Consciousness and how it got to be that way

Thursday, July 23, 2009

Cool Evolution Find: Fossil Virus

Not in stone of course, but in crocodilians' genomes. ERV covers well. Question for evolution, as she puts it: if this virus was good enough at what it did to work its way into a genome, why does it apparently have no descendants today? Two possibilities come to mind: 1) its descendants are still around, but we haven't discovered it yet (remember Nannarrup hoffmani? A whole new genus of metazoans found 7 years ago in Central Park, New York?). 2) the chance of becoming an ERV do not correlate over time with fitness.

Wednesday, July 22, 2009

Consciousness, Reduction, and Memory

A tool that I think we underutilize in the hard question of consciousness is the idea that if some entities are conscious, and some are not, then there is a boundary between the two categories. My suspicion so far is that any close examination of this boundary inevitably becomes a reductio ad absurdum, and the boundary evaporates, regardless of the examiner's initial intentions; and once the boundary has evaporated, we're left with the unintuitive non-assertion that there is no reason to think everything doesn't have some rudimentary consciousness - or the non-starter that nothing is conscious. The first assertion led Chalmers to his famous and misinterpreted statement about conscious thermostats.

You don't think thermostats are conscious? Fine. What about dogs? That's a slippery slope; as a furry, warm blooded vertebrate primate, you're subject to some pretty powerful biases about what the signposts for self-awareness are. Roger Penrose once (half-jokingly) conceded insects to the world of unconscious Turing machines, and Dan Dennett immediately challenged him: why? In other words, if dogs are conscious, why not octopi, crabs, E. coli, and the Melissa virus? Where's the line, and what is it? A 40 Hz wave? Unsatisfying, to say the least.

The point is this: if you believe that consciousness only occurs in what we on Earth call living things, then you must also believe that at one point it did not exist. Fair enough: so where and when did the first glimmer happen? It's not obviously a meaningless question to ask whether the first consciousness appeared in a trilobite scuttling about in a seabed on the piece of continental plate that is now Turkmenistan, a minute before sunrise on 28 June, 539,640,122 BCE (I think it was a Tuesday). It's tempting to dismiss point-of-origin stories like this, but the alternative is either to accept some provincial point-of-origin since the Big Bang, or accept that consciousness is a spectrum, in which case we're back to the thermostat (or to none of us being conscious). Both alternatives are counterintuitive, but modern science is littered with such choices; not surprising given how far we are out of our depth, i.e. collecting food, finding mates, and running from predators in East Africa.

So far I have not explicitly stated the materialist assumption that consciousness is related only the the matter of the entity in question, and how that matter is arranged - but there is the stickier question of within what limits that matter can vary and remain conscious. By that I mean, my brain is physically different from yours, and from a monolingual Greenlandic woman's. You could rob each of these three entities of their current level of consciousness by making physical changes to them, but all three were different to start with, so how do you know they were all conscious? Another not obviously meaningless question is to ask whether a capacity for consciousness must necessarily permeate an entire species. Why assume the conscious/non-conscious boundary follows species boundaries? Maybe on that fateful June 28 in the early Cambrian, there was just one single conscious trilobite, surrounded by zombie trilobites. And maybe some humans are conscious and some aren't.

This may seem to point the way to a reductive program, to test the boundaries of what can be conscious. We can't go looking for the boundary with a time machine to see where it all began, and of course even if we could there remains the challenge with the hard question that we have to rely on first-person accounts we get through third person reports - we can't build a consciousness meter to wave at trilobites, and they can't tell us that the sunrise was pretty. And even if they did it doesn't prove they experienced joy at seeing it; the whole problem is the inviolable subjective first-personness of it. But since we are assuming that consciousness relies on matter and arrangement (i.e. nervous systems) in a reproducible way, in a pattern that at least some humans can understand, we can still reductively investigate alterations of the material state of the basis of consciousness using human first-person accounts, in ways that don't veer off into other problems of behavior as such investigations often do. This still won't answer the hard question but it will at least show us to what things the hard question can apply.

