Comments vis a vis collective control....
[Martin Taylor 2016.10.13.15.49]
Comments vis a vis collective control....
Having read the report, all I can say about it is that both persons probably were controlling a perception of the relative distance between probe (stick tip) and target (disc), as they were asked to do.
The "synergy" exists because each one's motion acts as a disturbance to the other's controlled perception of relative distance, so it is compensated by the other's motion. If only one had been controlling a perception of the probe-disc distance, and the other had been controlling for placing either the disc or the probe at a particular place in space, there would have been no synergy as they define it. (It's not what I would have called "synergy", but they used the word.)
Martin
···
On 2016/10/13 12:06 PM, Warren Mansell wrote:
from Kent McClelland (2016.10.13.1410)
Martin Taylor 2016.10.13.15.49
I read the article that Warren sent, too, and my take on it is not quite the same as Martin’s. It seems to me that the results the authors report are consistent with the idea of cooperative or coordinated collective control, as we have been developing it from the PCT perspective. (The title of the article is "Can Discrete Joint Action Be Synergistic? Studying the Stabilization of Interpersonal Hand Coordination.�?)
This article by Romero et al. (2015) describes a lab experiment in which pairs of subjects were seated next to each other and asked to complete multiple trials of a tracking task, in which one individual holds a small disc-shaped target in his left hand while the other has a pointer in her right hand.
The task starts with the two individuals holding the pointer and target at arms length away from each other, and their goal is to bring target and pointer to the middle in front of them in the same plane and touch the pointer to the target. Their shoulders are immobilized by restraints to prevent any torso movement, and the angles of their shoulder, elbow, and wrist movements are recorded (from above), as well as the time it takes to match pointer to target. The target and pointer are taped to the the individuals’ hands to insure that they don’t change their grips on them during the experiment.
What the results of the experiment show, according to the authors, is that "the motor actions performed by coactors were synergistically organized at both the interpersonal and intrapersonal levels. More importantly, however, the interpersonal synergy was found to be significantly stronger than the intrapersonal synergies.�? What does this mean? It hinges on how they’re defining synergy.
The literature referred to in the article talks about “nested synergies�? in motor control where the movements of various joints of the body are organized and coordinated so that they don’t move independently but together perform a complex task with a smooth, efficient well-practiced motion. This sounds to me a lot like reorganization to control the perception of the overall task at a higher perceptual level than the control of the various joint movements individually. Synergy, then, seems to be the name they’re giving to control at higher levels of perception.
They quantify the “synergy�? by comparing the degrees of freedom for the various joint motions before and after a task is practiced. With more practice, their measurement of the degrees of freedom drops as the motions get smoother and more predictable.
The experiment in this article follows up on an experiment in which the same kind of task was done by single individuals holding the target in one hand and the pointer in the other. According to the authors of that article, as people got more practiced in this task (reorganized, I would say, to develop higher levels of perception) their arms independently showed more synergistic motions, and the two arms together showed an even greater improvement in synergy as they learned to “reciprocally compensate�? for each other.
Although the authors of the Romero article don’t directly compare their data for pairs of individuals working together to the data from this earlier article on single individuals, they report that their data follows a similar pattern. Higher level synergy seems to be occurring at the interpersonal level (just as if the two people have mutually reorganized to jointly control the same perception).
All this sounds a lot like collective control to me, and not just a matter of the two people disturbing each other, as Martin suggests. The pairs of subjects in the experiment had to do 300 trials of this target-hitting task, and the authors compared the first 15 trials for each pair to the last 15. Data from the first trials looks pretty highly variable, as it would be if people were just disturbing each other. Data from the last trials is much smoother, with the pointer moving efficiently to the target, which seems to me like the collective control of a shared perception and reference for the task. (It would have been interesting if they had asked pairs to trade roles at some point in the experiment.)
