[from Mary Powers 931110]
Here's my 2 cents on the feedforward/feedback debate.
It's been said that knocking a perception out of the loop results
in a "wrong perception", with greater and greater deviations in
output as it tries to correct the wrong thing. But this isn't
what's happening (except maybe in a simulation where each lower
level perception is getting a separate signal from the "world"?).
What is happening is not WRONG perception, it's NO perception.
When you're in that dark room headed for bed, what you see is
blackness, nothing, not a vision that you are walking through the
Taj Mahal. So you pay attention to all your other senses and
My sister (who had some horrific neurological problems a couple
of years ago) now has no sensation in her fingertips. So she
found that she couldn't put on her earrings the way she used to.
She still wears earrings - it's simply that she now has to look
into a mirror when she puts them on.
The point is that each perceptual function is not receiving an
isolated and unique signal (as is perhaps the case in an
electronic device). Whatever is going on in the world is sensed
in a variety of ways, and if one modality conks out, the others
take up the slack.
If one gets "wrong" signals, they are not coming from the
perceptual function that is inoperative: they are coming from
OTHER perceptual functions. When my mouth is numbed with
novocaine, the lip doesn't feel a thing. But my fingers feeling
the lip, feeling a part of me that usually is a co-feeling, with
sensations both from the finger and the lip, sends a signal that
reminds me of other times I've felt part of me that has no
sensation, and I come to the conclusion that, like those other
times, this unfeeling part is swollen. The lip is not swollen. We
say it "feels" swollen. It is not however, sending a "wrong"
swollen sensation. The active perception, in my fingers, is
providing the input that results in that conclusion.
And during the two hours or so that the lip is numb, I talk and
eat and so on, not because I'm feedforwarding messages to the
numb part of the lip, but because the rest of it is compensating,
just like Gary's fun experiments of talking while his tongue is
held at the roof of his mouth.