We can't quite cut out brain tissue and ask people whether they're conscious (the idea is to restore the previous state, when you know they were conscious as near as that can be known by a third-party). But what we can do, and have done is study cognitively abnormal humans who can communicate their experience. These break down into 1) people with some disorder, either through trauma or congenital condition and 2) people who change their brain chemistry either from some activity (meditation, extreme exertion) or consume mind-altering compounds. With #1, people usually remain in the same state. With #2, these occasions occur under very uncontrolled conditions and we have very limited options ethically - "go run a hundred miles then meditate for a month and tell me what it's like" - and scientifically - there are only so much agonists for receptor X and the brain doesn't cooperate in the way they're distributed.

If we have anything to say about it hopefully the numbers of people in category #1 will drop. If as time passes our ability to reversibly under- or over-stimulate parts of the brain increases, as I hope it will, then I hope future neuroscientists will be able to pick from a suite of compounds that block specific tissues in the brain (not just receptors) from interacting with the rest. Of course, this program might not be able to tell the difference between basic requirements of consciousness, and the provincial arrangements of our own brains - or primate, or mammalian, or vertebrate brains. (Note: I am not advocating kidnapping of and experimenting on aliens, though if you have one, call me). It seems to me the two components of consciousness in our normal cognition that would be of immediate interest and are relatively isolable in anatomical terms are memory (sensory, short- and long-term) and goal-orientated behavior, specifically with regard to pain and pleasure.

Regarding reductive investigations of memory: is it possible to remove consciousness in a way that is reportable later? In other words, say you find a molecule that shuts off only the here-and-now experience, but not anything else, including memory. While the subject is under the influence, she's same as she ever was, lucid, talking, responding - a classic philosophical zombie. You give the wash-out. She reports that she now remembers the conversation, remembers what happened while she was "under", but somehow didn't experience them at the time. Can this even be meaningful?

Science fiction thought experiments of memory implants come to mind: in the movie Blade Runner, androids that live only four years are given childhood memories so they don't realize they're androids; did they experience those childhoods? The reverse situation - that is, experience, but no memory, known as anterograde amnesia - is the subject of the movie Memento (category #1, abnormal human), and does occur in the real world, but there are also abundant real-world examples in category #2, as anyone who consumes alcohol can learn. A personal account illustrates this. At a friend's birthday party I overindulged. Among the many escapades that evening which charmed and delighted my fellow party-goers was the following groan I emitted while sitting in the hot tub: "Oh god, I'm going to be sick...what's the point of blacking out if you have to experience it anyway." At which point they wisely shooed me from the tub, and my prophecy was realized.

I tell this story not to concern you more for my liver than my brain, but because the interesting part is that I don't remember it. I did black out - I know this only from (effectively) third-hand accounts. Thanks to my ethanol-clogged NMDA receptors, I have no memory at all of that event (or many others that evening). Did I experience nausea? Where did the experience "go"? What evidence do I have that at that moment I was not a zombie, even to myself? One solution is that I'm silly to worry about where the experience goes - that at least in human brains, experience requires only sensory memory (in us, a second or so), or that it requires sensory and short-term memory (in us, five to ten minutes). But is there a drug even in principle like the one in the experiment above that could have saved me from the experience of nausea but preserved the memory? That's not an entirely dispassionate question, becuase I would make that trade in a second.

The second area of investigation - goal-seeking behavior - raises questions about whether it is meaningful to talk about consciousness in the absence of pain or pleasure. I'm not talking about full-body analgesia; I'm talking about not experiencing psychological discomfort in response to thoughts about seeing their kids at the end of the day or worrying about your mortgage. Granted, that's a little more involved than questions about memory.

