Sophont
Sunday, March 20, 2005
 
Senses
inviolet's blog - April 16th, 2004: "We've all heard it. It's spoken, written, taught everywhere: a human has five senses.

This knowledge is so basic, so completely accepted, that it is absolutely beyond question. Only a few crackpots insist that there is a mystical 'sixth sense'. Because everybody knows that there are really only five.

And everybody is wrong. Viz:

1. sight.

2. sound.

3. touch.

4. smell.

5. taste.

6. accelleration: every human body comes equipped with two three-dimensional accellerometers, one in each ear. Fluid in the 'semicircular canals' moves in response to accelleration (including gravity), the movement of the fluid causes tiny hairs to bend, and nerves at the base of those hairs relay the signal to the brain where it is interpreted as direct sensory data. And just as the eyes can be fooled with an optical illusion, the accellerometers can be fooled by a 'centripetal illusion': rotate in place for a minute and then stop, you will continue to feel the sensation of spinning.

7. proprioception: the human brain infers accelleration and position data by analyzing what muscle efforts are in effect. If the accellerometers in our ears were disabled, we would still be able to sense accelleration by observing (automatically) what muscles we must contract in order to hold our position. Proprioception is a computed sense, but it's computed at a low enough level to qualify as a physical sense: it registers on our consciousness as a feeling, not as ideas.

(I learned a lot about the sixth and seventh senses while flying airplanes with my friend Tripacer Driver. These two senses are actually quite dangerous when it comes time to fly in the clouds, without benefit of visual input.)

Anyway, my point is: If an entire planet can be completely, obviously mistaken about something so basic as the number of physical senses, about something so easily falsified, what other errors lurk within the phrase 'Everybody knows that!"

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