PZ Myers. 2005 Sep 09. Bird brains. <http://pharyngula.org/index/weblog/bird_brains/>. Accessed 2008 Aug 08.
Posted on M00o93H7pQ09L8X1t49cHY01Z5j4TT91fGfr on Friday, September 09, 2005
Bird brains
I'm teaching a course in neurobiology this term, and it's strange how it warps my brain; suddenly I find myself reaching more and more for papers on the nervous system in my reading. It's not about just keeping up with the subjects I have to present in lectures (although there is that, too), but also with unconsciously gravitating toward the subject in my casual reading, too.
"Unconsciously"…which brings up the question of exactly what consciousness is. One of the papers I put on the pile on my desk was on exactly that subject: Evolution of the neural basis of consciousness: a bird-mammal comparison. I finally got to sit down and read it carefully this afternoon, and although it is an interesting paper and well worth the time, it doesn't come anywhere near answering the question implied in the title. It is a useful general review of neuroanatomical theories of consciousness—even if it left me feeling they are all full of crap—but in particular it's an interesting comparative look at avian brain organization.
The paper briefly reviews four classes of models that attempt to locate the centers of consciousness, or "consciousness generators", in the mammalian brain. Alas, they all seem to contradict one another, and are all driven by the authors' hypotheses to invent validation in the structure, rather than by actual data that might lead to useful hypotheses. I won't get into these, other than to paste in the summary—while I'm not at all dazzled by any of them, it is handy to have such tidy summaries.
Classification of consciousness—brain theories
Bottom-up Top-down Sensory systems A B Motor systems C D A: A representative bottom-up theory proposed by Crick and Koch concerns the visual system and asserts that visual awareness is associated with activity in higher order visual areas that are in direct contact with prefrontal cortex. Although the "cortical system" covered by this theory includes the entire cerebral cortex, dorsal thalamus, claustrum (a nonlaminated structure deep to the cortex), and dorsal striatopallidal complex (caudate, putamen, globus pallidus—also referred to as basal ganglia and involved in motor control) in the forebrain as well as the motor control-related cerebellum and various brainstem projection systems, the generator neurons seem to be limited to temporal, parietal and prefrontal regions of the neocortex. Crick and Koch limit the generator structure further by assuming that activity in a subpopulation of neurons in cortical layer V, characterized by firing in burst patterns, is crucial. A prominent feature in the theory of Crick and Koch is the insistence that the primary visual cortex is not a generator structure.
B: The theory of Edelman and Tononi appears to be an example of a top-down sensory approach and focuses on the general features of consciousness—such as complexity and unity. It asser ts that consciousness is associated with activity in the temporal and frontal associative and motor regions of the cortex: a "dynamic core", characterized by "re-entrant" interactions within limited portions of the CNS. Possibly, thalamic neurons are included in the dynamic core. Structures supporting the dynamic core seem to be the septal region, amygdala, hippocampus, dorsal thalamus, and hypothalamus within the forebrain, as well as the reticular activating system in the brainstem. Edelman and Tononi seem to assume a larger and more dynamic population of generator neurons than Crick and Koch. In comparison to the latter, the inclusion of limbic system structures—septal region, amygdala, and hippocampus—that are related to emotion and learning make this theory more broadly based.
C: The theory suggested by Eccles may be said to represent a bottom-up approach, largely based on studies of the motor system. It takes consciousness to be associated with activity in cortical columns of the pre- or supplementary motor areas, for med by groups of generator pyramidal cells, organized in a specific way (dendrons). This means that Eccles's theory assumes the smallest and most well defined population of generator neurons of all the theories discussed here.
