solipsism; psychophysics; Checking inverted-T results

[From Bill Powers (950223.1650 MST)]

Martin Taylor (950223 14:30)--

     From previous discussions, I know you don't mean the following
     according to an interpretation easily put upon it--solipsism. So I
     hope you won't mind if I add something that I intend as
     clarification, not obfuscation.

It is very difficult to make plain the difference between my view and a
belief in solipsism (which, by writing to you, I "thus deny")(To
"refute" it would be considerably more difficult). I try to give an
inkling by talking about _evidence_ that I see for existence of a
reality independent of me. That is quite different from claiming that
there _is_ a reality independent of me; I can only point to the evidence
that I find convincing, and hope that others will also find it
convincing. I can't prove that such a reality exists, and neither can
anyone else, and that's the point. I think you understand this.

The other side of the coin is that I don't need to prove that I have
experiences, or as I term them with an eye to a model, perceptions.
Everything starts with perceptions; it's impossible to deny them without
first admitting that they are there. The only question is whether these
perceptions are _about_ something that is not a perception. Proof is not
available. We can only make a working hypothesis and go on from there.

Speaking particularly of rules:

     Yes, the sources are in the brain, in the same sense that the
     source of the wind-blown drift of leaves is the tree, not the wind.

The wind-blown drift of leaves is also a perception, just like the rules
we deduce which explain why the leaves concentrate in some places. It's
very easy to forget the basic situation, and assume that you know that
reality contains something just like leaves, and that something we
perceive as a wind moves them, and that there are rules in nature
pertaining to the relationship between leaf-things and wind-things.
Unfortunately we can't prove that such rules exist in nature; we make
them up, we use our own perceptions to check them, and there is nowhere
else to turn for corroboration.

     The environment (and if you like, the "environmental contingencies
     and regularities") validates what the brain proposes.

I beg to differ. Nature does no validating of anything. We do all of
that ourselves, using our own brains and perceptions and the rules we
make up for what will constitute validation.

     If the brain somehow creates a perceptual input function that
     defines something in the world that is not "contingently and
     regularly" affected by the body's actions, there is no control, and
     reorganization is likely to alter that particular perceptual
     function so that we do not see that aspect of the enviroment any

You see? That is a rule you made up yourself. I'm not arguing against
it, just pointing out where it came from.

     We see only those regularities our brain has defined, but we keep
     seeing only those that the world supports.

So you argue. Nature doesn't offer that argument, you do. We do keep
seeing regularities, but it is no simple matter to discover whether we
would see them whether we wanted to or not. And to claim that "the world
supports" these regularities is to assume the answer to the very
questions we're asking.

Well, this is a tough one to talk about.


Rick Marken (950223.1315)--

Thanks for the expert views on psychophysics. Your comment that number
scales are also "modalities" was astute -- that removes the last prop
under the idea that we can actually measure perceptions by external
Bruce Abbott (950223.1745 EST) --

Thanks for the matchup. I don't think the small differences in k are of
any import; they're probably less than interpersonal differences.

My next project will be to construct some 8192-entry disturbance tables
and an access function that will allow entering with a desired bandwidth
and getting back the next disturbance value. It's just a matter of
scaling the index to the table, and if necessary interpolating. That
will be a lot less cumbersome than handling 50 tables or so and getting
only a finite set of bandwidths. I'll distribute the tables as soon as
it's all done (to anyone who wants them).

I don't know why my posted numbers were different -- I probably changed
some little thing. Oh, I know -- I was using Xlength = Ylength to try to
get vertical and horizontal scaling the same. I think I changed it back
before sending the code to you. Anyway, I hope that was it. I don't have
a Pentium chip.
Best to all,

Bill P.

<[Bill Leach 950223.22:24 EST(EDT)]

[Bill Powers (950223.1650 MST)]

The exchange between you an Martin has been most interesting. The
difference between what you both believe is, I think, very tiny.

Martin uses leaves for his point and I would like to take another shot
(with the advantage of having just read your response).


The term is a perception (naturally). The observed effect is a
perception but the effect is a reality.

Thus, if I correctly understand Martin, what he is saying is that while
you may or may not be able to ignore the "laws of physics" (for example)
you ignore the reality at your peril -- or more specifically if you
survive the attempt it is likely that your perception will change (may
still be wrong but it will be affected -- and this may be overstating the

I think that Martin is right (egads not again!) in the idea that there
are real things about the environment that have a somewhat consistant
effect on perception experienced by DIFFERENT individuals.

I agree (and suspect that Martin does also) that we are quite a long way
from knowing much of anything about these "reality factors" though as a
rule most of humans believe that almost everything is a "law of nature",
"natural right", etc.

The environment (and if you like, the "environmental contingencies
and regularities") validates what the brain proposes.

I beg to differ. Nature does no validating of anything. We do all of
that ourselves, using our own brains and perceptions and the rules we
make up for what will constitute validation.

You are right but what I think that Martin is saying is that there are
things that happen in the physical world in a consistant manner whether
we perceive them as individual occurrances or not and whether we perceive
them as a "consistant law" or not. The idea then as I think that he is
try to express is that IF we do think about such things THEN it is rather
likely that all individuals will see the experience in at least a
somewhat common way -- NOT that they will explain causes in a similar
manner but that for example "if you let go of the apple (while on earth
anyway) then it falls to the ground".

While the 'normal' physical laws (such as gravity) seem to have yielded
well to rational analysis the "laws" of behaviour have not. In most of
the behavioural "sciences" we are still at the "apple attraction
property" point of explaination... ah someday