I found it interesting that the authors of this article use the word “control�? a lot, to refer to what the individual does, although they don’t indicate that they understand that this control is of perceptions, not physical actions. They also talk about the target and the pointer being “stabilized.�? In my own writing, I’ve found it to be convenient to make the same distinction between “control�? to refer to the behavioral process and “stabilize�? to refer to the physical consequences in the environment.
One indication of their different point of view from PCT is the authors’ description of the task as “discrete�? not “continuous�? even though it involves continuous motion from beginning to end. They’re still working in the old style mindset that behavior can somehow be chunked into discrete pieces.
But overall, this experiment, which comes out of the “embodied, embedded�? modern movement in biology and psych, has a lot of overlap with the PCT viewpoint and seems consistent with it, once you switch the vocabulary.
Kent
···
On Oct 13, 2016, at 3:33 PM, Martin Taylor <mmt-csg@mmtaylor.net> wrote:
[Martin Taylor 2016.10.13.15.49]
On 2016/10/13 12:06 PM, Warren Mansell wrote:
Comments vis a vis collective control....
Having read the report, all I can say about it is that both persons probably were controlling a perception of the relative distance between probe (stick tip) and target (disc), as they were asked to do.
The "synergy" exists because each one's motion acts as a disturbance to the other's controlled perception of relative distance, so it is compensated by the other's motion. If only one had been controlling a perception of the probe-disc distance, and the other had been controlling for placing either the disc or the probe at a particular place in space, there would have been no synergy as they define it. (It's not what I would have called "synergy", but they used the word.)
Martin
[From Rick Marken (2016.10.13.1650)]
···
On Thu, Oct 13, 2016 at 9:06 AM, Warren Mansell wmansell@gmail.com wrote:
WM: Comments vis a vis collective control…
RM: This looks to me like two people controlling for intercepting objects at the tips of each other’s hands. So my guess is that a model of the results could be very easily done; just put some PCT models out in the sun and combine them down on highway 61.
RM: Actually, if I can escape my alter ego for a moment (my son said he thinks I might actually be Bob Dylan, after all, he’s never seen the two of us in the same room together) I think the behavior in this experiment can be modeled by combining Bill’s arm model with my object interception model. Both people would be controlling the optical velocity of the object on the end of the other person’s hand; they would be doing that by varying the position of their own hand, which is attached to their wrist, elbow and shoulder; the movement of those components would be handled by Bill’s model of arm movement in the “Arm Control Reorganization” demo. Given that Bruce A. translated this demo into C I think he’s just the guy who can create this model. I bet such a model could account for all the results presented in the target article.
Best
Rick
–
Richard S. Marken
“The childhood of the human race is far from over. We
have a long way to go before most people will understand that what they do for
others is just as important to their well-being as what they do for
themselves.” – William T. Powers
[Martin Taylor 2016.10.13.23.20]
From Kent McClelland (2016.10.13.1410)
Martin Taylor 2016.10.13.15.49
I read the article that Warren sent, too, and my take on it is not quite the same as Martin’s. It seems to me that the results the authors report are consistent with the idea of cooperative or coordinated collective control, as we have been developing it from the PCT perspective.
Absolutely!
I don't think we have different takes on the experiment so much as we concentrated on different aspects of it. The situation is exactly what Kent described in his CSG'93 presentation
<http://www.mmtaylor.net/PCT/Movie/McClelland_CSG93.mp4> when the two parties agree on a reference value. If instead the disc-holder had decided on a reference value that the target disc and the probe tip should be separated by 10 cm, while the probe-holder had a reference value for them to touch, the situation would be Kent's conflicted collective control. Kent identifies the collective control aspect, while I concentrated on the "RC" (Reciprocal Compensation) and "DC" (Dimensional Compression) aspects that the authors were studying. "RC" is the direct effect of control -- the output opposing the disturbance--, while "DC" is the result of controlling one higher-level variable that is a function of the two variables you are measuring.
(The title of the article is "Can Discrete Joint Action Be Synergistic? Studying the Stabilization of Interpersonal Hand Coordination.�?)