D: The theory formulated by Cotterill may be said to be an example of a motor system top-down approach. According to this, consciousness is associated with activity in a circuit consisting of sensory and motor, cortical and thalamic structures. Fast feedback from muscle activity, making muscle spindles (sensory receptors for the degree of stretch within muscles) critical for the generation of consciousness, is a central par t of the theory. Fundamental to Cotterill's, as well as to other top-down theories, is a set of proposals implying that the neural basis for consciousness lies in the ability of an organism to know itself, or its proto-self, within its environment, by bodily movements and homeostatic functions. In all these top-down theories, several non-cortical regions seem to be included in the generator structure of consciousness. Cotterill includes the amygdala, hippocampus, dorsal thalamus, subthalamus, hypothalamus, and dorsal striato-pallidal complex (caudate, putamen, and globus pallidus) within the forebrain as well as multiple brainstem structures—the superior colliculus (involved in sensory and motor mapping of space), various structures involved with motor system regulation (cerebellum, substantia nigra, pontine nucleus, red nucleus, and inferior olive), and part of the autonomic nervous system (for control of visceral functions)—thus for ming a larger generator structure than any other theory discussed here. Additional motor system top-down ap- proaches include that of John, who includes the thalamus, limbic system, and dorsal striato-pallidal complex, and that of Parvezi and Damasio,(24) who incorporate the hypothalamus, intralaminar and reticular nuclei of the dorsal thalamus, basal forebrain, and various cholinergic, glutamatergic, noradrenergic, dopaminergic and serotonergic projection systems that regulate the activity of the cortex.
There's also a diagram of where these theories place the "conciousness generators" (in dark gray) in the human brain. As you can see, they all agree it is not in the brainstem or cerebellum, but from there anything goes.
Diagrammatic representations of the distribution of generator neurons (shaded in gray) for the four principal groups of brain-consciousness theories outlined in the present essay as they would appear for the human brain. For each theory, the lateral aspect of the human brain is shown on the left. The entire extent of the frontal lobe is shaded in B at the rostral (to the right) end of the cerebral hemisphere; within it lie motor cortices and, rostral to them, the prefrontal cortex. The occipital lobe is unshaded in both A and B, lying at the caudal pole (to the left) of the hemipshere. The parietal lobe (dorsally) and temporal lobe (ventrally) lie between the occipital and frontal lobes. The medial aspect of the hemisphere is shown for each theory on the right. The hippocampal formation, olfactory (piriform) cortex, and amygdala all lie within the temporal lobe, deep to the neocortical areas shown here.
The more productive part of the paper is the comparison between mammals and birds. Here's the premise:
We posit that, since highly complex cognitive abilities are correlated with presumed consciousness in at least some mammals, including but not limited to humans, and since highly complex cognitive abilities are evinced by birds, it is likely that consciousness is also present in birds. Given that hypothesis, we then can compare the anatomical organization of mammalian and avian brains. We reason that if (1) complex cognition and consciousness are present in both mammals and birds and (2) consciousness has any neural basis, then birds should have at least some neural features in common with mammals to generate consciousness.
That sounds promising, but several problems come to mind. 1) If no one can even agree on the neural features responsible for consciousness within mammals, how is this comparison going to identify commonalities? 2) Birds and mammals are related lineages, so many brain similarities are going to be consequences of shared history, not function. Why not go all out and compare more distinct lineages…say cats and octopus? 3) Since we don't even know what features of the areas of the brain are responsible for consciousness, we aren't going to be able to recognize if different regions in birds and mammals have independently acquired whatever mysterious property is involved. While I think the comparative approach is terrific, in this case it's premature and targeted at the wrong level.
But hey, you've got to start somewhere, and this wasn't one of those exasperating papers that I toss into the wastebasket. It has a good summary of the evidence for avian intelligence, listing the various features they've exhibited.
- Transitive inference. You can train pigeons (Pigeons! Birds that are archetypically stupid!) to recognize rank order, such as that A<>B, and B<C, and they can use that information to recognize tha A<C.
- Coherence. Pigeons can respond variably to the ambiguity in figures like the Necker cube. That suggests that they have a mental model of what it should be, and their impression of its orientation can "flip".
- Episodic memory. Scrub jays can recollect when, where, and what is stored in their food caches.
- Piagetian object constancy. Doves, magpies, parrots, and ravens aren't fooled if an object is hidden—despite being out of sight, they have a mental model of its position.
- Cognitive abilities. Gray parrots are singled out as particularly brilliant, with individuals able to count to 7, recognize the concept of "none", and able to understand the concepts of "same" and "different".
- Tool use. Ravens, parrots, and New Caledonian crows have all been shown to be able to make and use simple tools.
- Theory of mind. Scrub jays are able to attribute their own predilections to other members of the same species. Jays that rob caches are more likely to move their own caches than "honest" jays.
