A correction: LeDoux’s actual views on instrumental learning in vertebrates

I have to make a correction.  In my post on LeDoux’s views on consciousness and emotions, I made the following statement:

Anyway, LeDoux states that there is “no convincing” evidence for instrumental behavior in pre-mammalian vertebrates, or in invertebrates.  In his view, instrumental behavior only exists in mammals and birds.

As it turns out, this is is wrong.  In his hierarchy, he makes a distinction between instrumental learning that is habitual versus goal-oriented (action-outcome).  On my first pass reading his description of this, I assumed that a habit could only form after initial goal-oriented learning.  But while checking back on some details, I realized he actually describes learning that leads directly to habits without the goal-oriented stage.

In practice, an animal may engage in random trial and error behavior, some of which leads to a result that reinforces the behavior.  If repeated often enough, a habit develops.  Habitual learning can be distinguished from goal-oriented behavior by seeing what happens when the reward is later removed.  In goal-oriented behavior, the behavior quickly ends, but habits tend to persist for a while.  (Which of course is what a habit is all about.)

Habitual learning is much slower than the goal-oriented version, much more stimulus-response driven, far less flexible, but apparently it does happen.  I’ve dug around a bit in the literature, and it appears to be widely accepted.

So to correct the statement above, LeDoux does see instrumental learning as existing in all vertebrates, not just mammals and birds.  However, it is the goal-oriented learning he doesn’t see as having been demonstrated in pre-mammalian vertebrates.  Fish, amphibians, and reptiles he sees as only having the habit forming version.

I’m not sure what to make of this habitual type of instrumental learning.  Habits by and large appear to be largely nonconscious, so would learning them be as well?  Of course, LeDoux doesn’t even see goal-oriented instrumental learning as conscious, so in his view this distinction only amounts to different levels of sophistication in nonconscious learning.

As I mentioned in the other post, Feinberg and Mallatt, in The Ancient Origins of Consciousness, do see instrumental learning as indicating what they call affect consciousness, aka sentience.  And the indications of instrumental learning in all vertebrates drive their conclusion that all vertebrates are sentient.

But Feinberg and Mallatt don’t get into the distinction between habit and goal-oriented instrumental learning.  So I don’t know if this is a difference they overlooked, disagree with, or accept but see even the habit learning version as indicating affect consciousness.  A clue might be that, when deciding on their behavioral criteria for affect consciousness, they ruled out “persistence in pursuit of reward” as a criteria, because it “could reflect aroused but unconscious habits.”  (Emphasis added.)

A case could be made that even in habit learning, if not in habit persistence, there needs to be a valence, but both LeDoux and the literature make clear this happens in a representation or model free manner, which may not leave much room for it to fall even in primary consciousness.

A question then is, can goal oriented behavior be demonstrated in fish, amphibians, reptiles, or invertebrates?  LeDoux doesn’t think so, and notes that habit and goal-oriented behavior look alike without explicit tests to distinguish them, although maybe the rapidity of learning might provide clues.

So, this may complicate my new hierarchy, particularly the level where affects begin.  I’m going to have to give this some thought, and additional research, but wanted to get  the correction out.

Joseph LeDoux’s theories on consciousness and emotions

The cover of 'The Deep History of Ourselves'In the last post, I mentioned that I was reading Joseph LeDoux’s new book, The Deep History of Ourselves: The Four-Billion-Year Story of How We Got Conscious Brains.  There’s a lot of interesting stuff in this book.  As its title implies, it starts early in evolution, providing a lot of information on early life, although I didn’t find that the latter parts of the book, focused on consciousness and emotion, made much use of the information from the early chapters on evolution.  Still, it was fascinating reading and I learned a lot.

In the Nautilus piece I shared before, LeDoux expressed some skepticism about animal consciousness being like ours.  That seems to be a somewhat milder stance compared to the one in the book.  Here, LeDoux seems, at best, on the skeptical side of agnostic toward non-human animal consciousness.  The only evidence for consciousness he sees as unequivocal is self report, which of course only humans can provide.

In terms of consciousness theories, LeDoux regards Higher Order Theories (HOT) and Global Workspace Theories (GWT) as the most promising, but his money is on HOT, and he provides his own proposed theoretical extensions to it.  HOT posits that consciousness doesn’t lie in the first order representations made in early sensory regions, but in later stage representations that are about these first order ones.  In essence, to be conscious of a representation requires another higher order representation.

In typical HOT, these higher order representations are thought to be in the prefrontal cortex.  LeDoux attributes a lot of functionality to the prefrontal cortex, more than most neuroscientists.  Some of what he attributes I’ve more commonly seen attributed to regions like the parietal cortex.  But he presents information on the connections between various cortical and subcortical regions to the prefrontal cortex to back up his positions.