This article by Romero et al. (2015) describes a lab experiment in which pairs of subjects were seated next to each other and asked to complete multiple trials of a tracking task, in which one individual holds a small disc-shaped target in his left hand while the other has a pointer in her right hand.
The task starts with the two individuals holding the pointer and target at arms length away from each other, and their goal is to bring target and pointer to the middle in front of them in the same plane and touch the pointer to the target. Their shoulders are immobilized by restraints to prevent any torso movement, and the angles of their shoulder, elbow, and wrist movements are recorded (from above), as well as the time it takes to match pointer to target. The target and pointer are taped to the the individuals’ hands to insure that they don’t change their grips on them during the experiment.
What the results of the experiment show, according to the authors, is that "the motor actions performed by coactors were synergistically organized at both the interpersonal and intrapersonal levels. More importantly, however, the interpersonal synergy was found to be significantly stronger than the intrapersonal synergies.�? What does this mean? It hinges on how they’re defining synergy.
The literature referred to in the article talks about “nested synergies�? in motor control where the movements of various joints of the body are organized and coordinated so that they don’t move independently but together perform a complex task with a smooth, efficient well-practiced motion. This sounds to me a lot like reorganization to control the perception of the overall task at a higher perceptual level than the control of the various joint movements individually. Synergy, then, seems to be the name they’re giving to control at higher levels of perception.
I would reword this to say that "synergy" is a name they give to a statistical effect that from a PCT standpoint is the obvious result to be expected from control at successively higher levels of perception.
They quantify the “synergy�? by comparing the degrees of freedom for the various joint motions before and after a task is practiced. With more practice, their measurement of the degrees of freedom drops as the motions get smoother and more predictable.
The experiment in this article follows up on an experiment in which the same kind of task was done by single individuals holding the target in one hand and the pointer in the other. According to the authors of that article, as people got more practiced in this task (reorganized, I would say, to develop higher levels of perception) their arms independently showed more synergistic motions, and the two arms together showed an even greater improvement in synergy as they learned to “reciprocally compensate�? for each other.
Although the authors of the Romero article don’t directly compare their data for pairs of individuals working together to the data from this earlier article on single individuals, they report that their data follows a similar pattern. Higher level synergy seems to be occurring at the interpersonal level (just as if the two people have mutually reorganized to jointly control the same perception).
All this sounds a lot like collective control to me, and not just a matter of the two people disturbing each other, as Martin suggests.
But this kind of collective control is exactly two people reciprocally disturbing each other's controlled perception of the same thing. It's not "just a matter of" but a different view of the same process, a view that is useful in this case because it directly accounts for their "RC" measure, whereas the collective control view obscures "RC" as an unmentioned part of the collective control machinery.
The pairs of subjects in the experiment had to do 300 trials of this target-hitting task, and the authors compared the first 15 trials for each pair to the last 15. Data from the first trials looks pretty highly variable, as it would be if people were just disturbing each other. Data from the last trials is much smoother, with the pointer moving efficiently to the target, which seems to me like the collective control of a shared perception and reference for the task. (It would have been interesting if they had asked pairs to trade roles at some point in the experiment.)
I found it interesting that the authors of this article use the word “control�? a lot, to refer to what the individual does, although they don’t indicate that they understand that this control is of perceptions, not physical actions. They also talk about the target and the pointer being “stabilized.�? In my own writing, I’ve found it to be convenient to make the same distinction between “control�? to refer to the behavioral process and “stabilize�? to refer to the physical consequences in the environment.
One indication of their different point of view from PCT is the authors’ description of the task as “discrete�? not “continuous�? even though it involves continuous motion from beginning to end. They’re still working in the old style mindset that behavior can somehow be chunked into discrete pieces.
I didn't understand their reference to "discrete" unless it meant two discrete brains doing the job instead of one continuous brain. If it wasn't that, I don't know where they apply the word.
But overall, this experiment, which comes out of the “embodied, embedded�? modern movement in biology and psych, has a lot of overlap with the PCT viewpoint and seems consistent with it, once you switch the vocabulary.