While I have my doubts about the neuroanatomical comparisons, the authors bring up one very general point. In mammals, the neocortex—the hugely enlarged part of our forebrains that is the first thing you see when you crack open our skulls—is central to higher level thinking. The comparable structure in birds is called the hyperpallium, or Wulst (German for "bulge"), and the posterolateral portion of it is an important visual center, comparable to the striate cortex, or visual areas of our brain. The fascinating thing is that the cellular organization of these two areas with similar functions and perhaps similar roles in generating consciousness are very different.
The mammalian visual cortex is characterized by a beautifully layered organization. Different inputs segregate to different layers, and pyramidal neurons extend long dendrites orthogonal to those layers, like long antennae reaching up and sampling incoming data streams, each of which is segregated spatially. The Wulst, on the other hand, is organized like other nuclei of the brain, and the primary neurons are star-shaped, reaching out in all directions to contact their inputs. They lack the rigid but elegantly arrayed spatial segregation seen in us mammals.
The pictures below don't really do it justice, but a good neurohistologist (sometimes even a barely adequate one, like me) can pick out 6 discrete layers in an appropriate slice of mammalian visual cortex. The bird Wulst is alien-looking. Huge, but weird.
Photomicrographs of the visual lemnopallium in the barn owl (Tyto alba), common ferret (Mustela putorious) and eastern tube-nosed megabat (Nyctimene robinsoni). In the owl, the photomicrograph depicts a coronal section stained for Nissl substance (localized in cell bodies) through the visual hyperpallium, the Wulst (pial surface to the top of the page). Note the thick outer layer termed the hyperpallium apicale (HA), the high cell density of the nucleus interstitialis hyperpallii apicalis (IHA), and the deepest portion termed the hyperpallium densocellulare (HD). This region of the Wulst, forms what are termed pseudolayers, which are best thought of as flattened and stretched out nuclei rather than true layers as is evident in the cerebral cortex of the ferret and megabat pictured here. This architecture contrasts with the typical 6-layered cerebral cortex found in the primary visual cortex of mammals.
In their conclusion, the authors are a bit vague about the relevance of the earlier theories of consciousness to bird neuroanatomy. Parts fit, others don't, but since I think the theories are so nebulous that it's nearly impossible to draw any conclusions from that, they can't come down strongly one way or another. One suggestive observation is that bird brains are more similar to reptilian brains than mammalian brains are to stem amniotes'. If birds are conscious, that makes the assumption that the capacity for consciousness arose at that stem amniote-mammalian border suspect. The capacity, in the sense of having neural circuitry that could be adapted to generate consciousness, could have been present earlier.
Ann B. Butler, Paul R. Manger, B.I.B. Lindahl, Peter Århem. Evolution of the neural basis of consciousness: a bird-mammal comparison (p 923-936).
Science • EvoDevo • Organisms • 0 Trackbacks • Other weblogs • Permalink
-
http://www.economist.com/science/displayStory.cfm?story_id=2668085
In this case, the observation was serendipitous. Dr Bugnyar was conducting an experiment designed to see what ravens learn from each other while foraging. While doing so he noticed strange interactions between two males, Hugin, a subordinate bird, and Munin, a dominant one.
The task was to work out which colour-coded film containers held some bits of cheese, then prise the containers open and eat the contents. The subordinate male was far better at this task than the dominant. However, he never managed to gulp down more than a few pieces of the reward before the dominant raven, Munin, was hustling him on his way. Clearly (and not unexpectedly) ravens are able to learn about food sources from one another. They are also able to bully each other to gain access to that food.
But then something unexpected happened. Hugin, the subordinate, tried a new strategy. As soon as Munin bullied him, he headed over to a set of empty containers, prised the lids off them enthusiastically, and pretended to eat. Munin followed, whereupon Hugin returned to the loaded containers and ate his fill.
At first Dr Bugnyar could not believe what he was seeing. He was anxious about sharing his observation, for fear that no one would believe him. But Hugin, he is convinced, was clearly misleading Munin.
