[From Rick Marken (2006.12.25.1200)]
Bruce Nevin (2006.12.25 09:56 EST)--
Rick Marken (2006.12.24.2220)--
Yes, that is a simpler way to put it. What I am bearing in mind is that
the loop is closed through the environment, the CV is modeled as being
in the environment between the observed organism and the observer,
Actually, that's not quite true. The CV is a perceptual variable; a _function_ of certain environmental variables.
disturbances typically affect the CV in the environment and not at the
observed system's sensory input, and so on.
I would say that a disturbance is an environmental variable that influences the state of sensory variables of which the CV is a function. Consider a possible CV when catching a ball: vertical optical velocity. This CV is a function of the optical projection of the ball on the retina (a sensory variable) that is a function of the actual trajectory of the ball in the environment (one of the disturbances to the CV).
There are always at least
those two perceivers, the observer and the observed organism, and for
each perceiver there is a qi that corresponds (we believe) to the CV in
Yes, of course. But as the observer, my hypothesis is about the CV controlled by the observed organism. So I formulate hypotheses about the CV in terms of qi as perceived from the organism's perspective. So my hypotheses about the qi controlled when catching are formulated in terms of what the fielder sees, not in terms of what I see while watching the fielder catch the ball. So one hypothesis about the variable controlled by the fielder (that is, one hypothesis about a qi controlled when catching a ball) is that it is (d alpha/dt) where alpha is the vertical optical angle between the ball and some reference point, like home plate, as seen from the point of view of the fielder -- not of an observer in the stands.
There is no other way to model interactions of two
organisms around one CV.
This is a whole different question. And I don't think you can model interactions of two organisms around one CV. Each organism controls its own CV, of course. What you must be talking about is modeling interactions between organisms controlling CVs that are the same function of the same environmental variables. For example, person 1 might be controlling qi1, which is f(i1, i2..in) and person 2 might be controlling qi2, which is also f(i1,i2...in). But the inputs, i, for person 1 are seen from a different perspective than the same inputs for person 2. So even though the two CVs, qi1 and qi2, are functionally the same, the value of these CVs will always be different for person 1 and 2. This "control parallax" must, indeed, be taken into account when modeling interactions between two or more organisms.
Indeed, coordinated control with another is our
confirmation that what we perceive exists and is as we perceive it. To
identify the CV with qi is to leap past that on wings of assumption.
We only identify qi as a CV when it has passed the test for the controlled variable. We don't simply assume that any particular qi is a CV.
That is why I say that qi as a measure of input to the observed system
is one measure of the CV.
This sounds very strange to me. How can qi -- which is a hypothesis about a perceptual variable that is controlled -- be anything other than the CV, if it passes the test. qi is a guess about a measure of the organism's sensory environment that it is controlling. So qi is a measure of what _may_ be the variable that is controlled: the CV. For example, (d alpha/dt) is one qi that might be controlled when catching a ball. Suppose we do the test and find that (d alpha/dt) is controlled. Can't we then say that (d alpha/dt) _is_ a CV? It's not really a measure of the CV; it _is_ the CV.
What I think that in fact a measure of the
observer's sensory input is taken to be a measure of the CV, which rests
on the assumption that the two systems (observer and observed) are
controlling the same CV, and indeed that is one way of stating the Test:
are we controlling the same CV?
I don't see this at all. When I do the test I don't have to be controlling a variable in order to determine that another person is controlling it. All you have to do is hypothesize a CV (some variable qi) and see if it is protected from disturbance by actions of the organism. You don't even have to be able to directly perceive qi yourself (as in hypothesis about the very high frequency sounds echos controlled by bats) or even be there doing the testing (as in my Mind Reading demo) where the computer does the test automatically.
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