Behavior: The Control of Perception – Bill Powers rediscovered, again!

I decided to cruise by Slate Star Codex and saw a post with the title, What Intellectual Progress did I Make in the 2010S? Sounds ambitious, thought I do myself. [Hmmm...should I write such a post? Umm, err, I think not.*] This, the second paragraph, stopped me dead in my tracks:

I think the single most important thing I discovered this decade (due to a random comment in the SSC subreddit!) was the predictive coding theory of the brain. I started groping towards it (without knowing what I was looking for) in Mysticism And Pattern-Matching, reported the exact moment when I found it in It’s Bayes All The Way Up, and finally got a decent understanding of it after reading Surfing Uncertainty. At the same time, thanks to some other helpful tips from other rationalists, I discovered Behavior: The Control Of Perception, and with some help from Vaniver and a few other people was able to realize how these two overarching theories were basically the same. Discovering this area of research may be the best thing that happened to me the second half of this decade (sorry, everyone I dated, you were pretty good too).

It’s that reference to Behavior: The Control Of Perception, that caught my eye. It was published in 1973 by William Powers, positively reviewed a couple years later in Science, and had been central to the work that I’d done with David Hays in his computational linguistics research group at SUNY Buffalo in the mid-1970s. Back when I listed the ten books that had most influenced my thinking, that was one of them. [Note: I’ve got a number of posts about or at least mentioning Powers.]

But, for some reason, Powers’s thought never really caught on – though I note, in passing, that Ted Cloak, another forgotten thinker, also found his work valuable. By the mid-1980s or so a small group of thinkers had coalesced around him and began holding annual meetings. I never attended any of those, though I joined a mailing list for the group, and I presented with them at some meetings of the American Society for Cybernetics. Powers died in 2013, but I assume that group still meets.

Given that Powers has had relatively little influence, are those of us who HAVE been influenced by him wrong? I suppose that I’m not exactly in a position to offer up a defense, but I do find it interesting that Scott Alexander, proprietor of Slate Star Codex, should put his book front and center in his review of his intellectual decade. He prefaces his review Powers' book with a disclaimer (his italics): “Epistemic status: I only partly understood this book and am trying to review it anyway as best I can.” In the course of his review he expresses major doubts about aspects of Powers’s model. And the review ends in a string of questions without answers:

How useful is this book? I guess that depends on how metaphorical you want to be. Is the brain a control system? I don’t know. Are police a control system trying to control crime? Are police a “response” to the “stimulus” of crime? Is a stimulus-response pairing a control system controlling for the quantity of always making sure the stimulus has the response? I think it’s interesting and helpful to think of some psychological functions with these metaphors. But I’m not sure where to go from there.

That’s a mountain of doubt. And yet somehow that abstract, elegant, and elusive book moved the mountain.

I can understand Alexander’s reservations. When Hays, his other students, and I worked it over, we discarded and/or reworked major portions of the model. But despite that we kept the overall outline, including, believe it or not, his comments about consciousness and reorganization. In a way, especially those.

It’s that overall outline – though outline is an inadequate word, gestalt is perhaps better – that made it so attractive for us. It was and is a biologically grounded model of the mind based on classical control theory engineering – feedback loops, etc. It also assigned a coherent function to consciousness, Powers called it reorganization, but to appreciate the weight and valence of that them, you have to think about his whole model.

That it was based in cybernetics is perhaps why it never found favor. But the time Powers had published the book the so-called cognitive revolution was going into over drive. All the cool kids were thinking about digital computers, while Powers was thinking analog. Of course, we knew all that. Hays had been a first generation researcher in machine translation and, as such, one of the founders of computational linguistics. Our research group was ABOUT computational linguistics. But we, like so many others, were reaching for the mind. And we had decided/realized that computation alone wouldn’t get us there. So we took the gestalt that Powers had created and opened it up to include language, symbolic computation, in a more realistic way [see David Hays, Cognitive Structures, HRAF Press, 1981]. Powers kept us grounded in biology, we opened him up to language. That’s the line we took.

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Here’s a passage from Scott Alexander’s review of Behavior: The Control of Perception:

While I was driving on the highway a few weeks ago, I realized how much of what I do is perceptual control. For example, I was effortlessly maintaining the right distance from the car in front of me. If the car sped up a tiny bit, I would speed up a tiny bit. If the car slowed down a little bit, I would slow down a little bit. Likewise, I was maintaining the right angle relative to the road: if I found myself veering right, I would turn slightly to the left; if I found myself veering left, I would turn slightly to the right.

The theory goes further: while I’m in the car, I’m also operating as my own thermostat. I have a desired temperature: if I go below it, I’ll turn on the heat, and if I go above it, I’ll turn on the AC. I have a desired level of satiety: if I’m hungry, I’ll stop and get something to eat; if I’m too full, there’s maybe not a huge amount I can do but I’ll at least stop eating. I have a desired level of light: if it’s too dark, I’ll turn on the lights; if it’s too bright I’ll put down the sun visor. I even have a desired angle to be sitting at: if I’m too far forward, I’ll relax and lean back a little bit; if I’m too far back, I’ll move forwards. All of this is so easy and automatic that I never think about it.

