Predictions and retrodictions

I’ve often noted here the importance of predictions, both in terms of our primal understanding of reality, such as how to get to the refrigerator in your house, or in terms of scientific theories.  In truth, every understanding of reality involves predictions.  Arguably a fundamental aspect of consciousness is prediction.

Of course, not every notion involves testable predictions.  That’s often what is said separates science from metaphysics.  For example, various religions argue that we’ll have an afterlife.  These are predictions, just not ones that we’ll ever be able to test.  (Short of dying.)

But the border between science and metaphysics (or other forms of philosophy) is far blurrier than any simple rule of thumb can capture.  Every scientific theory has a metaphysical component.  (See the problem of induction.)  And today’s metaphysics may be tomorrow’s science.  Theories are often a complex mix of testable and untestable assertions, with the untestable sometimes being ferociously controversial.

Anyway, Sabine Hossenfelder recently did a post arguing that scientific predictions are overrated.  After giving some examples (somewhat contrived) where meaningless predictions were made, and a discussion about unnecessary assumptions in poor theories, she makes this point:

To decide whether a scientific theory is any good what matters is only its explanatory power. Explanatory power measures how much data you can fit from which number of assumptions. The fewer assumption you make and the more data you fit, the higher the explanatory power, and the better the theory.

I think this is definitely true.  But how do we know whether a theory has “explanatory power”, that it “fits the data”?  We need to look at the theory’s mathematics or rules and see what they say about that data.  One way to describe what we’re looking for is… accurate predictions of the data.

Hossenfelder is using the word “prediction” to refer only to assertions about the future, or about other things nobody knows yet.  But within the context of the philosophy of science, that’s a narrow view of the word.  Most of the time, when people talk about scientific predictions, they’re not just talking about predictions of what has yet to be observed, but also predictions of existing observations.

What Hossenfelder is actually saying is that we shouldn’t require a theory to be able to do that narrow version of predict.  It can also do predictions of existing data.  If we want to be pedantic about it, we can call these assertions about existing data retrodictions.

(We could also use “postdiction” but that word has a negative connotation in skeptical literature, referring to mystics falsely claiming to have predicted an event before it happens.)

Indeed, for us to have any trust in a theory’s predictions about the unknown, it first must have a solid track record of making accurate retrodictions, of fitting the existing data.  And to Hossenfelder’s point, if all a theory does make are retrodictions, it still might be providing substantial insight.

There is a danger here of just-so stories, theories which explain the data, but only give an illusion of providing insight.  Hossenfelder’s point about measuring the ratio of assumptions to explanation, essentially of valuing a theory’s parsimony, is somewhat a protection against that.  But as she admits, it’s more complicated than that.

For example, naively using her criteria, the interpretation of quantum mechanics we should all adopt is Everett’s many-worlds interpretation.  It makes fewer assumptions than any other interpretation.  (It’s the consequences, not the assumptions, that people object to.)  But the fact that none of the interpretations currently make unique and testable predictions (or retrodictions) is what should prevent our accepting any particular one as the right one.

So, in general, I think Hossenfelder is right.  I just wish she’d found another way to articulate it.  Because now anytime someone talks about the need for testable predictions, using the language most commonly used to describe both predictions and retrodictions, people are going to cite her post to argue that no such thing is needed.

Devs

I’ve seen the TV show Devs come up in a number of conversations on social media, and several people recommended it.  But it was JamesOfSeattle’s recommendation that finally got me to check it out.  The result was, as usual for a show I really enjoy, a weekend binge.

As the show starts, we find Lily Chan and her boyfriend, Sergei, both working as software engineers at a company called Amaya.  Amaya has cracked quantum computing, apparently the only company to do so, or at least to the extent it has.

The Amaya logo is an image of a little girl, whose picture is on company buses and various other locations.  There is a gigantic statue of the girl on the company campus, with the effect of the girl’s figure towering over the buildings.  (The look ends up being fairly creepy.)

Sergei’s team has a presentation with the company owner, Forrest, and Katie, the head of the company’s super secret project called “Devs.”  Forrest looks like a burnout, but his demeanor is informal and down to earth.

The team presents a simulation of a c-elegans worm.  Their simulation is able to completely predict the worm’s actions several seconds into the future.  Forrest is impressed with their ability to accurately predict the behavior of a living organism.  But when the simulation starts to diverge from the worm’s actual actions at 30 seconds, he asks Sergei to speculate what may be going wrong.  Sergei’s response is that the issue could be sheer complexity, or it might be that the simulation works fully somewhere in the multiverse, just not in this universe.

Forrest replies that he is not a fan of the multiverse, and suggests that Sergei go with the first explanation.  He then privately tells Sergei that he’d like him to transfer to the Devs project.  Sergei is excited and accepts.  However, when he sees the code and learns what the Devs project is actually about, he is first physically sick, then tries to steal some of the code, with horrible results.

