While I read your depiction of the boid models as causal theory
approaches, I looked the website you referenced and noted that
individual boid movements were based on three controlled variables:
* Separation: steer to avoid crowding local flockmates
* Alignment: steer towards the average heading of local flockmates
* Cohesion: steer to move toward the average position of local
flockmates
The author acknowledges these control processes in this statement: "At
the same time, the negative feedback provided by the behavioral
controllers tends to keep the group dynamics ordered. The result is
life-like group behavior".
While we may take issue with the terminology, "behavior controllers",
the processes described are not linear or open loop and, moreover, they
appear to be based on an individual boid's purposeful control of spatial
perceptions. Bottomline: Is this a good example for the point you are
making?
Best,
b
···
--
William J. Curry Capticom, Inc.
bill@powerseed.com 603.756.9933
[From Rick Marken (2001.08.07.2050 PDT)]
Bill Curry wrote:
While I read your depiction of the boid models as causal theory
approaches, I looked the website you referenced and noted that
individual boid movements were based on three controlled variables:
* Separation: steer to avoid crowding local flockmates
* Alignment: steer towards the average heading of local flockmates
* Cohesion: steer to move toward the average position of local
flockmates
The author acknowledges these control processes in this statement:
"At the same time, the negative feedback provided by the behavioral
controllers tends to keep the group dynamics ordered. The result is
life-like group behavior".
While we may take issue with the terminology, "behavior controllers",
the processes described are not linear or open loop and, moreover,
they appear to be based on an individual boid's purposeful control
of spatial perceptions. Bottomline: Is this a good example for
the point you are making?
I wrestled with myself about it. I believe that Reynolds started
off (in the mid 80s I think) describing his boids in S-R terms.
The purposive language at the website is fairly new. I went ahead
and included the boids as an example of a causal view of behavior
because 1) Reynolds shows no evidence of understanding that
"controlled variables" are perceptual variables that are kept in
reference states that can be autonomously adjusted by the boid and
2) he says things like "negative feedback provided by the behavioral
controllers tends to keep the group dynamics ordered" which is a
causal view of how negative feedback works; negative feedback doesn't
"keep the group ordered"; the order is a side effect of the fact
that the boids are controlling perceptual input variables.
But maybe I'm being too fussy. I may elimimate the boids from the
"Three's a Flock" section of the paper and include only the
"Braitenberg vehicles", which are control systems that are very
explicitly described as S-R devices. But while the boids are control
systems (and I acknowledge that in the paper) I still don't see any
evidence that Reynolds _sees_ the purposeful behavior of flocking
birds as anything other than caused output.
Best
Rick
···
--
Richard S. Marken Phone or Fax: 310 474-0313
Life Learning Associates e-mail: marken@mindreadings.com
mindreadings.com