In today’s New York Times, I profile the neuroscientist Giulio Tononi, who has been obsessed since childhood with building a theory of consciousness–a theory that could let him measure the level of consciousness with a number, just as doctors measure temperature and blood pressure with numbers.
There’s one fascinating aspect of Tononi’s work that I simply didn’t have room for in a newspaper article (even with my editor’s long-suffering generosity with the column inches). During each moment of consciousness, Tononi argues, our brain enters a specific state. That state is an imaginably complex pattern of activity in our neurons that allows us to have a conscious experience of a swim in the ocean or a tedious tax form or sitting in a quiet, dark room.
Tononi has been developing a mathematical way to represent different states of a brain, or any information-processing system. He envisions these states–or qualia–as multidimensional shapes. From one moment to the next, these qualia change shape as we experience different thoughts. The level of our consciousness is the height of these qualia-shapes. We go through out waking hours having different experiences and different thoughts, but our level of consciousness remains the same.
Tononi and his colleague David Balduzzi laid out a geometry of qualia in a paper they published last year. He argues that someday it may be possible to reconstruct that geometry by recording the activity of the brian. Scientists wouldn’t be able to read our innermost thoughts this way, but they could get a rough idea of the overall shape of different kinds of conscious experiences. And this mapping might allow them to finally tackle the famous question, “What is it like to be a bat?” It is certainly hard to imagine what it’s like to perceive the world with echolocation, using sound to perceive space. But while we may not ever be able to get inside a bat’s head, we might be able to map the shape of a bat’s qualia. Perhaps a bat’s qualia during echolocation looks like human qualia when we see things. Or maybe it has a shape more like that of hearing.
The bat’s qualia may, of course, end up looking like something else entirely–but at least then we would know that for a fact, rather than consoling ourself with thought experiments.
September 21st, 2010 at 2:58 am
Gorgeous stuff, Carl. I love this shape angle. Puts me in mind (heh) of the lovely work does on synchronization of brain waves. I suspect there’s overlap and will now head to the Times story to see what elsemyou turned up.
Best, David
September 21st, 2010 at 9:49 am
Its hard for me to see how a brain state is a “qualia”. It may reflect, or underlie qualia, but qualia is the experience of a brain state, not the state. And there’s the rub. How can we experience a brain state, if experience is caused by the brain? I haven’t read Tononi’s paper, but, it seems to me, asserting that
qualia = brain state
short-circuits the problem.
September 21st, 2010 at 11:32 am
[...] What Is It Like To Be A Bat? What Is It Like To Be You? and Sizing Up Consciousness by Its Bits [...]
September 21st, 2010 at 6:05 pm
Sounds like pseudoscientific bunk.
September 22nd, 2010 at 12:46 pm
[...] Blogs / The Loom « What Is It Like To Be A Bat? What Is It Like To Be You? [...]
September 22nd, 2010 at 2:40 pm
#2. Exactly, John. This “new” explanation of consciousness sounds just like all the others: merely a re-framing of the question (the “easy” problem of consciousness) that doesn’t get to the heart of the answer (the “hard” problem).
September 23rd, 2010 at 6:37 pm
” … recording the activity of the brian. ”
What about the activity of the carl?
September 27th, 2010 at 1:36 am
Thanks, Syphax. I was just too lazy to explain my thoughts
You more simply put it than I would’ve.
September 27th, 2010 at 9:54 pm
I agree With johnk – “qualia is the experience of a brain state, not the state”. That is the speciality of qualia. How can such article be allowed to be published, which is supposed to inform us about new discoveries but where the writer himself has mundane knowledge of the subject!
September 28th, 2010 at 3:12 pm
Although it may not be completely clear in Carl’s article, Tononi does claim to have a model for how a brain state becomes a qualia in the cited articles.
http://www.ploscompbiol.org/article/info:doi%2F10.1371%2Fjournal.pcbi.1000462
Although I can’t follow the math, I think the argument is hollow. My reading of the article is that a brain state, defined in mathematical terms rather than neuronal firing rates, specifies a quale. But it seems like hand-waving to me — like the cartoon of a two profs at a blackboard with a long complex mathematical formula where, in the middle, is the step “then a miracle happens”.
There is little argument that there may be an isomorphism between brain states and quale. For example, we might understand exactly which neurons must fire to generate the perception of a grandmother. We can even imagine selectively stimulating those neurons and generating the perception of a grandmother.
but this does not explain qualia. It shows the neural correlates of qualia, but not qualia. And, as far as I can tell, Tononi does not recognize this.
September 28th, 2010 at 8:23 pm
A single number to characterize a brain state? Yeah, good luck with that.
October 1st, 2010 at 9:51 am
Contrary to Tononi’s claim in the NY article, this paper: http://www.ncbi.nlm.nih.gov/pubmed/19910249 seems to show that for people in (partial) seizure the signal complexity actually increases.
Also, I find that the idea of representing consciousness by a single number is too simplistic to the point of being ridiculous.
Consciousness is not something like height or weight that can have its content be meaningfully codified into a single number (not even a set or matrices of numbers, in my opinion).
At most, the number can be said as a measure of the “network integrity” of brain nervous system, and what his experiments have shown is merely a crude correlation between this number and certain values such as signal complexity. Whether this value in fact represents consciousness, or even has any substantial connection with consciousness, is something too early to be concluded upon.
October 10th, 2010 at 1:49 pm
Why author has concluded “MAY” in his 1.6MB paper…