Lily, a highly intelligent engineer in her own right who works in the encryption division, is left trying to figure out what happened when Sergei goes missing.

What follows is an exploration of free will, determinism, quantum mechanics, the simulation hypothesis, and many other concepts.  Interpretations of quantum mechanics have an important role in the story.  And we learn that Forrest is more than just “not just a fan” of the multiverse, he is adamantly opposed to it, for reasons that are deeply personal.

The show actually manages to make us care whether the de Broglie-Bohm pilot wave interpretation of quantum mechanics or Everett’s many worlds interpretation is the right one.  And before we’re done, we see someone play out the quantum suicide experiment.

It’s difficult to go into much more detail without getting into spoilers.  Hopefully it’s clear that this is a pretty intelligent and philosophical show.

That said, a few cautions are in order.  First, it has a fair amount of language and violence.  Second, the show takes liberties with scientific accuracy.  I think this tweet from Sean Carroll sums it up best.

Finally, the show ends up taking sides in the quantum interpretation debate.  If you have strong feelings about that, it’s possible you won’t like the answer it lands on.

I’d also add that it has a very Stanley Kubrick sort of feel to it.  Alex Garland, the writer, director, and executive producer, keeps the pace slow and deliberate.  There are long stretches of time where not much happens except mood setting.  But it ends up working.

It’s also worth noting that this isn’t an ongoing series.  It’s a limited miniseries.  It has a definite ending.  (Although I suppose someone could try to do a sequel.)

So, if you’re looking for something thoughtful and fun, albeit dark and tragic at times, it’s worth checking out.

Postdictive perception and the consciousness finish line

(Warning: neuroscience weeds)

Recently I noted that one of the current debates in cognitive science is between those who see phenomenal and access consciousness as separate things, and those who see them as different aspects of the same thing.  Closely related, perhaps actually identical, is the debate between local and global theories of consciousness.

Diagram of the brain showing sensory and motor cortices
Image credit: via Wikipedia: Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436.

Local theories tend to see processing in sensory cortices (visual, auditory, etc) as sufficient for conscious perception of whatever sensory impression they’re processing.  One example is micro-consciousness theory, which holds that processing equals perception.  So formation of a neural image map in sensory cortices equals consciousness of that image.

(A lot of people seem to hold this processing equals perception idea intuitively.  It fits with ideas from people like Jaak Panksepp or Bjorn Merker.)

Another more sophisticated version is Victor Lamme’s local recurrent processing theory, which adds the requirement of recurrent processing in the sensory cortex, processing that involves feed forward signalling as well as feed back signalling in loops.  I discussed local recurrent theory a while back.

Global cognitive theories require that content have large scale effects throughout the brain to become conscious.  Similar to Lamme’s theory, they often see recurrent processing as a prerequisite, but require that it span regions throughout the thalamo-cortical system, either to have wide scale causal effects (global workspace theories) or to reach certain regions (higher order thought theories).

I mentioned that the local vs global debate may be identical to the phenomenal vs access one.  This is primarily because local theories only make sense if phenomenal consciousness is happening in the local sensory cortices independent of access consciousness.  That processing is inherently pre-access, before the content is available for reasoning, action, and report.

The latest shot in this debate is a paper by Matthias Michel and Adrien Doerig, which will be appearing in Mind & Language: A new empirical challenge for local theories of consciousness.

Michel and Doerig look at a type of perception they call “long-lasting postdiction”.  An example of postdiction is when subjects are shown a red disk followed in rapid succession by a green disk 20 ms (milliseconds) later, resulting in perceptual fusion, where the subject perceives a yellow disk.  This is an example of short-lasting postdiction.  In order for the fusion to occur, the red image needs to be processed, and then the green one, and then the two fused.

Short lasting postdiction could represent a problem for micro-consciousness theory, since it results in formation of image maps for each image in rapid succession but not in a way the leads to each being consciously perceived.  (It’s not clear to me this is necessarily true.  I can see maybe the two types of processing simply bleeding into each other.  And see below for one possible response from the micro-consciousness camp.)

Short-lasting postdictions are less of a problem for local recurrent theory, because it takes more time for the recurrent processing to spin up.  (The paper has a quick but fascinating discussion of the time it takes for information to get from the retina to the cortex and then to various regions, along with citations I may have to check out.)

It’s the long-lasting postdictions that are a problem for local recurrence.  The paper discusses images of pairs of vernier lines that are shown to test subjects.  The images are in various positions, changing every 50 ms or so across a period of 170-450 ms, resulting in a perception of the lines moving.

There are variations where one of the vernier lines are skewed slightly, but only on the first image, resulting in the subject perceiving the skew for the entire moving sequence, even though the verniers in the later images are aligned.  Another variation has two images, one early in the sequence and one toward the end, skewed in opposite directions, resulting in the two skewed images being averaged together and the averaged shape being perceived throughout the sequence.

