Study: Brain represents tools as temporary body parts | Hacker News Reader

Study: Brain represents tools as temporary body parts

scienceblog.com

52 pointsvaksel20 comments

Somewhat surprisingly, you can reproduce part of this result at your desk. (In a hilariously non-controlled, do-not-quote-me manner.)

Rest your right arm on your desk with your palm facing upward. Touch the inner side of your elbow and the tip of your middle finger, using your left hand. At this point, I thought "Wow, my arm is longer than I would have expected it to be."

Now, take a pen in your right hand and use it as a pointing device to follow the words of this sentence. Still holding the pen, replace your right arm on the table in the same position as you used before. Touch your inner elbow and fingertip again. (At this point, my first thought was "Oh crikey it got bigger." Its funny, I actually perceived extra stress in my left arm, as if I were stretching to cover a distance that I had had no noticeable difficulty with 15 seconds before.)

Your description could use some figures. ;)

Interesting. On trying it, I didn't try to stretch my left hand any further, but I did automatically curl my right arm much more to "make it fit".

Effect reproduced. Very interesting.

If above isn't clear (wasn't for me), read article on BBC (clear for me). Or to rephrase it:

Put arm on desk, palm facing up is convenient -- don't move this one. With hand from free (other) arm, point and touch the middle finger of the fixed arm, then the elbow. I did this many times (finger, elbow, finger elbow). Get an idea of how long this arm is.

Now use the fixed arm, pick up a pen, and trace along the screen. I did this for about 10 seconds. Put arm down back into formerly fixed position. Redo the finger-elbow touch with the free arm's hand.

Old hat. The reverse is actually more interesting! The representation of the brain is reflected in body parts. People think about the brain as being the seat of neuroplasticity but your limbs are actually learning patterns, as are your ears, your eyes. Anywhere there are neurons there is learning and memory. This means that 1. sometimes reaction is faster than transmission to and from the brain could allow for and 2. often input is filtered and enhanced before it gets to the brain based on previous experience.

While it's cool to think that we "become one" with our tools, until they can also form a part of this distributed memory grid they will always feel subtly wrong, clumsy, and foreign.

After time they really don't feel clumsy at all, that's what is amazing. To get a grasp on just how integrated a tool (Or better, a musical instrument) gets, try using a common device with the opposite hand and feel how clumsy it it feels in comparison. That's the natural pre-integrated state. Part of what is happening is that the brain actually devotes more neurons to the hand that is manipulating the tool. This probably makes up somewhat for the fact that the tool itself has no sensing ability.

The mind map for the hands of professional piano players have many more neurons devoted to the hands than in normal people for instance.

Classical guitar players use their fingernails to great effect when playing to generate widely variable sounds depending on how they employ them. One could argue that you fingernails function much as tools do in this case in the sense that they don't have nerve endings at the tips but instead transmit feeling through vibration down to the nail bed. The same thing is happening on a larger scale when you hold a screwdriver, the resistance and vibration is transmitted down to the hand which senses it. Over time more neurons get devoted to those sensing and manipulating areas.

More info here: http://health.howstuffworks.com/brain8.htm

And here: http://en.wikipedia.org/wiki/Sensory_homunculus

I would be interested in a similar study on how the mind perceives software. The mouse pretty much seems like an extension of the body, but what about the keyboard? I'm typing this message right now without even glancing down once at my keyboard. How does that happen?

What about software that, over time, becomes "muscle memory"? Vim or Emacs, for example. Or UNIX shell tools (grep, awk etc.). What about programming languages? Sometimes I start thinking about problems in terms of whatever programming language I happen to be using at the moment. When I work on a project, I have a feeling of structure. I sometimes visualize OO code as various compartments. How does that work?

When reading this all I could think about was Glamdring and the ancient's insistence on the soul of a warrior being embedded somehow in their weapons. I've always had a deep love of circus skills including Staff and Sword play, and remapping my "physio-spatial" model is second nature. The eerie part is when you can actually feel it happening, it feels like the sword/tool forces it's way into your consideration. I can only imagine what it must have been like for the blades and tools of old, with all their might and "magic"!!

Reminds me of body-controlled sports, like hang-gliding, snowboarding and motorbike riding: the way the craft responds to body placement really makes it feel like it is part of you.

I'm sure that this effect is separable from human intelligence, and tool-using animals (like chimps using sticks and beavers building dams) feel the same way, because it seems like the simplest way for the mind to integrate tools: after all, a stick behaves as if it were an extension of your hand, so why not reuse existing perceptual and motor control circuitry, rather than constructing entirely new subsystems.

(I'm not saying it's designed, but reuse is more probable than parallel reconstruction from scratch).

Heidegger vindicated at last!

Don't forget Marshall Mcluhan. He said tools and media were an extension of man as well.

I wonder what kind of tools this covers. Only things like screwdrivers, toothbrushes, or even things like cars?

I would say, cars most definitely yes. And we should not only consider concrete objects even. There's really no principal difference in the way we learn to operate the character in a video game, or an internet browser, from how we learn to walk with our legs and body - it's prediction and feedback just thee same. That's the plasticity of the brain.

I think it's a little misleading to talk about "temporary body parts" however, as if there are some distinct conditions for when a tool is like a part of your body and when it's simply a tool we learn intimately.

"Woa, is this hand really a part of me??"

The neocortex really is an amazingly extended phenotype.

  > there are some distinct conditions for when a tool
  > is like a part of your body and when it's simply a tool
  > we learn intimately.

Perhaps these are just different points along a continuum-- all tools (and limbs) are integrated into the body schema to varying degrees. Consider that dancers learn to exert far more exquisite control over their movements than most people do. Another example: a large portion of strength training gains are not simply due to muscle hypertrophy, but to the motor system learning how to recruit the muscles in more coordinated and controlled ways.

Edit: On re-read, it looks like we are agreeing with each other. :-)

s/no principal/in principle no/

I'd argue even that your keyboard and mouse can become a tool for your body.

I'd argue they become an unconscious synapse to the tools we perceive in the machine. Avatars in games, the cursor in editors, these are what we feel as the extensions of our will in their environments.

It obviously doesn't work with ladders you're carrying otherwise the slapstick genre would be 50% smaller.

I don't think carrying things makes them tools.

I would guess it does go as far as any whehicle you're driving and can "sense" its location in 3D space, i.e. know when it's about to bump something. That would make you very good at parallel parking.

Not me though, I suck at sensing where exactly the car ends, either that or my car randomly changes size throughout the week.

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