In the last post, I laid out the hierarchy I usually use to think of cognitive capabilities.  LeDoux has a similar hierarchy, which he discusses in a paper available online, although his is focused on types of behavior.  Going from simpler to more sophisticated:

  1. Species typical innate behavior
    1. Reflexes: Relatively simply survival circuits, centered on the brainstem regions
    2. Fixed Reaction Patterns: More complex survival circuits, often going through subcortical regions such as the amygdala
  2. Instrumental learned behavior
    1. Habits: Actions that persist despite lack of evidence of a good or bad consequence
    2. Action-outcome behaviors: Actions based on the remembered outcomes of past trial-and-error learning
    3. Nonconscious deliberative actions: Actions taken based on prospective predictions made on future outcomes
    4. Conscious deliberative actions: Deliberative actions accompanied and informed by conscious feeling states

On first review, I was unsure about the distinction between action-outcome and deliberative action.  Action-outcome seems like simply a less sophisticated version of deliberative action, particularly since episodic memory and imagined future scenarios are reputed to use the same neural machinery.  It seemed like just different degrees of what I normally label as imaginative planning.

But on further consideration, I can see a case that simply remembering a past pattern of activity and recognizing the same sequence, is not the same thing as simulating new hypothetical scenarios, specific scenarios that the animal has never experienced before.  Put another way, deliberative actions require taking multiple past scenarios and combining them in creative new ways.

Anyway, LeDoux states that there is “no convincing” evidence for instrumental behavior in pre-mammalian vertebrates, or in invertebrates.  In his view, instrumental behavior only exists in mammals and birds.

(This seems to contrast sharply with Feinberg and Mallatt in The Ancient Origins of Consciousness, who cite numerous studies showing instrumental learning in fish, amphibians, and reptiles.  One of the things I’m not wild about LeDoux’s book, is that while he has bibliographic notes, they’re not in-body citations,  making it very difficult to review the sources of his conclusions.)

Deliberative action, on the other hand, LeDoux only sees existing in primates, with humans taking it to a new level.  Apparently in this hierarchy, consciousness only comes into the picture with the most sophisticated version.  I think “consciousness” in this particular context means autonoetic consciousness, that is, introspective self awareness with episodic memory.

(Endel Tulving, the scientist who proposed the concept of autonoesis, doesn’t see episodic memory developing until humans.  However, there is compelling behavioral evidence that it developed much earlier, and is in, at least, all mammals and birds,  although it’s admittedly far more developed in humans.)

On emotions, LeDoux starts by bemoaning the terminological mess that exists any time emotions are discussed.  He reserves the word “emotion” for conscious feelings, and resists its application to the lower level survival circuitry, which he sees as non-conscious.  He points out that a lot of published results which claim to show things such as fear in flies, are actually just showing survival circuit functionality.  He sees survival circuits as very ancient, going back to the earliest life forms, but emotions as relatively new, only existing in humans.

In LeDoux’s view, emotions, the conscious feelings, are cognitive constructions in the prefrontal cortex, predictions based on signals from the lower level survival circuitry, reinforced by interoceptive signals from the physiological changes that the lower level circuitry initiate: changes in blood pressure, heart rate, breathing, stomach muscle clenching, etc.

LeDoux’s views are similar to Lisa Feldmann Barrett’s constructive emotions theory, and contrast with views such as Jaak Panksepp, who saw consciously felt emotion in the lowest level survival circuits.  Barrett also sees emotions only existing in humans, although she makes allowances for animals to have affects, simpler more primal valenced feelings such as hunger, pain, etc.  I’m not sure what LeDoux’s position is on affects.  He doesn’t mention them in this book.

My views on all this is that I think LeDoux is too skeptical of animal consciousness.  It doesn’t seem like a human without language could pass his criteria.  However, as always, this may come down to which definition of “consciousness” we’re discussing.  Human level consciousness includes introspective self awareness and far wider ranging imagination, enabled by symbolic thought such as language, than exist in any other species.  If we set that as the minimum, then only humans are conscious, but many will see that as too stringent.  In particular, I think a case could be made that it’s far too stringent for sentience.

On emotion, I do think LeDoux is right that the lower level survival circuitry, the reflexes and fixed reaction patterns in subcortical regions, shouldn’t be thought of as feeling states.  This means we shouldn’t take defensive behaviors in simpler animals as evidence for fear, or aggressive behavior as evidence for anger.