The main takeaway is that the conscious perception of the sequence appears to be formed after the sequence.  Given the relatively lengthy sequence time of up to 450 ms, this is thought to exceed the time it takes for local recurrent processing to happen, and bleeds over into the ignition of global processing, representing a challenge for local recurrent theory.

The authors note that local theorists have two possible outs.  One is to say that, for some reason, the relevant local processing actually doesn’t happen in these sequences.  This would require identifying some other mechanism that unconsciously holds the intermediate images.  The other is to say that the images are phenomenally experienced, but then subsequently replaced in the access stage.  But this would result in phenomenal experience that has no chance of ever being reportable.  (What type of consciousness are we now talking about?)  And it would make local theories extremely difficult to test.

Interestingly, the authors note that the longer time scales may need to be reconciled with the ones in cognitive theories, such as the global neuronal workspace, which identifies 300 ms as a crucial point in conscious perception.  In other words, while this is an issue for local theories, it could be one even for global theories.

All of this reminds me of the phi illusion Daniel Dennett discussed in his book Consciousness Explained.  He describes this illusion in the build up to discussing his own multiple drafts model, a variation of global workspace theory.  Dennett’s variation is that there’s no absolute moment when a perception becomes conscious.  His interpretation of the phi illusion, which seems like another case of postdiction, is that there is no consciousness finish line.  We only recognize that a perception is conscious retroactively, when it achieves “fame in the brain” and influences memory and report.

Anyway, I personally think the main flaw with local theories is that the processing in question is too isolated, too much a fragment of what we think of as an experience, which usually includes at least the sensory perception and a corresponding affective feeling.  The affect part requires that regions far from the sensory cortices become stimulated.  Even if the localists can find an answer to the postdiction issue, I think this broader one will remain.

Unless of course I’m missing something.

COVID-19 Vaccine

Broad Speculations

A week ago I received at COVID-19 vaccine injection as a part of a Phase 1 clinical trial.

Basically this is same vaccine and trial described here except the trial has expanded to include an older age group. I am in a group receiving the highest dose  250 mcg.  In a week I will be tested to antibodies. In a few weeks, I am supposed to receive a booster shot. The vaccine is called  mRNA-1273 and has messenger RNA that is used by the virus to build the spikes it uses to attach to cells. There is no live or dead virus itself in the vaccine so there should be no danger of actually getting COVID-19. This is a Phase 1 trial. That means the objective is to determine if the vaccine is safe and has few or no side effects. It is not to determine the effectiveness of the…

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Subjective report doesn’t support the idea that phenomenal consciousness is separate from access consciousness

One of the current debates in consciousness research is whether phenomenal consciousness is something separate and apart from access consciousness.  Access consciousness (A-consciousness) is generally defined as perceptions being accessible for reasoning, action decisions, and communication.  Phenomenal consciousness (P-consciousness) is seen as raw experience, the “something it is like” aspect of consciousness.

Most researchers accept the conceptual distinction between A-consciousness and P-consciousness.  But for someone in the cognitive-theories camp (global workspace theory, higher order thought, etc), P-consciousness and A-consciousness are actually the same thing.  P-consciousness is a construction of A-consciousness.  Put another way, P-consciousness is A-consciousness from the inside.

However, another camp, lead largely by Ned Block, the philosopher who originally made the A-consciousness / P-consciousness distinction, argues that they are separate ontological things or processes.  The principle argument for this separate existence is the idea that P-consciousness “overflows” A-consciousness, that is, that we have conscious experiences that we don’t have cognitive access to, perceptions that we can’t report on.

Block cites studies where test subjects are briefly shown a dozen letters in three rows of four, but can usually only remember a few of them (typically four) afterward.  However, if the subjects are cued on which row to report on immediately after the image disappears, they can usually report on the four letters of that row successfully.

Block’s interpretation of these results is that the subject is phenomenally conscious of all twelve letters, but can only cognitively access a few for reporting purposes.  He admits that other interpretations are possible.  The subjects may be retrieving information from nonconscious or preconscious content.

However, he notes that subjects typically have the impression that they were conscious of the full field.  Interpretations from other researchers are that the subjects are conscious of either only partial fragments of the field, or are only conscious of the generic existence of the field (the “gist” of it).  Block’s response is that the subjects impression is that they are conscious of the full thing, and that in the absence of contradicting evidence, we should accept their conclusion.

Here we come to the subject of a new paper in Mind & Language: Is the phenomenological overflow argument really supported by subjective reports?  (Warning: paywall.)  The authors set out to test Block’s assertion that subjects do actually think they’re conscious of the whole field in full detail.  They start out by following the citation trail for Block’s assertion, and discover that it’s ultimately based on anecdotal reports, intuition, and a little bit of experimental work from the early 20th century, when methodologies weren’t yet as rigorous.  (For example, the experimenters in some of these early studies included themselves as test subjects.)