I think a continuing focus on specific parts of the brain in a reductive search for absolute boundaries of consciousness - if indeed there are any - is wise for more than just theoretical reasons. Any research program that ignores its sources of financial support is one that won't move along very quickly. The hard problem of consciousness, while I consider it the central question of philosophy and science, is not one that promises any immediate application that can return effort invested in it. I'm obviously sympathetic to philosophy and science for its own sake, or I wouldn't be writing this out of personal passion. But we all want to see progress on this question, and being able to sell the research based on applications to Alzheimers, ADHD, and schizophrenia would go a long way to obtaining support and public awareness. Technology that we don't yet have that will require money to develop - or, technology that we do have that requires money to obtain and use. And in the end, I can't think of a better outcome anyway than that this research could end up helping human beings suffering with cognitive disorders.

Monday, July 20, 2009

Monkeys Can Respond to Grammar-Like Patterns in Sound

Article here. Essentially, tamarin monkeys showed a capacity for recognizing a pattern of phonemes, and then recognizing when a novel pattern appeared (if an affix was used in the wrong place).

Primates can frequently recognize language-like stimuli when exposed to them, but whether they can be trained to generate them is another question. (And we know they don't generate them spontaneously.) It seems to me there are two take-homes here. First, that many primates (including those not even that closely-related to us) have the hardware for linguistic pattern recognition. This raises the question of whether other linguistic substrates delivered over a time sequence could evince similar responses: chains of images for example. It would be interesting to compare human and non-human primates in these experiments (with sound and non-sound grammar).

The second, and to me more interesting, point to investigate is to what degree non-human primates can associate the patterned-sounds they're hearing with semantic content. No, it wasn't a concern at all in this experiment, but it's crucial to the development of language. While Endress et all conducted this experiment with particular reference to grammar acquisition, a model of vocabulary acquisition in human children uses much the same pattern-recognition skill: children learn words by looking for sequence rules, and take notice when they're violated. A chid learning English for the first time has no way to know that "word boundary" is two words, and where the dividing line is, until they figure out that English words don't often start with "db"; in fact words don't even have that sound combination so much (and of course they hear the words separately). The tamarins were doing some form of this.

What the tamarins can't do that childre can - or at least no one's shown that tamarins can do it, and I don't think anyone expects it - is that once they've parsed out the elements and learned the order they usually occur in, they can build a network and assign each element to an object or attribute they see in the real world. I wouldn't be blown away if a tamarin learns to be "surprised" (as in this experiment) by an "o" coming at the beginning of a word, as opposed to at the end. What the tamarins won't ever learn is that the -o ending means that the word in question is an object that is receiving action, as opposed to performing it. Yet somehow every normal Japanese child learns exactly this by age 5, and lots of other such content-sound relations as well.

Animals clearly can associate a few sets of sounds with concrete, specific content. Anyone who has ever had to spell out "W-A-L-K" to a fellow human in front of a dog knows this. But the extent of language perception in non-human animals is an interesting question because it gives us a chance to do some comparative biology with reference to the following questions. How how many of these sets of sounds can the dog (or the tamarin) learn? How generalizable is the ability - i.e., given the internal states of the animal as they reflect the outside world, how broad or distinct are the categories that can be covered by a single signifier - your dog understands tree, but does it understand redwood? Plant? How complex a relationship between signifiers can the animal construct, e.g., can the animal tell a difference between walk, walked, and don't walk? And to what degree are these things related - that is, do human children get a mnemonic benefit from pinning the sounds they learn into a richer network of semantic content? Pinning down these differences to the activity of physical structures in our brains will go a long way to understanding how we acquire and process language.

Bias Bias

So we're biased against seeing our biases: while it's nice to have experimental verification, this should not be surprising, else our biases would be subject to examination and we could get rid of them.

A frequent subtext of bias studies goes is this: "Look how distorted our perspective of the world is. It's good that we study these tendencies so that maybe we can diminish or eliminate them, and people would have a less distorted view of reality." It would be useful to ask what would humans be like without these biases. How would individuals behave differently? What would society look like? Aren't some of these biases fairly obvious beneficial self-deception strategies that evolved as a result of conspecific competition; would cutting them out of some humans (but not all) actually result in individuals handicapped in the survival and reproduction game, and wouldn't similar strategies redevelop over time? Most importantly, without our biases would we be happier? Is it meaningful to talk about waving a magic wand and re-wiring the brain to eliminate these biases, or are they so deep-wired as to require much more profound commensurate changes to retain a functioning central nervous system?

