Psych Studies/Model Tests

[From Rick Marken (930108.0900)]

Martin Taylor (930107 14:00) --

As to whether the results from one person are useful in dealing with another,
that depends entirely on what it is that is being measured. I have 30-year
old group (as you would say) data on the timing of reversing figures which
are every bit as tight as any PCT prediction of tracking.

I'll take your word for it; could you send me a reprint? It sounds
very interesting. I didn't mean to imply that all the data from
conventional psychology is useless. If you get group data where
the average results represent almost exactly what each individual
did (no between or within subject variance to speak of) then it
is certainly a worthwhile result.

In the past, metaphors like gold nuggets among the garbage have been used
on CSG-L. The metaphor is reasonable, but the question is whether the
nugget-to-garbage ratio is low enough to allow a real psychologist (PCT
oriented) to discard without consideration what fantasy psychologists
(non-PCT oriented) have done. I think there is a lot of good stuff that
can be used. Bill and Rick and others think not.

I just think that ratio is VERY low; but you do find nuggets,
especially where people are studying control most diretly
(as in operant studies and many perceptual studies). I don't
want to reject stuff without consideration -- but there is a
LOT of stuff out there so its tough to consider everything
carefully to see if it's worthwhile. If you (or anyone) knows
of studies with high quality results then, please, report
them; we certainly will consider them. But the garbage/nugget
analogy is approriate. When you are looking for gold, your
inclination is to spend as much time as possible looking in
the places where you think the gold is most likely to be found.
The same is true with research results -- I prefer to look for
great research where I think it might be found; looking for such
research in conventional psychology seems to me like looking for gold
in the LaBrea Tar Pits -- a good place to look for fossils,
not nuggests (though there might be some gold in the the Tar
Pits, I'd be inclined to search the foothills of the Sierras?).

Greg Williams (920108) ---

You say I'm a (the?) CSG gadfly. I'm also the CSG archivist, and here
are some quotes from previous posts on the net to show what you (and
Rick) actually have said. At one point, you say that correlations of
".99 upward" are needed for a "true science." And Rick says that
.99+ is a "reasonable" goal. My point is that you have not reached
that goal in predicting cursor position.

After reading this I got out my HyperCard conflict stack and
did a tracking run and model run (400 data points each) with a
low conflict and got a correlation between subject and model
mouse movements of .996831 -- the correlation with cursor
movements would be lower but at least we seem to have part of
a true science. I repeated this with a slightly higher level
of conflict and got a sublject/model correlation of .993398. Still
in the "true science" range. Higher conflicts will take us
well below .99 (to .98 maybe?) suggesting that there is something
to be learned there.

How about H = K * integral(C - T)? (K is a constant to be adjusted for best
fit to the data by running the simulation with the model in it). That's
just a first cut, of course, since it doesn't predict the cursor position
well enough for "true science."

I think the idea, now, is to use your S-R model in a real tracking
situation. As I understand the challenge, you are to derive an S-R
model (like your equation above) from your observation of the
relationship between S (cursor) and R (handle movement). Bill
apparently sent you that data. I'd throw in the disturbance too -- I
don't think it's an unfair advantage for you at all -- in many experiments
you CAN see the disturbance (or the cause thereof) even if the subject can't.
So I would suggest that Bill give you D, C and H from a tracking task.
Based on that data, you come up with an S-R model that generates H based
on what the subject can see (C and T).

Your model must then be tested by seeing if it can do what the subject
does -- control the cursor in a new situation. So your model must be
"run" (this could be cone analytically but it's easier with a computer
simulation) with a new disturbance -- to see if it generates the H that
controls the cursor (as the subject would).

Best

Rick

[Martin Taylor 930108 14:00]
(Rick Marken 930108.0900)

Is this the time to get back to the unresolved discussions on statistics?
I don't think so, but I'm willing. I'm starting off my information-theory-
leads-to-PCT with a basic discussion of probability and statistics, anyway,
so it will be part of that. But we could do it separately if you want.

Quite apart from that, I have a real problem with how a PCT approach to
psychophysics could differ from a conventional approach. In a typical
psychophysical experiment, a subject is asked to discriminate between
two possibilities for which event was presented on a particular trial, or
to react as fast as possible with one of two discriminative responses to
a pattern that might be of type A or of type B. There's no opportunity
for the subject to reduce the error of a perception. The action is
performed, the experimenter records which action it was, and the whole
cycle starts again with no informational connection between the last
action and the next presentation. The only feedback that can do anything
is an indication as to whether the action was right or wrong, and that
feedback can only contribute to reorganization, not to the actions or
perceptions on the next trial.

[Actually, there are contingencies between trials that can be used to
determine that the observer is not behaving in the same mode all through
the experiment. These are very small, though important in determining
what is going on inside the subject: Taylor, Forbes & Creelman, J. acoustical
Society of America, 1983, 74, 1367-1374 (Rick--I'll include it with the
other ones I' sending you). They aren't relevant to the question I am
raising here.]

Why should taking a PCT approach make any difference to the way psychophysical
experiments are done or interpreted? The results of psychophysical
experiments can put limits on the possible Perceptual Input Functions
and can perhaps speak to whether the perception is differentiated or the
output integrated (Avery Andrews 920101.2030). But from the other
direction, I really can't see the connection. The subject is presumed
to be satisfying a reference something like perceiving the experimenter
to be pleased with his/her performance, and the result of that is the
set of actions that have no direct feedback consequences on the experimental
presentations.

Martin