So they decided to actually test the proposition with experiments very similar to the ones Block cited, but with the addition of asking the subjects afterward about their subjective impressions.  Some subjects (< 20%) did say they saw all the letters in detail and could identify them, but most didn’t.  Some reported (12-14%) believe they saw some of the letters along the lines of the partial fragmentary interpretation.  But most believed they saw all the letters but not in detail, or most of the letters, supporting the generic interpretation.

All of which is to say, this study largely contradicts Block’s assertion that most people believe they are conscious of the full field in all detail, and undercuts his chief argument for preferring his interpretation over the others.

In other words, these results are good for cognitive theories of consciousness (global workspace, higher order thought, etc) and not so good for non-cognitive ones (local recurrent theory, etc).  Of course, as usual, it’s not a knockout blow against non-cognitive theories.  There remains enough interpretation space for them to live on.  And I’m sure the proponents of those theories will be examining the methodology of this study to see if there are any flaws.

Myself, I think the idea that P-consciousness is separate from A-consciousness is just a recent manifestation of a longstanding and stubborn point of confusion in consciousness studies, the tendency to view the whole as separate from its components.  Another instance is Chalmers himself making a distinction between the “easy problems” of consciousness, which match up to what is currently associated with A-consciousness, and the “hard problem” of consciousness, which is about P-consciousness.

But like any hard problem, the solution is to break it down into manageable chunks.  When we do, we find the easy problems.  A-consciousness is an objectively reducible description of P-consciousness.  P-consciousness is a subjectively irreducible description of A-consciousness.  Each easy problem that is solved chips away at the hard problem, but because it’s all blended together in our subjective experience, that’s very hard to see intuitively.

Unless of course I’m missing something?

h/t Richard Brown

The evolution of extraterrestrial life

This is the third or fourth video I’ve seen of Arvin Ash, and have been impressed with how level headed his thinking is.  (In other words, his biases seem to match up well with mine.)  This one on how alien life might evolve strikes me as right on the money.

(The first few minutes end up being an advertisement for Magellan TV.  It’s over around the 2:41 mark.)

Ash quotes Seth Shostak’s hypothesis that the intelligence we’re most likely to encounter would be machine life.  I think that’s right, although those machines might be be far more organic looking than our current ones.

As the video notes, evolution made life out of the most common elements lying around in the universe.  It strikes me that an advanced civilization would be able to utilize those most common elements for their machines.  And one which has mastered nanotechnology would probably produce machines that act a lot like life.  In other words, if we do encounter an alien intelligence, it might look a lot more like engineered life than what we think of as machines.

That said, per Fermi, I’m not holding my breath for such an encounter.  The Earth has been sitting here with an interesting biosphere for billions of years, with visible complex life for the last 600 million.  If there are alien civilizations sending probes out into the galaxy, we should have been discovered long ago, and the aliens (either as machines or engineered life) should have been here long before we evolved.

Maybe they are here, but hiding, either for a Star Trek style Prime Directive purpose, or for managing the zoo.  Or they could be here and out in the open, but we’re not able to recognize them.  An interesting exercise is to try to ponder what things we’ve always taken as natural that could conceivably be technological artifacts, as difficult for us to recognize as the significance of a fence is to a monkey.

It could be that they were once here but are now extinct, because civilizations all destroy themselves, apparently including their machine progeny.  Or it might turn out that interstellar exploration, even by machines, is so appallingly difficult or costly that no one bothers.

Or they might simply be too far away to have reached us yet.  That’s where my money is.  They may be so far away that we’ll never manage to encounter them before expansion of the universe separates us forever, or our machine progeny may someday encounter their machine progeny somewhere out in the universe, far from either of our places of origin.  (I’d say I hope I’m wrong about this, but I’m not sure that’s true.  It seems an act of faith to assume things would necessarily turn out well in such an encounter for the less developed civilization.)

In the meantime, I think Ash is right.  The type of alien life we’re most likely to encounter is microscopic and unicellular.  In that scenario, we’d probably be on the most developed side.  Probably.  (Remember the havoc a microscopic agent is currently causing in our world, not to mention the famous ending of War of the Worlds.)  Either way, I wonder how that will turn out for the less developed side.

 

Alpha

Poster for the movie AlphaThis weekend I finally got around to watching the movie Alpha.  This is a story set in prehistory, about 20,000 BC.  It’s about a boy who gets injured and separated from his hunting party, and ends up thrown together with an injured wolf.  He takes care of the wolf, and they develop a bond.  The idea is that we’re watching the beginning of the relationship between humans and dogs.

It’s a good movie.  I enjoyed it, and highly recommend it if you’re looking for something fun to watch.  But as much as I enjoyed it, I also noticed discrepancies with how anthropologists think societies at that time worked, and some issues with how wolves work.  I think it’s fun to talk about these things.  I’m not going to spoil anything, at least not anything that wouldn’t also have spoiled by watching the trailer, so if you haven’t seen it yet, this post should be safe.

