Hi Rick, the blind men were wrong but they were still feeling a part of the elephant and describing it. For example they can still describe the rough, long, trunk with holes at the end even though they don’t know it’s a trunk. We can use some if this information to understand the elephant, and we might have to if we can’t reach the trunk ourselves. It is hard to use such a filter but sometimes necessary…
···
On Fri, Feb 14, 2014 at 8:21 PM, Warren Mansell wmansell@gmail.com wrote:
WM: Hi Bruce and Rick, I think there is probably ‘value’ in most other studies and theories as they are studying the same elephant sometimes in ways we don’t have the time, inclination or technology to do,
RM: I take it you are alluding to my “Blind Men and the Elephant” paper reprinted in “More Mind Readings”. Remember, the guys studying the elephant were blind. So when asked to describe an elephant they described the feel of the part of the elephant that was near them – a snake, rope or wall – none of which is a correct description of an elephant. The elephant in the paper, of course, is control. So the point of the paper is that people who don’t know that behavior is control are going to approach the study of behavior are though it is S-R (behaviorist), selection by consequences (reinforcement theory) or commanded output (cognitive). The analogy to the “Blind Men and the Elephant” parable is meant to show that these different approaches to understanding behavior have as little value as do the blind men’s approaches to understanding an elephant.
RM: So I strongly disagree with the statement that “there is probably ‘value’ in most other studies and theories as they are studying the same elephant .” The “Blind Men” paper argues that if you can’t see the whole elephant – if you can’t see that behavior is control – then what you conclude about it is of little value and, possibly, of negative value because it can be quite misleading; behavior is not S-R or selection by consequences or commanded output. These are all ways of seeing control if you can only “see” it by feeling selected parts of it, as was the case for the blind men and the elephant – and as is the case for these “other studies and theories” that were not done in the context of an understanding that behavior is control.
W: but that needs to be seen ‘through control theory glasses’ to quote you Rick. This could even lead to the opposite conclusions to the original researchers, yet still be informative for a PCT model.
RM: Exactly! You have to see behavior through control theory glasses – see that behavior is a process of control, in fact, not in theory – before you have any chance of coming to correct conclusions about how it works. The EP people did not see behavior as control – indeed, they went out of their way to see it as commanded output. And thus they came up with a model that explains what they think they are seeing – commanded output – but doesn’t explain what is actually happening – control.
RM: I think this point – that behavioral research of any kind that is done without an understanding that behavior is control is useless at best and misleading at worst – has to be made forcefully if we are to honor Bill’s vision for this book. For, as Bill said in the proposal for the book:
WTP: This is going to be a revolution whether we like
it or not. There are going to be arguments, screaming and yelling or cool and
polite. It’s time to sink or swim.
RM: I think it’s time to stop playing Mr. Nice Guy with theorists who subjected Bill’s ideas to the “massive” (and often insulting) resistance to which Bill alludes in the book proposal. And I think you will agree, when you read that proposal again – especially the last few paragraphs – that Bill was ready to stop also.
Best regards
Rick
Warren
Sent from my iPhone
On 15 Feb 2014, at 02:54, Richard Marken rsmarken@GMAIL.COM wrote:
[From Rick Marken (2014.02.14.1900)]
–
Richard S. Marken PhD
www.mindreadings.com
The only thing that will redeem mankind is cooperation.
– Bertrand Russellat worst
Bruce Abbott (2014.02.13.1520 EST)–
BA: Nice, Rick. I had been thinking about doing this experiment myself but using a paper scale pasted to a wall and capturing the dynamics on video using my digital camera.
The video can be imported to, say, Microsoft’s Movie Maker program, and examined frame by frame to get position as a function of time and from that, velocity and acceleration.
RM: I would love to see that. You should do it. I was trying to keep mine very low tech; something you could do while visiting your granddaughter in Seattle;-)
BA: This experiment differs from the one used to determine the parameters of the EP model: the participant is consciously trying to maintain a constant joint angle. The EP model is supposed to model what happens under a change of load when the muscle lambdas are not voluntarily altered.
RM: This is a pretty incoherent experiment. What does it mean that the EP model is supposed to model what happens when the muscle lambdas are “not voluntarily altered”. What is voluntarily? What does consciousness have to do with it?
I thought the EP model was a model of how people move their limbs (it looks that way in the simulation; varying R results in nice smooth variations in elbow angle). Now you seem to be saying that it’s a model of some other kind of behavior; one that I don’t understand. It’s apparently the behavior of a person who can command different limb angles but isn’t controlling the limb at the commanded angle. In other words, it seems that you are saying that the EP model is a model of commanded output behavior. Since we know that the behavior of humans is not commanded output but controlled perceptual input, the EP model is apparently a model of the behavior of non-living systems. So EP is neither a competitor nor an alternative to PCT.So why are we even talking about it?