Powers’ theories go further. He agrees that my brain sets up a control system to keep my car the proper distance from the car in front of it. But how do I determine “the proper distance”? That quantity must be fed to the system by other parts of my brain. For example, suppose that the roads are icy and I know my brakes don’t work very well in the ice; I might keep a much further distance than usual. I’ll still be controlling the distance, I’ll just be controlling it differently. If the brain is control systems all the way down, we can imagine a higher-tier system controlling “accident risk” at some level (presumably low, or zero) feeding a distance level into a lower-tier system controlling car distance at whatever level it receives. We can even imagine higher systems than this. Suppose I’m depressed, I’ve become suicidal, I want to die in a car accident, but in order not to scandalize my family I have to let the accident happen sort of naturally. I have a top-level system controlling “desire to die” which tells a middle-level system controlling “accident risk” what level it should go at (high), which in turn tells a lower-tier system controlling “car distance” what level it should go at (very close).

It doesn’t even end there. My system controlling “car distance” is sending signals to a lower-tier system controlling muscle tension on my foot on the accelerator, giving it a new reference level (contracted muscles that push down on the accelerator really hard). Except this is an oversimplification, because everything that has to do with muscles is a million times more complicated than any reasonable person would think (at least until they play qwop) and so there’s actually a big hierarchy of control systems just going from “want to go faster” to “successfully tense accelerator-related muscles”.

And another:

Why do I like this theory so much? First, it correctly notes that (almost) the only thing the brain can actually do is change muscle tension. Yet we never think in terms of muscle tension. We don’t think “I am going to tense my thigh muscle, now untense it, now tense my ankle muscle, now…”, we just think “I’m going to walk”. Heck, half the time we don’t even think that, we think “I’m just going to go to the fridge” and the walking happens automatically. On the other hand, if we really want, we can consciously change our position, the level of tension in a certain muscle, etc. It’s just that usually we deal in higher-level abstractions that automatically carry all the lower ones along with them.

Second, it explains the structure of the brain in a way I haven’t seen other things do. I always hear neuroscientists talk about “this nucleus relays signals to that nucleus” or “this structure is a way station for this other structure”. Spend too much time reading that kind of stuff, and you start to think of the brain as a giant relay race, where the medulla passes signals onto the thalamus which passes it to the basal ganglia which passes it to the frontal lobe and then, suddenly, thought! The obvious question there is “why do you have so many structures that just relay things to other structures?” Sometimes neuroscientists will say “Well, some processing gets done here”, or even better “Well, this system modulates that system”, but they’re always very vague on what exactly that means. Powers’ hierarchy of fifth-tier systems passing their calculations on to fourth-tier systems and so on is exactly the sort of thing that would make sense of all this relaying. My guess is every theory of neuroscience has something at least this smart, but I’d never heard it explained this well before.

Third, it’s the clearest explanation of tremors I’ve ever heard.

I would emphasize that second reason, about explaining the structure of the brain. Alexander is right to be skeptical about the standard lingo used in talking about the brain as sending signals all over the place.

Compare Alexander’s paragraph with a passage from Sydney Lamb’s Pathways to the Brain (p. 1):

Some years ago I asked one of my daughters, as she sat at the piano, "When you hit that piano key with your finger, how does your mind tell your finger what to do?" She thought for a moment, her face brightening with the intellectual challenge, and said, "Well, my brain writes a little note and sends it down my arm to my hand, then my hand reads the note and knows what to do." Not too bad for a five-year old.

Lamb goes on to suggest that an awful lot of professional thinking about the brain takes place in such terms (p. 2):

This mode of theorizing is seen in ... statements about such things as lexical semantic retrieval, and in descriptions of mental processes like that of naming what is in a picture, to the effect that the visual information is transmitted from the visual area to a language area where it gets transformed into a phonological representation so that a spoken description of the picture may be produced....It is the theory of the five-year-old expressed in only slightly more sophisticated terms. This mode of talking about operations in the brain is obscuring just those operations we are most intent in understanding, the fundamental processes of the mind.

I agree with Lamb whole-heartedly, and Powers, and Alexander. My impression is that most of the neuroscientific effort goes into getting observations – using some really cool technology, too – but when it comes to thinking about what's going on, the inner child just takes over – and a rather dim one at that.

Lamb then goes on, in the rest of the book, to elaborate an account of language that makes sense of all these signals traveling all over the place. What we did in Buffalo back in the 1970s was, in effect, to take the kind of model Lamb has developed, and insert it into Powers’ model.

Note: Lamb, like Hays, was a first generation researcher in machine translation. They knew one another’s work quite well. My own work has been influenced by both of them.

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*Why not? you ask. Opportunity cost.

Writing such a post, to do it well, would be hours of work spread out over a day or three. It's not at all clear to me that I would learn much in the process nor is it obvious that such a post would be of much value to you, my readers. The time I'd spend writing such a post is time I could be doing other things, things more valuable to me, and possibly to you as well. But perhaps a quick a dirty review, a ramble, that might be of value. We'll see.