Bill, you are always kind to reply patiently
[From Bill Powers (2007.07.20.0855 MDT)]
I particularly like the interpretation of “what the frog’s eye tells the frog’s brain” (the title of a famous old paper):
**What the Frog’s Eye Tells the Frog’s Brain.
** Lettvin, J.Y., Maturana, H.R., McCulloch, W.S., & Pitts, W.H. (1959)
Proceedings of the IRE, Vol. 47, No. 11, pp. 1940-51.These are some famous names in cybernetics.
This is a very useful reference, and a new entry of this field for me. From those articles cite it, I think something similar to my work could be found.
It’s pretty clear that the frog can’t
reorganize its outputs (or inputs) enough to compensate for reversal of the retinal image. However, I’d like to see experiments that ask if smaller reorganizations are still possible, both at the output and the input. For E. coli reorganization to work, there has to be some fairly smooth path between the initial and final states, so there is always some indication of whether an error is getting larger or smaller. The reversal of the eye may make the gap between starting and ending organizations too large to bridge.
I agree that the reorganization ability is limited. I restrict the output of distances controllers, with an atan function in the “Ball - force mode”, in a plausible region for velocities controllers, so that the reorganization will get a stable result instead of trying to achieve some impossible mission all the time. The discussions about the architecture in the article are based on the assumption that frog’s neurons are as plastic as
human’s. It is possible that the ability of reorgnization is enhanced after tens of thousands of years. I’ll see if there is any study on frog’s brain after the “eyes reversal” or about the frog’s ability to adapt slight change
It may be that “biased random walk reorganization” would be a more informative name for this process. Not many people know that E. coli steers by using a biased random walk.
I misunderstood the meaning of “E. coli reorganization” at first as well.
The fact that these people can do many tasks normally after reorganizing shows, I think, that it is the perceptual side that reorganizes, not the output side. But you conclude that the input side does not reorganize. There are apparently good
argtuments for both statements, so we need to invent some clever experiments. I could argue that if it were the output side that reorganized, each new task would require adaptation before it could be done. If the perceptual system adapts to the sign reversal, the output functions can all remain as they were before because the perceptual signals then behave “normally.” But that’s just logical reasoning; we need some actual demonstrations.
That is the biggest point of this essay. There are three possible ways to reorganize a controller: changing the input side and keeping the output side, changing the output side and preserving the input side or changing both of them at the same time. I never try any experiment on the third one which seems likely to result in chaos. Eliminating the alteration is obviously the easiest way to adapt it. However, the output would become useless if the input is easy to change. It is possible that, internal mechanisms could
satisfy the reference without producing any output, since the reorganization is to seek a method reducing error.
Such explanations are still logically reasonnings and cannot proof the output side is the only one change in the living control systems’ reorganization. I tried to make a demostration by inverting the screen, but that is no more than adding a disturbance on the cursor, since the spatial perception was actually unchanged. Such demos are needed indeed.
In your essay you say
Another question is raised then, how many levels will this alteration influence? Though only two levels, the altered level and the level upon it, are needed to be changed, the reorganization will change all levels above the
altered one. It seems not an efficiency process.This question could be stated more clearly. Do you mean that the alteration also alters the organization of higher levels, or do you mean that it disturbs the perceptions that (unaltered) higher levels are controlling? I think the latter is what you mean. If so, then mere disturbances are not enough to cause reorganization unless the higher systems are unable to counteract the effects of the disturbances. Think of each level reorganizing independently of any other levels, on the basis of its own errors. (I think of “altering” a system as meaning changing its parameters, not just disturbing its variables).
This issue was discussed based on the assumption that only one controller’s perception is altered deliberately. As depicted in Figure 4, organizations of controllers setting references for the altered perceptions are change most. So I wonder, whether the organization of
higher levels would change while the altered controller and its upper one are not effective effectors during the reorganization process.
Figure 2, showing changes in the number of viable neurons, relates to a process called “pruning,” which means cutting branches off bushes and trees. Plum trees, I suppose. I am told that in the baby and infant, there are far more neural connections than in older children and adults; reorganizing seems to be in part a process of eliminating useless or wrong connections. David Goldstein told me about that – maybe he can expand on this and give you some references. My reorganization demonstrations start out with potential connections of all control systems to all possible controlled variables. Reorganization gradually strengthens the “good” connections and
removes the “bad” ones, not by “pruning” but by reducing the weights close to zero, which has about the same effect.
I see. On the other hand, I did not mention in the essay, the counterpart of the ventral root, the dorsal root which in charge of inputs, experiences a totally different development in the frog’s growth. Accompanies with the increment of the frog’s skin, the number of viable receptors keeps increasing.
It’s a nice paper, and I will make sure it’s seen at the CSG meeting next week. This much could be published as an introductory study, but clearly there is a very large area opening up here for exploring reorganization of control systems. This might keep you busy for some years to come! I don’t know of anyone else doing work like this, so you are a
pioneer.Best,
Bill P.
Thank you! I’m happy for I have something to contribute to the group. To a new field, efforts are worthy
Best regards,
Bo