[From Bill Powers (2003.05.25.1421 MDT)]
Bruce Gregory (2003.0525.1505) --
Why be contrary -- just to keep the Rick's pot boiling?
Have you ever begun a project about which you felt excited and confident?
Starting any new project means that whatever error there is -- that is,
whatever the remaining difference is between where you are and where you
hope to end up -- is producing whatever action you're carrying out. Maybe
for one of those 75-mile errors you simply turn the gain down to keep from
trying ridiculously hard, or maybe the errors are kept from getting very
large by the sense of progress toward the goal (that's called rate
feedback). But whatever the case, if there were no error signal you would
not be striving toward the goal.
With error signals come action and preparation for action. You feel a
heightened sense of physiological readiness.Maybe your heart beats a little
faster, your blood vessels constrict, your breathing quickens, your pupils
dilate, your blood glucose level rises. These are familiar feelings,
because you feel them during practically any situation of heightened
preparation for action -- being afraid, being angry, being horrified, being
in love, being exhilarated, everything but being depressed. In the context
of starting a new project that you really like doing, these feelings are
taken as positive -- you say you're enjoying the effort, or are excited at
the prospects, or are feeling optimistic.
This is the "good" feeling I've been trying to describe. It's not anything
as stupid as saying that I like errors. Remember, "error" does not mean
mistake. Presence of an error signal doesn't even mean that there's
anything wrong. Error signals are what make actions occur. They are
_motivations_. They are _drives_. They go with ambition, striving, wanting,
trying. They keep perceptions close to their reference levels by causing
the necessary output (the pedaling that keeps you breezing along). Errors
become problems only when they are very large and stay very large, meaning
that the perception you're trying to control is staying far from its
reference level.
What is a "large" error? In a tracking experiment it's a difference between
target and cursor positions that is frequently as large as 10% of the range
of movement of the target. When the disturbance is made large and fast
enough to make a subject's tracking error average 10% RMS, subjects say
they are losing control, they can't do it, it's too hard. And they are
still correcting 90 percent of the effects of disturbances! A minute of
tracking under conditions that create 10% error RMS is exhausting. And all
you're doing is moving a mouse through a range of 5 or 6 inches.
When Marc Abrams gets his stress esperiment going, I trust that one of the
experiments will involve using different degrees of difficulty, tailored to
produce known amounts of tracking error in each individual subject, like
1%, 2%. 5%, 10%, and 20%, If the indicators of stress are functions of
error in a control task, this should demonstrate the effect. For
comparison, of course, you would want to devise some simple task like
waving a fan that takes just as much physical effort to produce but doesn't
involve a tracking error signal.
I think it might also be informative to provide a really nice reward, like
$20, for selecting the option of learning to do something relatively
simple. When the person indicates he would like to try it, there should be
"signs of stress" (that is, preparation for action) even before the task is
started. And if asked, the subject might possibly indicate some sort of
positive feeling.
Best,
Bill P.