As it happened, Munin was no dummy either. He soon grew wise to the tactic, and would not be led astray. He even stooped to trying to find the food rewards on his own! This made Hugin furious. “He got very angry”, says Dr Bugnyar, “and started throwing things around.” Perhaps ravens have something else in common with people—a hatred of being found out. -
I find it neat that the ravens were named after Odin's two ravens, Thought and Memory.
#: Posted by on 09/09 at 03:52 PM
- Bernd Heinrich also argues that ravens posess "insight". I am almost convinced. I'll have to come back later once I read this more thoroughly.
-
Can we make some distinction between what behavior would indicate “consciousness” and what might otherwise indicate a sort of neurological programming so to speak? Is it possible for an animal to learn by quasi-Pavlovian methodology and yet not possess what one might define as a cognizant type awareness?
The behavior exhibited by the ravens in the above text is incredibly human-like awareness. The bit that suggests that thieving jays having a tendency to be more on edge about guarding caches than “honest” jays is truly interesting. But when does learning from behavioral patterns become “consciousness”? Consider a litter-box trained kitten. Is there a “consciousness” suggested in the cat’s resolve to poop in the box? Probably not.
My point is (yeah I’m wrapping it up) a comprehensive definition of consciousness is necessary before we can seek it out. I am sure that is why the researchers chose birds and humans for comparison.#: Posted by on 09/09 at 04:53 PM -
Even Pavlovian behavior implies a certain level of intelligence. In fact, given that Pavlov's experiments were on mammals, if birds also exhibit the same behavior, then this is, in and of itself, an interesting phenomenon.
I think that you underrate the intellectual capacity required for Pavlovian learning. It requires a memory and the neurological machinery to associate a cause and an effect. It's more than just instinct, it's a learned behavior.
As for the question of cats and litterboxes, I'd guess that whether it's instinct, learned behavior, or consciousness, it's not much different from the reason why we use the toilet and not the sink. Incidentally, it is much easier to train a cat to use a litterbox than it is to train a dog to paw the door to go outside when it has to use the toilet. On that topic, our two dogs used to use that as part of a trick. They knew that when one of them went to the door, one of us would get up to let them out so they could do their business. So at dinner time, one dog would start pawing the door, and one of us would get up from the table, and the other dog would use the opportunity to try to grab food off the table. Incidentally, the first dog didn't actually have to go, and wouldn't go outside, she'd just stand there in the doorway to keep whoever had opened the door standing there longer.
But hell, I'm sure it was just instinct.#: Posted by on 09/09 at 05:34 PM -
I'm teaching a course in neurobiology this term, and it's strange how it warps my brain...
Sounds like we urgently need a research project comparing the cerebral structures of neurobiology instructors with those of normal humans.#: Posted by on 09/09 at 05:41 PM -
Hyperion — ... given that Pavlov's experiments were on mammals, if birds also exhibit the same behavior, then this is, in and of itself, an interesting phenomenon.
Didn't B.F. Skinner's stimulus-response research on pigeons establish all that in the 1930s & '40s?#: Posted by on 09/09 at 05:46 PM -
Yes, what is conciousness?
And, as a non-scientist, my immediate question is "Why do we assume that there are two kinds of thought, concious and instinctual"?
I don't understand the difference between them. To me, in both instances an organism (Or part of one) has a state that it desires to get into (For example, it wants to eat) and it can recognize when it isn't in that state and take some course to correct it. How is conciousness different? Concious thought to me seems to differ from the behavior of an amoeba only in complexity.#: Posted by on 09/09 at 07:17 PM - There are differences in degree, but there are also qualitative differences. Consciousness requires some reflective or recurrent capability -- the ability to be aware that one is aware. It also involves active internal modeling of the external world, and evaluation of that mindstate against inputs.
-
Christopher: I think you posed the question badly, because "conscious" and "instinctive" aren't really exclusive. The revulsion I feel at the sight of a corpse is completely instictive, but it is also something I am totally conscious of.
One also has to distinguish self consciousness from awareness of one's surroundings, which often gets called phenomenal consciousness. Phenomenal consciousness in higher animals is supposed to be different than the reactive mechanisms of an amoeba because they are "felt" or "lived." A one celled organism may respond to light, but only creature's with bigger brains see the redness of the color.
The two kinds of consciouness may be related, that is, our reaction to the world may generate phenomenal consniousness because they are enveloped in self conciousness.#: Posted by rob loftis on 09/09 at 07:44 PM - Well, look around Mixing Memory blog and Cognitive Science blog reading group.