The first thing worth noting, is that the movie shows the tribe living in a particular location.  It’s plausible that was true for parts of the year, most likely the winter, but in general, hunter gatherer tribes moved around.  While there are scattered and isolated pieces of evidence for early permanent settlements, my understanding is that they only become consistent after around 13,000-12,000 BC in the Middle East with Natufian culture.

The other thing that stood out to me is that the tribe had a leader.  And it was implied that the tribal leader’s son might inherit that role.  Most of the stuff I’ve read about hunter-gatherer cultures don’t indicate that those types of roles existed.  These were likely egalitarian societies without any formal leadership.  Hunter-gatherer culture actually seems to resist anyone attempting to put themselves into that kind of position.  Someone might take on a leadership role temporarily to lead something like a hunting or war party, but that’s not what the movie portrays.

Of course, there’s a lot we don’t know about prehistoric cultures.  Most of what I’m saying here reportedly comes from studying modern hunter-gatherer cultures.  There’s no guarantee that prehistoric Europeans had a structure similar to the ones that colonialists came into contact with in the last few centuries.  But the human cognitive package hasn’t had time to change that much in the last 20,000 years, so it seems reasonable to assume they were similar.

(Every time I make this kind of statement, someone weighs in about the relatively quick evolution of lactose tolerance, the ability of Tibetans to live in high altitude conditions, or other cases of recent evolution.  But none of these represent fundamental changes in human nature.)

The movie implies that a wild wolf can be trained into acting more or less like a modern dog.  Genetically, dogs are gray wolves.  But a dog is not simply a tamed wolf.  There have been many stories of people who tried to adopt wolves.  A wolf is a much more difficult pet.  It tries much harder and much more persistently than any dog to escape, is more difficult to train, needs a lot more space for exercise, and has a higher chance of turning on its owner.

Put another way, you can’t convert a live wolf into a dog.  You can’t even take wolf cubs and raise them as pets and expect them to behave like modern dogs.  Modern dogs are separated from wild wolves by 20,000-40,000 years of domestication.  The early domestication of the dog likely took place across a large number of breeding generations.  It’s unlikely to have been anything someone planned.

The scenario I’ve most commonly read is that dogs probably followed a commensal pathway.  Packs of wolves likely started following bands of humans, living off heir refuse.  Over several generations, the wolves more likely to stick around were the ones most comfortable being around humans, setting off a process of self selection.  Humans also likely became increasingly more comfortable with them around.  This process might have taken several centuries, possibly even millenia.

There may have been a first person to realize they could train a dog.  And it seems plausible that first trained dog was female, since they’re generally easier to train than males.  But training dogs everyone was used to having around likely was far less dramatic than taming a wolf straight from the wild.  Of course, that would have made the story less entertaining, so the movie has some grounds for poetic license.

And who knows?  It’s conceivable that someone could have run into an unusually compliant wolf.  And as I noted above, there are enough uncertainties in our knowledge of prehistoric times to provide a space for the movie to work in.  It enabled me to suspend my disbelief long enough to enjoy it.

Have you seen the movie?  If so, what did you think about it?  Or about the plausibility of its scenario?

Final thoughts on The Evolution of the Sensitive Soul

This is the final post in a series I’ve been doing on Simona Ginsburg and Eva Jablonka’s bookThe Evolution of the Sensitive Soul, a book focused on the evolution of minimal consciousness.  This is a large book, and it covers a wide range of ideas.  A series of relatively small blog posts can’t do them justice.  So by necessity it’s been selective.  Similar to Feinberg and Mallatt’s The Ancient Origins of Consciousness, there’s a wealth of material I didn’t get to, and like that other book, I suspect it will inspire numerous additional posts in the future.

This final post focuses on various areas that G&J (Ginsburg and Jablonka) explore that caught my interest.  So it’s somewhat of grab bag.

The first has to do with memory.  Obviously memory and learning are closely related.  The consensus view in neuroscience is that the main way memory works is through the strengthening and weakening of chemical synapses, the connections between neurons.  In this view, engrams, the physical traces of memory, reside in circuits of neurons that follow Hebbian theory, often summarized as: neurons that fire together, wire together.

But it’s widely understood that this can’t be the full story.  Synapses are complex ecosystems of proteins, vesicles, neurotransmitters, and neuromodulators.  Proteins have to be synthesized by intracellular machinery.  So the strengthening or weakening of a synapse is thought to involve genetic and epigenetic mechanisms as well as ribosomes and other components.

G&J focus cite a study that shows that if synaptic processing is chemically inhibited, so that the synapses retract, long term memories are still able to recover.  In other words, the state of the synapse may be recorded somewhere other than the synapse itself.  If so, the synapse could be just an expression of an engram stored intracellularly, perhaps epigenetically, an epigenetic engram, an intriguing possibility that may eventually have clinical implications for Alzheimers and other types of neural degenerative diseases.