On the other hand, I think he’s wrong that feeling states don’t come around until sophisticated deliberative processing.  It seems like any goal-directed instrumental behavior, such as selecting an action for a particular outcome, requires that there be some preference for that outcome, some valence, input from the lower level survival circuits to the higher level ones that decide whether to pursue a goal or avoid an outcome.

This might be far simpler than what humans feel, perhaps only meeting Barrett’s sense of an affect rather than what Barrett and LeDoux see as the full constructed emotion, but they should be felt states nonetheless.  By LeDoux’s own criteria, that would include any animal capable of instrumental behavior, including mammals and birds.  Admittedly, there’s no guarantee these felt states are conscious ones, but again, definitions.

Comparing LeDoux’s book to Feinberg and Mallatt’s, I’m struck by how much of the disagreement actually does come down to definitions.  The real differences, such as which species are capable of operant / instrumental learning, seem like they will eventually be resolvable empirically.  The differences on consciousness, may always be a matter of philosophical debate.

What do you think of LeDoux’s various stances?

Update 9-11-19: The statement above about LeDoux seeing instrumental learning only in mammals and birds isn’t right.  Please see the correction post.

The problem of animal minds

Joseph LeDoux has an article at Nautilus on The Tricky Problem with Other Minds.  It’s an excerpt from his new book, which I’m currently reading.  For an idea of the main thesis:

The fact that animals can only respond nonverbally means there is no contrasting class of response that can be used to distinguish conscious from non-conscious processes. Elegant studies show that findings based on non-verbal responses in research on episodic memory, mental time travel, theory of mind, and subjective self-awareness in animals typically do not qualify as compelling evidence for conscious control of behavior. Such results are better accounted in “leaner” terms; that is, by non-conscious control processes.22 This does not mean that the animals lacked conscious awareness. It simply means that the results of the studies in question do not support the involvement of consciousness in the control of the behavior tested.

LeDoux makes an important point.  We have to be very careful when observing the behavior of non-human animals.  It’s very easy to see behavior similar to that of humans, and then assume that the same conscious states humans have with that behavior also apply to the animal.

On the other hand, and I’m saying this as someone who hasn’t yet finished his book, I think LeDoux might downplay the results in animal research a bit too much.  It does seem possible to identify behavior in humans that requires consciousness, such as dealing with novel situations, making value trade-off decisions, or overriding impulses, and then deduce that the equivalent behavior in animals also requires it.

But LeDoux makes an excellent point.  There are wide variances in what we can mean by the word “consciousness”.  In particular, he discusses a distinction between noetic and autonoetic consciousness.  Noetic consciousness appears to be consciousness of the environment and of one’s body.  Autonoetic appears to be consciousness of one’s mental thoughts.  He describes the autonoetic variety as providing the capability of mental time travel.

I’m not sure about this distinction, but in many ways it seems similar to the distinction between primary consciousness and metacognitive self awareness.  This always brings to mind a hierarchy I use to think about the various capabilities and stages:

  1.  Reflexes: fixed action patterns, automatic responses to stimuli.
  2. Perceptions: predictive models of the environment built with sensory input, expanding the scope of what the reflexes can react to.
  3. Attention: prioritization of what the reflexes react to, including bottom up attention: reflexive prioritization, and top down attention: prioritization from the next layer.
  4. Imagination / sentience: sensory action scenarios to resolve conflicts among reflexes, resulting in some being allowed and others inhibited.  It is here where reflexes become feelings, dispositions to act rather than automatic action.
  5. Metacognition: awareness and assessment of one’s own cognition, enabling metacognitive self awareness, symbolic thought such as language, and human level intelligence.

Noetic consciousness (if I’m understanding the term correctly) would seem to require 1-4.  Autonoetic might only come around with 5.  Although 4 enables the mental time travel LeDoux discusses, so this match may not be a clean one.  If I end up buying into the noetic vs autonoetic distinction, I might have to split 4 up.

But LeDoux’s point is that behavior precedes consciousness, and that’s easy to see using the hierarchy.  Unicellular organisms are able to engage in approach and avoidance behavior with only 1, reflexes.  The others only come much later in evolution.  It’s easy to see behavior driven by the lower levels and project the full hierarchy on them, because it’s what we have.

All of which is to say, that I think LeDoux is right that arguing about whether animals or conscious or not, as though consciousness is something they either have or don’t have, isn’t meaningful.  The real question is how conscious are they and what the nature of that consciousness is.

It’s natural to assume it’s the same as ours.  It’s part of the built in empathetic machinery we have as a social species.  But just because anthropomorphism is natural, doesn’t mean it’s right.  Science demands we be more skeptical.

Unless of course I’m missing something?