-
I think the simplest way to think of consciousness is through the negative thesis that, at any time, there's information in your brain you're not aware of and can't become aware of. Consciousness concerns the stuff that's not that stuff. Effectively, that's what Crick and Koch do; they go through the visual system and strike off the parts that contain information we have no awareness of. There's the further complication that we can apparently be aware of some things without knowing we're aware of them, but hey.
#: Posted by on 09/09 at 08:17 PM
-
One of the African grey parrots I bird-sit for is very fierce when we're alone--the only way I can put his food bowl back in the cage is to give him an almond first, so if he really wants to bite my hand as I reach in, he'd have to drop the almond, and he'd never do that. That's the basic terms of our relationship--he won't even tolerate my feeding him without a bribe first.
When his owner gets back, though, he punishes her for leaving by trying to make her jealous of him and me--he'll perch near me, flirt with me by standing on one leg and leaning toward me, coo, and fluff his feathers. He's all "I wuv Raven THIS much!", but it's totally an act.
I really think that feathered fraud has some degree of consciousness to plan and carry out that deception, even as clumsy as it is. -
I've got an ignorant, non-scientific question, and a possible bone to pick.
What's with all of this talk about 'mental models'? To be more precise, what, in the scientific lingo, does something have to be in order to count as a 'mental model'? Second, is there conclusive evidence to suggest that such mental modelling is occuring, or is it posited as the only conceivable means of explaining the phenomenon in question?
A lot of philosophers (myself included) wring their hands over whether mental representations are the best explanation of our own capacities to do x, y, and z. I'm curious to know whether 'mental models' are roughly synonymous with 'mental representations,' and further, if the scientists know something that the philosophers don't.
In part depending on the answers to these questions, I am highly skeptical of several of the criteria suggested: transitive inference, the Neckar cube, object constancy, (especially) tool use, and (at least some) cognitive abilities. It would seem to me that all of those capacities could be born out by an organism operating "in the dark" so to speak. Maybe the same is true for the other two (and a half criteria), although my impulse is to say the theory of mind evidence is compelling. Again, depending on what you mean by 'consciousness' and the particular understanding/status of 'mental models,' I'm not sure the evidence adequately supports the conclusion...
... then again, I also don't doubt the conclusion. So take this nugget of skepticism with a very large grain of salt.#: Posted by on 09/09 at 09:12 PM -
Christopher:
Regarding Pavlov & Skinner, no, that is incorrect.
Pavlov dealt with what is now called classical conditioning. This is the association of an inherent and natural response (Unconditioned Response) such as salivation to a stimulus not usually associated with that response (Conditioned Stimulus).
Skinner's work dealt more with, if memory serves, instrumental conditioning, rewards based on the overt response of the organism, and rewarding small incremental accomlishments as the goal behavior is acquired (shaping). Here you get terms such as positive and negative reinforcement and punishment and extinction.#: Posted by John M. Price on 09/09 at 09:25 PM -
This is a topic of particular fascination to me and I've been thinking about it a lot. Certainly I'm no neurophysiologist (not even a psychologist, just a minor in psych from 20 years ago and a whole lot of applied psychology since then) but I have had a keen interest in how we work as thinking beings for a very long time. One reason for this is that I have clinical depression and am therefore much more aware of my own cognitive process than might be usual.
Anyway, I've very gradually come to the tentative conclusion that consciousness is, in fact, pretty much just an illusion. In particular, continuity of consciousness seems illusory. Yes, consciousness is real, but it seems to arise not as its own thing but from a complex interaction of language, perception (including modeling) and memory, among perhaps other things. Individual episodes of "consciousness" are stitched together by memory to make what appears to be a seamless whole, but in fact is a patchwork consisting of some real memories, some approximations and some blatant (but relatively consistent) falsehoods. As far as the episodes themselves, such as the one I am experiencing as I write this and that you are experiencing as you read this, I feel (without any really firm evidence) that they arise due to focused attention and awareness. As I sit here I am aware of myself, I am aware of my own self-awareness and I am modeling not only my concept of consciousness but your reaction to the words that I use. Not to mention the myriad small things I'm doing in support of that attention, such as the processing taking place to make sure the keys are hit in the right order and I don't use "frodo" or "xphs" instead the word I intend.