Sunday, July 19, 2009

What Do Serial Killers and Suicidal Rats Have in Common?

Serial murder is such an astonishingly maladaptive behavior that I've often speculated whether we're not seeing a) a gene that, when heterozygous, is adaptive, but when homozygous, can lead to this behavior, or b) a toxoplasma gondii-like infection.

Toxoplasma gondii is the pathogen that makes the rodents it infects behave (basically) suicidally around predators, like cats; the cat eats the rat, the organism survives in the cat's gut, and when the cat defecates, it spreads more Toxoplasma. (I first read about this organism and the incredibly specific behavior an infection engenders in the work of Daniel Dennett, who is a big fan of this organism as a metaphor for other replicators.) Now it turns out that humans infected with Toxoplasma are also more likely to behave dangerously, judging by car accident rates. (Hat tip to Marginal Revolution).

Humans engage in many apparently maladaptive behaviors (serial murder among them) and this story gives us no reason to conclude that serial murder is the result of an infection, but it does show that even in humans, complex behaviors can be affected by an organism in ways similar to the other host species we've studied. Behaviors like serial killing are so inexplicable that hypotheses about their origins should include infection as a possible etiology.

I grant the full-on speculative nature of this post, and even if serial killers are infected with a T. gondii-like pathogen, then it remains to be explained a) whether the infection-induced behavior would have been the same in our hunter-gatherer ancestors (how can you be a serial killer in a band of 25 people?) and b) how exactly the behavior would improve transmission, which is clear in the case of rats and cats.

Thursday, July 2, 2009

Cows, Free Will, and Nuclei

I'm often amazed at the stupidity of cows. I encounter these mooing morons frequently on trail runs that pass through pasture lands. Frequently there will be a cow standing astride a path that I'm running along at constant speed, gazing in dumb fascination at me as I approach: 200 meters, 100 meters, 50 meters. Even though I've now been approaching the cow at constant speed in a straight line in the open for the last two minutes, it's often not until I'm within 10 meters that the cow will suddenly realize I'll eventually reach its position, and that's when it suddenly turns in a panic and runs away.

Of course, in no technical sense was my continuing along the same path clearly "predestined", even if you don't believe in free will - any number of plausible forces could intervene to stop me - I could decide to stop because I just ran up a steep hill, or a meteor could hit me, or I could turn left and run into the grass for no reason - but the cows' failure to move until I'm almost on top of them certainly does not result from any nitpicking of causality. Possibly the cows are conditioned by the ranch hands they see more often, and which do stop before they get too close. Or, funnier and just as likely, they're just too damn dumb to recognize the pattern (my straight-line path) and extrapolate it to realize that I'm going to get to their position - not until I'm barely ten meters away.

For the sake of argument let's explicitly assume that there is something in the universe that is not predestined to happen in a certain way at a certain time - and if you'll accept any example, you'll accept that the decay of a single radioactive nucleus fits the bill as non-predetermined. Sure, trillions of them decaying together will fit a pretty nice predictable curve, but it's hopeless to try to predict the decay of individual nuclei; nuclei of the same isotope are, by any measure we know, absolutely indistinguishable, and they decay randomly (that is, without any pattern that we can recognize). The question, then, is: is an individual decay really non-predetermined? Or are we cows that just can't recognize the pattern that they're following? Most importantly, is it possible in principle for a non-pattern-recognizer to ever tell the difference between these two alternatives?

Because the universe contains a finite number of elements, infinite computing power isn't possible; therefore there will never be an infinitely powerful pattern recognizer. Consequently, the question asked in the previous paragraph becomes very important. If it is not possible for a non-pattern-recognizer to tell the difference between inability to recognize a pattern in a system, and actual non-predetermination in that system, then we can never tell if we have free will, or are merely stupid.