Oh, I think it's a lot more than vocabulary. You are too generous! They are providing just a statistical description of observable actions, and doing what Bill P often inveighed against -- claiming that you have a mechanism because you can apply a word to the result you find. He called it the "dormitive principle": you slepp because you have a lot of the dormitive principle. You have a lot of the dormitive principle and hence you sleep. We have therefore explained sleep. In this case, by saying "synergy" as if it were some kind of principle rather than a statistical result of whatever might be responsible, they seem to think they have solved something (and a publisher allowed them to say so).
However, and this is something I wrote and then deleted from my earlier message, It is possible that the various "synergies" could provide suggestions as to some higher-level controlled perceptions that are not easily attacked by the TCV, such as a perception that might be a combination of the tensions in the muscles of the upper arm and forearm. It could be another tool in the PCT armoury. And then again, it might not.
Martin
···
Kent
On Oct 13, 2016, at 3:33 PM, Martin Taylor <mmt-csg@mmtaylor.net> wrote:
[Martin Taylor 2016.10.13.15.49]
On 2016/10/13 12:06 PM, Warren Mansell wrote:
Comments vis a vis collective control....
Having read the report, all I can say about it is that both persons probably were controlling a perception of the relative distance between probe (stick tip) and target (disc), as they were asked to do.
The "synergy" exists because each one's motion acts as a disturbance to the other's controlled perception of relative distance, so it is compensated by the other's motion. If only one had been controlling a perception of the probe-disc distance, and the other had been controlling for placing either the disc or the probe at a particular place in space, there would have been no synergy as they define it. (It's not what I would have called "synergy", but they used the word.)
Martin
Agreed. So it looks like a finding and a phenomenon desperately in need of an architecture to enact it.... PCT...
···
On 13 Oct 2016, at 21:33, Martin Taylor <mmt-csg@mmtaylor.net> wrote:
[Martin Taylor 2016.10.13.15.49]
On 2016/10/13 12:06 PM, Warren Mansell wrote:
Comments vis a vis collective control....Having read the report, all I can say about it is that both persons probably were controlling a perception of the relative distance between probe (stick tip) and target (disc), as they were asked to do.
The "synergy" exists because each one's motion acts as a disturbance to the other's controlled perception of relative distance, so it is compensated by the other's motion. If only one had been controlling a perception of the probe-disc distance, and the other had been controlling for placing either the disc or the probe at a particular place in space, there would have been no synergy as they define it. (It's not what I would have called "synergy", but they used the word.)
Martin
Thanks Rick, Martin, Kent. What is fascinating is that the authors don’t appear to feel the need to build any kind of working model of their findings. Surely that’s the only way to test a theory robustly? The potential of a PCT model is exciting…
Warren
···
On Thu, Oct 13, 2016 at 9:06 AM, Warren Mansell wmansell@gmail.com wrote:
WM: Comments vis a vis collectiv
e control…
RM: This looks to me like two people controlling for intercepting objects at the tips of each other’s hands. So my guess is that a model of the results could be very easily done; just put some PCT models out in the sun and combine them down on highway 61.
RM: Actually, if I can escape my alter ego for a moment (my son said he thinks I might actually be Bob Dylan, after all, he’s never seen the two of us in the same room together) I think the behavior in this experiment can be modeled by combining Bill’s arm model with my object interception model. Both people would be controlling the optical velocity of the object on the end of the other person’s hand; they would be doing that by varying the position of their own hand, which is attached to their wrist, elbow and shoulder; the movement of those components would be handled by Bill’s model of arm movement in the “Arm Control Reorganizat
ion” demo. Given that Bruce A. translated this demo into C I think he’s just the guy who can create this model. I bet such a model could account for all the results presented in the target article.
Best
Rick
–
Richard S. Marken
“The childhood of the human race is far from over. We
have a long way to go before most people will understand that what they do for
others is just as important to their well-being as what they do for
themselves.” – William T. Powers