From what I've read, there is a lot going on, all of it concurrent and most of it literally simultaneous. A huge volume of ordered chaos broken up, more or less, into subsystems that range from the cells of the retina to the complex processing in the frontal cortex and interactions between that and the limbic system. In essence, many voices that combine to form - well, I was going to say "one," but I think that it's really several voices. Not many, but more than one. Of course, the one you hear (and read) is the one that has language. In fact, "voices" is very misleading, because almost all of this chorus happens before any language.
Now, whether these "voices," these subsystems, correspond to various physical neural structures is something for the neuranatomists, neurophysiologists and neuropsychologists to figure out. (My inclination is that they do indeed correspond fairly precisely to those structures.) I continue to watch the research with fascination. This whole field is intensely interesting to me, since it concerns who and what we are at the most intimate level.
It doesn't get any more intimate than to describe the shape and mechanism of my own thoughts. -
What's with all of this talk about 'mental models'? To be more precise, what, in the scientific lingo, does something have to be in order to count as a 'mental model'?...I'm curious to know whether 'mental models' are roughly synonymous with 'mental representations,' and further, if the scientists know something that the philosophers don't.
"Model" in this sense is a simplified representation of a real-world entity. Among other problems, entities are so complicated that they are intractable (unmanageable) to work with and study directly, even assuming that directly manipulating the entity was possible. So we create a simplified representation of the entity and manipulate that instead, in order to make the problem of studying the entity tractable, and we assume that conclusions we draw about the model map back to reality in a predictable way.
Of course, the flip side is that in simplifying the representation enough to make it tractable, you have to make sure that you don't simplify it so much that you lose essential aspects (expressivity or power) of the real-world entity. If you do, your model is invalid to varying degrees, and manipulations of the model cannot be extrapolated back to the entity itself. And there's no one-size-fits-all rule for establishing validity of a model; it is a very complicated subject all in itself. -
I've got an ignorant, non-scientific question
P.S. Not so--your question lies at the very heart of science and how it is possible to sytematically study such a complicated universe. -
PZ
Looks to me like this has a lot to do with information processing and not a lot to do with consciousness. Are the two identical? Is my having a subjective experience of blue explained by answering the question "how does my eye/brain deal with visual stimuli of a specific wavelength?"
I'm not saying that this latter question isn't important, but I'm just not sure that it should be assumed that this answer also explains "consciousness."#: Posted by on 09/10 at 07:10 AM -
T.W. McKinney: You worry about certain operations and whether they are performable "in the dark". Isn't that the zombie hunch? My philosophical worry about mental representations is rather how we move from what is in our head (LTP etc.) to something more sentence like. (This is where eliminative materialism really messes with me... )
#: Posted by on 09/10 at 08:58 AM
- I am glad that you will be posting more brain stuff. Do you read Ramachandran?
-
> 3) Since we don't even know what features of the areas of the brain are responsible for consciousness, we aren't going to be able to recognize if different regions in birds and mammals have independently acquired whatever mysterious property is involved.
Is that true though? I have seen some programs and read some things about a certain region of the brain that are supressed during things like meditation. This *seems* to be a master filter of sorts, which collects and sorts the complex perceptions of other parts of the brain and presents a unified 'me'. When supressed, all sorts of things go wrong. We think that the flicker of a candle is our minds making it flicker, because we don't automatically assume it was a passing breath of air, we think we sense things in the room with us, we in some cases feel a false sense that our bodies are stretched out to contain the entire contents of the room (or in someone that goes really far, the entire universe), etc. Its the same supression that tends to underly hypnosis, where someone else's statements enter our consciousness as though they were our own thoughts, convincing us that reality itself has changed in some profound way. Without this filter, there is no "me", no seperation of the rest of the world, no unique self, just an extension of everything else that goes on around us and unable to act on any of it, without an external push. Or at least that 'seems' to be what happens. This is possibly supported by some mental conditions, which involve people that will do something if you ask them to or guide them to it, but otherwise have no self motivation. It also implies why some people have trouble defining their own existence, without attaching them selves to someone else and fall apart when they don't have anyone to latch on to.