G&J note that this may mean that epigenetic factors could have large scale effects on how fast synapses grow or weaken.  In their view, it may dramatically expand the computational power involved in memory.  They even speculate that it could be a system that operates independently of the synaptic one, transmitting information between neurons using migratory RNAs encapsulated in exosome vesicles.

This intercellular transmission could be the mechanism for some learning behavior, such as Kamin blocking, the phenomenon where if there is already an existing association between two stimuli, and a third concurrent one is introduced, that new one won’t become part of the association.  This mechanism is poorly understood at the neural level.

You might have noticed all the occurrences of “may” and “could” above.  G&J admit that much of this is speculative.  There’s no doubt that synaptic processes are supported by intacellular machinery, and exosome vesicles do exist.  But the idea that engram states are maintained epigenetically needs, I think, a lot more fleshing out, not to mention evidence.  And while the exosomes could conceivably be carrying molecular level memory type information, it seems more likely they’re much more banal metabolic signaling to surrounding glia.

Still, G&J note that there is intense research going on in this area.  And it always pays to remember that life is a molecular phenomenon.  So only time will tell.

On the next topic, like many animal researchers, G&J cite the views of Bjorn Merker approvingly, notably the idea that consciousness is a low level process starting in the brainstem.  (A view I’ve critiqued before.)  This puts them partially on the same page as F&M (Feinberg and Mallatt) in The Ancient Origins of Consciousness.  In the last post, I noted that G&J come to similar conclusions as F&M on when consciousness evolved.  In reality, they use F&M’s review of the research, as well as Merker’s material, in reaching their conclusions.

But this leads to a problem.  G&J have a different definition of consciousness than F&M.  F&M divide consciousness into three types: exteroceptive consciousness, interoceptive consciousness, and affective consciousness.  G&J’s definition seems to most closely align with F&M’s for affective consciousness.

But F&M’s embrace of brainstem consciousness (at least in pre-mammalian species) seems to hinge on the fact that they see exteroceptive and interoceptive processing as sufficient for consciousness.  G&J don’t; for them, affective processing is necessary.  But F&M’s data indicate that the type of learning necessary to demonstrate the presence of affects only happens in the forebrain.

The reason why pallial function in anamniotes is such a tough problem is that a fish whose pallium has been removed or destroyed can see, catch prey, and seems to act normally. However, such a fish cannot learn from its experiences or from the consequences of its actions. Nor is it able to learn the locations of objects in space. This is a memory problem, and the medial and dorsal pallia of vertebrates are known to store memories.

Feinberg, Todd E.. The Ancient Origins of Consciousness: How the Brain Created Experience (MIT Press) . The MIT Press. Kindle Edition.

On the one hand, forebrains go back to early vertebrates, so affective consciousness is preserved.  But in fish and amphibians, much of the exteroceptive and interoceptive processing is separate from affective processing.  This isn’t much of an issue for F&M, but it could be seen as weakening G&J’s conclusion that these early vertebrates had the same unified consciousness as later species.

Third topic: G&J late in the book note the existence of something I’d missed until now, a unicellular organism, warnowiid dinoflagellates, that have something called an “ocelloid”, which appears to be something like a camera style eye, much more sophisticated than the typical light sensors that exist at this level.  However, these protists are difficult to study in laboratory conditions.  They tend not to survive outside their natural habitat, which makes them difficult to study.  So the function of this structure is largely conjecture.  Still, if it is an eye, what kind of processing in a unicellular organism might such a complex structure be supporting?

Finally, G&J touch on the topic of machine consciousness.  Somewhat refreshingly for people who use the “embodied” language, they don’t rule out technological consciousness.  However, they note that it could be very different from evolved consciousness in animals.  Importantly, they see UAL as an evolutionary marker for consciousness in biology.  Its existence in technological systems may not necessarily indicate the presence of machine consciousness.  And they expect machine consciousness to require a body, but they allow it could be a virtual one.

As always, my take on these things is it depends on how we define “consciousness”.

As noted above, there is a lot more in this book, some of which I might touch on later.  But I think this is it for now.

Finally, and I should have linked to this in the last post, if you want a condensed version of their thesis, and don’t mind wading through some technical material, their paper on unlimited associative learning is online.

What do you think of the idea of epigenetic engrams?  Or the various definitional issues?  Or G&J’s approach overall?

Unlimited associative learning

Cover of The Evolution of the Sensitive SoulThis is part of a series on Simona Ginsburg and Eva Jablonka’s book: The Evolution of the Sensitive Soul, a book focused on the evolution of minimal consciousness.  This particular post is on the capabilities Ginsburg and Jablonka (G&J) see as necessary to attribute consciousness to a particular species.  The capability they focus on is learning, but not just any kind of learning, a type of sophisticated learning they call unlimited associative learning.