BA: As I noted in my previous post, conscious control of joint angle might work by adjusting the lambdas so as to compensate for load changes. That, of course, requires a level of control not present in the EP model simulated in my demo.
RM: What is “conscious control”? Control and consciousness are two different things, as you must know. Control occurs whether one is conscious or unconscious of it occurring. Are you saying that EP is a model of “unconscious control”? If so, it’s back to being a competitor of PCT because control is control, whether you are conscious of it or not.
BA: Have you tried not attempting to maintain a constant joint angle, but just letting the forearm sag as it will in response to the added load?
RM: I don’t even know what that means? My first guess is to just not control the angle at my elbow at all. The result would be my arm dangling at my side. Adding weight would just feel heavier in my hand. But I really don’t know how to stop controlling. I’m still controlling limb angle even when I just let my arm dangle as could be determined if someone tried to bend my forearm back past vertical while holding my upper arm stationary. I would resist that disturbance big time.
BA: As Martin Taylor has noted, the correct model will be the one that embodies, at some level of abstraction, the actual physiological mechanisms (while also accounting for joint dynamics).
RM: No, the correct model will be one that behaves like a person does (ie. controls limb angle) while not violating what we know about the physiology and physics of the situation. Judging the model by its fidelity to the physiology is, I think, like trying to fit it into a Procrustean bed. For several reasons. First, the physiology is itself a theory based on observations that are themselves guided by how we think the physiology works. So the “true” physiology today is likely to be considered “not quite right” tomorrow.
Second, it’s possible to build models that are consistent with our current understanding of the physiology and are dead wrong. After all, the behavioral model that is the basis of all research in psychology – the general linear model of behavior – is comfortably consistent with the most basic observations of neurophysiology, which is that there are afferent neurons that carry sensory data into the the central nervous system and efferent neurons that carry data from the central nervous system to the muscles and glands that produce behavior.So our most basic understanding of the neurophysiology of the nervous system is completely consistent with a model of behavior – the GLM – that we know to be wrong.
Finally, making consistency with the physiology being a criterion for a successful model is related to the idea that the behavior of organisms must obey the laws of matter, as discussed by Powers on pp. 16-18 of LCS III. Psychologists now seem to treat neurophysiology as the new “laws of matter” and use consistency with the neurophysiology as the measure of the correctness of a theory of behavior in the same way that they used to use the laws of physics for this purpose. But as Bill points out in that section of LCS III, it’s not just that the laws of matter (including neurophysiology) that govern behavior; it’s the organization of that matter that also matters. And the main organizational aspect of matter (and neurophysiology) that is ignored, even by models, like EP that get the neurophysiology right (in terms of what we now understand to be “right”), is the fact that the nervous system exists in a closed feedback loop that goes through the environment; the inputs to the nervous system (in a living system) are always a result of both independent events in the system’s environment (disturbances) and the muscular/glandular outputs of the nervous system itself. The EP model clearly doesn’t take this organizational fact into account – “clearly” because it doesn’t control.
Your lovely simulation of the EP model demonstrates this fact beautifully. It is not a control model. Therefore, it is not a model of human behavior. Period. Why you keep trying to find something of value in this model is beyond me. Your simulation of their model clearly demonstrates two very important facts about the EP model: 1) it doesn’t control and 2) it’s behavior looks like the behavior of a living system (in the sense that variations in R result in nice realistic variations in the angle at the elbow) until you apply disturbances and see that it is not controlling; it’s just generating output. So the model shows that behavior can look like commanded output rather than control; you can’t tell that control is actually going on until you test by applying disturbances to the presumed controiations in R result in nice realistic variations in the angle at the elbow) until you apply disturbances and see that it is not controlling; it’s just generating output. So the model shows that behavior can look like commanded output rather than control; you can’t tell that control is actually going on until you test by applying disturbances to the presumed controlled variable.
This is such a dynamite finding; and it’s thanks to your modeling effort. I hope that the paper you write based on this work will make these points clearly and forcefully. For the sake of PCT and Bill Powers’ legacy.
Best
Rick
I could easily design a robotic servo system to maintain a joint angle against disturbances, but I can pretty much guarantee that there are no electric servomotors actuating our joints.
Bruce
From: Control Systems Group Network (CSGnet) [mailto:CSGNET@LISTSERV.ILLINOIS.EDU] On Behalf Of Richard Marken
Sent: Thursday, February 13, 2014 2:29 PM
To: CSGNET@LISTSERV.ILLINOIS.EDU
Subject: A Bag of Books (was EP Model – Delphi version, revised – again!)
