🚀 go-pugleaf

[From Bill Powers (990427.1644 MDT)]

Bruce Abbott (990426.1405 EST)--

>>The disturbances of which you speak are caused by the ant, not by its
>>environment.
>
>O.K., have it your way: the environment has nothing to do with it.

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.
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.

>The
>ant's path is complex because the ant is complex, not because its direct way
>home is blocked at multiple points along the way.  Maybe you believe it; I
>don't.

If the ant's actions were totally and blindly automatic, the path taken by
the ant would reflect every obstacle and every disturbance. But it does
not. Generally, the ant's path is _not_ deflected by obstacles; it is
independent of them. The ant might turn aside on encountering a large
pebble, or it might simply climb over the pebble and stay on course. 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.

>>>In their absence the ant would make a bee-line (ant-line?)
>>>for the nest.
>
>>You are assuming that the _only_ goal is to return to the nest. I doubt
>>that this is ever the case.
>
>Yes I am.  I can do that in order to illustrate a point can't I?

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.

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.

>You are
>doubtless right if we are discussing real ants in all their marvelous
>detail, but I thought I was just using the example to make a point about how
>an ant whose only goal was to get to the nest by the straightest path
>possible would behave if nothing got in its way.

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.

>It's as if I were
>attempting to explain the motion of an ideal pendulum and you said "you are
>assuming an absence of friction.  I doubt that this is ever the case."
>True, but irrelevant to the present argument.
>What Simon was saying is that complex behavior does
>not necessarily require a complex organism, that the apparent complexity in
>behavior may arise because of the complexity of the terrain over the which
>the ant must crawl. 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. He saw a goal as essentially a bias
in a given direction, and behavior as the resultant of goal-driven
tendencies and effects from the environment, totally open-loop. It never
occured to him that the complexities of the behavior of even an ant could
arise from complex interactions among dozens of internal goals at multiple
levels, even in an ant, and be essentially independent of what appear to be
complexities of the environment.

>>Also, you are making up an observation to fit the conclusion you want to
>>draw. I think it would be very hard to find an ant that simply headed in a
>>straight line for its nest, even in the total absence of irregularities in
>>the terrain.
>
>This sounds like relevant criticism but it is not.  Again, as should be
>obvious, the example of the ant was not intended to provide a realistic
>model of a real ant, but to illustrate the point that in the absence of
>obstacles an ant controlling for heading directly for the nest would move
>directly for the nest. (Not a brilliant point but apparently one that needed
>to be made, given your previous responses.)

But that is not at all assured. You have to suppose that the ant is not
controlling other perceptions to which the presence or absence of obstacles
is irrelevant, such as scents and light variations. You have to assume that
its internal goal structure remains completely fixed, and that all goals
represent static (rather than time-varying) states of affairs. Your example
is indeed not a brilliant point; it rests on unspoken assumptions of which
you seem unaware.

>>Simon's statements about ants were glib, not scientifically useful.
>
>It's a _very_ simple but elegant point Simon was making:  don't assume, just
>because the observed actions are complex, that the system producing them
>must be complex.

Bruce, how would those statements of Simon's appear to you if you took away
all suggestions that he knew anything about PCT? Simon's argument is really
less like a PCT argument and more like that of Albert Weiss and others who
used the "raindrop analogy" of purposive behavior. One popular idea in
mid-century was that the behavior of organisms that seemed purposive was
analogous to the behavior of a drop of water on an irregular inclined
plane. Under the urging of gravity, the drop would move down the slope,
moving irregularly (Skinner would have said "capriciously") to the left and
right in a complex path as if it were guided by varying internal
motivations, and all the while seeking a goal of being at the bottom of the
slope. In fact, went this story, its path was completely predetermined by
factors outside it. The complex behavior of the drop reflected only
complexities in its environment and the unchanging force of gravity.

This analogy was concocted for the express purpose of showing that
apparently purposive behavior was really caused by the environment. Simon
was merely repeating this well-accepted way of denying inner purposes.

>There's nothing glib about it, and certainly there is
>scientific utility in keeping it in mind when attempting to puzzle out why a
>given system behaves as it has been observed to do. If Simon's insight were
>wrong, and complex actions required complex systems to perform them, there
>would be no way that the complex waveform of handle movement in the tracking
>task could be modeled so well by such a simple set of system equations.  Yet
>they are.  The excellent modeling of tracking actions by simple
>control-system equations confirms Simon's conjecture.

No, it would astonish Simon, were he to understand what he was seeing. The
problem is that the handle's movements are not irregular because irregular
forces are being applied to it, but because irregular disturbances are
being applied to the perception being controlled, and being counteracted by
the actions. There are plenty of small irregularities in the handle
movements that are uncorrelated with anything else in the environment (that
we know about). Simon didn't have any insight; he was merely repeating what
many others maintained about complex behavior.

We can explain, now, how it is that the environment can produce variations
in behavior that are as complex as the disturbances applied by the
environment. In fact, seeing how simple the system is that is needed to
counteract environmental disturbances, I think the proper conclusion is
that the environment isn't really as complex as it seems. "Complexity" is a
subjective term, and depends on how much you know. Once you understand
something, it's simple.

And furthermore, seeing a case in which behavior mirrors known disturbances
is not sufficient to show that complexities in behavior are strictly
confined to mirroring complex disturbances. We also have even more striking
cases of complexities in behavior in the absence of any known disturbances
-- in fact, people who indulge in many kinds of complex behavior seem to
seek out environments that are quiet and unobtrusive, to preclude the need
to waste energy counteracting them. If you see an organism producing
complex behavior in a complex environment, you may be quite mistaken in
assuming that the complex variations are highly correlated.

Best,

Bill P.