🚀 go-pugleaf

[From Bruce Abbott (990428.0800 EST)]

>Bill Powers (990427.1644 MDT) --

>>Bruce Abbott (990426.1405 EST)

>The environment has something to do with it. The environment includes the
>environmental feedback function through which the ant's actions affect its
>perceptions (according to PCT). When the ant comes up against a passive
>obstacle, the forces that result are caused entirely by the ant's muscles.

I never thought otherwise.

>Only if there is an independent active source of forces acting on the ant
>would we identify it as the "disturbing variable" in the standard PCT
>diagram.

In my view, the actions of one control system may disturb a variable being
controlled by another control system.  Hypothetical example:  The ant is
moving forward along a given path because of the actions of one set of
control systems; if this forward motion brings the ant to an obstacle in its
path, then a variable being controlled by another system (proximity) gets
disturbed and action is initiated to counter the effect of that disturbance.
The proximity system neither knows nor cares whether the obstacle was
brought into proximity by "an independent active source of forces" or by the
actions of another of the ant's own control systems.  It just "sees" a
disturbance to its controlled variable and takes action.

>If the ant's actions were totally and blindly automatic, the path taken by
>the ant would reflect every obstacle and every disturbance.

First, no one has asserted that the ant's actions are "totally and blindly
automatic."  (I am assuming you mean totally open loop.)

>But it does
>not. Generally, the ant's path is _not_ deflected by obstacles; it is
>independent of them.

Not the paths of the ant's _I've_ observed!  My observations indicate that
ants navigating on rough terrain do a _lot_ of direction-changing to go
around or over obstacles in their paths.

>The ant might turn aside on encountering a large
>pebble, or it might simply climb over the pebble and stay on course.

You are now defining "course" two-dimensionally.  Do you think the ant does?

>The
>ant does not veer off of upslopes or turn down downslopes, as Simon
>imagined. To the contrary; I know of ants which, on encountering a 6 x 6
>post sunk into the ground, climb up it, eventually ending up in my house.
>We are not seeing merely a confluence of forces, one due to the goal and
>the rest due to the environment, as Simon imagined.

Like the ant, you are veering off course, Bill.  I don't care what Simon may
have thought the mechanism was.  I've only been defending Simon's insight
that complex actions may reflect complexity in the environment rather than a
complex internal organization.  You haven't convinced me that this insight
is wrong.

>I suppose so, if your point is to write science-fiction. If pigs had wings
>they could fly. If ants had only a single goal, and used a perception that
>gave them continuous direct perception of their relation to it (such as the
>ability to see the goal-object at a distance, or smell it differentially in
>two antennae on a windless day), and if it had no other goals and there
>were no obstacles in the way, then yes, it would travel in a straight line
>toward the goal. But by the time you have specified all the necessary
>"if"s, you will have departed from the world of reality.

This is unfair, because neither Simon nor I ever intended to attempt a model
of any real ant.  Simon began with a common observation:  watching an ant on
the beach making its way back to its nest.  He observed that the ant had
many obstacles in its path, and often took a circuitous route as required to
get around them and continue toward the nest.  He noted that if you drew the
ant's path on paper it would appear to be complex -- lots of loops and
wiggles and sudden turns -- but that this complexity need not imply a
parallel complexity within the ant.  The path might be capable of being
fully accounted for by some fairly simple "rules" (my word) operating within
the ant, interacting with the complexities of the terrain the ant must cross.

Exactly what those "rules" (system equations) are is not the subject of this
discussion, no matter how much you insist that they are.

>Of course you are implying that if there were obstacles, the ant would not
>travel in a straight line toward its goal. That doesn't follow. If you see
>an ant traveling in a straight line, chances are that it's counteracting
>disturbances too small for you to see without a magnifying glass, thus
>leading you to think that there aren't any. Or you may be assuming that
>because the path remains undisturbed, there must not be any disturbing
>forces acting. It may be puzzling how one ant could climb right over the
>back of another ant while both ants continue on their paths, but you can
>always shrug and say that the net force must have just happened to come out
>zero for both ants.

A masterly example of a straw-man argument.  You have said nothing here that
has anything even remotely to do with Simon's conjecture.

>Your observations are too limited. An ant often deviates abruptly from its
>path when nothing at all is in its way. During our campground observations
>of individual ants, Tom and I would often look at each other and say "Now,
>why did it do THAT?" I doubt that you could find any correlation between
>the placements of small obstacles and the path of the ant, especially if
>you plotted the path from above.

More of the same.  I can't tell if you're _missing_ the point or
deliberately trying to obfuscate it.

>It's a simple point, Bill, and one with which you of
>>all people should have no quarrel.  The complex waveform of the plot of
>>handle movement in a tracking task mirrors the complexity of the
>>distrubances acting on cursor position, not any complexity in the five-line
>>Pascal model of the control system that can accurately simulate this
>>behavior.  HPCT is fundamentally simple, yet it is capable of generating
>>extremely complex actions if the environment requires them.  Not so?

>Yes, I understand your meaning here, but it is not Simon's meaning. I
>repeat, Simon considered the organism to be one gigantic input-output
>function, and said so in so many words.

Ah, now I understand the high-gain resistance.  I really don't have any
evidence that Simon held this view; it certainly was not expressed in
_Sciences of the Artificial_, at least as I recall it now.  And it isn't the
view I am attempting to defend here.  How did we shift from a simple
conjecture Simon made about the origins of the complexity of observed
behavior to a discussion about open- versus closed-loop models?  Simon's
conjecture does not entail an open-loop model, even if he had one in mind
when he made it.

Regards,

Bruce