

The Itch: reverse-engineering of human perception - mechanical_fish
http://www.newyorker.com/reporting/2008/06/30/080630fa_fact_gawande

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zby
It's packed with NLP tricks to capture your attention and sooooooo long. What
is really interesting in this article is this:

The account of perception that’s starting to emerge is what we might call the
“brain’s best guess” theory of perception: perception is the brain’s best
guess about what is happening in the outside world. The mind integrates
scattered, weak, rudimentary signals from a variety of sensory channels,
information from past experiences, and hard-wired processes, and produces a
sensory experience full of brain-provided color, sound, texture, and meaning.
We see a friendly yellow Labrador bounding behind a picket fence not because
that is the transmission we receive but because this is the perception our
weaver-brain assembles as its best hypothesis of what is out there from the
slivers of information we get. Perception is inference.

The theory—and a theory is all it is right now—has begun to make sense of some
bewildering phenomena. Among them is an experiment that Ramachandran performed
with volunteers who had phantom pain in an amputated arm. They put their
surviving arm through a hole in the side of a box with a mirror inside, so
that, peering through the open top, they would see their arm and its mirror
image, as if they had two arms. Ramachandran then asked them to move both
their intact arm and, in their mind, their phantom arm—to pretend that they
were conducting an orchestra, say. The patients had the sense that they had
two arms again. Even though they knew it was an illusion, it provided
immediate relief. People who for years had been unable to unclench their
phantom fist suddenly felt their hand open; phantom arms in painfully
contorted positions could relax. With daily use of the mirror box over weeks,
patients sensed their phantom limbs actually shrink into their stumps and, in
several instances, completely vanish. Researchers at Walter Reed Army Medical
Center recently published the results of a randomized trial of mirror therapy
for soldiers with phantom-limb pain, showing dramatic success.

A lot about this phenomenon remains murky, but here’s what the new theory
suggests is going on: when your arm is amputated, nerve transmissions are shut
off, and the brain’s best guess often seems to be that the arm is still there,
but paralyzed, or clenched, or beginning to cramp up. Things can stay like
this for years. The mirror box, however, provides the brain with new visual
input—however illusory—suggesting motion in the absent arm. The brain has to
incorporate the new information into its sensory map of what’s happening.
Therefore, it guesses again, and the pain goes away.

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mechanical_fish
Dang, you can't change urls after submission. Here's the one-page version,
which I prefer:

[http://www.newyorker.com/reporting/2008/06/30/080630fa_fact_...](http://www.newyorker.com/reporting/2008/06/30/080630fa_fact_gawande?currentPage=all)

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chrisconley
reading that made me really itchy

