[Martin Taylor 2006.01.15.15.27]
[From Rick Marken (2006.01.25.1200)]
Martin Taylor (2006.01.24.23.26) --
Rick Marken (2006.01.24.1350)
I don't believe that cursor position is the variable controlled.
Isn't the object of your demo that the subject chooses one of the
cursors and controls its position according to any pattern (s)he sees
fit?Oops. You're looking at the wrong demo!!
Sorry -- no wonder there was one level of misunderstanding!
The demo I was talking about is the "Nature of Control" tracking task. I suggested it to Erling as a way to get a feeling for the difference between passive perception, where you just look at the cursor while it moves, and active control of perception, where you control the perception of cursor position.
And I was thinking about his placing an envelope over the screen, not worrying about which demo he was looking at..
All this other stuff about perceptions going to zero -- actually, I still have no idea how it came up
Because you told him that the nonperception of the environmental variable was functionally the same as perceiving it to have a value of zero.
but it is completely irrelevant to the original point, which is simply that we can perceive without controlling what we perceive, and we often do, like when we watch a movie or listen to a concert. We do control for the movie or concert we attend. But once selected we don't generally control what we see or hear at these events.
I think we all agree on that, a point I thought had vanished from the discussion a while back.
>Here's the crux, very simply. You say, to paraphrase (I hope
correctly): Firing rate value non-zero indicates some value of the
perception; firing rate value zero indicates that the perception
doesn't have a value.I said, in the bit you quoted up above: "In the absence of some
special functional organization not specified in any model I know,
this arrangement would mean that zero firing rate corresponds to a
perception of the most leftwards imaginable position."Now you are asserting that there IS some such special functional
organization that changes the meaning of the perceptual signal when
its value is exactly zero. If its value is 10, 1, .1, .01, .001, the
thing perceived (in this case a position) is precisely that value,
but let that .001 be reduced by .001 and suddenly the thing perceived
is not that value. There's a new mechanism.This is close to correct I would say that non-zero perceptual signals represent different _states_ of a perceptual variable (like different degrees of honesty) but that zero is a special case where you are not experiencing the perceptual variable at all -- you can't see the honesty of the statement, for example. But I see the problem you have with it and I'm not sure how to solve it. But your approach has a problem, too. If zero neural firing represents a state of the variable -- its lowest possible state -- then how to you represent the non-perception of the variable, even of it's lowest possible state?
Exactly the conundrum I have been trying to get you to see. Two different perceptions are involved.
My view of it is that "perceiving that I am unable to perceive X" is itself a perception, independent of "I perceive X to have value V", and one that could be represented by a perceptual input variable in some control system. That control system might have a reference value "I want to be able to perceive X" and might result in an action "Take the envelope away from in front of the screen," or "Buy a plane ticket to Venice."
My suggested variant on your demo (which could work with either demo, I guess), takes note of the fact that "perveiving that I am able/unable to perceive X" is not actually a binary choice, but comes in degrees: "I can perceive X very clearly and precisely", "I can see X but not very clearly", "I can just about make out that X is there", "I can't see any sign of X". Likewise, the reference value for such a perception may not be for maximum clarity and precision of seeing X. An ability to see whether X is "big" or "small" might be enough to allow some higher-level perception to reach its own reference level.
I don't believe this (in my view necessary) perceptual control mechanism fits easily into the conventional HPCT hierarchy, but neither do I think it requires any drastic alteration to incorporate the notion that some (most? all?) perceptions are two-valued, indicating {value, precision}, much as values are ofted written in scientific papers (e.g. "This artifact has a carbon date of 2350 years BP +- 85 years).
Anyway, to back off from proposals of mechanism, to me it seems clear that I personally have some perceptions of whether, and with what precision, some other perceptions represent the states of some external variables, and that I am able to act to alter the values of those perceptions of precision.
Martin