There are many different types of learning, but they can be grouped into two broad categories: non-associative learning and associative learning, with associative being the more sophisticated.

Non-associative learning includes habituation and sensitization.  Habituation is when a sensory receptor responds less frequently to a constant or repetitive stimulus.  It’s why you don’t feel your clothes against your skin (until I called your attention to it) or the pressure of the piece of furniture you’re sitting in against your body.

Sensitization is the opposite.  If there is no stimulus for a long time, the sensory neuron is more likely to respond when one suddenly arrives.  Or if it arrives in an unexpected pattern (such as the feeling of something crawling on your leg).  Or if the previous stimulus was painful, then a relatively mild stimulus may still lead to an intense reaction.

Non-associative learning takes place in all kinds of living systems, including unicellular organisms.  In animals, in the cases I described above, it actually takes place in the peripheral nervous system.  Although it also happens in the central nervous system.  More sophisticated learning is built on top of it.

Historically, associative learning has been categorized into two categories: classical or Pavlovian conditioning, and operant or instrumental conditioning.

Classical conditioning is best exemplified by the case of Ivan Pavlov’s dogs.  Initially, in an experiment, the dogs would salivate when food was presented to them.  But if each time the food was presented, a bell was also rung, the dogs would start to salivate on the bell ring.  Eventually they would salivate on the ring so even if no food was presented.  Classical conditioning is association of two sensory stimuli, the conditioned stimulus (the bell) with the unconditioned stimulus (the food).

Operant conditioning involves association between an action and a reinforcement stimulus.  For example, if a rat in a cage, through random action and exploration, accidentally jumps on a lever, and a food pellet is released, the action (pressing the lever) becomes associated with a reinforcement stimulus (the food).  For it to be a reinforcement, the stimulus must involve some existing value for the organism, either attractive (like food) or aversive (like electrical shock).

G&J, somewhat pushing back against the traditional nomenclature, labeling classical conditioning as “world learning”, because it involves association between external stimuli.  They label operant conditioning as “self learning” because it involves associating an action by the self with reinforcement, a sensory stimulus.

  1. Non-associative learning
    1. Habituation
    2. Sensitization
  2. Associative learning
    1. Classical conditioning / World learning
    2. Operant conditioning / Self learning

G&J state that associative learning requires a brain.  So although we might see non-associative learning in creatures like ctenophores (comb jellies), we only see associative learning in creatures with some sort of central coordinating system.  That said, the definition of “brain” here is fairly liberal.  So many worm like creatures with slightly larger ganglion toward the front of their body seem to meet the standard.

(I found this brain requirement surprising, since classical conditioning is often said to be widespread.  But after reading G&J’s assertion, I tried to track down cases of classical conditioning in primitive organisms.  The main example was a starfish; G&J mention the one study showing it but dismiss it for methodological reasons.  They also briefly allude to studies finding it in unicellular organisms, but don’t seem to find those studies convincing.)

Primitive creatures generally only have what G&J call limited associative learning (LAL).  With LAL, the associations that form are relatively simple.  Although “relative” is a key word here, because even with LAL, things can get complex pretty fast.

But this isn’t the type of learning that signals minimal consciousness.  For that, we need a type of learning that allows associations between compound stimuli integrated across multiple modalities (hearing, sight, smell, etc) and complex combinations of motor actions.  When the capabilities for these types of associations start to arise, the possible combinations quickly increase exponentially, becoming virtually unlimited.

It is this type of learning: unlimited associative learning (UAL) that G&J see as a key indicator of minimal consciousness.  UAL requires sensory integration through multiple hierarchies, forming an integrated sensorium.  It also requires integration across possible motor systems, an integrated motorium.  And the sensorium and motorium become integrated with each other, with a concept G&J refer to as association units.  (G&J don’t use the words “sensorium” or “motorium”, but I find them helpful here to summarize a lot of detail.)

Each layer in the sensory hierarchies make predictions based on the signals from lower layers.  The lower layers respond with prediction error signaling, making the communication between each layer both feed forward and feed back in a recurrent fashion.  It’s with this sustained recurrent signalling that temporal thickness and synaptic plasticity is achieved, leading to memory and learning.  And when it spreads to motor systems, we get the global workspace effect.

It’s important to note that G&J do not claim that UAL is minimal consciousness, only that it is a key indicator of it.  In order to be capable of UAL, a species must have the underlying architecture, including the attributes listed in the last post.

However, UAL represents crucial capabilities that likely make minimal consciousness adaptive.  While it’s possible to see animals that are minimally conscious who, due to injury, pathology, or immaturity, show signs of minimal consciousness but aren’t capable of UAL, the healthy mature members of the species should be capable of it.  In this view, UAL is a key driver of the evolution of minimal consciousness.

