcorrection averaging out to a roughly straight course, but in the absence of feedback that's no more likely than a steady straight course to begin with.

Respectfully,
Myriad
 
Does anyone know if people born blind are actually better at this?
 
Interesting question. I'd tend to doubt it. If you are right footed you tend to walk left handed circles. Carry a lamp at night and you get worse (tighter circles)Maybe born blind people would walk larger circles, but I bet they would still circle.
 
my guess would be that people use their various senses as a constant self-righting mechanism, and if we don't have those senses available we don't self-right.
 
Why would it happen when driving? Let go of the steering wheel and the car will stay straight. At least it does in my cars.
 
DrDave said:
Why would it happen when driving? Let go of the steering wheel and the car will stay straight. At least it does in my cars.
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They drove some sort of small vehicle, which might not have been alligned properly, or maybe the steering was very sensitive.

Adam tried to keep the steering wheel fixed, and maybe that caused it to veer off course. Small subconscious movements would exacerbate that.
 
DrDave said:
Why would it happen when driving? Let go of the steering wheel and the car will stay straight. At least it does in my cars.
Click to expand...

Unless the car was involved in a crash - especially one from the side - or was extremely poorly built, cars will stay in a straight line. They're purposefuly built this way. Some mechanical faults and wear and tear could cause a slight bias to one side as well, and a small bias to one side is possible however, which could show over long distances.

McHrozni
 
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Hmm.. I think I'm pretty good at walking straight with my eyes closed. I just don't like doing it because I always feel like I'm about to walk into something.

Even if I'm on a huge open field, I feel like a brick wall will pop into existence in front of me.
 
Isn't this a well-known phenomenon that happens to lost hikers? Even with eyes and ears unhindered, people seem to be really bad at maintaining a steady course.
 
A car will stay pretty straight, but not exactly straight, from the wheel alignment. Plus, the ground is unlikely to be perfectly level, so the car is not going to go straight anyway. Other factors will make the car drift as well, such as the wind direction.
 
Soapy Sam said:
If you are right footed you tend to walk left handed circles.
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Except that the two of them didn't favor a side. I wish they had tested some of the crew members to get a larger sample size.

Bram Kaandorp said:
Adam tried to keep the steering wheel fixed, and maybe that caused it to veer off course. Small subconscious movements would exacerbate that.
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I think there was enough play in the steering mechanism to allow it to drift off course. Adam didn't have to make any movements for it to do that.


The episode is on again tonight, right before the new episode.

Steve S
 
McHrozni said:
Unless the car was involved in a crash - especially one from the side - or was extremely poorly built, cars will stay in a straight line. They're purposefuly built this way. Some mechanical faults and wear and tear could cause a slight bias to one side as well, and a small bias to one side is possible however, which could show over long distances.

McHrozni
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I think the idea in Mythbusters was that a person can not drive in a straight line.

In other words, someone who is holding the steering wheel, and trying to stay straight on a line.

Just letting go of the wheel means that you are not the one controlling the direction of the car. It's the human element they wanted to test, not the car.
 
Well, I take a longer step with my left foot than with my right. With my eyes open I can continually correct, but I bet with my eyes closed I'd end up veering right.

As for dogs being better at it, I doubt it. My dogs don't walk a straight line with their eyes open.
 
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