So.. It might not be accurate to say we don't at least have a theory, however I would agree with you that looking for something, without having some clue as to which part you should be looking for, is pretty silly, especially if no experimentation is done (or may be possible) to identify which bit is doing it. -
I think the people talking about learned and instinctive behovour here are on the wrong track entirely. It presumes the brain to function as a unified whole. It doesn't. Studies on induced temporary malfunction, brain damaged patients and those with genetic based malformations **all** indicate that rather than a unified whole, the brain is hundreds of un-unified processes, which certain specific structures are designed to filter for relevant information. Some filters do different things, a bit like having ten streams of data, each containing a lot of irrelevant information, but is 'filtered' to get rid of what the filter has learned to precieve as noise, then a 'final' filter organizes the whole thing into what 'appears' to be a unified whole. As far as the guy sitting at the display is concerned (or if it was an AI program, its decisions based on that data is concerned), it all appears to be a single choice. For that matter, even the logic of an AI can work that way. With several alternative choices being generated, which the final filter 'picks' one from, then acts on. If its memory only stores the one it picked, then as far as it is aware, no other choices, thoughts or actions existed, even if there had been dozens. Consciousness in the sense that humans have it may simply mean the ability to recognize that other option 'may' be possible and adjust the filter recursively, to search for the alternatives, which a less 'conscious' animal would never even recognize could be considered.
This seems to me to be a far better definition of consciousness and a reasonable cut-off point for saying what differenciates mere awareness of environment and awareness of self. The capacity to know that alternatives are possible, and actively consider them, by not simply taking the first action that the final filter in the system pops up into the animals awareness, but instead 'choosing' to look for alternatives by doing what we would describe as 'rethinking' them. - I'd be interested in your take on Jeff Hawkin's "On Intelligence", blurbed by no less than Jim Watson and Eric Kandel. His position on consciousness (other than "it's a question neuroscientists dread unnecessarily") is summarized as "what it feels like to have a cortex" (p194), not some "magical sauce ... added on top of the physical brain".
-
His position on consciousness... is summarized as "what it feels like to have a cortex," (p194), not some "magical sauce... added on top of the physical brain."
I'd have to read more, but, that kinda seems like an attempt to explain phenomenal consciousness in terms of something phenomenal (i.e. why should having a cortex feel like anything? - that's the question). That said, I don't think its a choice between that sort of explanation and the magical sauce. Still, bridging the gap between the physical and the phenomenal is very, very difficult-- enough that the idea of nonreducible consciousness has gained a few adherents over the years. I might even be one of them. The jury's still out.#: Posted by on 09/10 at 04:56 PM -
Applause all around!!! The above volley of discussion is what I had in mind when I suggested in a very simplistic way (the quasi-Pavlovian vs. cognizance bit) that philosophy fuels much of our explorative science. Most of what has been posted in this blog can be reduced to semantic postulations of “consciousness” and “awareness” with a side serving of sophistry about the validity of the science. The true point I wanted to make is what was proven here in your postings concerning the topic ; that this is the nature of our consciousness and the science trails our multifarious philosophical interpretations. Not that the science isn’t valid. This research is exciting and brilliant, not to mention a logical step for those of us who aren’t satisfied with a “ghost in the machine” type hypothesis and aren’t blessed to be content with a spiritual or otherwise metaphysical explanation.
Thank you all for a very exciting blog and thank you, PZ for posting the article. Love this site!#: Posted by on 09/11 at 06:47 AM -
Oh, and HYPERION,
I never mentioned "instinct".#: Posted by on 09/11 at 07:02 AM - Way to go.. I was reading this freaking paper on the plane so I could take what I was calling the "PZ Myers challenge" concerning your statement on that "ain't no justice" post about this BioEssays issue and garner a valuable pharyngula trackback. I think the reason why most of these theories sound kind of hokey is that the people trying to study it had to come up with some way to operationalize consciousness in order to do experiments and it may not line up with the colloquial use of the terms conscious and consciousness. I definitely don't think that birds have what I would want to call Consciousness (capital C), but the 'theory of mind' stuff is interesting. Certainly the ability to do transitive inference or episodic memory shouldn't be equated to the big C.