In many ways, UAL resembles one of the criteria that Todd Feinberg and Jon Mallatt used for affective consciousness in their book, The Ancient Origins of Consciousness.  Feinberg and Mallatt called this criteria “global non-reflexive operant learning”.  (Although they didn’t elaborate on this, and I didn’t find them to necessarily be consistent with the “global” or “non-reflexive” part in the studies they cited.)

As many others do, G&J take issue with Feinberg and Mallatt dividing primary consciousness up into three separate divisions: exteroceptive, interoceptive, and affective consciousness.  For G&J, there is only one consciousness, which at any time might be focused on exteroceptive, interoceptive, or affective content.

That being said, G&J reach conclusions very similar to Feinberg and Mallatt’s on which species have minimal consciousness: all vertebrates, including fish, amphibians, reptiles, mammals, and birds, as well as many arthropods such as ants and bees, and cephalopods such as octopusses.

In the last post for this series, we’ll discuss some additional areas that G&J explore, and I’ll provide my thoughts on their overall approach.

What do you think of UAL (unlimited associative learning)?  Do you think it’s a valid mark of minimal consciousness?

The seven attributes of minimal consciousness

Cover of The Evolution of the Sensitive SoulI’m still working my way through Simona Ginsburg and Eva Jablonka’s tome: The Evolution of the Sensitive Soul.  This is the second post of a series on their book.  I’m actually on the last chapter, but that last chapter is close to a hundred pages long, and the book’s prose is dense.  Light reading it isn’t.

Still, it includes a vast overview of the study of consciousness and the mind, not just in contemporary times, but going back to the 19th century and beyond.  For anyone looking for a broad historical overview of the scientific study of the mind, and is willing to put in some work to parse the prose, it’s worth checking out.

As I noted in the first post, G&J aren’t focusing on human level consciousness, that is, higher order metacognitive self awareness and symbolic thought, the “rational soul.”  Similar to the work by Todd Feinberg and Jon Mallatt, their focus is on minimal consciousness, often called “primary consciousness”.  They equate this minimal consciousness with sentience, the ability to  have subjective experiencing (they prefer “experiencing” to just “experience”), which they relate to Aristotle’s “sensitive soul.”

Even having defined this scope however, there remains lots of room for different interpretations.  In an attempt to more precisely define the target of their investigation, they marshal information from contemporary neurobiology and cognitive scientists, along with their theories, to describe seven attributes of minimal consciousness.

  1. Global activity and accessibility.  It’s widely agreed that consciousness is not localized in narrow brain regions.  Although the core ignition and distribution mechanisms might be localized to particular networks, it involves content widely available from disparate brain regions broadcast or made available to the other specialty processes that otherwise work in isolation.
  2. Binding and unification.  The unified nature of conscious perception, such as experiencing the sight of a dog rather than all the constituent sensory components.  Many theories see this being associated with the synchronized firing of neurons in various brain regions, built with recurrent connections between those regions.
  3. Selection, plasticity, learning, and attention.  We are generally conscious of only one thing at a time, or one group of related things.  This involves competition and selection of the winner with the losers inhibited.  It also involves plasticity, which enables learning.
  4. Intentionality (aboutness).  Conscious states are about something, which may be something in the world or the body.  The notion of mental representation is tightly related to this attribute.
  5. Temporal “thickness”.  Neural processing that is quick and fleeting is not conscious.  To be conscious of something requires that the activity be sustained through recurrent feedback loops, both locally and globally.
  6. Values, emotions, goals.  Experience is felt, that is, it has a valence, a sense of good or bad, pleasure or pain, satisfaction or frustration.  These are the attributes that provide motivations, impetus, to a conscious system, that propel it toward certain “attractor” states and away from others.
  7. Embodiment, agency, and a notion of “self”.  The brain is constantly receiving feedback from the body, providing a constant “buzz”, the feeling of existence.  This gives the system a feeling of bodily self.  (Not to be confused with the notion of metacognitive self in human level consciousness.)

G&J refer to this as “the emergentist consensus.”  It seems to pull ideas from global workspace theory, various recurrent loop theories, Damasio’s theories of self and embodiment, and a host of other sources.

It’s important to note that these attributes aren’t free standing independent things.  They interact with and depend on each other.  For example, for a sensory image to be consciously perceived (4), it must achieve (1) global availability by winning (3) selective attention by (2) binding, which results in (5) temporal thickness and strengthens the plasticity aspect of (3).  This process may trigger a reaction which goes through a similar process to achieve (6) value.  All with (7) as a constant underlying hum, subtly (or not so subtly) stacking the deck of what wins (3).

So that’s G&J’s target.  Their goal is to identify functionality, capabilities which demonstrate these attributes in particular species.  Their focus is on learning capabilities, which I’ll go into in the next post.

What do you think about these attributes?  Do they strike you as necessary and sufficient for minimal consciousness, the “sensitive soul”?  Or are they too much, bringing in inessential mechanisms?