[From Rick Marken (2010.08.25.2045)]
Bill Powers (2010.08.25.1710 MDT)--
Rick Marken (2010.08.25.1550) --
RM: The trials are spaced 5 seconds apart and after each
noise burst the subject is to write either "Y" or "N"; �"Y" if there
seemed to be a tone in the burst and the "N" if not.
BP: OK. So if a tone seems to have occurred in the middle of a noise, the
instructions are to write the letter "N" and if it didn't, the letter "Y".
No, the opposite.
BP: My point is that a very complex set of control systems and perceptual
functions is required to carry out this task. It's not simple.
Neither is tracking behavior; all those hand muscles and positions to
control. But I think it's possible to model the main aspects of the
task (as per our diagrams). I sent you my computer model of the task.
I'm attaching my computer implementation of Martin's at the end of
this post, unannotated I'm afraid. The annotated one didn't get much
attention so I'm not going to waste time on it for this one, which
will probably get the same amount of attention. I guess I'm on my own
here.
How does a
reference signal get sent to the system that writes one letter/numeral
instead of the one that writes a different letter/numeral?
See lower level control system in the diagram of both models which
gets it's reference from the system controlling the relationship
between ps (perceived stimulus) and pr (perceived response) in my
model or between ps and pri (the imagined response) in Martin's.
How does the
person know that when the tone exists, the right thing to do is to write one
thing, otherwise not to write that but to write something else?
They are told what to do in the instructions, same as in a tracking
task where they are told to move the mouse up or down (or right/left
in my versions) to affect the cursor position.
At the very least, a control system that emits an output has to monitor some
sensory effect of that output.
And it does in both my model and Martin's
This means that if a system is controlling the relationship between a
reference signal and a stimulus of some sort, that relationship must be
perceived.
Not in Martin's model. Martin's model just controls the response pr,
and it works fine to account for the results of the detection task;
mine controls both the response, pr, and the relationship between pr
and ps.
Both the stimulus and a perception affected by any response, real
or imagined, must be perceived in order to know if the right response was
emitted to establish the intended relationship between stimulus and
response. The brain never just assumes that the right relationship was
established.
That's what we are testing by developing the two models, one that does
what you say above and one that doesn't.
If the participant is trying to be sure that the actual response, when made,
matches the stimulus condition correctly, there should be a way of finding
out whether this is true. It could be arranged, for example, to use two
adjacent keyboard keys like T and F to indicate true and false, and then
occasionally print "F" when "T" is struck and "T" when "F" is struck.
Both Martin's model and mine would see this as an error and correct
it. This disturbance will not test for a difference between Martin's
and my model.
So we don't need to assume that the so-called basic principle is true; we
can find out when it is and isn't true. That's why we do experiments: to
test the premises.
If the "basic principle" is the one you mention above -- that the
subject must be controlling a relationship between ps and pr (as per
my model) -- then that's exactly what I'm trying to do; test that
basic principle. In fact, Martin's model does not behave according to
that basic principle (see code below) and yet it behaves exactly as my
model does in the yes/no detection task. So we have to develop an
experiment -- a variant of the yes/no detection task -- where these
models make different predictions. I have an idea of the kinds of
experiment that will distinguish between the models but I was hoping
to get some agreement about the models (in the form of programs)
before I proposed it. I'll wait.
Best
Rick
Dim YResp(30), NResp(30)
Cells(4, 7) = "Martin Model"
NTrials = Cells(1, 6)
cs = Cells(2, 6)
HR = 0
FA = 0
NH = 0
NFA = 0
PC = 0
NY = 0
NN = 0
For i = 1 To NTrials
rref = 0#
pri = 0
pr = 0
o = 0.5
If (Rnd(1) > 0.5) Then Tone = 1 Else Tone = 0
s = (Rnd(1) - 0.5) * 20 + 10 * Tone
Cells(i + 1, 1) = Tone
Cells(i + 1, 2) = s
If (s > cs) Then ps = 1 Else ps = 0
If Tone = 1 Then
NY = NY + 1
Else
NN = NN + 1
End If
'Higher level loop
For j = 1 To 15
'Imagination loop
p2 = ps - pri
rref = rref + 0.01 * (80 * (p2) - rref)
pri = Round(rref, 1)
If ps = 1 Then
YResp(j) = YResp(j) + rref
Else
NResp(j) = NResp(j) + rref
End If
Next j
For k = 16 To 30
o = o + 0.01 * (40 * (rref - o) - o)
pr = Round(o, 1)
If ps = 1 Then
YResp(k) = YResp(k) + o
Else
NResp(k) = NResp(k) + o
End If
Next k
'pr = Round(pr, 1)
Cells(i + 1, 3) = pr
a = Cells(i + 1, 1)
If (a = 1) Then NH = NH + 1
If (a = 1 And pr = 1) Then
HR = HR + 1
PC = PC + 1
End If
If (a = 0 And pr = 1) Then FA = FA + 1
If (a = 0 And pr = 0) Then PC = PC + 1
Next i
For i = 1 To 30
Cells(i + 1, 4) = YResp(i) / NY
Cells(i + 1, 5) = NResp(i) / NN
Next i
Cells(5, 6) = HR / NH
Cells(6, 6) = FA / (NTrials - NH)
Cells(7, 6) = PC / NTrials
···
--
Richard S. Marken PhD
rsmarken@gmail.com
www.mindreadings.com