Saturday, April 22, 2006

Zombie hunting

I was totally blown away by this post on immediate blogroll addition Neurotopia, drawing connections between the now-widely-reported phenomenon of Ambien zombies and the less well-known theoretical zombies discussed by philosophers. "Zombies" are beings that look like normal humans but have no consciousness; whether or not you believe that they're possible (not that they exist, mind you, but that they're possible -- people who believe in this kind of zombies are probably wrong, but they're not crazy) says a lot about your views on the "hard problem of consciousness." (If I recall correctly, the zombie's opposite number -- consciousness but nonhuman appearance -- is the "swamp man." Philosophers, huh?)

From Neurotopia:
Can there be a human who goes to work, has a wife, coaches little league, but has no conscious experience? Perhaps here we have a way to investigate the possibility. Does Ambien shut off excitatory (or activate inhibitory) neural circuits that directly disengage a "consciousness" module or diffuse neural net? Can a somnambulant Ambien user "learn" new things, be they cognitive or motor skills, and can these new skills be performed/recalled at a high skill level when fully conscious, despite a lack of mnemonic recall for the event itself? Or can he/she be made to become fully conscious while in this state e.g. through the use of pain or loud noise, or direct stimulation of other neural circuits? To what extent does Ambien actually interfere with conscious perception? Do Ambien users display their normal personality when they are having a somnambulatory event? Can we stick them in an MRI or EEG and observe how activation patterns differ when the person is conscious and when they are on Ambien?
This is a brilliant connection. People who take Ambien are being found to walk, eat, even drive without apparent awareness or memory, and this certainly looks a lot like the philosophical zombie. Zombified Ambien users are clearly reacting to the outside world -- for instance they avoid obstacles, at least to a certain extent, when they drive -- but they don't seem to be aware of it. In other words, when they see something they don't know that they see it, and they don't form memories of seeing it (or of knowing that they saw it). Looking at the differences between someone's neural reaction to a stimulus on Ambien and their unimpaired reaction could give a lot of insight into what it means to be conscious of something (and by extension, what it means to be conscious, period).

Neurotopia speculates that "David Chalmers must be wetting his pants," but I don't know. As I understand it, Chalmers wants the possibility of zombies to mean that consciousness can't be tracked to an observable physical process. Presumably, if it's possible for a zombie to exist, that's because it's possible for there to be a creature that is physically (including neurally) identical to a human but that lacks conscious experience anyway. This essentially makes any study of Ambien users inadmissible for Chalmers' purposes, though of course he'd be able to explain the findings away -- see my earlier comments on refuting pseudoscience with facts. If there turns out to be a measurable distinction between a "zombie" brain and a fully conscious one, that shows that there's some neural basis for consciousness, but the beauty of Chalmers' take on the "hard problem" is that this isn't enough to prove consciousness to be purely physically based. Nothing is.

So these guys are good news for neuroscience, and we should definitely chain them up in the shed behind the MEG lab. But there's no refuting a philosopher so spooky-minded that he wants to believe in zombies. Seriously, zombies. I ask you.


Laura said...

Did I tell you my zombie story from my grad school visit? If not, Anna summarizes it well.

[Side note: the fact that comments are taking so long to show up is making me wonder if one or two of mine got swallowed by the ether.]

4/22/2006 8:29 PM  
jess said...

Oh wow. Having a philosophical interest in zombie consciousness is one thing; having a theoretical interest in rotting flesh is, well, English students for you. It's sort of inevitable, isn't it? We're so into embodiment, and we have so little concept of the truth/fiction boundaries. I mean I wouldn't put it this glibly but I have a professional interest in cyborgs!

I'm going to go with the interpretation that your comments, and also everyone else's, are getting disappeared. I actually have a huge number of readers who engage in vociferous debate. You just can't see it.

4/23/2006 12:57 PM  
Evil Monkey said...

Hey, thanks for the glowing review. This is weird-- I work at UMCP, drop me a line via my blog!

4/23/2006 11:29 PM  
Alejandro said...

I agree with the point of the post. Chalmers believes that zombies are logically possible, and that this shows something important: that consciousness is not physical. The way he frames the problem, no empirical evidence at all can change his mind. Any being which we can realize from the outside that doesn't has consciousness is not a zombies in Chalmers' sense, because the whole point of a zombie is to be identical to a normal human being in all aspects (behavioural, neurological, computational...) which can be accessed from the third-person point of view... that is, by science. Of course, the fact that zombie are "by construction" impossible to be tested scientifically makes any scientifically-minded philosopher (e.g. Dennett) dismiss them as irrelevant.

I have a recent post on the subject which might be of interest.

4/24/2006 8:38 AM  
Lynne said...

Speaking of cyborgs:

4/24/2006 8:49 AM  

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