Playing Ball in Space

oo7tushar writes "Although most experiments in space seem simple they have profound results. Take this for example, astronauts trying to catch a ball in space. What's so hard about that? Nothing much really, down here on Earth. In space it's a completely different story. Here on earth our eyes see the ball and our brain anticipates it's movement according to gravity. In space the brain continues to anticpate gravity but unlike motion sickness (which is adapted to within days), astronauts continue to anticipate the path of a ball for 15 days (after which they start to show progress). What are the ramifications? The brain must have some sort of internal gravitation model."

Comments

Constants

[Jouster]

But is it 9.80 m/s/s or 32 ft/s/s in our heads?

Jouster

Just like...

[niftyeric]

this article. Oh well..

the Guinness effect

[tongue]

Does that explain why a dozen pints of guinness seems to amplify earths gravity to the point that I can't pick myself up off the bar or floor?

Nothing special...

[tom_newton]

about us having a "gravitation model" in our heads.
Surely it's just called "experience"?

What a bunch of crap

[yatest5]

What are the ramifications? The brain must have some sort of internal gravitation model."

Er, no, maybe it has some capacity to learn the way things move, which surprisingly, after 30-odd years of the same observed behaviour, proves a little hard to unlearn.

The ramifications? Well, people are going to, like have to, like, train for the new environment! Quick, call the cops!

Re:What a bunch of crap

[JordanH]

• The ramifications? Well, people are going to, like have to, like, train for the new environment! Quick, call the cops!

A much more serious ramification is that researchers are noting that children exposed to gravity seem to have a much greater facility with walking down staircases than those who aren't. It's a mutation!

Re:What a bunch of crap

[wickidpisa]

It was assumed that this was due to our "excellent" hand-eye co-ordination, but this experiment seems to show that instead we're predicting the motion in a gravity field. It shouldn't have taken 15 days for the astronauts to learn to adjust if they were really following the movement of the ball.

You are jumping to conclusions there. Even if you are right about the ability to catch being inherent rather than learned (I have doubts that it is. Don't believe everything you read.) it would have little bearing on this experiment. To test what you claim is true, you would need to have people who have not been catching under earth's gravity for the past X years try to catch in zero G. It is entirely possible that catching is inherent, yet because these scientists have been exposed to it for so long, they have also learned what to expect, and that may be why it took them longer to re-learn to catch. Someone with no experience catching under gravity may have been able to learn it more quickly.

Encoding Specificity

[Transient0]

An internal gravitation model would be theorizing far more than is necesarry to account for the data. In cognitive science, there has long been an understanding of encoding specificity. This simply means that data, including skill knowledge, is best retrieved from human memory under the same conditions which it was learned.

An example from the real world is underwater welding. When underwater welders were first being trained, the companies tried to simply train professional welders in all the ways that underwater welding was different from normal welding. But, in diong this, they found that when they were underwater, the welders had serious trouble calling on those skills which supposedly transferred over unchanged. As a result, they had to be entirely retrained in skills they had apparently already learned.

Similarly, if you lose your keys while you're stoned and then can't find them the next day. Psychological evidence shows that your best chance to find them is to get stoned again and then look for them.

Any number of other controlled psychological experiments have been performed to domonstrate this same effect(memorizing words under different lighting conditions, etc.). I don't see why gravitation would be any different.

Re:Encoding Specificity

[sunhou]

Re: learning welding underwater -- when I visited Australia, driving was a somewhat similar experience (driving on the opposite side of the road from what I was used to).

At first, it was hard because everything was the opposite of what I knew. But within a few days, I simply learned to reverse my innate responses, since I knew that those responses were backwards, and so it got easier. But after a couple of weeks, I had started to get accustomed to the new configuration, and so some of my natural responses were correct. That meant I could no longer just "do the opposite of what felt natural", and it actually got harder again and took more thought; I always had to think "is my gut feeling about what to do an old gut feeling from the US, or a newly acquired gut feeling from the past couple of weeks in Australia?"

I was there for about 4 or 5 weeks. When I got back to the US, within a day, I promptly drove on the wrong side of the road. (It was a small road with no traffic, so fewer cues, and I did catch myself within a few seconds before causing any major havoc.)

Or...

[ruiner13]

It could be that a baby born in space would not have such models. I'm guessing that is a learned response of the brain, not an inherited one. I took a Psychology of learning class in college once, and i learned many interesting things. For one, spacial perceptions depend a lot on the environment in which you are raised. For instance, if you live in a rectangular type house, you can generally make good guesses as to the dimensions of other rectangular shaped rooms. If you bring that person into a round room, the estimations are way off. It works in reverse, too. If you live in a round hut your entire life, you won't be able to make good guesses about rectangular rooms. Seems kinda analogous to the gravity story. I say we get some randy astronauts to give birth on the space station, and kinda have a truman show in space. We'll see how that baby will catch a ball then.

Re:Or...

[Peyna]

Yeah, reminds me of "The Forest People", by Colin Turnbull. He took a pygmy out of the forest where he lived and up on this mountain, and the guy thought that everything he saw was miniature versions of what they really were. His eyes had never had to look at anything more than 15-20 feet in front of him in the forest, and he had no clue what things looked like when they were that far away.

Maybe it isn't the gravity...