[From Rick Marken (2014.02.13.1130)]
The title of this thread is a play on Powers’ paper “A Bucket of Beans” (reprinted in LCS II) in which he uses a bucket on a rubber band (what else?) to demonstrate some properties of control. In this thread I describe a little experiment that demonstrates characteristics of limb position control using a bag of books. Keeping up the low tech experimentation tradition;-)
Earlier I had posted this observation about the behavior of the EP model:
RM: The fact that the EP model is not a control model is even more evident when one compares the behavior of the EP model to that of a control model that better represents what actually happens when increasing step disturbances of weight are applied to a limb. This is shown by the yellow line (labelled icv to indicate that these are the variations in limb angle that result when limb angle is controlled by an integral control system). Except for the brief “jerks” that occur at the points where the step disturbance increases, the control system keeps the limb angle right at the reference angle (0 in this case) protected from the increasing step disturbances. This corresponds to the behavior you would actually observe in a human. You could see this by by having someone hold a bag in their hand at a fixed angle from their body and then drop one pound weights one at a time into the bag. I think you will find that the behavior of the person’s arm angle over time will looks a lot more like the yellow plot (icv) than the green one (ep).
Since then I have actually performed this experiment. I think it’s worth doing it yourself so that you can get a feel for the difference between control and equilibrium.
First, start with the EP Model prediction of the effect of adding weight to a limb using Bruce’s EP model simulation. Set the EP model to run continuously with R=90 and C=90 (you’ll have to start with R=60 and then increase R to 90 after you set the model to “Run Continuously” and then press “Run Model” or the model will oscillate). Note the actual joint angle (shown in the Joint Angle box) is 90 degrees. Next add weight 1 kg at a time until you reach the max of 10 kg.The result is that the forearm sags about 1+ degree from a 90 degree angle at the elbow each time 1 kg (2.2 lbs) weights is added, ending at 101 degrees after 10 kg is added – an 11 degree increase in elbow joint angle. So the prediction of the EP model at the highest “gain” setting (maximum C value) is that adding weight to the hand while you are trying to maintain a particular angle (like 90 degrees) at the elbow will result in the angle increasing (forearm going down) as the weight increases.
We can test this prediction by having a friend hold a reasonably strong bag in their hand, palm up, while keeping their elbow at a 90 degree angle relative to the body. It’s nice to do this in a place where the hand can point directly at a reference point so that you can get a better idea of how much the hand position has changed when weight (in the form of books) is added to the bag. Now (gently) drop books into the bag one at a time and see what happens to the arm position. I found that volumes of our old World Book Encyclopedia work well; the volumes are all close to 2 lbs (~1kg). Dropping the books into the bag one at a time is equivalent to the step increase in weight produced by the EP program when the weight is ticked up by 1 kg at a time.
I think what you will see is behavior that is nothing like that of the EP model. What I observed is that each time a book is dropped into the bag there is a transient increase in the angle at the elbow, so that the hand dips below the reference point to which it is pointed, but the position of the hand is quickly restored to pointing at the reference point each time a book is added; the 90 degree reference angle at the elbow is quickly restored after each increase in weight; there is no increase in elbow joint angle with increasing weight. I could only fit about 14 lbs (6.5 kg) worth of books into my bag but at the end of the process the hand was still pointing exactly at the reference point. The EP model says it should have sagged 7 degrees below the reference point.
But these findings were based on the subject having visual control of joint angle. The EP Model is controlling blind, so to speak. So the proper way to test this is with the subjects eye’s closed. So once the subject has the elbow angle at 90 degrees and is pointing at a reference position,have him or her close the eyes and then start adding books and see what happens. When I did it with myself as subject I found that I was able to maintain the angle pretty well; again there was no continuous decrease in the angle as books were dropped into the bag, as per the EP model.
I think this little demo will give you at least a qualitative sense of how different control is from EP behavior. With eyes closed (the best test of the EP model) the response to a transient disturbance (a book dropping into a bad) is not a constant increase in elbow angle, as per the EP model; what actually happens is a transient lowering of the hand followed by an immediate raising of the hand back to (and sometimes slightly past) the reference position (the reference elbow angle). With continuous addition of books (and weight) to the bag there is not a continuous decrease in the position of the hand, as predicted by EP.
With eyes closed you are controlling a proprioceptive perception of elbow angle. This is a tougher perception to control than the visual perception of where the hand is pointing. But the proprioceptive perception can be controlled pretty well, though the actual position pointed to will vary a bit more when the eyes are closed then when they are open. But even with eyes closed there is not the the continuous increase in joint angle (decrease in the pointing position of the hand) predicted by the EP Model.
A more precise and formal version of this “Bag of Books” test, if done by the proponents of the EP model of limb position control, would surely have eliminated the EP model from contention as a model of limb position control since the EP model doesn’t control in this situation where people clearly do.
It would be nice if some of you actually did this experiment and let us know what you find.
Best regards
Rick
–
Richard S. Marken PhD
www.mindreadings.com
The only thing that will redeem mankind is cooperation.
– Bertrand Russell