[From Bill Powers (960712.1230 MDT)]
Hans Blom, 960712 --
Rick Marken (960712.0800) says
You're not going to forget to explain why blindfolded people can't
thread needles, are you?
And you reply:
I'd rather not explain X when not-X is the case. What makes you so
cocksure that this cannot be done? How many samples have you
acquired? Have you tried it? Although it's not easy -- because it
is not one of our standard activities, we have not developed a
"control system" for it -- it can be done. Have you tried it?
Fair enough question. Since I'm not very adept at threading needles, I
got my resident expert, Mary, to try it. I looked through the sewing
drawer and picked the biggest "Easy-Thread" needle I could find, and a
moderate size of thread (not too big, not too small), and asked her to
thread it with her eyes closed. She did it in a few seconds! I asked her
to do it again; this time it took her about a minute, but by gum, she
did it again. You are right!
Then I asked her how she did it. She said (with a bit of reportorial
license), "It's easy -- this needle's eye has a slit in the top and two
projections; all you have to do is get the thread between the
projections, and pull it down sideways through the slit. That's why it's
called an Easy Thread needle. Of course if you had given me an ordinary
needle there's no way I could have done it."
Then she told me a story from her childhood, about Mary Gash, a
professional seamstress, who was challenged at a party to thread a
needle in the dark (an ordinary needle). She was put in a closed room
with the lights out with a needle and thread. She did it, too! It took
her an hour and a half.
I asked my Mary to describe how she did it while doing it. She described
a great deal of feeling of the needle, to find the head and then to get
the head oriented the right way. Then she felt for the thread (already
in the hand holding the shank of the needle), picked up the loose end,
and stretched it, moving it sideways to feel where the needle was, then
moving it up to find where the head was. At the same time she kept
touching the top of the needle with a fingernail, locating the two
projections between which the thread had to go, and trying to bring the
stretched thread over the top of the needle and down into the slit. It
took many tries, but finally she got the thread in the slit and pulled
it down into the eye for the third time.
So Hans, you are absolutely right. There is no difference between
threading a needle with your eyes open and threading it with your eyes
closed. The model that is used by the control system simply generates
the same outputs it normally generates, and since they produce needle-
threading movements when your eyes are open, they also produce needle-
threading movements when your eyes are closed. How come you are so
smart, Hans, and we are so dumb?
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Best,
Bill P.