[qurob]

Whenever the jocks threw balls at the geeks at school, they never caught them either :)

Or you could read this article...

[pwagland]

also on Slashdot...

And again, I say, so what? It takes the human body a while to accustomise yourself to a new environment, this is hardly breaking news!

Any SysAdmin who has gone from Solaris to AIX could tell you exactly the same thing! :-)

Re:What a ridiculous notion

[iolaire_in_swe]

Err, what?
You claim a 50% INCREASE in g due to higher centrifugal force (current is 9.8ms^-2). This is clearly nonsense. Also: "100 million years ago the Earth's day was only about 18 hours long." is very unlikely - The geology doesn't bear it out at all (and yes I do have a degree in geology, so I may know what I'm on about).

Even if our day lasted only 12 current hours, that would not result in 50% of our current gravity - the mass of the earth masks any such effect. The variation of g from the pole (no angular motion) to the equator (max angular motion) is only about 0.6ms^-2.

Finally, there's no such thing as centrifugal force - it's simply the tendency of objects to continue in a straight line. Any high school student studying physics should be able to tell you that.

*sigh*

Isaac Asimov used this for a SF story

[Seth Finkelstein]

Isaac Asimov wrote a prescient short story "The Singing Bell", about this effect. The plot hinges on proving that a man has recently been to the moon, by catching him off-guard in catching something as if he was on the moon (i.e. he had adapted to the lunar gravity in terms of ball-catching). Absolutely great science-fiction story.

Sig: What Happened To The Censorware Project (censorware.org)

Re:What a ridiculous notion

[well_jung]

That it took practice is exactly correct. It's like catching a ball from a different quarterback that throws sidearm with his left hand. If the trajectory and acceleration are substantively different, it will take a while to get comfy. I suspect a well practiced juggler could adjust to the diffences in Space fairly quickly.

Honestly, that a coupla of guys with PHDs in Physics couldn't catch a ball doesn't suprise me all that much.

Dogs, calculus, and fetch.

[B1]

Has anybody else read Dirk Gently's Holistic Detective Agency? (Douglas Adams)

In one passage, I believe Dirk is explaining that we don't give credit to dogs for their ability to perform complex calculus in realtime.

For example, when you play fetch, your dog is able to analyze the trajectory and velocity of a thrown ball. Based on his observation of the throw, he solves a complex three-dimensional physics problem involving a system of differential equations based upon the underlying physics. He does this fast enough that he is able to position himself to catch the ball.

Of course, that's *most* dogs...our dog wasn't so good at catching things. I think he was more of an "arts" dog. :)

Re:Dogs, calculus, and fetch.

[Omerna]

I've read that book, and yes, you're correct. That was the first thing that came to mind when I read that article.

BTW, that series is really good if all you've read of his books is the Hitchhiker series.

Re:What a ridiculous notion

[Flavio]

I thought this stupid thread would've died already, but since it hasn't let's use some high school physics to show how wrong you are.

*Suppose* that 100 million years ago the earth's day were only 18 hours long. I don't know if it was, but suppose that.

Then the measured gravity acceleration would be

g = g_0 - Rw^2, where w is omega (the earth's period)

w = 2pi/64800
g = 9.8 - 6,37e6*(9.7e-5)^2 = 9.8 - 0.06 = 9.74 m/s^2

So I can't see how g could've been about 15.2 m/s^2, because reducing earth's period doesn't make much of a difference (as many people have stated without proof before me).

What amazes me is that you state that g was actually HIGHER (15.2 m/s^2) back in that day. Would you mind elucidating that?

How long did it take you to learn in gravity?

[weave]

How long did it take you to learn to catch a ball on Earth?

My father was never one who was into sports until one day when he felt guilty I guess and bought me a mitt when I was 8 and took me out back to play catch.

Guess what, I sucked. I don't know how long it took me to learn but I tell you what, once in a while someone tosses a set of keys to me across the room and I still can't catch em half the time.

So I don't see why this is a big deal. Now if it was a story about the difficulties of re-learning how to have sex in space, then I'd be interested! (No, my dad didn't teach me that either, thank god)

Re:What a ridiculous notion

[Latent IT]

I juggle.

Actually, a whole lot of juggling is putting your hand in the right place at the right time. You're not really watching all the balls in the air, if you're doing more than 3. If anything, a juggler relies on the anticipation *more* to catch a ball than say, a baseball outfielder, who can just follow the single ball in with his vision.

That being said, and getting back to the humor, yeah, I bet I could catch the ball better than those physics guys any day. ;)

bees, parachutes, & linear thinking

[hawk]

From other seminars I've attended in the past:

there's a certain amount of linear modeling the brain can do. Note that, for a small enough interval, a linear model can be made "good enough".

The interesting examples:

1. Move a beehive by a fixed amount each day while they're out gathering. The bees adjust to this (e.g., 10feet/day), and head to where they know it *will be*. Increase this amount by a fixed amount (10, 11, 12, etc.) and they can't do it.

2. Parachute landing. Don't look at the ground. You're falling at a rate the brain can't handle; if you watch, you compensate incorrectly, and often hurt yourself. (so hear the brain seems to expect the gravity induced quadratic, whereas you're moving at a linear rate?).

hawk